排序方式: 共有29条查询结果,搜索用时 169 毫秒
1.
A. é. Mistryukov I. D. Sadekov V. S. Sergienko G. M. Abakarov M. A. Porai-Koshits A. A. Shneider A. D. Garnovskii 《Chemistry of Heterocyclic Compounds》1989,25(12):1407-1409
The crystal and molecular structure of 2-phenylbenzotellurazole is determined by x-ray methods. The heterocyclic fragment of the molecule is planar. The dihedral angle between planes of the heterocycle and the 2-phenyl substituent is 31.2. Somewhat shortened Te-N intermolecular ocntacts (3.43 å) are seen in the crystal. These do not substantially affect the physical properties of the compound.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1690–1692, December, 1989. 相似文献
2.
In this paper the effects of coupling a non-resonant optical lattice to a gas are studied. When the lattice induces a periodic modulation of the gas density, strong Bragg diffraction of light can occur limiting the achievable intensities inside the lattice reducing the ability to manipulate the gas with the lattice. We calculate the evolution of the light fields by finding solutions to the wave equation with a periodic refractive index induced by the lattice. The local gas density perturbation induced by the lattice is determined by solving the Boltzmann kinetic equation in the collisional regime. 相似文献
3.
The acylation of benzene, toluene, and chlorobenzene with cinchomeronic acid anhydride in the presence of AlCl3 has given in each case both possible isomers of the corresponding aroylpyridinecarboxylic acid. It was found that the yields of reaction products and their isomeric compositions depend on the conditions of performing the reaction. The intramolecular cyclization of the isomeric keto acids in the presence of 2% oleum has given 2-azaanthraquinone and chlorine derivatives of it.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 514–518, April, 1980. 相似文献
4.
Arbatsky N. P. Kenyon J. J. Shashkov A. S. Shneider M. M. Popova A. V. Kalinchuk N. A. Hall R. M. Knirel Yu. A. 《Russian Chemical Bulletin》2019,68(1):163-167
Russian Chemical Bulletin - The K5 capsular polysaccharide (CPS) was isolated from the bacterium Acinetobacter baumannii (A. baumannii) SDF and studied by 1D and 2D 1H and 13C NMR spectroscopy... 相似文献
5.
N. P. Arbatsky M. M. Shneider A. S. Shashkov A. V. Popova K. A. Miroshnikov N. V. Volozhantsev Y. A. Knirel 《Russian Chemical Bulletin》2016,65(2):588-591
Capsular polysaccharide (CPS) was isolated from a nosocomial pathogen Acinetobacter baumannii (A. baumannii) NIPH67 and studied by sugar analysis, Smith degradation, and 1H and 13C NMR spectroscopy. The CPS was found to contain 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac), and the structure of the linear trisaccharide repeating unit of the CPS was established as →4)-α-Psep5Ac7Ac-(2→6)-β-d-Galp-(1→3)-α-d-GalpNAc-(1→. The genetic content of the capsule biosynthesis cluster of A. baumannii NIPH67, designated KL33, is consistent with the established CPS structure, and thus the capsule of the investigated strain was assigned to K33 group. Functions of proteins including two glycosyltransferases encoded by the genes of the K33 locus were assigned based on the structure of CPS and by the comparison with related proteins of other capsular types of A. baumannii. 相似文献
6.
The magnetic properties of Ba2Cu3O4Cl2 and Sr2Cu3O4Cl2 oxychlorides have been studied. A spontaneous manifestation of diamagnetism has been found at quasi-zero and low fields. The temperature of these transitions coincides with the temperature of the antiferromagnetic ordering in Ba2Cu3O4Cl2 (T NI ≈ 337 K) and Sr2Cu3O4Cl2 (T NI ≈ 386 K). The recorded diamagnetic signal is ?10?4 emu. It is comparable with the percentage of the superconducting phase in the sample. It is supposed that the arising superconductivity is due to the formation of the superconducting clusters with the direct overlap of the copper d orbitals owing to the frustration processes. 相似文献
7.
I. A. Makarov S. G. Ovchinnikov E. I. Shneider 《Journal of Experimental and Theoretical Physics》2012,114(2):329-342
The influence of interlayer hoppings on the superconducting transition temperature (T
c) in bilayer cuprates has been studied. The parameter of hopping between layers is expressed as t
⊥(k) = t
⊥(cos(k
x
) − cos(k
y
))2 and treated as a small perturbation for the states of two CuO2 planes described by the t-t′-t″-J* model. In the generalized mean field approximation for dx2 - y2{d_{{x^2} - {y^2}}} symmetry of the superconducting gap, neither the interlayer hopping or exchange interaction, nor the pair hopping between
CuO2 layers provides an additional mechanism of Cooper pair formation or an increase in T
c. In the concentration dependence of T
c, the bilayer splitting of the upper Hubbard band of quasi-holes is manifested as two peaks with temperatures slightly lower
than the maximum T
c for a single-layer cuprate. Interlayer antiferromagnetic spin correlations suppress bilayer splitting. 相似文献
8.
Under the assumption of long-range antiferromagnetic order at low temperatures, the spectral functions and the density of states are calculated in the two-dimensional Hubbard model with half-filling in the Hubbard-I approximation. The results are compared with the data obtained using an exact numerical technique, namely, the quantum Monte Carlo method. The influence of hopping to the next-to-nearest neighbor on the formation of the electronic structure is considered. 相似文献
9.
S. G. Ovchinnikov E. I. Shneider 《Journal of Experimental and Theoretical Physics》2005,101(5):844-855
Electron-phonon interaction is sequentially derived from a realistic p-d multiband model for the cuprates under conditions of strong electron correlations. The electronic structure is described using the representation of the Hubbard X operators in a generalized tight-binding method. Dependences of the diagonal and off-diagonal (on lattice sites) matrix elements of electron-phonon interaction on the wavevectors are found for three phonon modes, namely, breathing, apical breathing, and bending modes. The interactions of the breathing and bending modes with electrons are shown to contribute to the formation of kinks in the (0; 0)-(π; π) and (0; 0)-(π; 0) directions, respectively. A low-energy t-J* model with phonons is developed; apart from electron-phonon interaction, it also includes spin-phonon interaction. The elimination of phonons gives an effective electron-electron interaction that depends on the occupation number of a multielectron term and on the carrier concentration due to strong electron correlations. 相似文献
10.