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981.
982.
983.
G.Biju Kumar Hetal.V Patel Amrish C Shah Markus Trenkle Christine J Cardin 《Tetrahedron: Asymmetry》1996,7(12):3391-3396
N-Arylsulfonamides of (R)- and (S)-2-amino-1-butanol, on condensation with aromatic aldehydes produced diastereomerically pure 2-aryl-3-arenesulfonyl 4-ethyl-1,3-oxazolidines. The absolute configurations of one enantiomeric pair have been determined from two fully refined X-ray structures, supplemented by nmr data. 相似文献
984.
S. A. J. Wiegers B. Tieke U. Zeitler R. Fletcher A. K. Geim J. C. Maan M. Henini 《Czechoslovak Journal of Physics》1996,46(5):2461-2462
We have investigated the interaction of phonons with a 2DEG in the FQH regime with phonon drag thermoelectric power (TEP). We find that the TEP at filling factors with the same even denominator is identical and at other even denominator filling factors they differ only by a constant. Assuming these states to be Composite Fermions (CF), we can explain our observations by extending a zero magnetic field theory for phonon drag to the CF-phonon interaction. This analysis is further corroborated by the observed T4 dependence of the CF TEP. 相似文献
985.
The presented one-capacitor pinch driver, designed as a compact coaxial structure (including spark-gap and discharge section) consistent with the capacitor output, generates a current of 200 kA with 700 ns quarter-period, suitable for studying the optimization of Z-pinch radiative characteristics. The driver is described, measurements of its parameters summarized, and relations to our previous and future activities briefly reviewed.This work was supported in part by the Grant Agency of the Czech Republic under contract No. 202/93/1023. 相似文献
986.
Thermally induced phase conjugation by degenerate four-wave mixing in solutions of Rhodamine 6G in ethanol in the weak absorption region, low-reflectivity regime, and nonosecond time domain is reported. Evidence of oscillatory acoustic modes in the nonlinear medium is presented and existing theories are shown to explain satisfactorily the experimental results. 相似文献
987.
G. Baldsiefen H. Hübel W. Korten U. J. van Severen J. A. Cizewski N. H. Medina D. R. Napoli C. Rossi Alvarez G. Lo Bianco S. Signorelli 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):337-338
High-spin states in196Pb have been populated using the reaction170Er(30Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin. 相似文献
988.
J. Urban H. Sack-Kongehl K. Weiss 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,36(1):73-83
Structure and reactivity with oxigen of Cu clusters in the size range of 4.5±2.5 nm created by the inert gas aggregation technique were studied by HREM. The pure Cu clusters investigated under clean conditions show the structures of MTP's with a small lattice dilatation of the (111) plane of 1.25%. For icosahedral and decahedral particles this dilatation corresponds to a splitting of the nearest neighbour distance showing two different values, i.e. dilatation of 2.2% and contraction of 2.8% for the two edges of the deformed tetrahedral subunits, respectively. Oxidation at room temperature and air pressure of 1 bar only begins after a few minutes of exposure to air, after having undergone creation of probably non-stoichiometric intermediate states in the cuprite Cu2O structure with the bulk values of the bond lengths. 相似文献
989.
A. Mahoui J. Lapasset D. G. Sannikov J. Moret P. Saint Grégoire 《Zeitschrift für Physik B Condensed Matter》1995,99(4):543-549
The crystal structure [(C2H5)4N]2CuCl4 has been determined by X-ray diffraction at 243K. The room temperature phase (phase I) belongs to the space group P42/nm [1] whereas the low temperature phase (phase II) is orthorhombic and belongs to the space group Pnna. The phase transition at Tc=258K is of improper ferroelastic type and it is associated with the ordering of the CuCl4 2? and a partial ordering of the [(C2H5)4N]+ ions which are disordered in the high temperature tetragonal phase. At lower temperature, there occurs another instability which could correspond to a complete ordering in the crystal. 相似文献
990.
The temperature dependence of the NMR chemical shift of129Xe dissolved in liquid alkanes is examined in the context of the reaction field model. An essential feature of the theory is the inclusion of the temperature dependence of the density of thesolvent. The theory of free volume for liquids is incorporated into the reaction field model to account for this temperature dependence. Comparison of the theory with previously reported measurements indicates the sensitivity of the129Xe chemical shift to the free volume of liquids. Incorporation of free volume improves the agreement between measurement and theory for branched alkane solvents, and resolves the origin of the 62 ppm intercept in the plot of reaction field as a function of129Xe chemical shift for the n-alkanes. 相似文献