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131.
132.
Al. Al. Berlin und V. G. Omjan 《Colloid and polymer science》1980,258(8):994
Ohne Zusammenfassung 相似文献
133.
V. I. Al’shits V. N. Lyubimov A. Radowicz 《Journal of Experimental and Theoretical Physics》2005,101(1):107-119
The conditions of existence of the zero components of electric field E and electric induction D accompanying a volume acoustic wave propagating in a piezoelectric medium have been studied. General equations describing the positions of the zero-field lines E(m) = 0 and the zero-induction points m0, such that D(m0) = 0 on the unit sphere (m2 = 1) of the wave propagation directions, are obtained. General theorems determining the conditions ensuring the existence of such lines and points, even in triclinic crystals, are formulated. The relationship between such directions and various elements of the crystal symmetry is analyzed. The vector fields D(m), which are always orthogonal to the wave normals m, in the vicinity of the zero-induction points m0 exhibit certain orientational singularities characterized by the Poincaré indices n = 0, ±1, ±2. The general analytical expressions are obtained for the n values in crystals with arbitrary anisotropy and specified for a number of crystals belonging to various symmetry classes. The conditions of stability of the orientational singularities with respect to small perturbations of the material moduli and a change in the crystal symmetry are considered. 相似文献
134.
M. V. Yakunin G. A. Al’shanskii Yu. G. Arapov V. N. Neverov G. I. Harus N. G. Shelushinina O. A. Kuznetsov A. de Visser L. Ponomarenko 《Physics of the Solid State》2005,47(1):49-53
The structure of the quantum-well valence band in a Ge(111) two-dimensional layer is calculated by the self-consistent method. It is shown that the effective mass characterizing the motion of holes along the germanium layer is almost one order of magnitude smaller than the mass for the motion of heavy holes along the [111] direction in a bulk material (this mass is responsible for the formation of quantum-well levels). This creates a unique situation in which a large number of subbands appear to be populated at moderate values of the layer thickness d w and the hole concentration p s . The depopulation of two or more upper subbands in a 38-nm-thick germanium layer at a hole concentration p s = 5 × 1015 m?2 is revealed from the results of measuring the magnetoresistance in a strong magnetic field aligned parallel to the germanium layers. The destruction of the quantum Hall state at a filling factor ν = 1 indicates that the two lower subbands merge together in a self-formed potential profile of the double quantum well. It is demonstrated that, in a quasi-two-dimensional hole gas, the latter effect should be sensitive to the layer strain. 相似文献
135.
G. M. Abramova A. M. Vorotynov G. A. Petrakovskii N. I. Kiselev D. A. Velikanov A. F. Bovina R. F. Al’mukhametov R. A. Yakshibaev É. V. Gabitov 《Physics of the Solid State》2004,46(12):2225-2228
Electrical, resonant, and magnetic properties of intercalated copper chromium disulfide CuCrS2 are studied. It is established that CuCrS2 is an antiferromagnetic semiconductor with Néel temperature TN=40.7 K and an effective magnetic moment of 4.3µB. Anomalies in the electrical, magnetic, and resonant properties of CuCrS2 are found at Tc=110 K, which suggest an electron transition accompanied by alteration of the valences of the 3d-metal ions. 相似文献
136.
M.?Al?HajjEmail author N.?Guihéry J.-P.?Malrieu B.?Bocquillon 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,41(1):11-21
The Blochs theory of effective Hamiltonians has been used to improve the Real Space Renormalization Group approach. The effective interactions between elementary blocks of a periodic lattice can be extracted from the knowledge of the spectrum of the dimers or trimers of blocks. The potentialities of the method are illustrated on a series of quasi 1-D and 2-D problems. The spin gap of two-leg ladders is calculated and an estimate of the impact of ferromagnetic couplings between two-leg ladders on the gap is presented. The method satisfactorily identifies the phase transitions in the 1/5-depleted square lattice as well as in the spin-frustrated Shastry-Sutherland lattice. The J
2/J
1 checkerboard lattice is studied and a location of the phase transition between the Néel phase and the dimer phase is proposed.Received: 11 June 2004, Published online: 30 September 2004PACS:
71.10.-W Theories and models of many-electron systems - 71.15.Nc Total energy and cohesive energy calculations - 75.10.-b General theory and models of magnetic ordering 相似文献
137.
I. A. Luk’yanchikova D. V. Ivlev M. G. Kiselev G. A. Al’per 《Russian Journal of General Chemistry》2004,74(8):1156-1162
The concentration dependence of the viscosity of tert-butanol-water mixtures in the range of tert-butanol mole fractions from 0 to 0.02 was studied experimentally and by computer simulation. The methods of potentials of mean force and statistical geometry were successfully applied to analysis of physical factors responsible for the extrema in the composition-property dependences. The maximum in the concentration dependence of the viscosity is due to association of solvent molecules.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1250–1256.Original Russian Text Copyright © 2004 by Lukyanchikova, Ivlev, Kiselev, Alper.This revised version was published online in April 2005 with a corrected cover date. 相似文献
138.
1-Alkynylboronates form five-membered zirconacycles with Cp(2)ZrCl(2)/2-EtMgBr as indicated by deuterium labeling. The zirconacycles add aldehydes to form seven-membered zirconacycles. Hydrolysis of the latter provides 5-hydroxy-1-alkenylboronates in fair to good isolated yields. Both aliphatic and aromatic aldehydes undergo insertion. 相似文献
139.
The liquid-gas phase transition is analyzed from the topologic properties of the event distribution in the observables space. A multicanonical formalism allows one to directly relate the standard phase transition with neutral particles to the case where the nonsaturating Coulomb interaction is present, and to interpret the Coulomb effect as a deformation of the probability distributions and a rotation of the order parameter. This formalism is applied to a statistical multifragmentation model and consequences for the nuclear multifragmentation phase transitions are drawn. 相似文献
140.
A theory of spin manipulation of quasi-two-dimensional (2D) electrons by a time-dependent gate voltage applied to a quantum well is developed. The Dresselhaus and Rashba spin-orbit coupling mechanisms are shown to be rather efficient for this purpose. The spin response to a perpendicular-to-plane electric field is due to a deviation from the strict 2D limit and is controlled by the ratios of the spin, cyclotron, and confinement frequencies. The dependence of this response on the magnetic field direction is indicative of the strengths of the competing spin-orbit coupling mechanisms. 相似文献