全文获取类型
收费全文 | 412032篇 |
免费 | 3768篇 |
国内免费 | 1108篇 |
专业分类
化学 | 204543篇 |
晶体学 | 5920篇 |
力学 | 19436篇 |
综合类 | 7篇 |
数学 | 59494篇 |
物理学 | 127508篇 |
出版年
2020年 | 1983篇 |
2019年 | 1956篇 |
2018年 | 10974篇 |
2017年 | 11854篇 |
2016年 | 7907篇 |
2015年 | 4154篇 |
2014年 | 4551篇 |
2013年 | 14103篇 |
2012年 | 15026篇 |
2011年 | 25631篇 |
2010年 | 15521篇 |
2009年 | 15444篇 |
2008年 | 22726篇 |
2007年 | 26290篇 |
2006年 | 12388篇 |
2005年 | 18266篇 |
2004年 | 13570篇 |
2003年 | 12170篇 |
2002年 | 10044篇 |
2001年 | 10258篇 |
2000年 | 7980篇 |
1999年 | 6151篇 |
1998年 | 4937篇 |
1997年 | 4751篇 |
1996年 | 4915篇 |
1995年 | 4451篇 |
1994年 | 4191篇 |
1993年 | 4004篇 |
1992年 | 4492篇 |
1991年 | 4356篇 |
1990年 | 4071篇 |
1989年 | 3897篇 |
1988年 | 4199篇 |
1987年 | 3861篇 |
1986年 | 3736篇 |
1985年 | 5395篇 |
1984年 | 5484篇 |
1983年 | 4449篇 |
1982年 | 4824篇 |
1981年 | 4866篇 |
1980年 | 4621篇 |
1979年 | 4751篇 |
1978年 | 4763篇 |
1977年 | 4670篇 |
1976年 | 4651篇 |
1975年 | 4553篇 |
1974年 | 4399篇 |
1973年 | 4603篇 |
1972年 | 2594篇 |
1971年 | 1896篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Joo J.H. Choi J.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2004,32(6):2263-2264
A new type of microwave amplifier module, consisting of a solid-state amplifier, a predistortion linearizer, and a traveling-wave-tube (TWT), is realized. Measurements show a noise figure of 2.2 dB at 9.5 GHz and the third-order intermodulation distortion ratio of 53 dBc at 10 dB back off from P1 dB point. 相似文献
992.
Genetic algorithms are stochastic search algorithms that have been applied to optimization problems. In this paper we analyze the run-time complexity of a genetic algorithm when we are interested in one of a set of distinguished solutions. One such case occurs when multiple optima exist. We define the worst case scenario and derive a probabilistic worst case bound on the number of iterations required to find one of these multiple solutions of interest. 相似文献
993.
The supersymetric path integrals in solving the problem of relativistic spinning particle interacting with pseudoscalar potentials
is examined. The relative propagator is presented by means of path integral, where the spin degrees of freedom are described
by odd Grassmannian variables and the gauge invariant part of the effective action has a form similar to the standard pseudoclassical
action given by Berezin and Marinov. After integrating over fermionic variables (Grassmannian variables), the problem is reduced
to a nonrelativistic one with an effective supersymetric potential. Some explicit examples are considered, where we have extracted
the energy spectrum of the electron and the wave functions.
PACS numbers: 03.65. Ca-Formalism, 03.65. Db-Functional analytical methods, 03.65. Pm-Relativistic wave equations. 相似文献
994.
995.
996.
997.
We consider some regression relations for record values X(n), n > 0, generated by a sequence of independent random variables
X1, X2, X3,... with a common continuous cumulative distribution function F(x). New characterizations of distributions based on regression
properties of record values are obtained. Bibliography: 7 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 339, 2006, pp. 5–14. 相似文献
998.
M. A. Kachalova 《Journal of Mathematical Sciences》2007,140(5):699-715
The additive structure of the Hochschild cohomology ring for a Möbius algebra is described. We use the structure of the bimodule minimal projective resolution of the algebra, constructed in a previous paper. Bibliography: 4 titles. 相似文献
999.
1000.
We consider the interpolation Nevanlinna-Pick problem with infinitely many interpolation nodes in the class S[a, b] and rational matrix functions associated with this problem and orthogonal on the segment [a, b]. We obtain a criterion of complete indeterminacy of the Nevanlinna-Pick problem in terms of orthogonal rational matrix functions.
__________
Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 6, pp. 764–770, June, 2007. 相似文献