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61.
62.
Wolfgang A Herrmann Karl Öfele Denise v. Preysing Sabine K Schneider 《Journal of organometallic chemistry》2003,687(2):229-248
Due to the great importance of palladium-catalyzed Heck-type reactions in scientific and industrial chemistry, a lot of publications and reviews have been published during the last years describing this matter under different aspects. This article presents a summary of catalytic applications of palladium complexes with phosphorus ligands containing a metallated sp3-carbon centre (“palladacycles”) or with N-heterocyclic carbene ligands in C-C and C-N coupling reactions of aryl halides including recent results of mechanistic discussions about their role in the catalytic cycle. 相似文献
63.
Wolfgang Staubach 《Journal d'Analyse Mathématique》2003,91(1):389-400
In this paper, we present an explicit calculation of the heat kernel, fundamental solution and Schwartz kernel of the resolvent
for the Heisenberg Laplacian using Wiener path integrals and their realizations via the Trotter product formula. This also
gives another derivation of mehler’s formula. 相似文献
64.
Vipul Dav Wolfgang G. Glasser Garth L. Wilkes 《Journal of Polymer Science.Polymer Physics》1993,31(9):1145-1161
Fibers were spun from isotropic and anisotropic dimethylacetamide solutions of cellulose esters. Take-up speeds of the dry jet/wet spinning process varied. Water served as the coagulant. The mechanical properties of the fibers increased as spinning progressed from the isotropic to the anisotropic state of the solution. A trade-off in solubility and fiber properties was noted as the butyryl acetyl ratio decreased. Whereas high butyryl content enhances both overall solubility and the formation of liquid–crystalline solutions at lower concentration, it results in lower fiber modulus and strength. Morphology of the fibers depended on the coagulation rate which was influenced by the concentration of the sppinning solution. The level of orientation and crystallinity of the fibers increased somewhat when they were spun from liquid-crystalline solutions. © 1993 John Wiley & Sons, Inc. 相似文献
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Wolfgang M. Ruppert 《manuscripta mathematica》1998,96(1):17-22
If K is a number field of degree n over Q with discriminant D
K
and if α∈K generates K, i.e. K=Q(α), then the height of α satisfies with . The paper deals with the existence of small generators of number fields in this sense. We show: (1) For each $n$ there are
infinitely many number fields K of degree $n$ with a generator α such that . (2) There is a constant d
2 such that every imaginary quadratic number field has a generator α which satisfies .?(3) If K is a totally real
number field of prime degree n then one can find an integral generator α with .
Received: 10 January 1997 / Revised version: 13 January 1998 相似文献
67.
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Novel oscillatory flow results of phenoxy/organoclay nanocomposites are analysed considering the blocking effect of nanostructure on polymer chain mobility. The modification provoked by this hindering effect on loss tangent spectrum is investigated. The study of three different systems, involving a pristine montmorillonite and two montmorillonites modified with one alkyl tail and two alkyl tails, respectively, leads to conclude that polymer-alkyl repulsive interactions play the most important role in the chain mobility obstruction process. Our results suggest that polymer-alkyl interactions increase with temperature. 相似文献
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