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131.
TheK-Shell Electron-Capture ProbabilityP
K
for the Electron Capture of139Ce has been measured using the coincidence method. The detectors used have been a NaJ(Tl)-detector with Be-window for the Lanthan-X-ray, a Ge(Li)- and a 76.2 mm Ø×76.2 mm-NaJ(Tl)-detector for the 166 keV--ray. The escape-effect of the Lanthan-X-ray in the NaJ(Tl)-detector was investigated. The experimental results areP
K
K= 0.726±0.010 andP
K
=0.801±0.034 using K=0.906±0.026. 相似文献
132.
Willy Friedrichsen Winfried Seidel Tony Debaerdemaeker 《Journal of heterocyclic chemistry》1983,20(6):1621-1628
6,6-Diphenylfulvene (6) reacts with 2,4,6-triphenylpyrylium-3-olate (7) to give three [π2 + π-4] cyclo-adducts 8, 9, 10. Reduction of 8 with sodium borohydride yields a cage-like compound 12 whereas the action of the same reagent on 9 results in the formation of three carbinols 13, 14, 15 . Treatment of 9 with acetic acid/hydrogen chloride yields an isomer 18 . The structures of both 12 and 18 have been established by X-ray crystallography. 相似文献
133.
Tanja Hischer María Fernández Andrés R. Alcántara Winfried Hartmeier 《Tetrahedron》2005,61(31):7378-7383
Asymmetric benzoin condensation was performed using recombinant benzaldehyde lyase (BAL) from Pseudomonas fluorescens Biovar I. To enable the conversion of hydrophobic substrates, the enzyme was entrapped in polyvinyl alcohol and suspended in hexane. Compared to the reported application of the biocatalyst in an aqueous phase containing 20% DMSO, the productivity of the resulting gel-stabilised two-phase system was 3-fold better. The entrapment process had an efficiency of >90%, no enzyme or cofactor was lost during reaction or storage. The entrapped enzyme was stable in hexane for 1 week at 4 °C and more than 1 month at −20 °C. Without preceding optimisation the novel benzoins (R)-1,2-di(3-furanyl)-2-hydroxyethanone, (R)-2-hydroxy-1,2-di(3-thienyl) ethanone, (R)-1,2-di(4-ethoxyphenyl)-2-hydroxyethanone, (R)-1,2-di(3-ethoxyphenyl)-2-hydroxyethanone, (R)-2-hydroxy-1,2-di(3-tolyl)ethanone, and (R)-1,2-di(benzofuran-2-yl)-2-hydroxyethanone were prepared with yields up to 31.8% and enantiomeric excess >99%. 相似文献
134.
In this article the topologically exact sequences
of locally convex spaces are characterized for which for every locally convex space F the map id : FE F Q is a homomorphism, or equivalently, the map id L : FK F E is a topological injection. This is motivated by the problem of lifting Q-valued functions with certain given properties to E-valued functions with the same or slightly weaker properties, which may also be considered as the investigation of parameter dependences of solutions of linear (differential) equations. Applications to partial differential equations and to Fredholm functions are given. 相似文献
135.
Winfried Geyer 《Order》1993,10(4):363-373
In this paper, we consider the following reconstruction problem: Given two ordered sets (G, ) and (M, ) representing join- and meet-irreducible elements, respectively together with three relationsJ,,
onG×M modelling comparability (gm) and maximal noncomparability with respect tog (gm, butgm*) and with respect tom (gm, butgm*). We determine necessary and sufficient conditions for the existence of a finite latticeL and injections :GJ(L) and :MM(L) such that the given order relations and the abstract relations coincide with the one induced by the latticeL. 相似文献
136.
137.
Winfried Sickel Leszek Skrzypczak 《Proceedings of the Steklov Institute of Mathematics》2014,284(1):216-234
We investigate the compactness of embeddings of certain subsets of Nikol’skii-Besov spaces (defined on ? d ), consisting of essentially subradial functions, into Lebesgue spaces. Particular decay properties of radial functions are our main tool here. 相似文献
138.
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140.