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  • 1
    ISSN: 1613-9674
    Keywords: Magnetic resonance imaging ; Computed tomography ; Maxillo-facial region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance imaging (MRI) studies were obtained in 49 cases of various diseases in the maxillo-facial region and the results compared with X-ray computed tomography (CT). Bot MRI and CT scans were performed in 44 cases. In 31 cases (70%), MRI provided similar or superior information to that of CT in the evaluation of various diseases. In 10 cases, MRI was superior to CT in defining the images of diseases, 7 cases of these were carcinomas. CT was superior to MRI in 5 cases, especially in demonstrating calcifications and bony changes. Artifacts caused by prosthetic metals and patient motion disturbed MR images. Our experience with MRI lead us the conclusion that it holds great potential and that it already had some advantages over CT in the maxillo-facial region.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 85-94 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In der vorliegenden Studie wurde die Permeation und Separation von Kohlendioxid durch eine wassergequollene Chitosanmembran untersucht. Die Chitosanmembran wurde durch in einem Trägergas enthaltenen Wasserdampf gequollen und zeigte nach dieser Behandlung eine hohe Gaspermeabilität. Bei Raumtemperatur durchdrang vorzugsweise Kohlendioxid die gequollene Chitosanmembran mit einer Permeabilität von 2,5·10-8 cm3 (STP) cm(s cm2 cmHg)-1 und einem CO2/N2 Trennfaktor von 70.Diese Trennleistung für Kohlendioxid wird durch die basischen Eigenschaften der Aminogruppen den Chitosanmolekülen hervorgerufen.Die Membranherstellungsbedingungen, wie zum Beispiel die Essigsäurekonzentration der Gießlösung, beeinflußten die Permeationsgeschwindigkeit. Der Einfluß der Arbeitstemperatur wurde ebenfalls untersucht. Um die Trennleistung der Membran zu erhöhen, wurden verschiedene Methoden der Membranbehandlung und Arbeitsbedingungen untersucht.
    Notes: The permeation and separation of carbon dioxide through a water-swollen chitosan membrane was studied. A chitosan membrane was swollen by water vapor contained in a feed gas and, thus treated, exhibited a large gas permeability. Carbon dioxide preferentially permeated through the swollen chitosan membrane with a permeability of 2.5·10-8 cm3 (STP) cm(s cm2 cmHg)-1 and a CO2/N2 separation factor of 70 at room temperature. This separation performance for CO2 resulted from the basic properties of the chitosan amino groups. The membrane preparation conditions, such as acetic acid concentration of the casting solution, affected the membrane permeation rate. The effect of the operation temperature was also measured. To increase the separation performance of the membrane, several methods of membrane treatment and operation were evaluated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1841-1846 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For a potential use of spiroorthoesters which polymerize with essentially zero shrinkage during polymerization, the preparation of spiroorthoester (I) bearing the perfluoroalkyl group was carried out. Spiroorthoester I was prepared by the reaction of ε-caprolactone with 2-(F-octyl)ethyl glycidyl ether (II), obtained from 2-(F-octyl)ethanol and epichlorohydrin, in the presence of catalytic amount of BF3OEt2. Spiroorthoester I underwent the cationic ring-opening polymerization by virtue of BF3OEt2 to obtain poly(ether-ester) with 2.7% expansion on polymerization. The presence of the perfluoroalkyl group had no significant effect on the polymerization of the spiroorthoester.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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