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31.
32.
The reactions of π-cyclopentadienylnickel carbonyl dimer with 3,3,3-trimethylpropynyldiphenylphosphine and phenylethynyldiphenylphosphine are described. The products have been characterized by elemental and mass spectral analysis, infrared and NMR spectroscopy. An acetylene bridged complex (π-C5H5Ni)2Ph2PC2-t-Bu, containing an uncoordinated phosphorus atom, has been prepared. The complex can be oxidized to the phosphine oxide derivative (π-C5H5Ni)2Ph2P(O)C2-t-Bu and converted to the phosphonium salts with methyl iodide or ethyl bromide. These are the first reported π-complexes of phosphonium salts. The complex (π-C5H5Ni)2Ph2PC2-t-Bu forms the novel mixed metal derivative [PdCl2][(π-C5H5Ni)2Ph2PC2-t-Bu]2 from bis(benzonitrile)-palladium dichloride. The dicarbonyl complexes Ni(CO)2(Ph2PC2R)2 (R t-Bu, Ph), the phosphine oxide complex (π-C5H5Ni)2(Ph2P(O)C2Ph) and the trinuclear nickel carbonyl derivative Ni(CO)3[(π-C5H5Ni)2Ph2PC2Ph] are described. 相似文献
33.
Experimental data on initial hydrate formation conditions have been obtained for the nitrogen-propane-water system in the L1HG, L1L2H, and L1L2HG regions, where L1 is the water rich liquid phase, L2 is the hydrocarbon rich liquid phase, H is the hydrate and the G is the vapor phase. The measurements covered a range of temperatures from about 275 to 293 K and pressures from about 0.3 to 17.0 MPa. The concentrations covered for the L1HG region extended from 0.94 to 75.0 mole percent propane in the gas phase, and for the L1L2H region they extended from 83.1 to 99.0 mole percent in the condensed liquid phase. Four-phase measurements were made at concentrations of propane from 18.1 to 71.1 mole percent in the gas phase.The experimental data were used to find a fitted binary interaction parameter for predicting hydrate formation in systems containing nitrogen and propane. 相似文献
34.
We are dealing with a numerical method for solving the problem of minimizing a difference of two convex functions (a d.c. function) over a closed convex set in
n
. This algorithm combines a new prismatic branch and bound technique with polyhedral outer approximation in such a way that only linear programming problems have to be solved.Parts of this research were accomplished while the third author was visiting the University of Trier, Germany, as a fellow of the Alexander von Humboldt foundation. 相似文献
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36.
Fulton R Jensen T Johnson DR Kagan H Kass R Morrow F Whitmore J Wilson P Bortoletto D Chen W Dominick J McIlwain RL Miller DH Ng CR Schaffner SF Shibata EI Shipsey IP Yao W Battle M Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Sharma V Skwarnicki T Thulasidas M Zhu G Csorna SE Letson T Alexander J Artuso M Bebek C Berkelman K Browder T Cassel DG Cheu E Coffman DM Crawford G DeWire JW 《Physical review D: Particles and fields》1991,43(3):651-663
37.
Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Skwarnicki T Stone S Thusalidas M Yao W Zhu G Barnes AV Bartelt J 《Physical review D: Particles and fields》1991,44(3):593-600
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39.
A simple semi-empirical approximation for the exchange energy (Ex), coupled with a tractable representation of the Coulomb energy (EC), has been found to yield very accurate results for the isotropic part of the interaction energy (Eint = Ex + EC) between two closed shell systems. The expression for Eint is based on the knowledge of the first order Coulomb energy and the first three terms in the asymptotic long range expansion of the second order Coulomb energy for the interaction and contains but one adjustable parameter which occurs in Ex. The usefulness of this approach for evaluating Eint is tested critically by using the non-bonded H(1s)H(1s) (3Σu+) interaction as a model (accurate values of the total interaction energy, the exchange energy, and various orders of Coulomb energies, are available for a wide range of R for this system). The results obtained for both Eint and (dEint/dR) are inremarkable agreement with the exact results of Kotos and Wolniewicz for R > 3 ao. Since the law of corresponding states for inert gas pairs holds equally well for the HH(3Σu+) interaction, our analysis of this simple system yields valuable information on the reliability of the approach for other van der Waals dimers. 相似文献
40.
In this paper,we are interested in HSS preconditioners for saddle point lin- ear systems with a nonzero(2,2)-th block.We study an approximation of the spectra of HSS preconditioned matrices and use these results to illustrate and explain the spectra obtained from numerical examples,where the previous spectral analysis of HSS precon- ditioned matrices does not cover. 相似文献