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51.
52.
Polyester elastomers were prepared by block copolymerization of dimethyl terephthalate (DMT), butanediol (BDO), and polytetramethylene glycol (PTMG). Polyester from DMT and butanediol forms a high-melting hard segment in block copolyester to prevent undue chain slippage when fibers are stretched. High elongation was provided by soft segment which consisted of condensation product from DMT and PTMG. Experiments were carried out to determine the effect of composition variables on the properties of these elastomers, such as glass transition temperature, elongation at break, tenacity, and elastic recovery. The study on molecular characteristics of the elastic polyester showed that a leather-like region exists between glassy and rubbery regions. These elastomers were melt-spun to give elastic fibers which are competitive with commercially available Spandex-type fibers. 相似文献
53.
[reaction: see text] Radical cascade reaction with various 1,4-dienes and 1,4-enynes using dimethyl 2-(iodomethyl)cyclopropane-1,1-dicarboxylate as a homoallyl radical precursor smoothly proceeds through an iodine atom transfer mechanism to give functionalized bicyclo[3.3.0]octane derivatives in good yields. 相似文献
54.
Visible photoluminescence (PL) of nanocrystalline silicon (nc-Si) embedded in single crystal CaF2 formed on Si(1 1 1) has been studied and the influence of ex situ rapid thermal annealing (RTA) on the surface morphology and PL spectra has been studied. It has been found that the PL intensity and uniformity was improved by RTA with appropriate temperature and short annealing time. 相似文献
55.
Hiroshi Tanaka Takeo Yoshioka Yasutaka Shimauchi Akihiro Yoshimoto Tomoyuki Ishikura Hiroshi Naganawa Tomio Takeuchi Hamao Umezawa 《Tetrahedron letters》1984,25(31):3351-3354
The tricyclic quinone 8 was successfully synthesized from naphthazalin, and the total synthesis of (±)-2-hydroxyaklavinone via 8 was accomplished in an overall yield of about 18% through the regio-controlled route. 相似文献
56.
Results are given of the application of the CNDO/2 method to bonding in alkyllithium aggregates. Calculations relative to monomers and dim ers of methyl-, ethyl-, and vinyllithium, plus methyllithium tetramer are described. 相似文献
57.
Summary A simple and accurate method is described for the microdeter-mination of phosphorus and arsenic in some pharmaceutical organic compounds. It is based on the conversion of phosphorus and arsenic into phosphate and arsenate ions respectively, followed by precipitation with quinoline and sodium molybdate reagents. The excess quinoline in the supernatant is spectrophotometrically measured at 312.5 nm in an ammonium acetate background of pH 5.5. The results obtained with 24 structurally different phosphorus and arsenic compounds show an average recovery of 99% and a mean standard deviation of ±1%. Excipients and diluents normally used in drug formulations do not interfere.
Spektrophotometrische Bestimmung von Phosphor und Arsen in organischen Arzneimitteln
Zusammenfassung Eine einfache und genaue Methode zur Mikrobestimmung von Phosphor und Arsen in einigen organischen Arzneimitteln wurde angegeben. Sie beruht auf der Umsetzung des Phosphors zu Phosphat und des Arsens zu Arsenat sowie deren Fällung mit Chinolin und Natriummolybdat. Der Chinolinüberschuß wird spektrophotometrisch bei 312,5 nm in Ammonium-acetat bei pH 5,5 gemessen. Die mit 24 strukturell verschiedenen Phosphorbzw. Arsenverbindungen erhaltenen Resultate ergaben eine durchschnittliche Wiederfindungsrate von 99% und eine rel. Standardabweichung von ±1%. Arzneimittelträger und Verdünnungsmittel stören nicht.相似文献
58.
Professor R. Engelbrecht-Wiggans Professor R. J. Weber 《International Journal of Game Theory》1983,12(2):123-127
An example is given of a sequential auction in which, at equilibrium, the expected profit of an informed bidder may be strictly less than the expected profit of an uninformed bidder. This phenomenon is interpreted in terms of the internal game between a player's “types” which arises in a setting of incomplete information. 相似文献
59.
Munetaka Nakata Masaaki Sugie Harutoshi Takeo Chi Matsumura Tsutomu Fukuyama Kozo Kuchitsu 《Journal of Molecular Spectroscopy》1981,86(1):241-249
The microwave spectra of four isotopic species of dichlorine monoxide (OCl2) have been observed, and the rotational constants have been obtained. The rm structure for each isotopic species has been determined by Watson's method. The equilibrium structure has been estimated by taking proper averages of rm structures to be and ∠eClOCl = 110.886(6)°. The general applicability and the merit of the present method for estimating the equilibrium structure are pointed out. 相似文献
60.