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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.
181

Jahresforschungsbericht / Technische Universität Dresden

14 January 2013 (has links) (PDF)
Der Forschungsbericht vermittelt einen Einblick in die vielfältige, leistungsfähige und interdisziplinäre Forschungslandschaft an der Technischen Universität Dresden.
182

Jahresforschungsbericht / Technische Universität Dresden

14 January 2013 (has links) (PDF)
Der Forschungsbericht vermittelt einen Einblick in die vielfältige, leistungsfähige und interdisziplinäre Forschungslandschaft an der Technischen Universität Dresden.
183

Jahresforschungsbericht / Technische Universität Dresden

14 January 2013 (has links) (PDF)
Der Forschungsbericht vermittelt einen Einblick in die vielfältige, leistungsfähige und interdisziplinäre Forschungslandschaft an der Technischen Universität Dresden.
184

Jahresforschungsbericht / Technische Universität Dresden

14 January 2013 (has links) (PDF)
Der Forschungsbericht vermittelt einen Einblick in die vielfältige, leistungsfähige und interdisziplinäre Forschungslandschaft an der Technischen Universität Dresden.
185

Jahresforschungsbericht / Technische Universität Dresden

14 January 2013 (has links) (PDF)
Der Forschungsbericht vermittelt einen Einblick in die vielfältige, leistungsfähige und interdisziplinäre Forschungslandschaft an der Technischen Universität Dresden.
186

Preparation of Methylcellulose from Annual Plants

Ye, Daiyong 30 September 2005 (has links)
Este trabajo presenta los resultados de la investigación sobre la preparación y caracterización de las metilcelulosas a partir de las plantas anuales.Las pastas del miscanthus, el cardo, y el eucalipto, se prepararon mediante el proceso IRSP (Impregnation Rapid Steam Pulping) y se blanquearon con las secuencias del TCF (Total Chloride Free), que usan peróxido de hidrógeno y hidróxido de sodio (NaOH). Con el aumento de la severidad del proceso de obtención de las pastas, la accesibilidad y la reactividad de las pastas aumentaron mientras que la viscosidad y el número de la kappa disminuyeron. Se desarrolló un nuevo y sencillo método de metilación para preparar las metilcelulosas a partir de la madera y las plantas anuales en el laboratorio. Cada metilcelulosa de las pastas blanqueadas con las secuencias del TCF se sintetizó en una mezcla de isopropanol con metano de yodo a 600C durante 22 horas después la pasta del TCF se mercerizó en una solución del hidróxido de sodio al 40% durante 1 hora. La mercerización y la metilación se repitieron para obtener un grado de sustitución (DS) más alto. Los resultados de la espectroscopía infrarroja de transformada de Fourier (FTIR) (Fourier Transform Infrared Spectroscopy) mostraron que los grupos del OH de la celulosa habían sido sustituidos parcialmente por grupos del metoxil. Los modelos de sustitución supramolecular de las metilcelulosas se determinaron mediante espectroscopía de resonancia magnética nuclear del carbono-13. La viscosidad intrínseca de las metilcelulosas se midió con agua destilada, una solución al 4% de NaOH, o DMSO. Las propiedades reológicas de las metilcelulosas se midieron con DMSO, una solución al 4% de NaOH o agua destilada. Las metilcelulosas sintetizadas tenían unas propiedades similares a las metilcelulosas comerciales. Los volúmenes hidrosolubles y alcalinosolubles de la metilcelulosas se determinaron mediante extracción con disolventes.Las metilcelulosas se prepararon a partir de pastas de lino, yute, cáñamo, sisal, y abacá mediante metilaciones heterogéneas y homogéneas. Estas pastas se blanquearonmediante el proceso ECF (Elemental Chlorine Free). La mutilación inhomogénea de las pastas blanqueadas mediante el proceso ECF se sintetizó en una mezcla de isopropanol con metano de yodo a 600C durante 22 horas después la pasta del ECF se mercerizó durante 1 hora en una solución de NaOH al 50%. La mutilación homogénea de la pasta blanqueada mediante ECF se realizó en DMSO con metano de yodo a 300C durante 48 horas. Para esta metilación homogénea se usó una metilcelulosa con un grado de sustitución más bajo, que se disolvió completamente en DMSO. La espectroscopía infrarroja de transformada de Fourier (FTIR) de las metilcelulosas mostró la existencia de grupos de metoxiles sobre las moléculas de metilcelulosa. Se utilizó la espectroscopia de resonancia magnética nuclear del carbono 13 para medir los grados de sustitución de las metilcelulosas. Los pesos moleculares de las metilcelulosas hidrosolubles se determinaron con la cromotagrafía de exclusión por tamaños (SEC). Las viscosidades intrínsecas se midieron en una solución de NaOH al 4%. Las metilcelulosas preparadas a partir de pastas de elevadas accesibilidades y reactividades tenían las mejores grados de sustitución, pesos moleculares, viscosidades y viscosidades intrínsecas.Se investigaron las accesibilidades y reactividades de las pastas del ECF. Los volúmenes de glucosa y de xilosa de estas pastas se determinaron mediante HPLC (High performance liquid chromatography) después de la hidrólisis. Las accesibilidades de adsorción de yodo de estas pastas eran bajas y sus fragmentos accesibles estaban entre el 1,31% y el 5,16%. En la región amorfa, sus fragmentos accesibles estaban entre el 5% y el 24%. Las imágenes del SEM (Scanning Electrón Microscopy) mostraron que sus fibrillas tenían distintas estructuras morfológicas. Los resultados de la espectroscopía infrarroja de transformada de Fourier (FTIR) mostraron que, después de los pretratamientos, habían disminuido tanto la media de la intensidad de los enlaces de hidrógeno como los índices de cristalinidad relativos. Sus reactividades aumentaron significativamente después de la mercerización preliminar. Las accesibilidades y reactividades de la pasta del abacá se mejoraron con los tratamientos de impregnación con agua, la mercerización a 15 bares de presión, la explosión de vapor y la mercerización preliminar. La desintegración, el incremento de los huecos, el debilitamiento de la intensidad de los enlaces de hidrógeno, la depolimerización, y la decristalización son esenciales para mejorar las accesibilidades y las reactividades, pero el factor decisivo es la especie de la planta.Hemos estudiado los factores que influyen en el peso molecular (Mw) de las metilcelulosas hidrosolubles preparadas a partir de plantas anuales. El tiempo y la temperatura de impregnación y las condiciones de cocción influyeron de manera diferente en el peso molecular (Mw) de metilcelulosas preparadas a partir de los cardos recogidos en primavera y en verano, el miscanthus y el eucalipto. Se compararon los efectos de los pretratamientos (la impregnación con agua, la mercerización preliminar, la mercerización con presión y la explosión de vapor) en la pasta del abacá. Cuando se pretrató la pasta del abacá, su metilcelulosa hidrosoluble consiguió un peso molecular más alto. De entre los pretratramientos analizados, la explosión de vapor resultó el más adecuado. Para conseguir metilcelulosas con un peso molecular más alto deben perfeccionarse las condiciones de la preparación de las pastas blanqueadas mediante ECF. La especie de las plantas es el factor decisivo para conseguir el peso molecular más alto de las metilcelulosas y para seleccionar los pretratamientos más adecuados.Los parámetros del proceso de obtención de pastas, las condiciones de la metilación, las especies de las plantas, los pretratamientos, y la estructura morfológicas de las pastas influyó en los grados de sustitución de las metilcelulosas preparadas a partir de plantas anuales. Una severidad de impregnación más alta, una temperatura del proceso de obtención de pastas más alta y un incremento del tiempo del mismo proceso consiguieron grados de sustitución más altos. Un aumento de reactivos de la metilación causó un aumento de grado de sustitución. Las pastas obtenidas de distintas especies produjeron grados de sustitución diferentes, trabajando con las mismas condiciones de metilación. Los pretratamientos aumentaron el grado de sustitución de las metilcelulosas.Esta investigación contribuye a encontrar las condiciones apropiadas para metilcelulosas diseñadas a medida, sintetizadas a partir de plantas anuales. Esta investigación demuestra que estas plantas tienen la capacidad de ser preparadas para conseguir metilcelulosas de alta calidad y de alto valor aptas para distintas aplicaciones, como la industria alimentaria, la de la construcción o la farmacéutica. La industria puede utilizar estas plantas anuales de crecimiento rápido para producir metilcelulosas, con lo que, además, se evitará el uso de madera.Palabras clave: abacá, accessibilidad, blanqueo mediante TCF, cáñamo, cardo, eucalipto, grado de sustitución, lino, metilación, metilcelulosa, miscanthus, peso molecular, plantas anuales, proceso de obtención de pasta IRSP, sisal, yute. / Preparation and characterization of methylcelluloses from some annual plantswere investigated.Miscanthus, cardoon, and eucalyptus pulps were produced by Impregnation Rapid Steam Pulping (IRSP) process and bleached by Total Chloride Free (TCF) sequences using hydrogen peroxide and sodium hydroxide. With an increase of pulping severities, accessibilities and reactivities of bleached pulps increased while viscosities and kappa numbers decreased. A novel facile methylation was developed in order to prepare methylcelluloses from wood and annual plants. Each methylcellulose of TCF bleached pulps was synthesized in isopropanol slurry with iodomethane at 600C for 22 hours after the TCF bleached pulp was mercerized in 40% NaOH solution for 1 hour. The mercerization and methylation were repeated in order to obtain a higher degree of substitution (DS). Fourier Transform Infrared (FTIR) spectra showed OH groups of cellulose were partially substituted by methoxyl groups. Supramolecular substitution patterns of methylcelluloses were determined by 13C nuclear magnetic resonance (NMR) spectroscopy. Intrinsic viscosities of methylcelluloses were measured in distilled water, 4% NaOH solution, or dimethyl sulphoxide (DMSO). Rheological properties of methylcelluloses were measured in DMSO, 4% NaOH solution or distilled water, in which the synthesized methylcelluloses had similar properties as commercial methylcelluloses. Watersoluble and alkali-soluble contents of methylcelluloses were determined by solventextraction.We used iodomethane to synthesize methylcelluloses from Elemental Chloride Free (ECF) bleached abaca, hemp, flax, jute, and sisal pulps via heterogeneous and homogeneous methylations. The heterogeneous methylation was carried out in isopropanol with iodomethane at 600C for 22h after a ECF bleached pulp was mercerized in excessive 50% NaOH solution for one hour at ambient temperature. The homogeneous methylation was carried out in dimethyl sulfoxide with iodomethane at 300C for 48h using a methylcellulose of low degree of substitution. Fourier Transform Infrared (FTIR) spectra of the synthesized methylcelluloses showed the existence of methoxyl groups on methylcellulose molecules. The degrees of substitution of the synthesized methylcelluloses were measured by 13C Nuclear Magnetic Resonance (NMR) spectroscopy. The molecular weights of the waterVI soluble methylcelluloses were determined by Size Exclusion Chromatography (SEC). Intrinsic viscosities of the synthesized methylcelluloses were measured in 4% NaOH solution. Methylcelluloses with better properties, such as greater degrees of substitution, molecular weights, viscosities, and intrinsic viscosities, were prepared from the pulps with higher accessibilities and reactivities. The factors influencing the preparation of methylcelluloses from these pulps were discussed.Pretreatments (water-soaking, pre-mercerization, mercerization under a pressure of 15 bars, and steam explosion) were used to improve the accessibilities and reactivities of celluloses of bleached flax, hemp, sisal, abaca, and jute pulps for the synthesis of methylcellulose. Glucose and xylose contents of these pulps were determined by High Performance Liquid Chromatograph (HPLC) after hydrolysis. Degrees of crystallinity of these pulps were determined by X-ray Diffraction (XRD) spectra. Figures of Scanning Electron Microscope (SEM) showed that their fibrils had different morphological structures. The iodine adsorption accessibilities of these pulps were low and accessible fractions ranged from 1.3% to 5.2%. Accessible fractions in amorphous cellulose were calculated in the 5% to 18% range. The accessibilities of these pulps were hemp pulp > flax pulp > sisal pulp > jute pulp > abaca pulp. Fourier Transform Infrared (FTIR) spectra showed that mean hydrogen bond strengths were weakened and relative crystallinity indexes were decreased by pretreatments. The accessibility and reactivity of the abaca pulp were improved by water soaking, mercerization under 15 bars pressure, steam explosion and preliminary mercerization, of which steam explosion and pre-mercerization were thebest treatments. Species was the main factor for the accessibility and reactivity.We studied the factors that influenced the molecular weights (Mw) of watersolublemethylcelluloses prepared from annual plants and juvenile eucalyptus. Miscanthus and cardoon stalks, and bleached pulps of abaca, jute, sisal, hemp, and flax were used as the annual plant materials. A higher concentration of NaOH solution during the impregnation led to a spring cardoon methylcellulose having a lower molecular weight. As the impregnation times increased, so did the molecular weights of the water-soluble methylcelluloses of spring cardoon. The impregnation conditions had less influence on the methylcelluloses of summer cardoon than on the methylcelluloses of spring cardoon. As the cooking times increased, so did the molecular weights of miscanthus methylcelluloses. A lower pulping severity increased the molecular weight of eucalyptus methylcellulose. The preliminary treatments (water soaking, pre-mercerization, mercerization under pressure andsteam explosion) improved the molecular weights of water-soluble abaca methylcelluloses. The steam explosion method was the best of the preliminary treatments for the abaca pulp. Different species led to different molecular weights for methylcelluloses synthesized from ECF bleached pulps, and these were further improved by preliminary mercerization. The molecular weight of -cellulose methylcellulose changed as the ratio of the methylation reagent was varied. In order to synthesize an optimum Mw of methylcellulose, the different raw materials can be chosen, the pulping parameters adjusted (including impregnation and cooking), the cellulose pretreated, and the methylcellulose conditions changed. The plant species is the decisive factor for the Mw of methylcellulose.The pulping parameters, the methylation conditions, the species, the pretreatments, and the morphological structures of pulps influenced the degrees of substitution of the methylcelluloses prepared from the annual plants. A higher impregnation severity, a higher pulping temperature, and a longer pulping time caused a higher degree of substitution. An increase of methylation reagents led to an increase of degree of substitution. Methylcelluloses of different degrees of substitution were synthesized from the pulps of different species when a same methylation condition was used. The pretreatments increased the degrees of substitution of methylcelluloses.This investigation contributes to find appropriate conditions for the production of methylcellulose from annual plants. The present investigation demonstrates these annual plants have the capacities to produce upgraded and high quality methylcelluloses for varied applications, such as additives of foods, construction, pharmaceutics, polymerization, paints, and detergents etc. The industry can utilize these annual fast-growth plants to produce methylcelluloses. Therefore, a lot of wood will be saved.Keywords: abaca, accessibility, annual plants, cardoon, degree of substitution, eucalyptus, flax, hemp, IRSP pulping, jute, methylation, methylcellulose, miscanthus, molecular weight, sisal, steam explosion, TCF bleaching.
187

Redovisningsinformationens betydelse vid kreditbedömning av små och medelstora företag

Engström, Annelie, Mattsson, Christian January 2012 (has links)
Sammanfattning Titel: Redovisningsinformationens betydelse vid kreditbedömning av små och medelstora företag. Nivå: C-uppsats i företagsekonomi. Författare: Annelie Engström och Christian Mattsson. Handledare: Ann W Dörner. Datum: Juni 2012. Syfte: Syftet med denna studie är att undersöka hur kreditgivare använder sig av redovisningsinformation vid kreditbedömningen av små och medelstora företag. Forskningsfrågorna är: Stämmer redovisningsinformationen överens med kreditgivarnas behov av information vid kreditbedömning av små och medelstora företag? Vilka delar av redovisningsinformationen är viktiga vid en kreditbedömning av små och medelstora företag? Metod: I denna studie används en mixad metod vilket innebär att en kvantitativ metod används vid insamling av data och en kvalitativ metod vid analyseringen av data. Empirisk data har samlats in med strukturerade frågeformulär med fasta svarsalternativ som skickats ut till respondenterna. Sekundärdata har sökts fram ur relevant litteratur, artiklar och tidigare undersökningar. Resultat och Slutsats: De flesta kreditgivare är nöjda med den information som ges. Balans- och resultaträkning är de viktigaste rapporterna vid en kreditbedömning. Rörelseresultatet är den viktigaste resultatposten, kassalikviditet och soliditet är de viktigaste nyckeltalen. Förslag till fortsatt forskning: Följande två frågor har uppkommit under arbete och föreslås därmed som ämnen till framtida studier. Vilken redovisningsinformation saknar kreditgivare och vad skulle de vilja förbättra i den nuvarande informationen. Revisionspliktens betydelse vid kreditbedömning. Uppsatsens bidrag: Denna uppsats utreder vilka av årsredovisningens delar som är viktiga vid kreditbedömning. Detta kan vara till hjälp för att utveckla bedömningsunderlag för framtida rapporter. Nyckelord: Kreditbedömning, kreditgivning, redovisningsinformation, årsredovisning, finansiella rapporter / Abstract Title: The relevance of accounting information in the credit-granting process concerning small and medium firms. Level: Final assignment for Bachelor Degree in Business Administration. Authors: Annelie Engström and Christian Mattsson. Supervisor: Ann W Dörner. Date: June 2012. Aim: The purpose of this study is to examine how creditors use accounting information in the credit-granting process concerning small and medium-sized firms. The research questions are: Does the provided accounting information fulfill the creditor’s needs of information in the credit-granting process of small and medium-sized firms? What parts of the accounting information is important in the credit-granting process of small and medium-sized firms? Method: The design of this study is both quantitative and qualitative in nature. The primary data is collected by a quantitative method. To obtain empirical data, structured questionnaires have been sent out with fixed response alternatives to the respondents. Secondary data, have mainly been taken from literature, articles and previous studies. Result and Conclusions: Not all but most creditors are satisfied with the provided information. The balance sheet and the income statement are the most important reports when credit-granting decisions are to be made. The operating profit is the main performance record and cash liquidity and solvency are the most important ratios. Suggestions for future research: Two questions arose during the study and is thereby suggested as topics for future studies. What are the creditors missing in today’s accounting information and what needs improvement? The mandatory auditing importance of credit-granting. Contribution of this thesis: This paper investigates which parts of the Annual Report that is important for credit-granting. This may help to develop the assessment basis for future reports. Key words: Granting of credit, credit process, accounting information, annual report, financial reports
188

Risk och osäkerhetsfaktorer i årsredovisningen

Örtenvik, Mikael, Forsström, Ann January 2012 (has links)
Titel: Risk och osäkerhetsfaktorer i årsredovisningen   Nivå: C-uppsats i ämnet företagsekonomi   Författare: Ann Forsström och Mikael Örtenvik   Handledare: Fredrik Hartwig   Datum: 2012 – April   Syfte: Syftet med vår studie är att undersöka den frivilliga rapporteringen av risk och osäkerhetsfaktorer i årsredovisningar.   Metod: Vi har använt en abduktiv ansats och genomfört en kvalitativ såväl som kvantitativ innehållsanalys av utvalda bolags årsredovisningar. Vi prövar 5 olika hypotester genom multipel regessionsanalys. Vår insamlade data redovisas både i tabell- och textform.   Resultat & slutsats: Undersökningen visar att det finns en signifikans i hypotes 5: det finns ett samband mellan ett bolags skuldsättningsgrad och antalet redovisade risker och osäkerheter.  Övriga hypoteser har ingen signifikans och förkastas därmed. Vid genomgången av undersökningsbolagens årsredovisningar finner vi dock att det finns betydande skillnader i redovisningen av risker och osäkerheter mellan de undersökta bolagen.    Förslag till fortsattforskning: Det skulle vara intressant med en jämförelse av bolag som verkar inom samma typ av försäljning t ex. tjänstesektorn inom IT och där göra en djupare analys av vilka typer av risker bolagen utsätts för och hur de hanterar dem, en kvalitativ undersökning med intervjuer.   Uppsatsens bidrag:  Uppsatsen kan, av intressenter i branschen industri, ses som en upplysning om hur väl bolagen tillämpar reglerna kring risk- och osäkerhetsfaktorer.   Nyckelord: Risk, osäkerhetsfaktorer, ÅRL, IAS, årsredovisning. / Title: Risk and uncertainties in annual report   Level: Final assignment for Bachelor Degree in Business Administration   Author: Ann Forsström and Mikael Örtenvik   Supervisor: Fredrik Hartwig   Date: 2012– April   Aim: The aim of our study is to investigate the voluntary reporting of risks and uncertainties in the financial statements.   Method: We used an abductive approach and perform a qualitative as well as quantitative content analysis of selected company´s annual reports. We test five different hypothesis by multiple regression analysis. Our collected data is presented both in tabular and textual form.   Result & Conclusions: The survey shows that there is an significance in hypothesis 5: there is a correlation between a company's gearing and the number of reported risks and uncertainties. Other hypotheses have no significance and hence rejected. In evaluating the companies' annual survey, we find that there are significant differences in the reporting of risks and uncertainties among the surveyed companies.   Suggestions for future research: It would be interesting to compare the companies working in the same type of sale for example. services in IT and where to do a deeper analysis of the types of risks companies are exposed to and how they handle them, a qualitative study with interviews.   Contribution of the thesis: The essay may, by stakeholders in the business industry, seen as an enlightenment on how well companies are applying the rules on risk and uncertainties.   Key words: Risk, uncertainties, ÅRL, IAS, annual report.
189

Årsredovisningens nytta :  För ickeprofessionella investerare / The value of an annual report :  For a non professional investor

Malmberg, Henrik, Runströmer, Jacob January 2012 (has links)
Syfte: Uppsatsen ska undersöka hur svenska icke professionella investerare använder årsredovisningen i sina val av kapitalplacering och vilken nytta årsredovisningen har i valet. Uppsatsen ska även undersöka om icke professionella investerare har några problem i tolkningen av årsredovisningar. Metod: Uppsatsen använder både kvantitativ och kvalitativ metod i form av intervjuer och enkät. Slutsats: 50 % av de icke professionella investerarna anser att de har nytta av årsredovisningar vid kapitalplaceringsbeslut. VD-ordet, förvaltningsberättelsen och revisionsberättelsen används mest. Det som upplevs svårast är värderingar i balansräkningen, kassflödesanalys och noter. Förslag till fortsatta studier: Genomföra en liknande undersökning med intervjuer av icke professionella investerare. Ta reda på vilken hänsyn det tas till investerare med lägre ekonomisk kunskap vid upprättandet av årsredovisningar. / Aim: The essay should examine how Swedish non-professional investors use annual reports in their choices of capital investment in securities and what benefits the annual report has in their choices. The essay should also examine if the non-professional investors have some problems in their interpretation of the annual reports. Method: The essay use both qualitative and quantitative methods in form of interviews and survey. Conclusion: 50% of the non-professional investors think that they have benefits from the annual report in their capital investment decisions. CEO:s statement in the annual report, management report and auditor's report is used the most. The most difficult parts are the values in the balance sheet, cash flow statement and notes. Suggestion for future research: Conducting a similar study with interviews with non professional investors. Find out which account is taken of investors with less financial knowledge in the preparation of annual reports.
190

Water uptake of hardwoods

Michalec, Jiri, Niklasova, Sylvie January 2006 (has links)
This study investigate water uptake in six different species of hardwood in tangential and radial section. Alder (Alnus glutinosa) and beech (Fagus sylvatika) represent semi-diffuse-porous hardwoods. Aspen (Popolus tremula) and birch (Betula pubescens) represent diffuse-porous group; oak (Quercus robur) and ash (Fraxinus excelsior) the ring-porous hardwoods. Spruce (Picea abies) was used as a reference sample. Significantly higher water uptake was observed in the diffuse-porous and the semi-diffuse-porous group. Water uptake varied among the species, nevertheless tangential section was more permeable in general. Any impact of density or annual rings width on water uptake was observed. Correlation between ratio of earlywood and latewood and water uptake in dependence on hardwood group was found out. Ring-porous species had low rate of earlywood and low water uptake, whereas diffuse-porous and semi-diffuse-porous hardwoods had high rate of earlywood and high water uptake. Relation between water uptake and microstructure of wood was observed.

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