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排序方式: 共有417条查询结果,搜索用时 343 毫秒
1.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330024 相似文献
2.
It is shown that the three-dimensional Navier-Stokes equation for incompressible fluid can be represented as an equation including
only quaternions as co-ordinate operators and variables. Only the quaternion operations such as a quaternion product and a
quaternion conjugation over these variables are used. 相似文献
3.
L. V. Stepanova 《Journal of Applied Mechanics and Technical Physics》2008,49(1):142-147
This paper discusses the problem of finding the eigenvalue spectrum in determining the stress and strain fields at the tip
of an antiplane-shear crack in a power-law material. It is shown that the perturbation method provides an analytical dependence
of the eigenvalue on the material nonlinearity parameter and the eigenvalue of the linear problem. Thus, it is possible to
find the entire spectrum of eigenvalues and not only the eigenvalue of the Hutchinson-Rice-Rosengren problem.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 173–180, January–February, 2008. 相似文献
4.
5.
T. A. Stepanova V. I. Sheichenko L. P. Smirnova V. I. Glyzin 《Chemistry of Natural Compounds》1981,17(6):520-526
Six flavanones have been isolated for the first time from Siberian tansy, and two of them have proved to be new compounds. 相似文献
6.
E. A. Kuznetsova S. V. Zhuravlev T. N. Stepanova 《Chemistry of Heterocyclic Compounds》1970,4(2):183-185
The reduction of some dihydrothiazolobenzothiazolium salts with sodium borohydride may take place in two directions: with the formation of thiazolidino[2, 3-b]benzathiazolines and with the cleavage of the C-S bond to give N-(-mercaptoethyl)benzothiazolines. The behavior of thiazolidino[2, 3-b]benzothiazoline under the conditions of acid and alkaline hydrolysis has been studied.For communication VI, see [1]. 相似文献
7.
Andrey Shatskiy Anton Axelsson Elena V. Stepanova Jian-Quan Liu Azamat Z. Temerdashev Bhushan P. Kore Bjrn Blomkvist James M. Gardner Peter Dinr Markus D. Krks 《Chemical science》2021,12(15):5430
A protocol for stereoselective C-radical addition to a chiral glyoxylate-derived N-sulfinyl imine was developed through visible light-promoted photoredox catalysis, providing a convenient method for the synthesis of unnatural α-amino acids. The developed protocol allows the use of ubiquitous carboxylic acids as radical precursors without prior derivatization. The protocol utilizes near-stoichiometric amounts of the imine and the acid radical precursor in combination with a catalytic amount of an organic acridinium-based photocatalyst. Alternative mechanisms for the developed transformation are discussed and corroborated by experimental and computational studies.A protocol for stereoselective C-radical addition to a chiral glyoxylate-derived N-sulfinyl imine was developed through visible light-promoted photoredox catalysis, providing a convenient method for the synthesis of unnatural α-amino acids. 相似文献
8.
N. A. Keiko L. G. Stepanova I. D. Kalikhman M. G. Voronkov 《Chemistry of Heterocyclic Compounds》1976,12(10):1094-1097
The conditions of heteropolar and radical thiylation of 2-formyl-2,5-diethoxy-2,3-dihydro--pyrans were studied. Oxidation of the carbonyl group occurs along with the Cannizzaro reaction in the reaction of 2-formyl-2,5-diethoxy-2,3-dihydro--pyran with silver oxide in alkaline media. Oxidation of 2-formyl-2,5-dibutylthio-2,3-dihydro--pyran with silver oxide leads to stable 2,5-dibutylthio-2,3-dihydro--pyran-2-carboxylic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1319–1322, October, 1976. 相似文献
9.
N. A. Keiko Yu. A. Chuvashev T. A. Kuznetsova L. G. Stepanova L. I. Larina L. V. Sherstyannikova M. G. Voronkov 《Russian Chemical Bulletin》1998,47(7):1379-1381
Cyanosilylation of α-butylthioacrolein with trimethylsilyl cyanide occurs as 1,2-addition. Concurrent rapid dimerization of
α-butylthioacrolein occurred both in the presence and in the absence of H2PtCl6·6H2O as a catalyst to give 2,5-dibutylthio-2,3-dihydro-4H-pyran-2-carbaldehyde, whose cyanosilylation afforded the corresponding cyanohydrin. The latter is prone to retrodiene degradation
upon heating.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1418–1420, July, 1998. 相似文献
10.
Molecular mobility in thermotropic polyesters and side-chain polymers with different struc-ture of mesogens and spacers has been studied by dielectrical method in dilutesolutions. The results made it possible to establish the multiplicity of dielectric relaxationtransitions which reflects the small- and large-scale types of molecular motion. It was shownthat dielectric relaxation processes occurring in accordance with local mechanism (relaxationtimes 10~(-9)--10~(-7)s. and the activation energy 10--50kJ/mol) are due to the mobility of kineticchain elements of different length within a monomer units. It was found that the dielectricrelaxation process connected with a large-scale form of molecular motion (relaxation times10~(-5)--10~(-6)s. and the activation energy 100kJ/mol) did not depend on the molecular massbut was infiuenced by factors changing the conformational state of the macromolecule. It isestablished tha the cooperative reorientation mobility of associated mesogenic fragments isthe source of the large-scale process. 相似文献