Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1990-1994  (7)
  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Addiction 88 (1993), S. 0 
    ISSN: 1360-0443
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin , Psychologie
    Notizen: Eighty-two Caucasian patients receiving treatment for alcohol-related problems and eighty four controls were DNA typed for variants in the alcohol dehydrogenase (ADH2 and ADH3) and mitochondrial aldehyde dehydrogenase (ALDHJ gene loci. No association was observed between individual, or combined gene frequencies and the presence of alcohol-related problems.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1379-1390 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Two crystalline melting peaks have been observed by differential scanning calorimetry for low molecular weight poly[3,3-bis(ethoxymethyl) oxetane] (polyBEMO) samples, Mn 〈 1 × 104 g/mol, whereas only one melting peak has been observed for samples of higher molecular weight, Mn 〈 1 × 104 g/mol. Crystallization of low molecular weight samples at large supercoolings produces the lower melting form while low supercooling or annealing favors the higher melting species. Enthalpy of fusion values obtained by DSC for a multiple melting endotherm sample range from 28 to 39 J/g for crystallization temperatures from 58 to 35°C, respectively. Optical microscopy studies indicate that the lower melting peak corresponds to a spherulitic type morphology and the higher melting peak correlates to a fine grained crystal structure. Wide angle X-ray powder diffraction studies do not detect differences in the crystal structures of samples exhibiting either one or two melting peaks, which suggests that the multiple melting phenomenon is due to differences in morphology rather than the presence of different crystal forms.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1617-1623 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The area under the linear loss modulus-temperature curves, LA, has been shown to be related to the chemical composition of the material. In addition, it can be significantly affected by morphology in multicomponent polymer systems. To characterize LA quantitatively, base-line corrections for instrumental contributions to LA were evaluated by several different methods and the results compared. In some instances, the calculation method affects only the LA magnitude, while general trends are unchanged; whereas in others, qualitative differences also become important. Not all of the methods described can be utilized universally. However, a straight-line-type of base line, similar to that which is used in infrared spectroscopy and differential scanning calorimetry, provides a widely applicable means of quantifying the loss area.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 49-56 
    ISSN: 1042-7147
    Schlagwort(e): Damping ; Glass transition ; IPNs ; Loss modulus ; Morphology ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: The shape of the glass transition plays a critical role in the engineering performance of polymers in sound and vibration damping, as well as other applications. The transition may be affected by fillers, plasticizers, blending, IPN formation, etc. A collection of data, both original and literature, is presented which illustrates how the phenomenon works. Emphasis is placed on the role of the area under the linear loss modulus-temperature curve, which may be evaluated in a fashion similar to other spectroscopic techniques. In addition, the loss area can be significantly affected by morphological factors.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1731-1741 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The areas under the linear loss modulus versus temperature curves (loss area, LA) and tan δ versus temperature curves (TA) were evaluated for a number of acrylic, methacrylic, styrenic and butadiene based copolymers and interpenetrating polymer networks, IPNs, as a function of crosslink density and comliosition, and were compared with values predicted by group contribution analysis. The LAs of the sequential IPNs, cross-poly(n-butyl methacrylate)-inter-crosspolystyrene, were found to exhibit up to 30% larger LAs than the poly(n-butyl metacrylate-stat-styrene) copolymers, which had LAs slightly less than the values predicted from the group contribution analysis. At constant chemical composition (50% n-butyl methacrylate, 50% styrene), LA equals 14.4 GPa K for the IPN, attributed to a synergistic effect resulting from the IPN's microheterogeneous morphology, as compared with 10.7 GPa K for the single phase, miscible copolymer. Increases in the LA with increased concentration of polymer, network II were also observed for cross-poly(ethyl acrylate)-inter-crosspolystyrene and cross-polybutadiene-inter-cross-polystyrene IPNs. On the other hand, cross-polybutadiene-inter-cross-poly(methyl methacrylate) IPNs had LAs much lower than were predicted by the group contribution analysis, which were attributed to lower miscibility in this system relative to the other systems evaluated. In general, decreased crosslink densities and lower concentrations of network II increased TA. These findings demonstrate how the morphology of a multiphase polymeric material can affect LA and TA, with significant increases In damping capability over the average of the component polymer values.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 1321-1329 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: At a constant isothermal crystallization temperature (Tc), the crystalline morphologies of several polymers have been found to be a function of the melt-liquid temperature (T1). At a constant Tc below a critical crystallization temperature (T*c [about 0.9 T*m(K)], a transition from a nonspherulitic to a spherulitic morphology occurs when the melt liquid is heated above a melt-liquid transition temperature, (Tlt) [approximately 1.03 Tm (K)], where Tm is the observed melting temperature of the sample. The melt-liquid transition temperature, Tlt, which experimentally affects the visible morphology of a semicrystalline polymer, is apparently indistinguishable from the thermodynamic melting temperature, T*m, determined by the Hoffman-Weeks procedure. The X-ray powder diffraction patterns of spherulitic and nonspherulitic morphologies were identical, independent of the heating-cooling cycle. This suggests that the transition that occurs at TIt does not affect the arrangement of polymer molecules in the crystallite, but only the manner in which the crystallites are arranged in the supermolecular morphology. The evidence suggests, at least for the polymers studied, that a residual order exists in the melt until the T*m or TIt of the particular polymer is reached. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 21 (1991), S. 68-68 
    ISSN: 0045-205X
    Schlagwort(e): Life and Medical Sciences
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...