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  • Polymer and Materials Science  (41)
  • CHEMISTRY  (19)
  • Life and Medical Sciences  (6)
  • 1965-1969  (66)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1805-1806 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 4 (1966), S. 2831-2842 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetra- and heptanuclear N-heterocycles, their dimers and their polymers have been prepared by condensation of o-phenylenediamine or 3,3'-diaminobenzidine with 2,3-dihydroxyquinoxaline, 2,3,2,3'-tetrahydroxy-6,6'-bisquinoxaline, or 2,3,7,8-tetrahydroxy-1,4,6,9-tetraazaanthracene in polyphosphoric acid, or with the O-phenyl derivatives of the latter three compounds in phenol. The condensation products are highly colored compounds with characteristic absorption spectra. The polymers show good thermal stability.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 815-820 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically allowed forms of the poly-N-methyl-L-alanine chain were found by calculation of conformational energies as a function of the rotation angles of its chain bonds. The lowest energy form seems to be a right-handed, approximately threefold helix.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 299-306 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The predominant role of van der Waal interactions in determining the helical conformations of a simple synthetic linear polymer, as well as helical polypeptides, was pointed out in systematic studies by Liquori et al.1,2. In the case of homopolypeptides the conformational analysis carried out on the basis of a simple semiempirical function describing the van der Waal pairwise interactions between the non directly bonded atoms lead to the conclusion that only five helices are allowed (Rα, β, γ, δ, Lα).2,3In view of the close similarities with poly-L-alanine, we have investigated by x-ray and conformational analysis the molecular conformation of poly(S-lactic acid) which has recently been described by Kleine and Kleine4 and Schuls and Schwaab5 and studied in solution by Goodman and D'Alagni.6 In fact, this polymer may be related to the polypeptide by the interchange of a peptide bond with ester bond along the main chain. This operation is expected to involve only a relatively small change in the steric interaction within the possible helical conformation, but obviously rules out any possibility of hydrogen bonding.
    Additional Material: 8 Ill.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism of respiration in the bullfrog has been analyzed by means of pressure recordings from the buccal cavity, the lungs and the abdominal cavity, by cinematography and cinefluorography, and by electromyography of buccal, laryngeal and abdominal muscles. Gas flow was investigated by putting frogs in atmospheres of changing argon and nitrogen content and monitoring the concentration of the nostril efflux.Three kinds of cyclical phenomena were found. (1) Oscillatory cycles consist of rhythmical raising and lowering of the floor of the mouth, with open nares. They have a definite respiratory function in introducing fresh air into the buccal cavity. (2) Ventilatory cycles involve opening and closing of the glottis and nares and renewal of a portion of the pulmonary gas. More muscles are involved and the pattern of muscular activity is more complex than in the oscillatory cycles. (3) Inflation cycles consist of a series of ventilation cycles, interrupted by an apneic pause. The intensity of the ventilatory cycles increases before this pause and decreases immediately thereafter. This results in a stepwise increase in pulmonary pressure, to a plateau (coincident with the pause) followed by a sudden or stepwise decrease.The respiratory mechanism depends on the activity of a buccal force pump, which determines pulmonary pressure whose level is always slightly less than the peak pressure values of the ventilation cycles. The elevated pulmonary pressure is responsible for the expulsion of pulmonary gas during the second phase of the next ventilation cycle. This pressure is maintained by the elastic fibers (and the smooth masculature) of the lungs.
    Additional Material: 16 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 859-864 
    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 linear polymer with a high melting point is obtained from the water-formaldehyde-hydrogen sulfide system in the presence of sulfuric acid. This polymer is substantially formed by a polythiomethylene chain with a few oxymethylene units. Its formation involves a topochemical reaction of the mercaptomethanol present in solution on the first separation solid of the system. On heating, the polymer loses oxymethylene units; in the same way, the first solid product separated from the system loses formaldehyde and undergoes a morphological and chemical transformation to polythiomethylene.
    Additional Material: 2 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 909-919 
    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: Ion-permselective membranes containing polyethylene in their base material have been examined by direct transmission electron micrography and x-ray diffraction. All of the electron micrographs showed white lines of about 100 A. thickness between somewhat thinner black lines composed of granules. These lines often occur as black-white-black triplets. We tentatively explain these structural elements by assuming that they are cross sections of the crystallite platelets, characteristic for polyethylene, reacted on both of their faces during sulfochlorination. It is known, that these platelets are about 100 A. thick, X-ray diffraction experiments also showed the characteristic lines of polyethylene crystallites, their intensity decreasing after sulfonation. The velocity of heterogeneous sulfochlorination of polyethylene sheets decreases abruptly when the film contains 6% S and 7% Cl (after hydrolysis). This m̰eans six substituted sites on a chain element across the platelet for a 100% crystalline film and accordingly less for a partially amorphous material. It is known that five CH2 groups of each chain element are exposed at the surface of the platelets, in good agreement with our findings.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 782-785 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Simple method for the potentiostatic determination of teh pitting potential in one single experimentA simple and fast method is described for the determination of the pitting potential of stainless steels. By using wire electrodes to which a constant DC-potential is applied one may scan potential ranges of any size in one single experiment. Tests with four autenitic steels in 1 N NaCl have shown that addition of Mo and Si displaces the pitting potential to higher values at room temperature; at higher temperature, however, this effect vanishes. Addition of NaBr and NaJ to the NaCl-solution produces a considerable increase of the pitting potential of Mo-free stainless steels. The experimental principle can be used also for the investigation of stress corroison cracking.
    Notes: Es wird eine einfache und schnelle Methode zur Ermittlung des ochfraßpotentials von nichtrostenden Stählen beschrieben. Durch die Verwendung von Drähten als Meßelektroden, an die eine festliegende gleichspannung angelegt wird, kann in einem einzigen Versuch ein beliebig großer Potentialbereich geprüft werden. Versuche mit 4 austenitischen Stählen in 1 n NaCl zeigen, daß Mo und Si das Lochfraßpotential bei Raumtemperatur anheben; dieser Effekt geht jedoch bei höherer Temperatur verloren. Zusäte von NaBr und NaJ zur NaCl-Lösung führen zu einer beträchtlichen Zunahme des Lochfraßpotentials von molybdänfreien nichtrostenden Stählen. Das Versuchsprinzip kann auch zur Unter suchung von Spannungskorrosion verwendet werden.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1296-1299 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 715-729 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: At low temperatures a single strand of dAT copolymer tends to form a double helix with a loop at one end (hairpin). At slightly higher temperatures a branched structure (consisting of many hairpins connected by coiled regions) appears. The equilibrium properties of this branched structure are studied here by a propagator method. In particular the radius of gyration RG is calculated; under typical conditions, RG is expected to show a minimum at a temperature slightly below melting, in agreement with viscosity measurements. The present calculation is restricted to rather sharp transitions, for which the size of each helical region is large, even at the melting point. Then, in a rather broad range of molecular weights, M, RG is proportional to M1/4(as in the Zimm-Stockmayer theory of simple branched polymers).
    Additional Material: 10 Ill.
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