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   268090篇
  免费   2402篇
  国内免费   629篇
化学   142491篇
晶体学   4164篇
力学   11935篇
综合类   9篇
数学   29552篇
物理学   82970篇
  2019年   2297篇
  2018年   3126篇
  2017年   3116篇
  2016年   4498篇
  2015年   2664篇
  2014年   4299篇
  2013年   10704篇
  2012年   8101篇
  2011年   9942篇
  2010年   7101篇
  2009年   6885篇
  2008年   9339篇
  2007年   9559篇
  2006年   8932篇
  2005年   8100篇
  2004年   7456篇
  2003年   6770篇
  2002年   6667篇
  2001年   7336篇
  2000年   5668篇
  1999年   4363篇
  1998年   3864篇
  1997年   3851篇
  1996年   3593篇
  1995年   3334篇
  1994年   3493篇
  1993年   3196篇
  1992年   3670篇
  1991年   3674篇
  1990年   3608篇
  1989年   3461篇
  1988年   3579篇
  1987年   3464篇
  1986年   3291篇
  1985年   4366篇
  1984年   4637篇
  1983年   3880篇
  1982年   4007篇
  1981年   3936篇
  1980年   3917篇
  1979年   3883篇
  1978年   4195篇
  1977年   4117篇
  1976年   4189篇
  1975年   3861篇
  1974年   3899篇
  1973年   4055篇
  1972年   2852篇
  1971年   2383篇
  1970年   2178篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
The state of the art in the Internet information resources for biosensors is considered, and the classification of the websites is given  相似文献   
972.
Moscow Institute of Electronic Engineering. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 89, No. 1, pp. 132–150, October, 1991.  相似文献   
973.
Germline and somatic instability of the human genome was studied, using synthetic oligonucleotides specific for simple repeat motifs. The following probes were used: (GTG)5, (GACA)4, (GATA)4, (CT)8, (TTAGGG)3, (GT)8, (GAA)6 and (GGAT)4. Each of them is unique with respect to the target regions recognized in the genome. Thus compilation of the various fingerprint data provides a complex map of the genome (and its deviations). While the fingerprints of differentiated somatic tissues never showed any alterations, in tumor tissues (namely gliomas) many changes could be detected. Most of the latter reflect secondary karyological aberrations. In nearly one third of the gliomas, drastically amplified and apparently monomorphic DNA fragments were identified. This marker should make it possible to deal with causal pathogenetic mechanisms as well as novel diagnostic strategies.  相似文献   
974.
Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 122–123, July–August, 1991.  相似文献   
975.
976.
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   
977.
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   
978.
979.
Kalman's theory is extended to a complete, smooth, and irreducible algebraic curve of arbitrary genus.  相似文献   
980.
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   
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