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  • Articles: DFG German National Licenses  (3)
  • Autonomously replicating sequence  (1)
  • Physics  (1)
  • nuclear magnetic resonance (NMR) imaging  (1)
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  • Articles: DFG German National Licenses  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 23 (1993), S. 547-548 
    ISSN: 1432-0983
    Keywords: Autonomously replicating sequence ; Recombinant DNA ; Nested deletions ; Mutagenesis ; Schizosaccharomyces pombe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasmids pSP1 and pSP2 are two new Schizosaccharomyces pombe ars1 multicopy vectors with the Saccharomyces cerevisiae LEU2 and URA3 genes as selectable markers. They are derivatives of S. cerevisiae integrative plasmids. These plasmids allow classical molecular genetic techniques, such as mutagenesis, nested deletions and sequencing, to be performed directly.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: nuclear magnetic resonance (NMR) imaging ; hydroxypropyl cellulose matrix ; water penetration rate ; slow-release formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An NMR imaging method was developed to estimate the rate of water movement in slow-release capsule matrices of pseudoephedrine HC1 and hydroxypropyl cellulose (HPC). Test capsules were first placed in a USP method 2 (paddles, 50 rpm) dissolution apparatus. Each plug was removed from the dissolution medium at predetermined times, blotted dry, and placed within the magnetic field of a General Electric 400-MHz wide-bore NMR spectrometer equipped with a microimaging accessory. Images were recorded along the transverse plane of each plug. The water penetration rate was determined by comparison of the cut and weighed contour plots of the images acquired. After 1 hr, the plugs tamped to 200 N exhibited water penetration to the center, while only 45% of the drug was released. The percentage dry matrix was fitted to the lost equation to obtain a diffusion coefficient of 4.15 × 10−6 cm2/sec. NMR imaging is set forth as an important and practicable technique to investigate drug formulations. In the HPC matrix system of this study, the NMR imaging results convincingly revealed the rate of hydration front penetration not to be a rate-limiting step in the drug release process.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3027-3042 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of low-density polyethylene, that is, a density of less than 0.925 g/cm3, has traditionally been accomplished by the use of free-radical initiators at high ethylene pressures or of an alpha olefin comonomer such as 1-butene at lower pressures. We investigated an alternative route to branched, low-density polyethylene with a single monomer, ethylene, as the feed in conjunction with multicomponent catalyst systems capable of in situ dimerization of ethylene and subsequent copolymerization to produce low-density polyethylene. This article discusses the details of the evaluation of a number of dual-functional systems based on Ziegler-Natta catalysts. Specific, well defined, dual-functional catalyst systems which could easily produce branched, low-density polyethylene with levels of 20-30 branches per 1000 carbon atoms were developed. Variations in the relative number of component catalysts resulted in systematic, predictable changes in the properties of the polyethylene produced, which demonstrated the utility of the dual-functional catalyst concept.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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