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991.
Maxim V. Pavlov 《Communications in Mathematical Physics》2007,272(2):469-505
The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. The class of
symmetric hydrodynamic type systems is defined and the calculation of the associated Riemann surfaces is greatly simplified for this
class. Many interesting and physically motivated examples are investigated. 相似文献
992.
R. Centore P. Riccio S. Fusco A. Carella A. Quatela S. Schutzmann F. Stella F. De Matteis 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2719-2725
We have prepared new polyesters containing quadratic, nonlinear optical (NLO) active chromophores covalently incorporated into the main chain. In these polymers, the sequence of the chromophore units along the main chain is rigorously head to tail. All the polyesters are processable, both in the melt and in solution. For one polyester, a full second‐order NLO characterization has been performed. An out‐of‐resonance d33 coefficient of 21 pm/V at 1368 nm has been measured. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2719–2725, 2007 相似文献
993.
O. E. Kvyatkovskii 《Crystallography Reports》2004,49(1):4-14
It is shown that, proceeding from the first principles, it is possible to separate the contributions from short-and long-range interactions to the lattice dynamics and dielectric properties of crystalline dielectrics. The cluster calculations of local force constants and potentials for the matrix and impurity atoms in ferroelectrics with the perovskite structure were made by the Hartree-Fock MOLCAO-SCF method. The parameters of the Devonshire-Slater-Barrett single-ion model are calculated for barium titanate and potassium niobate. The influence of the quantum statistics on the Curie temperature in these ferroelectrics and the isotope effect in barium titanate are also considered. 相似文献
994.
This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel.
From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission
electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the
block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant
in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different
values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly
oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical
particle model with a locked aspect ratio. 相似文献
995.
N. Foroughifar A. Mobinikhaledi M. Amrollahi M. Zendehdel 《Applied magnetic resonance》2004,26(4):483-488
C(2)-H exchange incis-[(en)2Co(HIm)(enH)]Br4 (Im, imidazole; en, ethylenediamine) was studied over a pD range of 9.4 to 10.2 at 60°C where thecis-[(en)2Co(Him)(enH)]4+ andcis-[(en)2Co(HIm)(en)]3+ are the species present in significant concentrations.Cis-[(en)2Co(HIm)(enH)]4+ has pKa1 7.86 and pKa2 9.82 with pKa1 corresponding to coordinated enH ionization and pKa2 to ImH ionization. The kinetic data may be interpreted in terms of an intramolecular H-D exchange mechanism, where the “dangling”-ND2CH2CH2ND2 group acts as a base to remove the imidazole C(2)-H proton from the coordinated DIm moiety. 相似文献
996.
The norm kernel of the A=12 system composed of two 6He clusters, and the L=0 basis functions (in the SU(3) and angular momentum-coupled schemes) are analytically obtained in the Fock-Bargmann space. The norm kernel has a diagonal form in the former basis, but the asymptotic conditions are naturally defined in the latter one. The system is a good illustration for the method of projection of the norm kernel to the basis functions in the presence of SU(3) degeneracy that was proposed by the authors. The coupled-channel problem is considered in the algebraic version of the resonating-group method, with the multiple decay thresholds being properly accounted for. The structure of the ground state of 12Be obtained in the approximation of zero-range nuclear force is compared with the shell-model predictions. In the continuum part of the spectrum, the S-matrix is constructed, the asymptotic normalization coefficients are deduced and their energy dependence is analyzed. 相似文献
997.
The triple differential cross-section for K-shell ionization of silver and copper atoms by relativistic electrons have been
computed in the coplanar symmetric geometry with the inclusion of exchange effects following the multiple scattering theory
of Das and Seal [1] multiplied by suitable spinors. Present computed results are marginally improved in some cases from the
previous computed results [2]. Present results are compared with measured values [3] and with previous computation results
[2]. Some other theoretical computational results are also presented here for comparison.
相似文献
998.
We solve the problem of diffraction of fluctuating radiation by an optically thin irregular layer (phase screen) with developed turbulent structure. It is shown that in the case of diffraction of radiation with saturated fluctuations and a narrow-band frequency spectrum by a weakly turbulent moving phase screen, the measured frequency spectrum of intensity fluctuations in the observation plane allows one to obtain information on the form of the spectrum of irregularities of an optically thin irregular layer in a wide size range significantly exceeding the size of the first Fresnel zone. Similarly to the well-known phase method of diagnostics of randomly irregular media, the conventional scintillation method modified in such a way yields undistorted information on the form of the irregularity spectrum. However, in contrast to the phase method, it also allows one to obtain data on the drift velocity of irregularities in the studied irregular layer. 相似文献
999.
N. V. Vysotina N. N. Rozanov V. E. Semenov V. A. Smirnov S. V. Fedorov D. N. Christodoulides 《Optics and Spectroscopy》2005,98(6):895-903
The polarization structure of nonparaxial spatial solitons in a transparent medium with the electronic mechanism of Kerr nonlinearity is studied theoretically. It is demonstrated analytically in the weak nonparaxiality approximation that the regime of polarization locking, in which all the field components have the same propagation constant, is the only stable regime. Estimates of the rate of transition of the initial metastable regime of rotation of the polarization ellipse to the regime of polarization locking are presented. Based on a numerical solution of the nonlinear Maxwell equations, the presence of the nonparaxial regime of polarization locking is confirmed and the main characteristics of the corresponding spatial solitons are obtained. 相似文献
1000.
V. I. Vershinin 《Journal of Analytical Chemistry》2005,60(9):880-891
Russian standards in training conventional graduates and bachelors are considered. These standards determine the status and volume of analytical chemistry courses at different higher educational institutions. An analysis of the educational standards, standard curricula, and the aims of teaching analytical chemistry suggests the advisability of changing the content of the course, particularly at industrial (branch) higher educational institutions. The provision of the analytical chemistry course with special literature (manuals, textbooks), equipment, and computer software is considered. 相似文献