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991.
Franz A. Pohl und Willy Bonsels 《Fresenius' Journal of Analytical Chemistry》1958,161(2):108-114
Zusammenfassung Es wird eine spurenanalytische Methode zur Bestimmung von Verunreinigungen in hochreinem Indium beschrieben. Die Elemente Blei, Eisen, Cadmium, Kupfer, Thallium, Wismut und Zink werden durch Isopropylätherextraktion aus Halogensäuren angereichert und polarographisch bestimmt. Die Bedingungen zur extraktiven Anreicherung werden eingehend behandelt. Zur Vermeidung von Einschleppungen wird weitgehend im geschlossenen System gearbeitet. Die Bestimmung der genannten Elemente ist bis 10–6% mit einer Genauigkeit von besser als ± 10% möglich. 相似文献
992.
993.
A new efficient palladium(II)-catalyzed oxidative carbocyclization has been developed. It was found that allene-substituted olefins 1 cyclized in the presence of 1 mol % Pd(O2CCF3)2 and p-benzoquinone (2 equiv) to give bicyclic ring systems 2 in good to excellent yields. The cyclization constitutes a new type of carbon-carbon bond forming reaction between an allene and an olefin under oxidative conditions. 相似文献
994.
995.
J. Franz G. Guzielski G. Huber G. Mecklenbrauck W. Mecklenbrauck E. Rössle U. Glawe U. Strohbusch B. Johnsson G. G. Jonsson R. Petersson 《Zeitschrift fur Physik C Particles and Fields》1981,10(2):105-116
Absolute cross sections for inclusive electron scattering on H, D, Be, Al, and Si have been measured in the kinematical region 0.08 (GeV/c)2<Q 2<1.0 (GeV/c)2 and 0.3 GeV<v<6.5 GeV. The measurements have been performed at incident energies of 3, 5, 6, and 7 GeV and at the fixed scattering angle of 10°. A careful treatment of radiative corrections due to elastic electron nucleus scattering, quasielastic and inelastic scattering on the bound nucleons has been applied to the measured cross sections. The comparison of the nuclear cross sections with the elementary ones leads to a value ofA eff<A with a rapid onset of this effect at small values of the scaling variablex′. 相似文献
996.
Franz Konecny 《Journal of multivariate analysis》1983,13(4):605-611
An approximation theorem of stochastic differential equations driven by semimartingales is proved, based on approximation of semimartingales by a sequence of processes with piecewise monotonic sample functions. 相似文献
997.
DDDr. Franz Langmayr 《Monatshefte für Mathematik》1979,86(4):285-300
An important problem in the field of Diophantine Approximation was solved in 1891 byHurwitz. He could show that any irrational number can be approximated by infinitely many rationals in such a way that the modulus of the difference multiplied with the square of the denominator is less than 5–1/2, and there 5–1/2 is best possible.-The generalization of this problem in the direction of simultaneous Diophantine Approximation is still unsolved.Furtwängler in 1925 gave lower bounds for the maximum difference, conjecturing that these were best possible.-Here it is shown that in the two dimensional caseFurtwängler's bounds are indeed best possible for certain irrationals lying in cubic number fields which are not totally real. Yet by considering totally real cubic fields we are led to replaceFurtwängler's conjecture by a new one. 相似文献
998.
Franz Aurenhammer 《Discrete and Computational Geometry》1987,2(1):49-64
A criterion is given that decides, for a convex tilingC ofR
d
, whetherC is the projection of the faces in the boundary of some convex polyhedronP inR
d+1. Its applicability is restricted neither by the properties nor by the dimension ofC. It turns out to be conceptually simpler than other criteria and allows the easy examination of various classes of cell complexes. In addition, the criterion is constructive, that is, it can be used to constructP provided it exists.Research was supported by the Austrian Fonds zur Foerderung der wissenschaftlichen Forschung. 相似文献
999.
Franz Embacher 《Foundations of Physics》1984,14(8):721-738
Newtonian and Machian aspects of the stationary gravitational field are brought into formal analogy with a stationary electromagnetic field. The electromagnetic vector potential equals (up to a factor) the timelike Killing vector field. The current density is given by the contraction of the Killing vector with the Ricci tensor. A coordinate-dependent split in electric and magnetic field vectors is given, and some results of classical electrodynamics are used to illustrate the analogy. In the linearized theory, the usual Maxwell equations are obtained. The analogy also holds from the point of view of particle motion. The geodesic equation is brought into a special form that exhibits an analog to the Lorentz force. Two examples (which have played an important role in the theoretical discovery of Machian effects) are considered. 相似文献
1000.
Günter Michl Dawit Abebe Franz Bucar Asfaw Debella Olaf Kunert MartinG. Schmid Efrem Mulatu Ernst Haslinger 《Helvetica chimica acta》2000,83(2):359-363
Two new bisdesmosidic triterpenoid saponins, i.e. 1 and 2 , were isolated, besides the three known saponins 3 – 5 , from the MeOH extract of the aerial parts of Achyranthes aspera Linn. (Amaranthaceae). Their structures were elucidated as β‐D ‐glucopyranosyl 3β‐[O‐α‐L ‐rhamnopyranosyl‐(1→3)‐O‐β‐D ‐glucopyranuronosyloxy]machaerinate ( 1 ) and β‐D ‐glucopyranosyl 3β‐[O‐β‐D ‐galactopyranosyl‐(1→2)‐O‐α‐D ‐glucopyranuronosyloxy]machaerinate ( 2 ) by NMR spectroscopy, including 2D‐NMR experiments (machaerinic acid=3β,21β‐dihydroxyolean‐12‐en‐28‐oic acid). The other saponins were identified as β‐D ‐glucopyranosyl 3β[O‐α‐L ‐rhamnopyranosyl‐(1→3)‐O‐β‐D ‐glucopyranuronosyloxy]oleanolate ( 3 ), β‐D ‐glucopyranosyl 3‐β‐[O‐β‐D ‐galactopyranosyl‐(1→2)‐O‐β‐D ‐glucopyranuronosyloxy]oleanolate ( 4 ), and β‐D ‐glucopyranosyl 3β‐[O‐β‐D ‐glucopyranuronosyloxy]oleanolate ( 5 ) (oleanolic acid=3β‐hydroxyolean‐12‐en‐28‐oic acid). 相似文献