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  • 1
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Zusammenfassung Nachdem gezeigt wurde, unter welchen Bedingungen die Ableitung einer Potentialgleichung in der Magnetogasdynamik möglich ist, wird diese diskutiert. Da sie beim Übergang vom unterkritischen in den überkritischen Bereich den Typ ändert, ist das Variationsverfahren die einzige Möglichkeit, eine geschlossene Lösung für beide Bereiche zu erhalten. Es wird das zur Potentialgleichung gehörige Variationsproblem abgeleitet und für die Umströmung eines Zylinders mitk=1,5 gelöst. Die beiden Figuren (Figur 1 im Maßstab 1∶33 und Figur 2 im Maßstab 1∶16,6) stellen die Strömungslinien und die Linien gleicher Mach-Zahl für einen Zylinder mit dem RadiusR=1m bei einem MagnetfeldH=10000 Γ und einer AnströmgeschwindigkeitU=500 m/sec dar.
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  • 2
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Improved measurements of the ratio of scattering cross sections for various molecular rotational states are reported for scattering of TlF in rotational states ¦J, M〉=¦1, 0〉 and ¦1, 1〉, and CsF in rotational states ¦2, 0〉 and ¦2, 2〉 by rare gases. The results are interpreted in terms of an angle dependent attractive potentialV=−2ε(r m /r) 6(1+q 6 P 2(cosΘ) in which the repulsive part of the interaction is neglected. The “high energy” approximation is used to calculate the cross section, which contains the velocity dependence and the state dependence as factors. The experiments show for all scattering partners with the exception of He and Ne, that the state dependence is velocity independent. In those cases this result provides a justification for the neglect of the repulsive potential term. The results for the anisotropy parameterq 6, which to a good approximation depends only on properties of the moleculus, are:q 6=0.23±0.01 for TlF,q 6=0.28±0.02 for CsF.
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  • 3
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a previous paper the anisotropy parameter of the attractive part of the intermolecular potential has been determined from total cross sections measured by scattering of TlF-molecules in selected rotational states by rare gases. In this series of papers, further measurements on the systems TlF-He, Ne, Ar, Xe, CH4, and CsF-He, Ar will be described. In the case of CsF-He, it has been possible to determine the anisotropy parameter of the repulsive part of the potential additionally, by comparing cross sections related to different rotational states over a large velocity range and by using the high energy approximation. The determination of the anisotropy parameter for the repulsive potential requires knowledge of the parameters of the angle averaged potential. Part I describes the determination of these parameters for a Lennard-Jones-potential from measurements of the velocity dependence and the absolute value of the total cross section by scattering of not state selected CsF-molecules by He and Ar. Since these systems show no glory undulations in the experimentally accessible velocity range, they require an evaluation procedure, which is independent of the appearance of such undulations. The procedure described below only uses the velocity dependence of the cross section itself by fitting of quantum mechanically calculated cross sections. The finite resolving power of the apparatus and the influence of velocity distributions are taken into account. The results are communicated, the parallel evaluation of an experiment on K-Ar serves as a test for the procedure described.
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  • 4
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The type I carbonaceous chondrites, with volatiles between 24 and 30% (at 1000 C, N2 atm.), contain the maximum percentage of the low-temperature ground mass, in which the high-temperature minerals are dispersed as ‘microchondrules’. In the type II carbonaceous chondrites (vol. 12–24%), the loosely cohering aggregates of microchondrules, ‘grape-bunch chondrules’, reach a maximum. The type III carbonaceous chondrites and some enstatite chondrites (vol. 2–12%) contain the maximum of the ‘partly coalesced chondrules’, in which microchondrules of olivine and nickel-iron appear. The ureilites are interpreted as impact shocked aggregates of microchondrules in differing states of coalescence. The ‘fully coalesced chondrules’ are characteristic for the ordinary chondrites with volatiles below 1%. It appears that the evolution of chondrules with the decrease of volatiles in meteorites subdivides into: (A) primary condensation of microchondrules with diameters of 0.01 mm; (B) secondary accretion of the former into the chondrules of diameter range ±1 mm. The observations may be explained through the hypothesis that at the highest-temperature stage of condensation of the asteroid-type parent body was an incandescent cloud (preserved through the solidification of chondrules at an early stage of degassing) covered with cosmic dust. The carbonaceous chondrites orginate from the marginal incandescent fog and the correspondingly deeper zones of the incandescent cloud mantle. The absence of typical chondritic rocks on earth may be explained by the slower cooling rate of this celestial body of relatively greater mass.
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  • 5
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2,3,6-Glucose-tricarbanilate prepared by degradation of cellulosetricarbanilate in 1-hydroxy-2-methoxy-ethane in presence of p-toluenesulfonic acid was condensed with phosphorpentoxide in a mixture of chloroform-dimethyl sulfoxide. Light scattering measurements gave degrees of polymerization up to 640. Contrarily to cellulose- and amylosetricarbanilates there was no definite relation between the STAUDINGER-Indices and molecular weights. Also no angular dependence of the scattered light was found. The products therefore are branched. The side chains are bound to the carbanilate groups, for after alkaline saponification of the polyglucosans the degrees of polymerization decrease to about 60. Degradation experiments with α-amylase and cellulase, optical rotation in tetraethylammoniumhydroxide and viscosity measurements of polyglucosans compared with those of different cellodextrins showed clearly that only 1,4-β-glucosidic linkages are present in the synthetic polysaccharides and that the products are not branched.
    Notes: 2,3,6-Glucosetricarbanilat  -  aus Cellulosetricarbanilat durch Alkoholyse in 1-Hydroxy-2-methoxy-äthan in Gegenwart von p-Toluolsulfosäure hergestellt  -  wurde in Chloroform/Dimethylsulfoxid durch Phosphorpentoxid kondensiert. Streulichtmessungen der Polykondensate ergaben Polymerisationsgrade bis 640. Zum Unterschied von Cellulose- und Amylosetricarbanilaten wurde keine eindeutige Beziehung zwischen STAUDINGER-Indices und Molekulargewichten gefunden. Die Streulichtintensität ergab keine Winkelabhängigkeit. Die Produkte müssen daher verzweigt sein. Die Seitenketten sind an die Carbanilatgruppen gebunden, denn nach alkalischer Verseifung lagen die Polymerisationsgrade bei ca. 60. Aus Abbauversuchen mit α-Amylase und Cellulase, Drehwerten in Tetraäthylammoniumhydroxid und vergleichenden Viskositätsmessungen an den Polyglucosanen und verschiendenen Cellodextrinen geht hervor, daß nur 1,4-β-glucosidische Bindungen in den synthetischen Polysacchariden vorliegen und daß die Produkte unverzweigt sind.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Experiments for preparing hexachlorotitanates by reaction of TiCl4 with alkali chlorides or calcium chloride in pressure bombs at 550-750°C are described. Pure K2TiCl6 and Cs2TiCl6 were obtained, whereas the reaction products from LiCl, NaCl and CaCl2 contained not more than 4 to 6.5 weight per cent of titanium. A content of up to 0.24 weight per cent trivalent titanium is found at higher temperatures resulting from evolution of elemental chlorine from the titanium tetrachloride.
    Notes: Es werden Versuche zur Darstellung von Hexachlorotitanaten aus TiCl4 und Alkalichlorid oder Calciumchlorid in Druckbomben bei Temperaturen von 550-750°C beschrieben. K2TiCl6 und Cs2TiCl6 können dabei rein und wasserfrei erhalten werden, während mit LiCl, NaCl und CaCl2 nur Produkte mit Titangehalten von max. 4 bis 6,5 Gew.-% entstehen. Mit steigender Versuchstemperatur treten in den Präparaten durch Cl2-Abspaltung aus dem TiCl4 entstandene Gehalte an dreiwertigem Titan auf, die bis zu 0,24 Gew.-% betragen können.
    Additional Material: 2 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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