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   267954篇
  免费   2057篇
  国内免费   625篇
化学   142136篇
晶体学   4164篇
力学   11931篇
综合类   9篇
数学   29512篇
物理学   82884篇
  2019年   2298篇
  2018年   3120篇
  2017年   3115篇
  2016年   4492篇
  2015年   2662篇
  2014年   4286篇
  2013年   10696篇
  2012年   8079篇
  2011年   9920篇
  2010年   7095篇
  2009年   6888篇
  2008年   9324篇
  2007年   9517篇
  2006年   8884篇
  2005年   8076篇
  2004年   7425篇
  2003年   6737篇
  2002年   6664篇
  2001年   7326篇
  2000年   5659篇
  1999年   4361篇
  1998年   3861篇
  1997年   3847篇
  1996年   3585篇
  1995年   3332篇
  1994年   3490篇
  1993年   3189篇
  1992年   3664篇
  1991年   3666篇
  1990年   3599篇
  1989年   3458篇
  1988年   3568篇
  1987年   3463篇
  1986年   3285篇
  1985年   4360篇
  1984年   4633篇
  1983年   3873篇
  1982年   4006篇
  1981年   3932篇
  1980年   3909篇
  1979年   3881篇
  1978年   4191篇
  1977年   4109篇
  1976年   4174篇
  1975年   3849篇
  1974年   3895篇
  1973年   4050篇
  1972年   2851篇
  1971年   2378篇
  1970年   2177篇
排序方式: 共有10000条查询结果,搜索用时 31 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