• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 111
  • 38
  • 32
  • 19
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 6
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 255
  • 27
  • 25
  • 18
  • 17
  • 15
  • 13
  • 13
  • 13
  • 12
  • 11
  • 11
  • 11
  • 10
  • 10
  • 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.
51

The Synthesis of Sulfated Carbohydrates Using a Sulfate Protecting Group Strategy

Ingram, Laura Jane 08 1900 (has links)
Sulfated carbohydrates play key roles in a wide range of biological processes such as blood clotting, viral entry into cells, amyloidogenesis, neurite outgrowth, tumor growth and metastasis. However, their synthesis still remains a considerable challenge. A general approach to the synthesis of sulfated carbohydrates was examined in which sulfate group is incorporated at the beginning of the syntheses as a protected sulfodiester. Towards this end, a series of sulfuryl imidazolium salts (SIS), a new class of sulfating agents, was prepared and examined as reagents for incorporating 2,2,2-trichloroethyl-protected sulfate esters into monosaccharides. The SIS that contained a 1,2-dimethylimidazolium moiety proved to be a superior sulfating agent compared to SIS bearing no alkyl groups or bulkier alkyl groups on the imidazolium ring. Difficult O- and N- sulfations that required prolonged reaction times and a large excess of the SIS bearing a 1-methylimidazolium group were achieved in high yield and in less time when employing less than half the 1,2-dimethylimidazolium derivative. Efforts were then made to apply the sulfate protecting group strategy to the total synthesis of a class of chondroitin sulfate glycosaminoglycans. These studies revealed some of the limitations of the sulfate protecting group approach to the synthesis of sulfated oligosaccharides. Studies on the selective introduction and isomerization of the carbobenzyloxy protecting group into 2,3-diols of 4,6-O-benzylidene galactose derivatives are also reported.
52

Méta-analyse des effets de l'oligofructose et de l'inuline sur le risque de cancer colorectal dans deux modèles murins rats traités par un carcinogène, et souris Min /

Tournié, Johanne Corpet, Denis. January 2008 (has links) (PDF)
Reproduction de : Thèse d'exercice : Médecine vétérinaire : Toulouse 3 : 2008. / Titre provenant de l'écran titre. Bibliogr. p. 79-91.
53

Targeting unopposed neutrophil elastase in chronic respiratory inflammation with heparin oligosaccharides

Leung, On-yue, Valeria. January 2009 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 90-103). Also available in print.
54

The Synthesis of Sulfated Carbohydrates Using a Sulfate Protecting Group Strategy

Ingram, Laura Jane 08 1900 (has links)
Sulfated carbohydrates play key roles in a wide range of biological processes such as blood clotting, viral entry into cells, amyloidogenesis, neurite outgrowth, tumor growth and metastasis. However, their synthesis still remains a considerable challenge. A general approach to the synthesis of sulfated carbohydrates was examined in which sulfate group is incorporated at the beginning of the syntheses as a protected sulfodiester. Towards this end, a series of sulfuryl imidazolium salts (SIS), a new class of sulfating agents, was prepared and examined as reagents for incorporating 2,2,2-trichloroethyl-protected sulfate esters into monosaccharides. The SIS that contained a 1,2-dimethylimidazolium moiety proved to be a superior sulfating agent compared to SIS bearing no alkyl groups or bulkier alkyl groups on the imidazolium ring. Difficult O- and N- sulfations that required prolonged reaction times and a large excess of the SIS bearing a 1-methylimidazolium group were achieved in high yield and in less time when employing less than half the 1,2-dimethylimidazolium derivative. Efforts were then made to apply the sulfate protecting group strategy to the total synthesis of a class of chondroitin sulfate glycosaminoglycans. These studies revealed some of the limitations of the sulfate protecting group approach to the synthesis of sulfated oligosaccharides. Studies on the selective introduction and isomerization of the carbobenzyloxy protecting group into 2,3-diols of 4,6-O-benzylidene galactose derivatives are also reported.
55

Prebiotic activity of isomalto-oligosaccharides

Ketabi, Ali Unknown Date
No description available.
56

Total synthesis of methyl 8(S)-, 9(S)-, 11(S)- and 12(S)- hydroxyeicosatetraenoates & of oligosaccharides from Haemophilus influenzae type B / Total syntheses of methyl 8(S)-, 9(S), 11(S)- and 12(S)- hydroxyeicosatetraenoates and of oligosaccharides from Haemophilus influenzae type B.

Wang, Zhi Yuan January 1987 (has links)
A general approach to the asymmetric syntheses of HETEs in both enantiomeric forms was developed. The syntheses of 8(S)-, 9(S)-, 11(S)- and 12(S)-HETE methyl esters, starting from D-arabinose, were accomplished. / A practical approach to the solution synthesis of fragments from Haemophilus influenzae type b capsular polymer was established, which opens a route to the development of a new vaccine against meningitis. The major aspects of this approach, stereocontrolled glycosidation, selective protection and deprotection, and efficient phosphorylation were detailed. The normal solution syntheses of the mono-, di- and tetrasaccharides were accomplished. / A new class of spacer for the linkage of the oligosaccharide with a protein was introduced. The spacer and the spacer-linked tetrasaccharide were prepared.
57

An electrochemical approach to selective oligosaccharide synthesis

France, Robert January 2004 (has links)
This thesis describes investigations into the use of electrochemical oxidation as a method for the activation of glycosyl donors, and in particular the application of this technique to the selective activation of one electrochemically active glycoside over another. The synthesis of twenty eight electrochemically active monosaccharide donors, including thio-, seleno- and O-glycosides with varying protecting group patterns and anomeric substituents is described, together with the synthesis of three electrochemically active monosaccharides with the potential to act as both glycosyl donors and glycosyl acceptors. The electrochemical analysis of these monosaccharides is reported and gives a detailed insight into the effect of various factors on the oxidation potentials of the monosaccharide donors and allows some general conclusions to be drawn. In addition the analysis of six monosaccharides by cyclic voltammetry at scan rates of up to 25 000 Vs<sup>-1</sup> allows their homogenous kinetics to be outrun and formal oxidation potentials obtained. Investigations into selective electrochemical glycosylations are reported, and the applicability of the analytical electrochemical studies to synthetic electrochemical reactions is demonstrated. Selective glycosylations are possible with selenoglycoside donors and either thio- or O-glycoside acceptors to give disaccharides. However the selective activation of selenoglycosides over thioglycosides is shown to be complicated by some underlying pathway for indiscriminate activation of both donor and acceptor. In contrast the use of an O-glycoside donor experiences no such problems. More detailed work on the underlying problems experienced with the thioglycoside acceptor was conducted, and the results are reported here. Investigations into electrochemical activation of the disaccharides are discussed, and the thioglycoside is shown to be easily activated to give a trisaccharide. At the time of writing this is believed to be the only electrochemically mediated trisaccharide synthesis reported in the literature. The O-glycoside however is shown to be inactive under the electrochemical oxidation conditions employed.
58

A preliminary analysis of platelet von willebrand factor oligosaccharides

Kagami, Kazuo, Williams, Sybil, Horne, McDonald, Gralnick, Harvey 05 1900 (has links)
No description available.
59

Production and separation of galacto-oligosaccharides from lactose by [beta]-galactosidase immobilized on nanofiltration membranes

Pruksasri, Suwattana, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 174-181).
60

The use of crude cell extracts of lactic acid bacteria optimized for beta-galactosidase activity to form galactooligosaccharides with lactose, mannose, fucose, and N-acetylglucosamine

Lee, Vivian Shin Yuan. January 2009 (has links)
Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Sept. 10, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Sciences, Agricultural, Food, and Nutritional Sciences, University of Alberta." Includes bibliographical references.

Page generated in 0.0361 seconds