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   283261篇
  免费   2702篇
  国内免费   842篇
化学   151910篇
晶体学   4310篇
力学   12423篇
综合类   34篇
数学   32198篇
物理学   85930篇
  2020年   2381篇
  2019年   2594篇
  2018年   3453篇
  2017年   3410篇
  2016年   4988篇
  2015年   3139篇
  2014年   4807篇
  2013年   11641篇
  2012年   9091篇
  2011年   11010篇
  2010年   7790篇
  2009年   7481篇
  2008年   10172篇
  2007年   10290篇
  2006年   9640篇
  2005年   8749篇
  2004年   8015篇
  2003年   7205篇
  2002年   7072篇
  2001年   7586篇
  2000年   5921篇
  1999年   4562篇
  1998年   4009篇
  1997年   3976篇
  1996年   3745篇
  1995年   3444篇
  1994年   3609篇
  1993年   3316篇
  1992年   3794篇
  1991年   3780篇
  1990年   3708篇
  1989年   3571篇
  1988年   3653篇
  1987年   3555篇
  1986年   3363篇
  1985年   4461篇
  1984年   4735篇
  1983年   3939篇
  1982年   4096篇
  1981年   4022篇
  1980年   3977篇
  1979年   3962篇
  1978年   4279篇
  1977年   4176篇
  1976年   4252篇
  1975年   3912篇
  1974年   3952篇
  1973年   4115篇
  1972年   2874篇
  1971年   2405篇
排序方式: 共有10000条查询结果,搜索用时 15 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