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  • 1985-1989  (6)
  • 1965-1969
  • 1960-1964
  • 1989  (6)
  • General Chemistry  (3)
  • Polymer and Materials Science  (3)
Materialart
Erscheinungszeitraum
  • 1985-1989  (6)
  • 1965-1969
  • 1960-1964
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1475-1484 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: By use of agarose gel electrophoresis, the sieving of spherical particles in agarose gels has been quantitated and modeled for spheres with a radius (R) between 13.3 and 149 mm. For quantitation, the electrophoretic mobility has been determined as a function of agarose percentage (A). Because a previously used model of sieving [D. Rodbard and A. Chrambach (1970) Proc. Natl. Acad. Sci. USA 65, 970-977] was found incompatible with some of these data, alternative models have been tested. By use of an underivatized agarose, two models, both based on the assumption of a single effective pore radius (PE) for each A, were found to yield PE values that were independent of R and that were in agreement with values of PE obtained independently (PE = 118 nm × A-0.74): sieving by altered hydrodynamics in a cylindrical tube of radius, PE, and sieving by steric exclusion from a circular hole of radius, PE. The same analysis applied to a 6.5% hydroxyethylated commercial agarose yileded a steeper PE vs A plot and also agreement of the above tow models with the data. The PE vs A plot was significantly altered by both further hydroxyethylation and factors that cause variation in the electro-osmosis found in commercial agarose.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1040-0397
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Five crown ethers with four ring oxygen atoms and different types of pendant groups were used to prepare ion-selective electrodes by coating a membrane containing the crown ether on the tip of a silver wire incorporated in a flow cell. A flow injection analysis study was conducted to determine the potentiometric selectivities of the crown ethers for lithium, sodium, potassium, magnesium, and calcium ions. It was found that crown ethers with neutral side arms show selectivities for lithium over other ions, while those of acidic side arms show selectivities for potassium over the other ions. The effect of the addition of trioctylphosphine oxide to the electrode matrix was also investigated. A comparison is made between the potentiometric selectivities of the crown ethers for certain metal ions and their selectivities in extracting the ions into an organic phase.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1911-1925 
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Carboxy-terminated polybutadiene neutralized with Cu2+ (CuPBD) and its blend with poly(styrene-co-4-vinylpyridine) (SVP) were examined by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), and extended x-ray absorption fine structure (EXAFS) spectroscopy. The DSC results indicate that in the blend substantial mixing occurs in the CuPBD-rich phase, although complete miscibility is not achieved, and the SVP-rich phase remains relatively pure. The TEM micrographs indicate that the morphology, while irregular, is reasonably described as bicontinuous, with a domain size of order 100 nm. The SAXS patterns show that the ionic aggregates present in CuPBD are destroyed upon blending, which is interpreted as being due to steric hindrances between ionic groups coordinated to vinylpyridine nitrogens. The EXAFS radial structure function of the blend exhibits a marked decrease in the Cu-Cu peak in comparison with CuPBD, indicating a change in local structure upon blending. The results indicate that some of the SVP is miscible with CuPBD owing to complexation between the pendant pyridine groups and the Cu2+ ions, which disrupts the ionic aggregates. However, the two materials are not fully miscible, leading to a rather coarse two-phase morphology.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 101 (1989), S. 1235-1243 
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis vor kurzem war die Produktion von Galliumarsenid, Indiumphosphid und verwandten Halbleitern eine Domäne der Materialwissenschaftler und Elektroingenieure. Durch geschickten Einsatz der klassischen Chemie, veranschaulicht an der thermischen Reaktion von Me3Ga und AsH3, ist es möglich, Halbleiter in kommerziellem Maßstab herzustellen. Es gibt jedoch einige Nachteile dieser Methoden, so die Umwelt- und Gesundheitsrisiken bei der Handhabung pyrophorer und giftiger Materialien, Probleme bei der Kontrolle der Stöchiometrie und unerwünschte Nebenreaktionen. Kann der anorganisch oder metallorganisch orientierte, präparativ arbeitende Chemiker auf diesem wichtigen Gebiet durch Konzeption und Entwicklung neuer Reagentien für die Produktion von Halbleitern eine nützliche Rolle spielen? Wir glauben, die Antwort lautet ja, und in dem vorliegenden Beitrag diskutieren wir einen neuen Weg zur Herstellung von dünnen GaAs- und InP-Filmen, basierend auf III/V-Komplexe als einziger Quelle. Diese Komplexe weisen starke Bindungen zwischen den Elementen der III. und V. Hauptgruppe des Periodensystems auf, und sie tragen Substituenten, die leicht thermisch eliminiert werden können. Die III/V-Komplexe sind gegenüber Luft und Feuchtigkeit stabiler und erheblich weniger toxisch als Addukte oder Mischungen aus III- und V-Verbindungen.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0570-0833
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 1208-1215 
    ISSN: 0570-0833
    Schlagwort(e): Gallium arsenide ; Semiconductors ; Single-source precursors ; Metallacycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Until recently, the production of gallium arsenide, indium phosphide, and related compound semiconductors has fallen in the domain of the materials scientist and the electrical engineer. By clever use of classical chemistry, exemplified by the thermal reaction of Me3Ga and AsH3, it is possible to make semiconductors on a commercial scale. However, there are some drawbacks associated with the existing methodology, including the environmental and health hazards of handling pyrophoric and toxic starting materials as well as stoichiometry control problems and undesirable side reactions. Can the synthetic inorganic and organometallic chemist play a useful role in this important area by designing and developing new reagents for the production of semiconductor materials? We believe the answer is yes, and in this article we discuss a new approach to the preparation of GaAs and InP thin films based on single-source precursors. These compounds feature strong σ-bonding between the group III and V elements, together with substituents that are capable of facile thermal elimination. The III/V precursors are more stable toward air and moisture and considerably less toxic than either adducts or mixtures of group III and V compounds.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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