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We reduce the problem on multiplicities of simple subquotients in an -stratified generalized Verma module to the analogous problem for classical Verma modules. 相似文献
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A new, highly potent activator for molybdenum hexacarbonyl and 2-fluorophenol is described. An "instant"catalyst formed in situ from molybdenum hexacarbonyl and 2-fluorophenol shows high activity for cross- and ring-closing alkyne metathesis reaction. The use of 2-fluorophenol can be combined with other activation methods to allow alkyne metathesis at relatively low temperature (80 degrees C). 相似文献
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We study the structure of the semigroup IO n of all order-preserving partial bijections on an n-element set. For this semigroup we describe maximal subsemigroups, maximal inverse subsemigroups, automorphisms and maximal nilpotent subsemigroups. We also calculate the maximal cardinality for the nilpotent subsemigroups in IO n which happens to be given by the n-th Catalan number. 相似文献
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Natalya F. Salivon Yaroslav E. Filinchuk Volodymyr V. Olijnyk 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):m57-m58
The title complex, [CuCl(C4H8OS)]n, contains infinite spiral (CuS)n chains linked by bridging Cl atoms into layers. The Cl atoms do not form polymeric fragments with CuI, but combine into isolated centrosymmetric Cu2Cl2 units. The compound is non‐isomorphous with the Br‐containing analogue, which contains Cu8S8 rings linked by Br atoms into chains. The O atom of the 1,4‐oxathiane molecule does not realize its coordination abilities in the known copper(I)–halide complexes, while in copper(II)–halide complexes, oxathiane is coordinated via the S and O atoms. This falls into a pattern of the preferred interactions, viz. weak acid (CuI atom) with weak base (S atom) and harder acid (CuII atom) with harder base (O atom). 相似文献
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Volodymyr Kysil Sergey Tkachenko Caroline Williams Marina Churakova 《Tetrahedron letters》2007,48(36):6239-6244
New trimethylchlorosilane (TMSCl) promoted multicomponent reaction (MCR) of ethylenediamine(s), diverse carbonyl compounds, and isocyanides is proposed for the synthesis of a variety of highly substituted 3,4,5,6-tetrahydropyrazin-2-amines including corresponding spirocyclic compounds. 相似文献
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Stepan Oryshchyn Volodymyr Babizhetskyy Olga Zhak Jean-Yves Pivan Arndt Simon 《Journal of solid state chemistry》2010,183(11):2534-2543
The new ternary pnictides Er12Ni30P21 and Er13Ni25As19 have been synthesized from the elements. They crystallize with hexagonal structures determined from single-crystal X-ray data for Er12Ni30P21 (space group P63/m, a=1.63900(3) nm, c=0.37573(1) nm, Z=1, RF=0.062 for 1574 F-values and 74 variable parameters), and for Er13Ni25As19 (Tm13Ni25As19-type structure, space group P6?, a=1.6208(1) nm, c=0.38847(2) nm, Z=1, RF=0.026 for 1549 F-values and 116 variable parameters). These compounds belong to a large family of hexagonal structures with a metal-metalloid ratio of 2:1. HRTEM investigations were conducted to probe for local ordering of the disordered structure at the nanoscale. The magnetic properties of the phosphide Er12Ni30P21 have been studied in the temperature of range 2<T<300 K and with applied fields up to 5 T. The magnetic susceptibility follows the Curie-Weiss law from 4 to 300 K. The measured value of μeff=9.59 μB corresponds to the theoretical value of Er3+. 相似文献