首页 | 官方网站   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   330篇
  免费   0篇
数理化   330篇
  2018年   10篇
  2017年   8篇
  2016年   13篇
  2015年   5篇
  2014年   5篇
  2013年   9篇
  2012年   5篇
  2011年   8篇
  2010年   4篇
  2009年   6篇
  2008年   9篇
  2007年   5篇
  2006年   7篇
  2003年   2篇
  2002年   2篇
  2001年   6篇
  2000年   4篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1993年   4篇
  1992年   2篇
  1991年   5篇
  1990年   8篇
  1989年   8篇
  1988年   9篇
  1987年   11篇
  1986年   14篇
  1985年   7篇
  1984年   4篇
  1983年   13篇
  1982年   5篇
  1981年   8篇
  1980年   6篇
  1979年   14篇
  1978年   12篇
  1977年   11篇
  1976年   5篇
  1975年   4篇
  1974年   5篇
  1972年   6篇
  1971年   7篇
  1970年   6篇
  1969年   2篇
  1968年   6篇
  1967年   8篇
  1966年   6篇
  1965年   5篇
排序方式: 共有330条查询结果,搜索用时 11 毫秒
321.
This paper is concerned with the Hess case in the Euler–Poisson equations and with its generalization on the pencil of Poisson brackets. It is shown that in this case the problem reduces to investigating the vector field on a torus and that the graph showing the dependence of the rotation number on parameters has horizontal segments (limit cycles) only for integer values of the rotation number. In addition, an example of a Hamiltonian system is given which possesses an invariant submanifold (similar to the Hess case), but on which the dependence of the rotation number on parameters is a Cantor ladder.  相似文献   
322.
323.
Substituted 5-arylazopyrimidines and 2-arylazopyrimidines have been synthesized and investigated as dichroic dyes with positive dichroism, for liquid crystals. A promising series of 2-aryl-5-arylazopyrimidine dyes has been found, and a method is proposed for their synthesis by condensation of 2-aryl-5-aminopyrimidines with nitrosobenzenes in a superbasic medium.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 209–214, February, 1993.  相似文献   
324.
The Hamiltonian representation and integrability of the nonholonomic Suslov problem and its generalization suggested by S. A. Chaplygin are considered. This subject is important for understanding the qualitative features of the dynamics of this system, being in particular related to a nontrivial asymptotic behavior (i. e., to a certain scattering problem). A general approach based on studying a hierarchy in the dynamical behavior of nonholonomic systems is developed.  相似文献   
325.
In this paper we consider the dynamics of a rigid body with a sharp edge in contact with a rough plane. The body can move so that its contact point is fixed or slips or loses contact with the support. In this paper, the dynamics of the system is considered within three mechanical models which describe different regimes of motion. The boundaries of the domain of definition of each model are given, the possibility of transitions from one regime to another and their consistency with different coefficients of friction on the horizontal and inclined surfaces are discussed.  相似文献   
326.
In this historical review we describe in detail the main stages of the development of nonholonomic mechanics starting from the work of Earnshaw and Ferrers to the monograph of Yu. I.Neimark and N.A. Fufaev. In the appendix to this review we discuss the d’Alembert–Lagrange principle in nonholonomic mechanics and permutation relations.  相似文献   
327.
This paper is concerned with the motion of a helical body in an ideal fluid, which is controlled by rotating three internal rotors. It is proved that the motion of the body is always controllable by means of three rotors with noncoplanar axes of rotation. A condition whose satisfaction prevents controllability by means of two rotors is found. Control actions that allow the implementation of unbounded motion in an arbitrary direction are constructed. Conditions under which the motion of the body along an arbitrary smooth curve can be implemented by rotating the rotors are presented. For the optimal control problem, equations of sub-Riemannian geodesics on SE(3) are obtained.  相似文献   
328.
329.
Oxygen diffusion in atactic poly(methyl methacrylate) has been studied by anthracene luminescence quenching in geminate pairs anthracene-oxygen at 77–130 K. Analysis of the experimental data shows that the luminescence quenching is well accounted for by a polychromatic model assuming a log-normal diffusion coefficients distribution due to inhomogeneity of polymer structure. Energy activation is equal to 30 ± 1 KJ/mol. All diffusion coefficients data in the range 77–300 K demonstrate a good linear Arrhenius law. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 127–131, 1998  相似文献   
330.
The regularities of lateral scattering of ions in amorphous and polycrystal targets were derived. In contrary to well known LSS' method the proposed theoretical procedure enables to calculate root-mean-square deviations of ranges and lateral ranges for arbitrary ratios of target atom to ion masses within a wide range of energies from several MeV to energies near the binding energy of the atoms in solids. The theoretical estimates of root-mean square lateral deflection of ions are in good agreement with experimental results of different authors.  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-23

京公网安备 11010802026262号