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   380029篇
  免费   3559篇
  国内免费   1166篇
化学   186007篇
晶体学   5054篇
力学   19527篇
综合类   14篇
数学   66976篇
物理学   107176篇
  2020年   2571篇
  2019年   2741篇
  2018年   13630篇
  2017年   13475篇
  2016年   11304篇
  2015年   4317篇
  2014年   5532篇
  2013年   12981篇
  2012年   13455篇
  2011年   21711篇
  2010年   13771篇
  2009年   13741篇
  2008年   17301篇
  2007年   19455篇
  2006年   10680篇
  2005年   10720篇
  2004年   10141篇
  2003年   9645篇
  2002年   8491篇
  2001年   8264篇
  2000年   6549篇
  1999年   4967篇
  1998年   4440篇
  1997年   4354篇
  1996年   4258篇
  1995年   3883篇
  1994年   4013篇
  1993年   3752篇
  1992年   4218篇
  1991年   4073篇
  1990年   3997篇
  1989年   3858篇
  1988年   3934篇
  1987年   3849篇
  1986年   3649篇
  1985年   4855篇
  1984年   5103篇
  1983年   4259篇
  1982年   4412篇
  1981年   4345篇
  1980年   4317篇
  1979年   4297篇
  1978年   4567篇
  1977年   4496篇
  1976年   4514篇
  1975年   4175篇
  1974年   4188篇
  1973年   4322篇
  1972年   3039篇
  1971年   2552篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Moscow Institute of Electronic Engineering. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 89, No. 1, pp. 132–150, October, 1991.  相似文献   
103.
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   
104.
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   
105.
106.
Kalman's theory is extended to a complete, smooth, and irreducible algebraic curve of arbitrary genus.  相似文献   
107.
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   
108.
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   
109.
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   
110.
Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 159–163, September–October, 1991.  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