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  • Articles  (20)
  • Wiley-Blackwell  (18)
  • Mineralogical Society of America  (2)
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  • Articles  (20)
  • 1
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 13C NMR spectra of some polysaccharides and their methyl derivatives have been analysed. The numbers and positions of the assigned 13C NMR signals give some information about the structure of the monomer unit and the positions of the glycosidic linkage but no information about the anomeric configuration. In this case the 1J(C-1, H) coupling constants make it possible to identify the anomeric configuration, because the mean differences of the J values for the α- and β-anomers are 12 Hz (at least 5 Hz) with the higher values for the α-anomers.
    Notes: Die 13C-NMR-Spektren einer Reihe von Polysacchariden und ihrer Methylderivate wurden aufgenommen, zugeordnet und für die methylierten Polysaccharide außerdem die Kopplungskonstanten 1J(CH) bestimmt. An Beispielen wird gezeigt, daß die Zahl der 13C-Signale und deren Lage im Spektrum Aussagen über den Aufbau der Polysaccharide, sowie über die Verknüpfungsstellen der glykosidischen Bindung gestatten. Während aus den Signallagen die anomere Konfiguration nicht eindeutig zu ermitteln ist, gelingt dies bei den methylierten Polysacchariden mit Hilfe der Kopplungskonstanten 1J(C-1, H); diese weisen Unterschiede von durchschnittlich 12 Hz (aber mindestens 5 Hz) zwischen den α- und β-Anomeren auf, wobei die gröβeren Werte den α-Anomeren entsprechen.
    Additional Material: 3 Tab.
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  • 2
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: H-NMR investigations using a high resolution 220 MHz spectrometer were performed on methyl, acetyl and benzoyl derivatives of mannan from ivory nuts and Tubera salep, and on the corresponding d-mannopyranose derivatives. With the exception of the C(1) configuration the structure of these polysaccharides may be determined by comparing the coupling constants and chemical shifts of the substituted polysaccharides with those of the corresponding monosaccharide derivatives. The particularly broad signals in the spectra of low as well as high molecular weight acetyl and benzoyl mannans and furthermore, the differences between the chemical shifts of protons in 1,2,3,4,6-penta-O-acetyl-d-mannopyranose and those of the benzoylated mannans, are discussed in terms of relatively small flexibility of the polymer chains or chain segments in solution. In addition studies to determine the type of glycosidic bonds in polysaccharides from a comparison of the δH(1)-values of various polyglycan derivatives are reported.
    Notes: Die PR-Spektren einiger Methyl-, Acetyl- und Benzoylderivate von Mannan aus Steinnuß und Tubera salep sowie der d-Mannopyranose wurden analysiert. Durch einen Vergleich der Kopplungskonstanten und der Signallagen von entsprechend substituierten Polymeren und Monomeren wird, mit Ausnahme der Konfiguration an C(1), die Struktur dieser Polysaccharide bestimmt. Es wird auf charakteristische Unterschiede der Resonanzlagen von H(1) in Polysacchariden mit α-bzw. β-glycosidischen Bindungen hingewiesen. Dieser Befund eröffnet die Möglichkeit, auch in solchen Fällen eine Entscheidung über die Art der glycosidischen Bindung zu treffen, in denen, wie im Falle der Mannoside mit äquatorialständigem H(2), der Wert der Kopplungskonstante J12 keine Aussage erlaubt.Die auffallend große Breite der Signale in den Spektren der nieder- und hochmolekularen Acetyl- und Benzoylmannane wird auf eine geringe Beweglichkeit der Kette oder einzelner Kettensegmente bei Mannanderivaten in Lösung zurückgeführt.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 45 (1960), S. 267-269 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 50 (1961), S. 549-556 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Expressions are derived from free volume considerations which predict the concentration dependence of viscosity and glass temperature for polymer-diluent systems. Experimental data for several systems were examined and general agreement with theory was found over broad ranges of concentration. Particular emphasis is placed on the limited amount of information required for the application of these expressions to describe the viscous properties of polymer-diluent systems.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3213-3215 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 141-163 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A previously reported synthetic procedure was used to graft oligo-p-hydroxybenzoic acid (oligo-PHBA) to COOH-functional acrylic copolymers. Most of the products were side-chain LC copolymers. Length of the mesogenic oligo-PHBA groups averaged up to five aromatic rings per group. Because these long mesogenic groups have a strong tendency to form LC domains, it was possible to prepare LC side-chain copolymers having as little as 5 mol % of mesogenic monomer. Thus this synthetic procedure provides a versatile route for exploration of the properties of LC copolymers having relatively few but especially effective mesogenic groups. The potential utility of such LC copolymers as binders for nonbake coatings was assessed. Variables studied were molecular weight and Tg of the acrylic copolymer backbone, number and average length of oligo-PHBA segments, and the presence or absence of a flexible spacer between the acrylic backbone and the PHBA segments. Optimum LC copolymers have moderate (15,000-30,000) Mn, low (-10°C) backbone Tg, and low (5-7.5 mol %) population of long (5 PHBA units) oligo-PHBA units. Such copolymers have two major advantages as coatings binders: They form concentrated, stable, low-viscosity dispersions in common solvents, a very desirable characteristic for application. Coating films have excellent adhesion to metal, and they have an extraordinary combination of hardness (H-2H) and impact resistance (〉 80 in. Ib). These properties are key indicators of coating performance and indicate that LC copolymers have excellent potential for use as binders for nonbake coatings. Other properties remain to be investigated.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1063-1078 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Carboxyl functional liquid crystalline (LC) acrylic copolymers were synthesized and were compared with carboxyl functional control copolymers of M̄n about 5000-15,000. Both types were crosslinked with a hexakismethoxymethyl melamine (HMMM) resin at 150°C, a temperature below the clearing points of the LC copolymers. Birefringent phases were visible in the crosslinked films made from LC polymers. FT-IR indicated the presence of unreacted COOH in all crosslinked materials. Unreacted COOH groups in crosslinked LC copolymers appeared only slightly higher than those in crosslinked amorphous copolymers. The potential utility of these LC copolymers as binders for thermosetting coatings was assessed. Variables studied were HMMM content, the length of PHBA grafts, Tg and M̄n of the acrylic copolymer backbone, and functionality. Optimum LC copolymers have low backbone Tg (〈O°C) and low functionality (〈 7.5 mol %). Cured films of such copolymers have both high hardness (〉 35 KHN), high impact resistance (〉 80 in. ib), excellent adhesion, and good solvent resistance.
    Additional Material: 6 Ill.
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  • 8
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0173-0835
    Keywords: Two-dimensional zymography ; Photorhabdus luminescens ; Protease ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional zymography which combines two-dimensional electrophoresis with zymography was used to analyze proteases and other proteins produced by different phase variants of two strains of Photorhabdus luminescens. Both the primary and secondary phases of P. luminescens strains Hp and Hm secreted proteases. The protease in P. luminescens Hp has a molecular weight (Mr) of 57 000 and an isoelectric point (pI) of 4.4 whereas that in P. luminescens Hm has an Mr of 59 000 and pI of 4.9. Several putative protease degradation products were clearly visible in the zymograms from both bacterial strains. Two-dimensional zymography also showed that several secretory proteins were present only in particular phase variants and therefore could be used as specific markers. Unexpectedly, the two-dimensional zymography revealed that a nonsecretory protease with an Mr of 47 000 and a pI of 4.0 was present in the cell extracts of all phases of both P. luminescens Hp and Hm. The application of the two-dimensional zymography for the identification of other enzymes was also discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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