首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   99篇
  免费   0篇
化学   6篇
力学   1篇
数学   39篇
物理学   53篇
  2022年   1篇
  2020年   1篇
  2019年   3篇
  2018年   2篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   4篇
  2013年   3篇
  2012年   2篇
  2010年   1篇
  2009年   1篇
  2008年   4篇
  2007年   4篇
  2006年   1篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   4篇
  2001年   3篇
  1999年   2篇
  1998年   4篇
  1997年   6篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1987年   4篇
  1986年   3篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   4篇
  1981年   6篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1974年   3篇
  1970年   2篇
  1967年   1篇
排序方式: 共有99条查询结果,搜索用时 250 毫秒
91.
Indole and its derivatives with various substituants in the 1 and 2 positions of the indole ring react with 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene and 2-trifluoromethyl-3,3-dicyanoacrylic acid esters to give C3-alkylation products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1193–1195, May, 1991.  相似文献   
92.
93.
The Poisson superalgebra realized on smooth Grassmann-valued functions with compact support has a central extension at some values of the superdimension. We find formal deformations of these central extensions. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 156, No. 2, pp. 250–269, August, 2008.  相似文献   
94.
Measurements have been made for pure crystals and for ones containing oxygen after exposure to neutrons and to a 660 MeV proton beam. The conductivity for a pure crystal is unaltered, whereas that of an oxygen-bearing crystal decreases. The two types of crystal differ only slightly in optical absorption. It is concluded that there is no single mechanism responsible for the coloring and conductivity reduction in oxygen-bearing fluorite crystals.  相似文献   
95.
The usual rules for constructing the Lagrangian of fictitious particles in gauge theories is generalized. The gauge invariant and multiplicative renormalizability of the theory with generalized action in nonlinear gauges is proved.Translated from Izvestiya Vysshikh, Uchebnykh Zavedenii, Fizika, No. 6, pp. 11–15, June, 1981.The author thanks I. A. Batalin and B. L. Voronov for discussing the problems considered here.  相似文献   
96.
This paper completes the review of the theory of self-adjoint extensions of symmetric operators for physicists as a basis for constructing quantum-mechanical observables. It contains a comparative presentation of the well-known methods and a newly proposed method for constructing ordinary self-adjoint differential operators associated with self-adjoint differential expressions in terms of self-adjoint boundary conditions. The new method has the advantage that it does not require explicitly evaluating deficient subspaces and deficiency indices (these latter are determined in passing) and that boundary conditions are of explicit character irrespective of the singularity of a differential expression. General assertions and constructions are illustrated by examples of well-known quantum-mechanical operators like momentum and Hamiltonian.  相似文献   
97.
We discuss a problem of constructing self-adjoint ordinary differential operators starting from self-adjoint differential expressions based on the general theory of self-adjoint extensions of symmetric operators outlined in [1]. We describe one of the possible ways of constructing in terms of the closure of an initial symmetric operator associated with a given differential expression and deficient spaces. Particular attention is focused on the features peculiar to differential operators, among them on the notion of natural domain and the representation of asymmetry forms generated by adjoint operators in terms of boundary forms. Main assertions are illustrated in detail by simple examples of quantum-mechanical operators like the momentum or Hamiltonian. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 3–36, August, 2007.  相似文献   
98.
We introduce two remarkable identities written in terms of single commutators and anticommutators for any three elements of an arbitrary associative algebra. One is a consequence of the other (fundamental identity). From the fundamental identity, we derive a set of four identities (one of which is the Jacobi identity) represented in terms of double commutators and anticommutators. We establish that two of the four identities are independent and show that if the fundamental identity holds for an algebra, then the multiplication operation in that algebra is associative. We find a generalization of the obtained results to the super case and give a generalization of the fundamental identity in the case of arbitrary elements. For nondegenerate even symplectic (super)manifolds, we discuss analogues of the fundamental identity.  相似文献   
99.
It is shown that A:= H1, η (G), the sympectic reflection algebra over ?, has TG independent traces, where TG is the number of conjugacy classes of elements without eigenvalue 1 belonging to the finite group G ? Sp(2N) ? End(?2N) generated by the system of symplectic reflections.

Simultaneously, we show that the algebra A, considered as a superalgebra with a natural parity, has SG independent supertraces, where SG is the number of conjugacy classes of elements without eigenvalue -1 belonging to G.

We consider also A as a Lie algebra AL and as a Lie superalgebra AS.

It is shown that if A is a simple associative algebra, then the supercommutant [AS, AS] is a simple Lie superalgebra having at least SG independent supersymmetric invariant non-degenerate bilinear forms, and the quotient [AL, AL]/([AL, AL] ∩ ?) is a simple Lie algebra having at least TG independent symmetric invariant non-degenerate bilinear forms.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号