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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

N,N-diethyl-N'-naphthoylacylchalcogourea to metal (II)complexes as precursors for ternary metal chalcogenide thin films via AACVD

Ezenwa, Emmanuel January 2016 (has links)
In this thesis complexes of acylchalcogoureas with cadmium (II), lead (II) and nickel (II) have been synthesised and investigated as single source precursors for the formation of metal chalcogenide thin films viaaerosol assisted chemical vapour deposition (AACVD). Routes to binary thin films have been explored using homoleptic complexes of the general structure bis(N,N-diethyl-N'-naphthoylchalcogoureato)metal(II). Analysis of the thin films produced showed the successful deposition of the binary materials from the synthesised complexes when characterised by powder XRD, ICP-OES, SEM and EDX. Routes to ternary thin films with the general structure MExE'1-x, where M represents a metal (Cd, Ni and Pb); and E chalcogen (S or Se) have been investigated using heteroleptic metal complexes of cadmium, nickel or lead including different chalcogen containing N,N-diethyl-N'-naphthoylchalcogoureato ligands and diethyldithiocarbamate. The precursors were fully characterised and novel compounds had their crystal structures determined. The heteroleptic complexes were thermolysed by AACVD forming the MExE'1-x thin films. In the cases of lead, nickel and cadmium the thin films produced showed that the composition of the film tended heavily towards the metal selenide. Ternary films of type MS1-xSex was prepared by mixing their binary precursors of type bis(N,N-diethyl-N'-naphthoylselenoureato)metal(II) and bis(N,N-diethyl-N'-naphthoylthioureato)metal(II) [metal = Cd, Ni and Pb]. In the case of lead and cadmium chalcogenide films variation of the ratio of sulphur and selenium containing precursors allowed for the full transition in composition between metal sulphide and metal selenide. In the case of CdS1-xSexthe band gap of the films was determined from UV-visible spectroscopy to vary from 2.4 eV (CdS) to 1.7 eV(CdSe). In the case of NiS1-xSex the movement from sulphide to selenide was less simple with multiple phases of nickel chalcogenides produced.
232

Sedimentação orgânica recente da Lagoa do Caçó-Maranhão (MA)

Oliveira, Fernanda Barreto Lagoeiro de 11 September 2017 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-09-11T16:53:03Z No. of bitstreams: 1 DISSERTAÇAO FERNANDA LAGOEIRO.pdf: 2000959 bytes, checksum: 76bc23adde3524dc614b7249095d11c5 (MD5) / Made available in DSpace on 2017-09-11T16:53:03Z (GMT). No. of bitstreams: 1 DISSERTAÇAO FERNANDA LAGOEIRO.pdf: 2000959 bytes, checksum: 76bc23adde3524dc614b7249095d11c5 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Fundação de Amparo a Pesquisa do Estado de São Paulo / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / Neste estudo foi caracterizada a sedimentação recente de matéria orgânica da Lagoa do Caçó (MA), localizada em uma região fortemente influenciada pela Zona de Convergência Intertropical (ZCIT), uma das responsáveis pela dinâmica climática do Brasil. Foram coletados cinco testemunhos ao longo de um perfil batimétrico com respectivamente 1.5; 3; 4; 6 e 9 metros de coluna d’água. Este perfil apresenta uma clara zonação biológica com presença de macrófitas na margem (0 a 0.5m), passando por uma região com macrófitas associadas a algas epifíticas (0.5 a 2m), a uma região com vegetação submersa (2 a 5.5m), até completa ausência de vegetação (acima de 5.5 m). A caracterização da sedimentação recente da lagoa foi feita através da análise de marcadores orgânicos, que possuem a propriedade de identificar a origem e o estado de preservação da matéria orgânica depositada. Foram utilizados os seguintes marcadores: conteúdo de carbono, nitrogênio e razão C:N; composição isotópica do carbono e do nitrogênio; petrografia da matéria orgânica (identificação e classificação de fragmentos microscópicos) e quantificação de derivados de clorofila. Os resultados demonstraram uma alta produtividade na margem da lagoa, que decresce com a profundidade, gerando, portanto, dados característicos para cada ambiente, permitindo, então, que os registros obtidos sejam utilizados como padrões para avaliação das paleoprofundidades da Lagoa do Caçó (MA). A razão entre a matéria orgânica não vascular e a matéria orgânica vascular mostrou ser o melhor marcador de profundidade. A análise dos testemunhos curtos possibilitou dividir o período estudado em cinco fases segundo os dados gerados pelos marcadores orgânicos. Os resultados sugerem a elevação do nível do lago durante as fases I a IV e em seguida uma diminuição do nível do lago até a fase V representada pelos dias atuais. Variações no nível do lago foram relacionadas com as precipitações anuais e os casos de secas (causadas pelos eventos El Niño) e chuvas abundantes (causadas pela La Niña), que possibilitaram sugerir a influência desses mecanismos no nível do lago / Elemental, isotopic compositions and palynofacies observations of organic matter in surficial sediments from a transect across Lagoa do Caçó (MA – Brazil) have been analyzed to investigate the processes that participate in the production and deposition of sedimentary organic matter. Five cores were collected along a bathymetric profile with 1,5; 3; 4; 6 and 9 meters respectively. This transverse profile starts in a margin (0 to 0,5m), provides a clear biological zonation with the occurrence of emergent macrophytes, declines through a region with macrophytes in association with epiphytic algae (0,5 to 2 m), exceeds a region with submerged vegetation (2 to 5,5 m) up to a complete absence of vegetation (over 5,5 m). The variation of these parameters shows in the marginal zone a gradient between 0 to 4 meters decreasing for TOC, C/N, chlorophyll derivates, and d13Co/oo and increasing for d15N o/oo values. They start at 0,5 m with values around 22, 14, -25 o/oo and between 0 and 1 o/oo and reach 10, 8, -29 o/oo and 5 o/oo respectively at 4 meters water deep characterizing therefore this emergent macrophytes vegetation. These values remain stable between 4 and 10 meters to the phytoplanktonic production with weaker marginal influence. The palynofacies results show a same pattern marked by an increase of the terrestrial organic matter from the margin to the center. Concluding, it is strictly relevant to consider that the bulk and isotopic compositions mark the biological zonation of Lagoa do Caçó (MA- Brazil), which show that the high productivity occurs in the marginal area linked to macrophyte vegetation and tend to decrease until disappear at 4 meters. The variations of these elemental, isotopic and petrographyc parameters obtained from the five cores collected in those different zones of Caçó Lake have provided 5 paleohydrological phases marked by an increase of the lake level until the last unit when it starts to decrease. These lake level changes are probably linked to the regional hydrological balance whic h is associated to the annual rainfall distributions influenced, at the same time, by the Pacific and Atlantic variability.
233

Certificação de beta-N-metil-amino-alanina: um modelo para produção de materiais de referência de substâncias orgânicas obtidas in-house / Certification of beta-N-methyl-amino-alanine: a model for in-house preparation of reference materials of organic substances

Vinicius Marcondes Rezende 04 May 2011 (has links)
Materiais de Referência (MR) de substâncias químicas têm ampla aplicação, sobretudo na área analítica, servindo de referência para validação de métodos, calibração de instrumentos e controle de qualidade, estabelecendo a comparabilidade de resultados analíticos em escala global e permitindo a transferência da exatidão entre métodos, laboratórios e padrões. Norteado por essas necessidades, o trabalho apresenta uma proposta para certificação de MR baseada nas orientações preconizadas por diretrizes e normas internacionais, principalmente as que seguem o ISO Guia 34, para estabelecer as propriedades certificadas através de técnicas analíticas de Espectrometria de Massas de Alta Resolução, Ressonância Magnética Nuclear, de ¹H e de ¹³C, e de Análise Elementar CHN. A certificação contemplou as caracterizações qualitativa e quantitativa, ensaio de estabilidade e o cálculo da estimativa da incerteza da medição. Como resultado, foi produzido e certificado um lote piloto de MR de β-N-metilamino-alanina (BMAA), uma toxina obtida in-house através de síntese química e purificação, cujos valores de propriedades certificadas foram rastreáveis ao SI e acompanhadas da estimativa da incerteza da medição. / Reference Materials (RM) of chemicals have wide application, particularly in the analyses, providing a reference for validation of methods, instrument calibration and quality control, establishing the comparability of analytical results on a global scale and enabling the transfer of accuracy between methods, laboratories and standards. Guided by these requirements, the paper presents a proposal for certification of MR based on the guidelines recommended by international guidelines and standards, especially those which follow the ISO Guide 34, to establish the certified properties through analytical techniques of mass spectrometry High resolution Nuclear Magnetic Resonance, ¹H and ¹³C, and CHN elemental analysis. The certification included qualitative and quantitative characterization, stability test and the calculation of the estimate of measurement uncertainty. As a result, was produced and certified a pilot batch of RM β-N-methylamino-alanine (BMAA), a toxin obtained in-house via chemical synthesis and purification, whose property values are certified and traceable to the SI accompanied by an estimative of the uncertainty of measurement.
234

O Grupo Carrancas e a frente da Nappe Andrelândia na borda sul do Cráton do São Francisco: Proveniência sedimentar e implicações tectônicas / The Carrancas Group and the Andrelandia Nappe front in the southern portion of the São Francisco Craton: sedimentary provenance and tectonic implications

Alice Westin Teixeira 21 June 2011 (has links)
O Sistema de Nappes Carrancas compõe um sistema de nappes que circunda ao sul o Cráton do São Francisco e é formado pela Unidade Biotita Xisto e pelas formações Campestre e São Tomé das Letras do Grupo Carrancas. A Unidade Biotita Xisto contém veios de quartzo e xistosidade anastomosada e é formada por quartzo, biotita, muscovita, clorita e, localmente plagioclásio, carbonato e granada. A Formação Campestre é formada por quartzitos intercalados a filitos/xistos que variam de cloritóide filitos grafitosos, com muscovita, quartzo e turmalina e, localmente, granada a xistos com granada, estaurolita e cianita. A investigação da Unidade Biotita Xisto como autóctone em relação ao Cráton do São Francisco, seu potencial agrupamento com o Grupo Carrancas em uma megassequência deposicional, bem como sua comparação com a unidadealóctone Xisto Santo Antônio (Nappe Andrelândia) constituem parte dos objetivos deste estudo. Para tal, foram feitas análises químicas e isotópicas (Sr e Nd) em rocha total e geocronologia U-Pb em cristais de zircão detríticos, tanto na Unidade Biotita Xisto como na Formação Campestre, com intuito de elucidar a relação entre as mesmas e compará-las com dados da literatura disponíveis para o Xisto Santo Antônio. A Unidade Biotita Xisto apresenta características químicas compatíveis com sedimentos que sofreram intemperismo químico de intensidade e período de tempo moderados, depositados em ambientes de colisão continental, com área-fontecomposta essencialmente por rochas félsicas. Assinaturas de elementos traço e isotópicas de Sr ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' entre 0,713 e 0,715) e Nd (\'\'épsilon\' IND.Nd\' entre -6 e -5) indicam contribuição de arco magmático e crosta continental e diferem, portanto, daquelas esperadas em ambientes de margempassiva. A mesma contribuição é observada para o Xisto Santo Antônio, cuja área fonte registra importante assinatura de material juvenil. As idades U-Pb LA-MC-ICP MS obtidas em cristais de zircão mostram contribuição principal de rochas do final do Criogeniano e contribuição secundária do Riaciano. A classe modal ao redor de 665 Ma é comparável com a idade cristais de zircão detrítico do Xisto Santo Antônio, o que aponta parauma mesma área-fonte principal para ambas unidades. A deposição dos sedimentos precursores da Unidade Biotita Xisto ocorreu entre 630-611 Ma, sendo as fontes principais os granulitos cálcio-alcalinos e rochas vulcânicas co-genéticas, além de granitos sin-colisionais da Nappe Socorro-Guaxupé. A pouca representatividade de idades paleoproterozóicas e a ausência de assinaturas químicas de margem passiva, inviabilizam as rochas do Cráton doSão Francisco como parte da área-fonte. Desta forma, a Unidade Biotita Xisto não é autóctone em relação ao Cráton do São Francisco, sendo, potencialmente, a unidade que compõe a frente da Nappe Andrelândia. Por outro lado, a Formação Campestre possui assinatura geoquímica de sedimentos que sofreram uma intensa reciclagem e alteração da composição do sedimento original. As assinaturas químicas de elementos traço e isotópicas Sr e Nd indicam contribuição de crosta continental superior, com componente de crosta antiga e sem afinidade com sedimentos depositados em margem passiva (\'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' entre 0,74 e 0,76; \'\'épsilon IND.Nd\' entre -18 e -15). Os zircões detríticos analisados forneceram idades U-Pb LA-MC-ICP-MS variadas, do Toniano ao Mesoarqueano, correlacionáveis com rochas vulcânicas e plutônicas do Cráton do São Francisco, com as faixas marginais do Cráton de Angola e/ou faixas orogênicas do Cráton Amazônico e com rochas dos arcos Mara Rosa e Goiás.A abrangência das idades U-Pb da Formação Campestre e das formações Chapada dos Pilões e Paracatu, permite a correlação, no Orógeno Brasília, entre os Grupos Carrancas e Canastra. A paleogeografia mais provável é a de um ambiente de rifte, antecessor à deriva e aoestabelecimento de uma margem continental passiva. / The Carrancas Nappe System composes a system of nappes that surround the southern margin of the São Francisco Craton and is formed by the Biotite Schist Unit and by the Campestre and São Tomé das Letras formations of the CarrancasGroup. The Biotite Schist Unit encompass quartz veins and anastomosed schistosity and is formed by quartz, biotite, muscovite, chlorite and, locally plagioclase, carbonate and garnet. The Campestre Formation is composed by interleaved quartzites and phyllite/schist that varies from graphite-chloritoid phyllites, with muscovite, quartz, tourmaline and garnet, and locally garnet schists and schists with garnet, staurolite and kyanite. The investigation of the Biotite Schist Unit as authochtonous in relation to the São Francisco Craton, it´s potencial grouping with the Carrancas Group in a deposicional megassequence, as well as it´s comparison with the allochthonous Santo Antônio Schist (Andrelândia Nappe) is part of the goals of this study. For this purpose, chemical and isotopic (Sr and Nd) whole rock analysis were obtained, along with U-Pb detrital zircon data, in the Biotite Schist Unit and also in the Campestre Formation, in order to elucidate the relationship between these units and compare them with literature data available for theSanto Antônio Schist. The Biotite Schist Unit show chemical characteristics compatible with sediments that underwent chemical weathering of moderate intensityand time, deposited in continental collision setting, with source region composed essentially by felsic rocks. Trace elements and Sr isotopic signatures ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' between 0,713 and 0,715) and Nd (\'\'épsilon IND.Nd\' between -6 and -5) points to contribution from magmatic arc and continental crust, and are different from the expected for passive margin settings. The same contribution is observed in the Santo Antônio Schist, which source area registers an important juvenile material signature. The U-Pb LA-MC-ICP MS zircon data show major contribution from rocks of the later Cryogenian and minor contribution from the Ryacian. The modal class around 655 Ma is comparable with the U-Pb detrital zircon data from the Santo Antônio Schist, pointing to the same source area for both units. The deposition of the precursors sediment of the Biotite Schist Unit occurred between 630 - 611 Ma, and the main sources were the calk-alcaline granulites and co-genetic volcanic rocks, besides the Socorro-Guaxupé Nappe sin-collisional granites. The low representation of Paleoproterozoic ages and the absence of passive margin chemical signatures preclude the rocks of the São Francisco Craton as part of the source area. Thus, Biotite Schist Unit is not an autochthonous unit in relation to the São Francisco Craton, and is, potentially, the unit that composes the Andrelândia Nappe front. On the other hand, the Campestre Formation has geochemical signatures of sediments that underwent intense recycling and alteration of the original sediment. The trace element and Sr and Nd isotopic signatures indicates upper continental crust contribution, with older crust component and no affinity with passive margin sediments ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' between 0,74 and 0,76; \'épsilon\' IND.Nd\' between -18 and -15). The U-Pb LA-MC-ICP MS detrital zircon data provide varied ages, from the Tonian to the Mesoarchean, correlated withvolcanic and plutonic rocks of the São Francisco Craton, with the marginal belts of the Angola Craton, and/or orogenic belts of the Amazonian Craton and with the Mara Rosa and Goiás magmatic arcs. The range of the U-Pb ages of the Campestre Formation and the Chapada dosPilões and Paracatu formations, allows the correlation, in the Brasília Orogen, of the Campestre and Canastra groups. The most likely paleogeography is that of a rift setting, before the continental drift and the establishment of a passive continental margin.
235

Etude des transferts élémentaires et mécanismes biogéochimiques dans le continuum sol-plante-vin par l'utilisation de traceurs isotopiques et biochimiques / Study of elemental transfers and biogeochemical mechanisms in the soil-plant-wine continuum using isotopic and biochemical tracers

Blotevogel, Simon 29 November 2017 (has links)
Dans l'ouest de l'Europe, une grande importance est accordée à la composante sol dans l'élaboration des vins. La nutrition minérale est la principale voie par laquelle le sol peut avoir une influence sur la vigne et par conséquent sur le vin qui en est issu. Dès lors, ce travail de thèse appréhende la question plus large des transferts élémentaires entre le sol et la plante à travers de l'utilisation d'outils géochimiques en milieu viticole. Une combinaison de techniques impliquant des indicateurs classiques tels que les rapports élémentaires ou des bilans de masses ainsi que des traceurs plus innovants comme les rapports isotopiques du Cu et la résonance paramagnétique électronique (RPE) est utilisée. Dans un premier temps, l'influence du sol sur la composition élémentaire du vin a été étudiée dans plus que 200 vins provenant d'Allemagne, d'Espagne, de France, et d'Italie. A cette échelle, le type de sol (classé comme calcaire ou non-calcaire) et les conditions météorologiques apparaissent comme des critères discriminants. Par la suite, deux parcelles viticoles de Soave (Italie) aux sols contrastés ont été étudiées afin de d´déterminer l'influence du type du sol sur les vignes. Même si les sols présentent des propriétés pédologiques différentes, une pédogénèse complexe a induit des propriétés géochimiques similaires. Dans les vignes, les traceurs élémentaires et biochimiques montrent que la variabilité inter-annuelle et inter-individuelle est plus grande que la différence liée au sol lui-même. Néanmoins, il est possible de déterminer quel est le sol considéré par l'étude des rapports isotopiques du Sr. Parmi tous les nutriments et éléments toxiques généralement étudiés pour leur mobilité dans les sols, le cuivre a été suivi dans la dernière partie de cette thèse, essentiellement du fait de son épandage toujours massif comme fongicide en viticulture. En effet, les pesticides cupriques comme la bouillie bordelaise sont utilisés depuis environ 150 ans en viticulture. Le Cu s'accumule d`es lors dans les sols et les conséquences ´ecotoxicologiques en font un sujet de plus en plus sensible. Parmi les pesticides analysés dans notre étude, les rapports isotopiques du Cu varient autant entre les différents fongicides que dans les sols étudiés dans la littérature, rendant ainsi impossible l'utilisation de ces isotopes comme traceurs d'origine du Cu dans les sols. [...] / In western Europe, soil is of primordial importance for wine making. Soil qualities are often discussed and an influence on wine flavor is frequently inferred. However, evidence for a role of soil chemistry on wine composition and taste is scarce, but mineral nutrition of grapevine plants is one possible way of influence. This thesis approaches the complex question of elemental cycling between soil and plant through the use of geochemical tracers in vineyard environments. A combination of traditional tracers such as elemental ratios and mass balances as well as innovative tools such as Cu isotope analysis and electron paramagnetic resonance (EPR) are used on different observation scales. The influence of soil type on wine elemental composition was investigated using over 200 wine samples from France, Germany, Italy and Spain. Results of chemical analysis were then statistically linked to environmental conditions. At this scale, elemental contents of wine vary depending on soil type (calcareous or not), meteorological conditions, and wine making practice. To determine which soil properties can influence the chemical composition of grapevine plants, two vineyard plots on contrasted soils in Soave (Italy) were examined. Soil forming mechanisms were studied along two catenas and subsequently linked to elemental composition of grapevine plants and biochemical markers of plant health. Even though soil morphology was different, complex soil forming processes led to similar geochemical properties of soils. Differences in plant chemical compositions between soil types are small compared to inter-individual and inter-annual variability. However the use of Sr isotopic ratios allows the determination of the pedological origin of plants. In a next step, the fate of Cu pesticides in vineyard soils was studied. Cu-based pesticides have been used for almost 150 years in European vineyards and Cu accumulates in soils, so that the fate of Cu and its ecotoxicological implications are of growing importance. Therefore, Cu mobility in vineyard soils and transfer to grapevine plants were investigated using stable Cu-isotope ratios and EPR-measurements. Isotope ratios of Cu-based fungicides vary largely between products, covering Cu isotope ratios in soils reported in literature and thus making source tracing impossible. However, Cu isotope ratios are useful for tracing biogeochemical mechanisms of Cu transport in soils. The vertical transport of Cu in different soil types was investigated in the Soave vineyard using a combination of mass balance calculations, kinetic extractions and δ65Cu-isotope ratios. Results suggest that Cu can be transported to depth even in carbonated environments. Besides it is shown that heavy organic-bound Cu is lost from carbonated soil columns likely caused by dissolution of Cu carbonates by organic matter. [...]
236

Oceanic Interfaces: Investigations of Biogeochemical Changes Across Nutriclines and Frontal Boundaries

Adornato, Lori R 15 March 2007 (has links)
Biogeochemical changes across oceanic interfaces, and method development to study such changes, are described in this work. The interfaces studied include the Subtropical Front in the Pacific Ocean and the boundary at the base of the euphotic zone. Both interfaces are characterized by accumulations of phytoplankton, although the forcing functions that result in increased biomass are distinctly different. The Subtropical Front, located at approximately 30°N in the Pacific Ocean, was detected during a cruise in the summer of 2002 by its diagnostic 34.8 salinity outcrop, in spite of the absence of its associated temperature signature. The front displayed elevated concentrations of large diatoms; Rhizosolenia and Hemiaulus, with concentrations penetrating deeper in the water column south of the front. Rhizosolenia species were dominant on the warmer, high salinity side of the front, while Hemiaulus prevailed on the cooler, low salinity side. While high cell counts were enumerated by net tows, the elevated biomass was not visible in satellite color imagery. Size fractionated chlorophyll data revealed > 10 um cells were found below 200 m, indicating export of large cells out of the euphotic zone. This confirms observations by other investigators that fronts represent important regions of episodic export, although such export may go undetected if the biomass is not visible in ocean color images. Another region of interest was the narrow layer at the base of the euphotic zone. During stratified conditions, the layer was characterized by a fluorescence maximum, a primary nitrite maximum, and a nutricline. While fluorescence maxima have proven easy to detect using commercial fluorometers, nutrient distributions have proven more difficult. The Spectrophotometric Elemental Analysis System (SEAS) permitted detection of low concentrations of nitrite, nitrate, and phosphate with nanomolar sensitivity and 1 Hz or better sampling frequency. Using multiple wavelength spectroscopy, the range of nitrate concentrations from 2 nM to 20 uM have been detected. Profiles of nitrite obtained across the North Pacific Subtropical Gyre revealed the close correlation between nitrite and chlorophyll fluorescence maxima, suggesting that the nitrite maximum is formed by phytoplankton when insufficient light is available to permit reduction of nitrite to ammonia.
237

Extant benthic Foraminifera from two bays along the SW coast of South Africa, with a comment about their use as indicators of pollution

Toefy, Rashieda January 2010 (has links)
<p>The results of the multivariate analyses suggest that most of the variation in the composition of the samples was of an intra-sample nature, illustrating large scale patchiness in foraminiferal distribution. There were, however, definite differences between communities around Robben Island and in St Helena Bay, and least variation was found between the control and pipeline sites, and between the stations of each site. When the trace metal concentrations and the percentage nitrogen increased, the richness, diversity and abundance of foraminifera tended to decrease. Sediment grain size positively affected abundance but negatively affected diversity and richness. In both areas mean grain size did not, however, appear to play a very large role in influencing diversity. Cadmium, copper, chromium, the percentage nitrogen and the mean grain size were identified as the most important variables influencing the community structure by the BIOENV BEST routine in PRIMER. The trace metals and percentage nitrogen only had negative effects on the diversity and abundance as well as on the abundance of the dominant genera, whereas the mean grain size had variable effects.</p>
238

Les intervencions de la mestra en el procés de planificació oral de text escrit

Ríos García, Isabel 11 June 1999 (has links)
Este trabajo se llevó a cabo en un contexto escolar en el cual una maestra y su grupo clase realizaban actividades cotidianas para aprender a escribir, bajo una perspectiva de utilización funcional de la escritura en la que se enseñan y aprenden de forma integrada el código y los aspectos discursivos y textuales que exige el dominio de la lengua escrita.La actividad concreta objeto de estudio fue la tarea de planificación del texto, de forma colectiva y a través de la interacción oral, en una clase de 5 años, de un colegio público de la ciudad de Castellón.Los textos escritos correspondían a páginas del LIBRO DEL FIN DE SEMANA o a NOTÍCIAS para el PERIÓDICO DE LA CLASE. Son textos breves como corresponde a las dificultades de textualización ­desconocimiento del código en muchos casos, conocimiento escaso en otros- de un grupo de educación infantil, pero poseen algunas de las características de realización de textos de escritores "expertos", es decir que planifican lo que van a escribir. Son nueve sesiones de escritura en las que se ha estudiado la interacción para llevar a cabo la tarea de planificación del texto que debe ser escrito a continuación.
239

Dirvinio ir karčiojo kiečių biologinės charakteristikos nevienodos amoniakinės taršos vietose / Various biological parameters of Artemisia absinthum L. and Artemisia campestris L. growing in the areas effected by different level pollution by ammonia

Skėrytė, Neringa 15 June 2009 (has links)
Magistro darbe tiriama dirvinio ir karčiojo kiečių biologinės cherakteristikos nevienodos amoniakinės taršos vietose. Darbo tema: Dirvinio ir karčiojo (pelyno) kiečių biologinės charakteristikos nevienodos amoniakinės taršos vietose Darbo objektas - dirvinis kietis ir pelynas - paplitę Lietuvoje augalai, pasižymintys gausiomis vaistingomis medžiagomis - eteriniais aliejais ir flavonoidais. Darbo tikslas - nustatyti skirtingų (AB "Achema" atžvilgiu) vietų karčiojo kiečio, pelyno (Artemisia absinthum L.) ir dirvinio kiečio (Artemisia campestris L.) fiziologines-biochemines savybes. Darbo metodai - Kjeldalio metodas azoto nustatymui, atominės absorbcijos spektroskopija sunkiųjų metalų nustatymui. Salsburo ir sojos agaras mikroorganizmų auginimui. Darbo rezultatai - ištirtos tokios dviejų rūšių kiečių fiziologinės-biocheminės savybės: dirvožemio azoto ir sunkiųjų metalų koncentracija, kiečių įvairių organų masė, kiečių įvairių organų azoto koncentracija, kiečių antžeminių organų flavonoidų koncentracija, kiečių epifitinių mikroorganizmų skaičius, įvertinta kaip oro amoniakinė tarša ir dirvožemio tarša sunkiaisiais metalais reikšmingai įtakoja ištirtus kiečių fiziologinius rodiklius. Atlikti tyrimai parodė, kad dirvožemio ir abiejų rūšių augalų azoto koncentracija išsidėsto tokia tvarka: dirvožemio < stiebų < lapų < žiedų < skrotelių. Tirtos vietos pagal dirvožemio ar organų azoto koncentraciją nesiskyrė. Didžiausios dirvožemio sunkiųjų metalų koncentracijos nustatytos abiejų... [toliau žr. visą tekstą] / Topic of the master degree diploma: Various biological parameters of Artemisia absinthum L. and Artemisia campestris L. growing in the areas effected by different level pollution by ammonia. Artemisia absinthum L. and Artemisia campestris L. are common wild growing species in Lithuania. Despite these species are rich in flavonoids and essential oils till now in our country biology and biochemistry of these species have not received bigger attention. Present work aimed at evaluation of Artemisia absinthum L. and Artemisia campestris L. physiological-biochemical parameters depending on sampling site distance from the nitrogen fertilizer factory. Methods. Following physiological-biochemical parameters of these species were analysed: soil nitrogen and heavy metal concentrations, dry mass and nitrogen concentration of various organs of selected plant species, abundance of epiphytic microflora. Results. During vegetation period sampling was performed three times: in July, 2; July, 24, and September, 24. Obtained parameters were evaluated in respect of aerial ammonia pollution and heavy metal pollution of the soil. Present study showed that nitrogen concentration of the soil and various organs of both Artemisia species fell into following ascending order: soil < stems < leaves < inflorescences and fruits < rosettes. Between selected sites no differences were observed according to the soil and plant nitrogen concentration. The highest concentrations of heavy metals were observed... [to full text]
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Análisis de los factores determinantes de la baja calidad de la enseñanza de la lengua española en octavo grado,distrito educativo 15-05, en la Republica Dominicana.

Santos Familia, Tavito de los 24 May 2013 (has links)
El presente trabajo consiste en un análisis de distintas teorías y estudios lingüísticos que han contribuido a la fundamentación y la didáctica del idioma español, así como el impacto en su aprendizaje y desempeño. En el orden metodológico y bajo un enfoque multimodal, la investigación contó, además de la revisión documental, con la aplicación de diversas técnicas e instrumentos de campo: entrevistas, encuestas, y observaciones, que permitieron identificar algunos factores determinantes en el rendimiento académico y la calidad de la educación pública dominicana. / The present project consist of an analysis of the different theories and linguistic studies, that have contributed to the support and teaching of the Sapnish Language, such as, the impact of its learning and management. In the methodological order and under a multi-model focus, the research included, also a literature review, with the application of diverse technics and field instruments experience like: interview, survey and observation that allows the identification of some determinant factors in the academic achievement and the quality of the Dominican Public Education.

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