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981.
982.
983.
Diane Ung Guillaume Viau Franoise Fivet-Vincent Frdric Herbst Vincent Richard Fernand Fivet 《Progress in Solid State Chemistry》2005,33(2-4):137-145
Co50Ni50 particles with very unusual shapes, resembling dumbbells or diabolos, are obtained by reducing mixtures of cobalt and nickel acetates in sodium hydroxide solution in 1,2-propane diol. These particles consist of a central column richer in cobalt than the overall composition, capped with two terminal platelets that are richer in nickel. These hybrid shapes are the result of a two-step growth mechanism due to a difference in reactivity of the two metal ions. The sodium hydroxide concentration controls the length and diameter of the column, in the ranges 50–250 nm and 5–15 nm, respectively, and the diameter of the platelets in the range 25–50 nm. The X-ray diffraction patterns show a mixture of hcp and fcc phases in various proportions depending on the particle shape. High-resolution electron microscopy shows that the hcp phase is located mainly in the central column and the fcc phase mainly in the terminal platelets. The particles are ferromagnetic at room temperature. When the volume fraction of the central column is high enough and the hcp phase is predominant and not much faulted, high coercivity (up to 1900 Oe) is observed. 相似文献
984.
Fatima Zohra Trodi Guillaume Lucas Mustapha Bencharif Jean-François Halet Samia Kahlal Jean-Yves Saillard 《Journal of Cluster Science》2007,18(3):729-740
Density functional theory (DFT) calculations carried out on a series of [M4(CO)12N2]2+ and M4(CO)12N2 (M=Fe, Ru, Os) predict that the M4N2 square bipyramidal (octahedral) architecture should be stable for the particular electron count of 6 skeletal electron pairs (or 60 metal valence electrons). This octahedral architecture is electron-deficient with respect to the Wade-Mingos rules and exhibits a through-cage N–N bond of order one. Thus, these hypothetical clusters present a new coordination mode of dinitrogen. 相似文献
985.
Simon T. Belt Guillaume Massé W.Guy Allard Jean-Michel RobertSteven J. Rowland 《Tetrahedron letters》2003,44(51):9103-9106
The structures of two polyunsaturated monocyclic triterpenes have been elucidated using NMR spectroscopy following their isolation from the common marine diatom, Rhizosolenia setigera. The structure of a related monocyclic sesterterpene is proposed on the basis of mass spectral comparisons with the two monocyclic triterpenes. 相似文献
986.
Bismuth triflate catalyzes the ring opening of epoxides with aromatic amines under aqueous conditions. The reaction proceeds rapidly and affords the corresponding β-amino alcohols in excellent yields. 相似文献
987.
Abstract— Phylogenetic analysis of the retrotransposon and retrovirus suggests an evolutionary relationship between them and indicates that transactivation of the long terminal repeat (LTR)-containing retroelements could be ubiquitous. Using constructs expressing a reporter gene under the control of the entire or deleted LTR of 1731, which is a retrotransposable element of Drosophila melanogas-ter , we were able to show that the UVB-irradiation activation of the 1731-LTR requires the same short sequence of U3 region in a human epithelial cell line as in Schneider's Drosophila cell line (S2). This sequence is similar to the binding sequence of the members of the nuclear factor-kB (NF-kB)/rel family. In addition, human colonic carcinoma cells (HT29), in response to UVB-irradiation, produce some extracellular factor(s) that activates the 1731-LTR in nonirradiated cells. 相似文献
988.
We describe a method for complete solution of the superelliptic Diophantine equation ayp=f(x). The method is based on Baker's theory of linear forms in the logarithms. The characteristic feature of our approach (as compared with the classical method) is that we reduce the equation directly to the linear forms in logarithms, without intermediate use of Thue and linear unit equations. We show that the reduction method of Baker and Davenport [3] is applicable for superelliptic equations, and develop a very efficient method for enumerating the solutions below the reduced bound. The method requires computing the algebraic data in number fields of degree pn(n-1)/2 at most; in many cases this number can be reduced. Two examples with p=3 and n=4 are given. 相似文献
989.
A. Mirmelstein A. Podlesnyak V. Voronin S. Lebedev B. Goshchitskii P. Allenspach J. Mesot U. Staub M. Guillaume P. Fischer A. Furrer 《Physica C: Superconductivity and its Applications》1992,200(3-4):337-343
The crystal structure and the crystalline-electric-field splitting of the Er3+ 4f-shell in the high-Tc superconductor ErBa2Cu3Ox (x = 6.95, 6.18) disordered with fast neutron irradiation has been investigated by elastic and inelastic neutron scattering techniques, respectively. The results yield evidence for the absence of a charge transfer between the planes and chains under disorder and point to the atomic displacements being the main radiation-induced defects in the CuO2 planes. 相似文献
990.
Vives G Giansante C Bofinger R Raffy G Del Guerzo A Kauffmann B Batat P Jonusauskas G McClenaghan ND 《Chemical communications (Cambridge, England)》2011,47(37):10425-10427
Selective nucleophilic substitution on a perfluorophenyl unit comprising a BODIPY fluorophore using an alkanethiol or a primary amine offers a quantitative fluorophore labelling strategy, while retaining high photostability and emission quantum yields approaching unity. 相似文献