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961.
Henk D.L Hollmann János Körner Simon Litsyn 《Journal of Combinatorial Theory, Series A》1997,80(2):388-393
We show that if the collection of all binary vectors of lengthnis partitioned intokspheres, then eitherk2 orkn+2. Moreover, such partitions withk=n+2 are essentially unique. 相似文献
962.
963.
Kokovi M. Lawson DakuRoger F. Newton Simon P. PearceJulia Vile Jonathan M.J. Williams 《Tetrahedron letters》2003,44(27):5095-5098
Reverse-phase glass beads have been employed in Suzuki reactions to provide, in aqueous media, a route to diverse polar substrates in good yield and with low levels of palladium leaching. 相似文献
964.
Simon N. Chandler-Wilde Peter Monk Martin Thomas 《Journal of Computational and Applied Mathematics》2007
In this paper we study, via variational methods, a boundary value problem for the Helmholtz equation modelling scattering of time harmonic waves by a layer of spatially varying refractive index above an unbounded rough surface on which the field vanishes. In particular, in the 2D case with TE polarization, the boundary value problem models the scattering of time harmonic electromagnetic waves by an inhomogeneous conducting or dielectric layer above a perfectly conducting unbounded rough surface, with the magnetic permeability a fixed positive constant in the medium. Via analysis of an equivalent variational formulation, we show that this problem is well-posed in two important cases: when the frequency is small enough; and when the medium in the layer has some energy absorption. In this latter case we also establish exponential decay of the solution with depth in the layer. An attractive feature is that all constants in our estimates are bounded by explicit functions of the index of refraction and the geometry of the scatterer. 相似文献
965.
Stephan Müller David Scheidegger Carsten Haber Wilhelm Simon 《Journal of separation science》1991,14(3):174-177
Fused silica columns of 4.6 μm i.d. were coated with 3-sulfopropylsilane as a cation exchanger and 3-(2-aminoethyl-amino)-propylsilane as an anion exchanger. Fast separations of cations (< 25 seconds) and of anions (< 35 seconds) were obtained, using a potentiometric microelectrode as a detector. In proceeding towards smaller i.d.s, a mixture of alkali metal cations could be separated successfully in an uncoated fused silica capillary of 2.3 μm i.d. as a result of retention by the surface silanol groups at pH 9.4. 相似文献
966.
Strain distributions in the cold drawing of polycarbonate cylindrical bars were obtained at three nominal strain rates using the method of photoplasticity. Optical-mechanical constitutive equations were interpreted based on a physical model. The strain distribution in the necked portion of the rod is shown to be nonuniform, regardless of the strain rate. Comparison between the integrated diameters and the measured diameters gives an average error between 4 and 12 percent. An interesting trend in the fringe patterns with and without a central loop has been observed and attributed to the higher strain-rate effect for patterns without a central loop. 相似文献
967.
P. Simon 《Acta Mathematica Hungarica》2002,94(1-2):31-43
968.
Xavier Fradera Jordi Poater Sílvia Simon Miquel Duran Miquel Solà 《Theoretical chemistry accounts》2002,108(4):214-224
This article presents an overview of recent advances in the study of electron pairing through the use of localization and
delocalization indices obtained from double integration over atomic basins of the exchange–correlation density in the framework
of the atoms-in-molecules theory. These localization and delocalization indices describe the intra- and interatomic distribution
of the electron pairs in a molecule. The main results of the application of these second-order indices to the analysis of
molecular structure and chemical reactivity are briefly reviewed. It is shown that localization and delocalization indices
represent a powerful tool to describe the electron-pair structure of molecules, which, in turn, provides deeper insight into
relevant chemical phenomena such as electron correlation effects and the formation of localized α, β electron pairs.
Received: 8 April 2002 / Accepted: 26 June 2002 / Published online: 6 September 2002
Acknowledgements. Financial help was furnished by the Spanish DGES projects no. PB98-0457-C02-01 and BQU2002-04112-C02-02. J.P. thanks the
Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for benefiting from a doctoral
fellowship, no. 2000FI-00582. M.S. is indebted to the Departament d'Universitats, Recerca i Societat de la Informació of the
Generalitat de Catalunya for financial support through the Distinguished University Research Promotion, 2001. We also thank
the Centre de Supercomputació de Catalunya for providing us with computing facilities.
Correspondence to: M. Solà e-mail: miquel.sola@udg.es 相似文献
969.
970.
Received May 20, 1997; accepted in final form July 21, 1997. 相似文献