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  • Chemistry  (3,413)
  • Polymer and Materials Science  (1,785)
  • ASTROPHYSICS
  • SPACE SCIENCES
  • Wiley-Blackwell  (3,949)
  • 1975-1979  (3,949)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1175-1186 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure of a clean copolymer of ethylene and tetrafluoroethylene is investigated by measuring the ESCA spectra of the core and valence levels. The chemical composition and alternating (〉95%) structure of the copolymer, characterized separately by classical methods, is verified by analyzing the C 1s core-level spectrum. The comparison of the experimental valence band with an original EHCO band-structure calculation, and with similar data for a model of polymer with block structure, shows that the combined methods allow us to distinguish between the two compounds through their valence-band spectra.
    Additional Material: 5 Ill.
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch direkte Copolymerisation oder durch polymeranaloge Reaktion wurden auf der Basis von Poly[N-(2-hydroxypropyl)methacrylamid] wasserlösliche Copolymere hergestellt, die in Seitenketten farbige Substratgruppen für Chymotrypsin tragen. Substrat war L-Phenylalanin-p-nitroanilid, das über seine Aminogruppe an die endständige Carboxylgruppe der Seitenkette gebunden war. Die Spaltbarkeit des so gebundenen Substrates wurde durch die Michaelis-Konstante, durch die maximale Geschwindigkeit und durch den Prozentsatz an Substrateinheiten ausgedrückt, der für das Enzym zugänglich ist. Hauptsächlich wurde der Effekt der Länge und der chemischen Struktur der Seitenkette untersucht. Es wurde gefunden, daß sie länger als 6 Atome sein muß, daß allgemein die Spaltung durch längere Ketten begünstigt wird. Die ε-Aminocapryl-Gruppe als Seitenkette ist für die Spaltung am günstigsten, Während Seitenketten mit einigen Glycyl-Gruppen obwohl länger weniger günstig sind. Polymere mit einem höheren Gehalt an Substrateinheiten sind besser spaltbar.
    Notes: Water-soluble copolymers based on poly[N-(2-hydroxypropyl)methacrylamide] and bearing in their side chains a chromogenic substrate for chymotrypsin were prepared by direct copolymerization or polymeranalogous reaction. The substrate was L-phenylalanine-4′-nitroanilide linked by its amino group to the terminal carboxylic group of the side chain. The cleavage of the substrate thus bonded, was expressed by means of the Michaelis constant, the maximum velocity, and the percentage of substrate unit accesible to the enzyme. The effect of length and chemical structure of the side chain was investigated in the first place. It was found that the chain must be longer than 6 atoms; longer chains are generally more favourable for this cleavage. The ε-aminocaproyl group provides a chain that is most favourable for the cleavage, whereas chains with several glycyl units, though longer, are less favourable. Polymers with higher content of the substrate units undergo cleavage more readily.
    Additional Material: 4 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 493-498 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A series of α-oxobenzimidazolinic merocyanines differently substituted on the ‘phenolate’ part and bearing a paraffinic chain on one heterocyclic nitrogen, has been studied by 13C NMR. Electron donating substituents bring about an increase of the electronic density on the 3 methine carbon and an increase of the alternation of electron density on the 3,4-dimethine bridge. A bathochromic shift of the lower energy electronic transition is also observed. Furthermore, the low field resonance of the 3 methine proton is probably due to a specific interaction between this proton and the ‘phenolate’ oxygen atom. This implies the existence of a favoured trans configuration for merocyanine dyes.
    Notes: Une série de mérocyanines α-oxo benzimidazoliniques diversement substituées sur la partie ‘phénolate’ et possédant une chaǐne grasse sur l'un des azotes hétérocycliques, a été étudiée en RMN du carbone- 13. Des substituants donneurs d'électrons provoquent une augmentation de la densité électronique sur le carbone méthinique C-3 et une augmentation de l'alternance de la distribution de charge sur le pont diméthinique 3,4. Corrélativement un déplacement bathochrome de la transition électronique de plus basse énergie est observé. Par ailleurs, l'apparition de la résonance à champ faible du proton méthinique H-3 semble due à une interaction spécifique intervenant entre ce proton et l'atome d'oxygène ‘phénolate’, ce qui suppose l'existence d'une configuration trans privilégiée pour les mérocyanines.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 578-581 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectrometry has been used in an attempt to resolve the ambiguity in the structures of the isomeric dihydro-oxazin-6-ones and N-acyl-azetidin-2-ones.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2929-2931 
    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: The technique for staining unsaturated additives within cotton fibers reacts osmium tetroxide with a sorbyl moiety which has been attached to the cellulose chain. Resulting electron micrographs indicate that contrast is considerably enhanced. Measurements of fibrillar size averaged 0.30 nm, closely approximating the values in the literature.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 149-155 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Double-loop tendons of fixed and adjustable lengths, and tendons with inner porous tapes both for anastomosis to tendon stumps have been made from readily available materials. By using stainless steel wire and polymer fibers, breakloads have been obtained that range from 20 to 100 lb and elongations have been reduced to less than 2%. Pore sizes up to 50 × 250 μ2 were achieved by using woven, knitted, and braided polyester tapes. For all tendons, Silastic was used to isolate inner fibers and to effect smooth gliding. Preliminary evaluation of these devices, after being implanted in the feet of chickens for 4 weeks, indicates that anastomotic strength of unions formed by use of loops is about 1000 g compared to more than 2000 for unions formed by tissue ingrowth.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 10 (1976), S. 311-323 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this investigation was to study bone growth into porous polyethylene rods as a function of time and pore structure. Previous studies have indicated the biocompatibility of solid polyethylene materials which are currently being used clinically. Porous polyethylene rods were implanted in the femurs of mongrel dogs which were sacrificed four, eight, and 16 weeks postoperatively. The implants were then sectioned and examined histologically and microradiographically. Quantitative techniques were employed to determine the amount of bone ingrowth as a function of time and pore size. The pore structures of the materials were evaluated using optical microscopy and mercury intrusion porosimetry.The results of this investigation have demonstrated that porous polyethylene is capable of accepting bone growth into pores as small as 40 μm. The optimum rate of bone ingrowth was observed in pore sizes of approximately 100 to 135 μm, with no increase in the rate of bone ingrowth observed in samples possessing larger pore sizes. No adverse tissue response was found at implant times up to 16 weeks in pore sizes of 100 μm or larger.
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 498-507 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The major metabolic pathway of the (-) enantiomer and the (+) enantiomer of 2-hydroxy-N-cyclopropylmethylmorphinan in dogs was shown to be conjugation with glucuronic acid and/or sulfate. Gas chromatography mass spectrometry, nuclear magnetic resonance spectroscopy and X-ray crystallography were used to identify additional metabolites of the two enantiomers in dog urine after hydrolysis with Glusulase. Metabolites of the (-) enantiomer were identified as 2-hydroxymorphinan and 2,7β-dihydroxy-N-cyclopropropylmethylmorphinan. The major metabolites of the (+) enantiomer in hydrolyzed dog urine were identified as 2-hydroxymorphinan, 2,3-dihydroxy-N-cyclopropylmethylmorphinan and 2-methoxy-3-hydroxy-N-cyclopropylmethylmorphinan. In addition, tentative or partial structures were postulated for three minor metabolites of the (+) enantiomer: 2-methoxy-3-hydroxymorphinan, a metabolite containing a hydroxyl group on either carbon 4, 5, 6 or 7 and a methylated catechol metabolite containing a hydroxyl group on carbon 4, 5, 6 or 7. Thus, the major oxidative pathways of the (-) enantiomer were N-dealkylation and aliphatic hydroxylation, while the (+) enantiomer mainly underwent N-dealkylation and aromatic hydroxylation, followed by phenolic methylation. Analysis of urine from a human subject administered the (-) enantiomer suggested that the metabolism of this isomer by man was similar to its metabolism by dog.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 1097-1162 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A multiordering parameter model for glass-transition phenomena has been developed on the basis of nonequilibrium thermodynamics. In this treatment the state of the glass is determined by the values of N ordering parameters in addition to T and P; the departure from equilibrium is partitioned among the various ordering parameters, each of which is associated with a unique retardation time. These times are assumed to depend on T, P, and on the instantaneous state of the system characterized by its overall departure from equilibrium, giving rise to the well-known nonlinear effects observed in volume and enthalpy recovery. The contribution of each ordering parameter to the departure and the associated retardation times define the fundamental distribution function (the structural retardation spectrum) of the system or, equivalently, its fundamental material response function. These, together with a few experimentally measurable material constants, completely define the recovery behavior of the system when subjected to any thermal treatment. The behavior of the model is explored for various classes of thermal histories of increasing complexity, in order to simulate real experimental situations. The relevant calculations are based on a discrete retardation spectrum, extending over four time decades, and on reasonable values of the relevant material constants in order to imitate the behavior of polymer glasses. The model clearly separates the contribution of the retardation spectrum from the temperature-structure dependence of the retardation times which controls its shifts along the experimental time scale. This is achieved by using the natural time scale of the system which eliminates all the nonlinear effects, thus reducing the response function to the Boltzmann superposition equation, similar to that encountered in the linear viscoelasticity. As a consequence, the system obeys a rate (time) -temperature reduction rule which provides for generalization within each class of thermal treatment. Thus the model establishes a rational basis for comparing theory with experiment, and also various kinds of experiments between themselves. The analysis further predicts interesting features, some of which have often been overlooked. Among these are the impossibility of extraction of the spectrum (or response function) from experiments involving cooling from high temperatures at finite rate; and the appearance of two peaks in the expansion coefficient, or heat capacity, during the heating stage of three-step thermal cycles starting at high temperatures. Finally, the theory also provides a rationale for interpreting the time dependence of mechanical or other structure-sensitive properties of glasses as well as for predicting their long-range behavior.
    Additional Material: 26 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 8 (1979), S. 259-264 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman and infrared spectra of difluorophosphine and difluorophosphine-d1 in the gaseous and solid phases from 100 to 3000 cm-1 have been recorded. The six fundamental frequencies have been assigned on the basis of group frequencies, depolarization ratios, band types and isotopic shifts. A normal coordinate analysis was carried out. Very little mixing was found to occur between the normal modes. Thermodynamic functions were calculated from the observed frequencies and previously reported moments of inertia.
    Additional Material: 5 Ill.
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