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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.
41

Phytochemical studies of extracts from Aloe succotrina

Makhaba, Masixole January 2017 (has links)
Magister Scientiae - MSc (Chemistry) / Global climate change and geographical differences are two major parameters known to have, either, direct or indirect influence on the production of secondary metabolites in plants, which in-turn may affect the quality and/or quantity of the overall metabolites. The primary purpose of this thesis was to evaluate the phytochemistry of the whole leaf of Aloe succotrina Lam. spp. - a South African native plant - through a chromatographic spectroscopic approach-against available data accumulated for the cultivated population. Preliminary screening of the crude extracts i.e. HEX, DCM and EtOAc on TLC aluminium plates precoated with silica gel 60 F254 followed by various chromatographic separation, led to the isolation of five known compounds: ?-sitosterol (1) and two anthrone-C-glycosides (2 and 5), including two coumarin derivatives-the aglycone (3) and glycoside derivative (4). Notably, apart from 5 and 2, the accumulation of 1, 3 and 4 in A. succotrina Lam. spp. is reported for the first time. Structural elucidation of the individual compounds was achieved by extensive spectroscopic analysis i.e. MS, IR, 1H and 13C-NMR spectroscopy and in some cases comparison to the literature. A comparative HPLC chromatogram of the crude MeOH extract of the leaves of A. succotrina Lam. was developed for qualitative (and quantitative) identification of the active metabolites, which could be realized by VWD with detection at 290 nm.
42

Purification of Ethyl Diazoacetate by Vacuum Distillation for use in Cyclopropanation Reactions

Olukanni, Ayobami, Eagle, Cassandra T, Adesina, olumide, Mohseni, Reza M. 12 April 2019 (has links)
Environmentally friendly insecticides have long been desired in the production of food. Pyrethiod compounds not only decompose under light and heat, but they are highly toxic to insects while having effectively no toxicity to mammals. The cis-cyclopropane ring in pyrethiod insecticides is the most challenging component to synthesize. We are exploring the best parameters for the most effective cis-Cyclopropanation reactions. An alkene and a diazo compound react together in the presence of a dirhodium catalyst to produce cyclopropanes. First however, the starting materials must be pure. My part of the project is to purify ethyl diazoacetate(EDA). Column chromatography has been used, but yielded no fraction containing EDA as determined by Gas chromatography/Mass spectrometry. Extraction of EDA with sodium carbonate solution yielded similar results. Thus, I turned to distillation at reduced pressure. This method produced EDA in high enough purity to be used in cyclopropanation reactions. The purity of EDA was determined by H-1 nuclear magnetic resonance spectroscopy.
43

Studium syntézy ethylesteru kyseliny mléčné z jejích solí / The Study of Ethyllactate Synthesis from Lactic Acide Salts

Hlavatá, Daniela January 2015 (has links)
This diploma thesis deals with senthesis of lactic acid ethyl ester from slats of lactic acid. The literature review has been processed in the theoretical part of the diploma thesis. It is focused on manufacturing technologies of lactic acid esters, mainly on ethyl lactate by conventional and non-conventional ways of producing. Also the literature review involves producing of lactic acid and slats of lactic acid by fermentation because subsequently is possible produce ethyl lactate from that two substances. The laboratory apparatus for preparation of ethyl lactate and methyl lactate has been designed, realized and verificated function of it in the experimental part. There were carried out laboratory experimnets for production ethyl lactate and methyl lactate in this apparaturs.
44

Effects of trinexapac-ethyl on ornamental grass species

May, Alvin Scott 07 August 2010 (has links)
Studies were conducted to evaluate the effects of trinexapac-ethyl (TE) on height reduction, tillering, chlorophyll content, color, flowering, and root development of three ornamental grasses: Calamagrostis ×acutiflora 'Karl Foerster', Miscanthus sinensis 'Variegatus', and Pennisetum ×advena 'Rubrum'. Two applications of TE reduced height in all grasses and improved chlorophyll content in C. 'Karl Foerster' while delaying flowering in M. 'Variegatus' and P. 'Rubrum'. Tillering was slightly increased in M. 'Variegatus' with two TE applications. Shoot dry weight (SDW) and root dry weight (RDW) were reduced in C. 'Karl Foerster', SDW was reduced in P. 'Rubrum' and SDW and RDW were unaffected by applications of TE in M. 'Variegatus'. TE is effective for growth control in ornamental grass production systems; however, the results are species specific and should be tested further before widespread use on other ornamental grass species.
45

Low field modulation of complex species

Fletcher, Kerra Rose 07 January 2008 (has links)
No description available.
46

Model Chromia Surface Chemistry: C<sub>2</sub> Alkyl Fragment Reactions and Probe Molecule Interactions

Brooks, John Daniel 29 October 2010 (has links)
The thermally induced reaction of chlorinated ethanes on the nearly-stoichiometric α-Cr₂O₃ (102) surface results in the formation of gas phase hydrocarbons including ethylene, ethane, acetylene, 2-butene, 2-butyne and dihydrogen, and deposition of surface chlorine adatoms. No surface carbon or combustion products are observed in any reactions indicating that no thermally induced C-C bond cleavage occurs and surface lattice oxygen is not incorporated into surface intermediates. A combination of photoemission and Auger electron spectroscopies indicates the surface reactions of the chlorinated ethanes proceed via C-Cl bond cleavage to form surface chlorine adatoms and surface C₂-alkyl hydrocarbon fragments (i.e. ethyl, ethylidene and ethylidyne). Temperature programmed desorption studies indicate that both ethyl and ethylidene intermediates are selective towards ethylene. However, ethylidyne is more selective towards acetylene, but also produces ethylene in significant quantities. Chlorine adatom deposition leads to deactivation of surface Cr reaction centers by simple site blocking. The interaction of water with nearly-stoichiometric α-Cr₂O₃ (001) and (102) surfaces is structure sensitive. Water is sensitive to the difference in coordination number of Cr surface cations between the two surfaces, and on the α-Cr₂O₃ (001) surface, water has also demonstrated sensitivity to the degree of surface Cr cation reduction (and/or reduced coordination). These observations allowed for the development of a surface treatment recipe for the nearly-stoichiometric (001) surface. / Ph. D.
47

Vliv požití ethanolu na tvorbu ethylesterů mastných kyselin pro účely průkaznosti zbytkového alkoholu v krvi / The Effect of Consumption of Ethanol on Formation of Fatty Acid Ethyl Esters for the Purposes of Detection of Residual Alcohol in Blood

Strachoňová, Jana January 2009 (has links)
Blood ethanol is a widely accepted marker for recent ethanol intake (within the last 4-6 h). However, the rapid elimination of ethanol from the body nearly always makes it impossible to assess ethanol ingestion beyond the most recent 6-8h. But serum fatty acid ethyl ester (FAEE) is detectable in the blood both when ethanol is presented and long after ethanol has been removed from the circulation. For this FAEE should be better marker for prior ethanol intake.
48

POPULAÇÃO DE PLANTAS E REGULADOR DE CRESCIMENTO AFETANDO A PRODUTIVIDADE DE CULTIVARES DE TRIGO

Fernandes, Eliana Cuéllar 27 February 2009 (has links)
Made available in DSpace on 2017-07-25T19:29:43Z (GMT). No. of bitstreams: 1 ElianaFernandes.pdf: 2300440 bytes, checksum: be71036a0fe8687a5f4c3207149fd0cd (MD5) Previous issue date: 2009-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The maximization of the farm inputs use and an efficient crops management can develop the yield potential for area. With the aim of evaluate the effect of trinexapac-ethyl growth regulator and plants populations in the agronomical characteristics, diseases severity, yield components and yield of wheat cultivars with different resistance to the lodging, three experiments was established in the Farm School of the Ponta Grossa State University, in the year of 2008. The experimental design was complete randomized blocks, in a factorial design 6 x 2 with four repetitions for the three experiments. The treatments consisted of six plants populations (150, 300, 450, 600, 750 and 900 seeds of wheat m-2) and of the use or not of the trinexapac-ethyl growth regulator in the rate of 100 g ha-1, applied between 1 and 2 perceivable knot. The treatments were applied in three experiments that deferred to wheat cultivars of different lodging answers: resistance (OR-1), moderately resistant (BRS 208) and moderately susceptible (Safira). The number of tillers per plant, the foliar area per plant and the stem diameter had diminished with the increase of the plants population, independent of the cultivar. The plant height of the BRS 208 cultivar increased with the plants population increase. The plants height and the length of peduncle, had decreased with the trinexapacethyl application, as well as the lodging percentage in the BRS 208 and OR-1 cultivars. To Safira and OR-1 cultivars the yield was greater with the use of trinexapac-ethyl, but without effects in the BRS 208 cultivar. To Safira and OR-1 cultivars the yield adjustment equation in relation to the plants population was quadratic, occurring an increase of the yield with the increase of the plants population of, until a limit, variable with the cultivar. / A maximização do uso de insumos agrícolas e um manejo eficiente das lavouras podem aumentar o potencial produtivo por área. Com o objetivo de avaliar o efeito do regulador de crescimento trinexapac-ethyl e de populações de plantas em características agronômicas, severidade de doenças, omponentes da produção e produtividade de cultivares de trigo, realizou-se três experimentos na Fazenda Escola da Universidade Estadual de Ponta Grossa, no ano de 2008. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 6 x 2 com quatro repetições para os três experimentos. Os tratamentos constaram de seis populações de plantas (150, 300, 450, 600, 750 e 900 sementes de trigo m-2) e do uso ou não do regulador de crescimento trinexapac-ethyl na dose de 100 g ha-1, aplicado entre o 1º e o 2º nó perceptível. Os tratamentos foram aplicados em três experimentos que diferiram em cultivares de diferentes respostas ao acamamento: resistente (OR-1), moderadamente resistente (BRS 208) e moderadamente suscetível (Safira). O número de perfilhos por planta, a área foliar por planta e o diâmetro do colmo diminuíram com o aumento da população de plantas, independente da cultivar. A altura da planta da cultivar BRS 208 aumentou com o aumento da população de plantas. A altura das plantas e o comprimento do pedúnculo diminuíram com a aplicação do trinexapac-ethyl, bem como a porcentagem de acamamento nas cultivares BRS 208 e OR-1. Para as cultivares Safira e OR-1 a produtividade foi maior com o uso do trinexapac-ethyl, porém sem efeitos na cultivar BRS 208. Para as cultivares Safira e OR-1 a equação de ajuste da produtividade em relação à população de plantas foi quadrática, ocorrendo um aumento da produção com o aumento da população, até um limite, variável com a cultivar.
49

Densidades de semeadura e reguladores de crescimento afetando o trigo

Hilgemberg, Pâmella 19 August 2010 (has links)
Made available in DSpace on 2017-07-25T19:29:48Z (GMT). No. of bitstreams: 1 Pamella Hilgemberg.pdf: 1006022 bytes, checksum: 658a9e23cc65477b9afe8672032cdf1a (MD5) Previous issue date: 2010-08-19 / A correct management with lower costs in the crop can make a difference when one considers the maximization of yield for area of wheat crop management techniques should be adjusted to provide the greater profitability for producers of wheat. The aim of this study was to evaluate the effect of growth regulators and plant densities in three wheat cultivars. The experiments were deployed Farm School Capão da Onça in 2008, winter season. The treatments were sowing densities (150, 300, 450, 600, 750 and 900 seeds m-2) and with or without the growth regulator trinexapac-ethyl, in cultivars BRS208 and OR1. In the cultivar Safira, the treatments were six sowing rates (150, 300, 450, 600, 750, 900 seeds m-2) and regulators, trinexapac-ethyl and cycocel & ethepon. In all experiments, the regulators were applied between 1˚ and 2 ˚ node visible. Increasing the plant population decreased the number of tillers per plant, leaf area per plant, n ˚ green leaves per plant mother and increased productivity for the cultivars safira and OR1. In the experiments did not observe the presence of lodging, even in the cultivar safira, more susceptible. To cultivate safira observed an effect of regulators in the length of flag leaf, and to cultivate OR1, trinexapac-ethyl affected the width of the flag leaf. In the cultivar safira saw the effect of regulators in the reduction in height, which occurred specifically in 2 ˚, 3˚ and 4˚ internodes. The use of growth regulators in the experiments gave a decrease of plant height, for and the cultivar safira, regulators contributed to higher productivity, which was not observed OR1 and BRS208. / Um manejo correto com custos menores na cultura pode fazer diferença quando se considera a maximização da produtividade por área da cultura do trigo. Assim, as técnicas de manejo devem ser ajustadas de forma a proporcionar maior lucratividade o aos produtores de trigo. O objetivo deste trabalho foi avaliar o efeito de reguladores de crescimento e de densidades de plantio em três cultivares de trigo. Os experimentos foram implantados da Fazenda Escola Capão da Onça, no ano de 2008, safra inverno. Os tratamentos foram seis densidades de semeadura (150, 300, 450, 600, 750 e 900 sementes m-2) e o uso ou não do regulador de crescimento trinexapac-ethyl, para as cultivares BRS208 e OR1. Para a cultivar Safira, os tratamentos foram seis densidades de semeadura (150, 300, 450, 600, 750 e 900 sementes m-2) e os reguladores trinexapac-ethyl e cycocel & ethepon. Em todos os experimentos os reguladores foram aplicados entre o 1˚ e 2˚ nó visível. O aumento da população de plantas diminuiu o número de perfilhos por planta, a área foliar por planta, n˚ de folhas verdes por planta mãe e aumentou a produtividade para as cultivares safira e OR1. Nos experimentos não foi observada a presença de acamamento, mesmo na cultivar Safira, mais suscetível. Para a cultivar Safira observou-se efeito dos reguladores no comprimento da folha bandeira, e para a cultivar OR1, o trinexapac-ethyl afetou a largura da folha bandeira. Para a cultivar safira verificou-se o efeito dos reguladores na diminuição de altura, que ocorreu mais especificamente no 2˚, 3˚ e 4˚ entrenós. O uso de reguladores de crescimento nos experimentos conferiu uma diminuição de altura das plantas, e para a cultivar safira, os reguladores promoveram maior produtividade, o que não ocorreu para OR1 e BRS208.
50

ÉPOCAS DE APLICAÇÃO DE REGULADOR DE CRESCIMENTO E DE SOMBREAMENTO ARTIFICIAL AFETANDO CULTIVARES DE TRIGO

Martins, Lorena Müller 07 August 2012 (has links)
Made available in DSpace on 2017-07-25T19:29:55Z (GMT). No. of bitstreams: 1 Lorena M Martins.pdf: 771181 bytes, checksum: 1ad497598f87d45c93be44bf7385481f (MD5) Previous issue date: 2012-08-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of the growth regulator trinexapac-ethyl aims to reduce height of wheat plants avoiding lodging and losses caused by it. In addition, causes changes leaf architecture the plant have a better utilization of solar radiation. With the aim to evaluate the effects of application times of the growth regulator trinexapac-ethyl with or without artificial shade at different growth stages of wheat, two experiments were carried out in the Farm School of State University of Ponta Grossa, in the municipality of Ponta Grossa, Parana, two in 2010 and one in 2011. The experimental design was the randomized blocks with four replications in a factorial design, in 2010 was 4 x 3 (times of application of trinexapac-ethyl x time shading) in wheat cultivars Quartzo and Supera in 2011 in schedule 4 x 4 (time of application of trinexapac-ethyl x time shading), the cultivar Quartzo. Treatments consisted of four periods of application of trinexapac-ethyl (without application, tillering, between first and second perceivable knot and between second and third perceivable knot) at a dose of 100 g ha-1 in both the years and four seasons of shading (without coverage, the booting stage to silking + 15 days (x), X + 15 days) in the year 2011 three times (without coverage, the silking + 15 days (x) and X + 15 days) in 2010. No interaction was observed between treatments for the evaluated characteristics. In both trials no differences were observed for stem diameter, leaf area and harvest index. The shade did not affect the number of spikes per meter, grains per spikelet, number of tillers per plant in two years and the lowest grain yield occurred when the shading was done at the end of anthesis and grain filling (X + 15). The number of spikelets per spike was not affected by shading in the 2010 harvest, but the 2011 the period of shading done at the end of silking + 15 days increased the number of spikelets. The trinexapac-ethyl did not affect most of the yield components evaluated. Shading not affect the plant height. In the 2011 harvest, with the application of growth regulator between the first and second knot and between the second and third knot visible to the plant height was lower. The yield was not affected by timing of application of trinexapac-ethyl. In the 2011 harvest shading done at the end of anthesis and grain filling (X + 15 days) resulted in lower productivity. / O uso do regulador de crescimento trinexapac-ethyl visa reduzir a altura das plantas de trigo evitando assim o acamamento e as perdas ocasionadas por ele. Além disso, muda a arquitetura foliar fazendo com que a planta tenha um melhor aproveitamento da radiação solar. Com o objetivo de avaliar os efeitos de épocas de aplicação do regulador de crescimento trinexapacethyl associado ou não ao sombreamento artificial em diferentes estádios de desenvolvimento do trigo, realizaram-se três experimentos na Fazenda Escola da Universidade Estadual de Ponta Grossa, no município de Ponta Grossa, Paraná, dois no ano de 2010 e um no ano de 2011. O delineamento experimental foi de blocos ao acaso com quatro repetições em esquema fatorial, sendo que no ano de 2010 foi 4 x 3 (épocas de aplicação do trinexapac-ethyl x épocas de sombreamento) nas cultivares de trigo Quartzo e Supera e no ano de 2011 no esquema 4 x 4 (épocas de aplicação do trinexapac-ethyl x épocas de sombreamento), na cultivar Quartzo. Os tratamentos consistiram de quatro épocas de aplicação do trinexapacethyl (sem aplicação, no perfilhamento, entre o 1 e o 2 nó perceptível e entre o 2 e o 3 nó perceptível) na dose de 100 g.ha-1 em ambos anos e de quatro épocas de sombreamento artificial (sem cobertura, da fase de emborrachamento ao espigamento, do espigamento + 15 dias (x) e x + 15 dias) no ano de 2011 de três épocas (sem cobertura, do espigamento + 15 dias (x) e x + 15 dias) no ano de 2010. Não houve interação entre os tratamentos para as características avaliadas. Em ambos dos ensaios não foram observadas diferenças para diâmetro do colmo, área foliar, e índice de colheita. O sombreamento artificial não afetou o número de espigas por metro, de grãos por espigueta e de perfilhos por planta nos dois anos e o menor peso de grãos ocorreu quando o sombreamento foi realizado no final da antese e enchimento de grãos (X + 15). O número de espiguetas por espigas não foi influenciado pelo sombreamento na safra 2010, porém na safra 2011 o sombreamento no final do espigamento + 15 dias aumentou o número de espiguetas por espiga. O trinexapac-ethyl não influenciou a maioria dos componentes de produção avaliados. O sombreamento não interferiu na altura de plantas. Na safra 2011, com a aplicação do regulador de crescimento entre o primeiro e segundo nó e entre o segundo e terceiro nó perceptível a altura de plantas foi menor. A produtividade não foi afetada pelas épocas de aplicação do trinexapac-ethyl. Na safra 2011 o sombreamento artificial efetuado no final da antese e enchimento de grãos (X + 15 dias) resultou em menor produtividade.

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