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   268448篇
  免费   2058篇
  国内免费   631篇
化学   142351篇
晶体学   4169篇
力学   11936篇
综合类   9篇
数学   29593篇
物理学   83079篇
  2019年   2298篇
  2018年   3120篇
  2017年   3116篇
  2016年   4492篇
  2015年   2661篇
  2014年   4288篇
  2013年   10710篇
  2012年   8103篇
  2011年   9918篇
  2010年   7101篇
  2009年   6889篇
  2008年   9324篇
  2007年   9539篇
  2006年   8896篇
  2005年   8087篇
  2004年   7439篇
  2003年   6744篇
  2002年   6671篇
  2001年   7338篇
  2000年   5675篇
  1999年   4371篇
  1998年   3866篇
  1997年   3856篇
  1996年   3595篇
  1995年   3343篇
  1994年   3508篇
  1993年   3205篇
  1992年   3685篇
  1991年   3678篇
  1990年   3614篇
  1989年   3469篇
  1988年   3577篇
  1987年   3466篇
  1986年   3290篇
  1985年   4368篇
  1984年   4644篇
  1983年   3883篇
  1982年   4020篇
  1981年   3941篇
  1980年   3922篇
  1979年   3892篇
  1978年   4198篇
  1977年   4122篇
  1976年   4182篇
  1975年   3862篇
  1974年   3906篇
  1973年   4064篇
  1972年   2857篇
  1971年   2385篇
  1970年   2182篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
In 1980 Chern and Terng defined a Bäcklund transformation for affine minimal surfaces. In this paper we show that this Bäcklund transformation can be simply represented by an involution and translation of the affine conormal.  相似文献   
92.
93.
Moscow Institute of Electronic Engineering. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 89, No. 1, pp. 132–150, October, 1991.  相似文献   
94.
A new microscopic model of anomalous muonium for the elemental semiconductors is proposed. The relevant configuration consisting of both a diamagrentic molecule Si−Mu and an unpaired orbital e is contained into a semivacancy of the real lattice. By using the unrestricted Hartree-Fock computational method the principal properties of the system are established. A dynamical version of the model together with a question on the formation of such system are discussed.  相似文献   
95.
A random-medium model which is a correlated distribution of points (particles) randomly positioned in the 3-dimensional space is considered. The construction of the medium starts from a noncorrelated (Poisson) distribution of parent particles, each of them initiates a finite Markov chain of its descendants. The complete collection of correlation functions of all orders within the scope of the model have been obtained. The use of the 3-dimensional stable law (Lévy law) as a transition probability allows us to present the correlation function in an explicit form. Proceedings of the XVII Seminar on Stability Problems for Stochastic Models, Kazan, Russian, 1995, Part II.  相似文献   
96.
97.
Kalman's theory is extended to a complete, smooth, and irreducible algebraic curve of arbitrary genus.  相似文献   
98.
A method is proposed for evaluating the resistance of a flywheel rim to radial stresses in free rotation. The method is based on loading a rim segment in pure bending and calculating the limiting moment and the corresponding limiting angular velocity. Applicability of the method is substantiated theoretically by investigating the similarity of the radial stress diagrams in rotation and pure bending. The method is verified experimentally for the strained state of a rim segment in pure bending.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 4, pp. 521–526, July–August, 1993.  相似文献   
99.
The equation for the Noether operator is obtained. It gives the necessary conditions for complete integrability of the field equations. For several double-component models the Hamiltonian pairs and the recursion operators are presented.  相似文献   
100.
Poly (n-butylisocyanate)-benzene solutions prepared by solubilization at 45°C, followed by aging at room temperature were found to be metastable for months, although, eventually, they separated into a birefringent polymer-rich phase and an isotropic solution. These metastable solutions, as well as isothermally phase-separated biphasic samples, flowed and exhibited dynamic moduli indicative of low polymer connectivity. By contrast samples prepared by a freeze-thaw cycle were uniformly and highly birefringent and showed network (gel) behavior at room temperature. The mechanism of gel formation is most likely the exclusion of the polymer from the benzene crystal during crystallization, forcing the polymer to align and exist at grain boundaries. Films formed from solutions have different moduli than those formed from gels, and are consistent with the proposed mechanism.  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