全文获取类型
收费全文 | 120877篇 |
免费 | 9146篇 |
国内免费 | 7047篇 |
专业分类
化学 | 71069篇 |
晶体学 | 1545篇 |
力学 | 6809篇 |
综合类 | 446篇 |
数学 | 14330篇 |
物理学 | 42871篇 |
出版年
2023年 | 1205篇 |
2022年 | 2468篇 |
2021年 | 2917篇 |
2020年 | 3159篇 |
2019年 | 3325篇 |
2018年 | 3641篇 |
2017年 | 3527篇 |
2016年 | 4545篇 |
2015年 | 3408篇 |
2014年 | 4694篇 |
2013年 | 6480篇 |
2012年 | 7009篇 |
2011年 | 7222篇 |
2010年 | 5527篇 |
2009年 | 5475篇 |
2008年 | 5803篇 |
2007年 | 5424篇 |
2006年 | 4970篇 |
2005年 | 4397篇 |
2004年 | 3777篇 |
2003年 | 3346篇 |
2002年 | 3474篇 |
2001年 | 3056篇 |
2000年 | 2452篇 |
1999年 | 2152篇 |
1998年 | 1981篇 |
1997年 | 1747篇 |
1996年 | 1696篇 |
1995年 | 1399篇 |
1994年 | 1411篇 |
1993年 | 1333篇 |
1992年 | 1249篇 |
1991年 | 1305篇 |
1990年 | 1301篇 |
1989年 | 1169篇 |
1988年 | 1008篇 |
1987年 | 980篇 |
1986年 | 951篇 |
1985年 | 994篇 |
1984年 | 949篇 |
1983年 | 856篇 |
1982年 | 832篇 |
1979年 | 806篇 |
1978年 | 816篇 |
1977年 | 810篇 |
1976年 | 920篇 |
1975年 | 812篇 |
1974年 | 844篇 |
1973年 | 848篇 |
1972年 | 752篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
We consider the application of asymptotic methods of nonlinear mechanics (the Krylov-Bogolyubov-Mitropol'skii method) and
the method of separation of motions in nonlinear systems for the construction of an approximate solution of a nonlinear equation
that describes a nonstationary wave process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 3, pp. 357–371, March, 1998. 相似文献
162.
Yu. A. Mitropol’skii Nguyen Dong Anh Nguyen Dyk Tynh 《Ukrainian Mathematical Journal》1998,50(11):1731-1737
We construct the second approximation for random oscillations described by the Van der Pol equation which are under the action
of a broadband random process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1517–1521, November, 1998. 相似文献
163.
The electronic spectrum of an icosahedral quasicrystal with a central-atom decoration of the Amman-Mackay network is investigated
in the tight-binding approximation. The quasicrystal is described as a structural limit of the optimal cubic approximants
with increasing period. The electronic spectra for the first four optimal cubic approximants do not contain the hierarchical
gap structure which is typical for the Cantor set of the spectrum of a one-dimensional quasicrystal. At the same time, as
the order of the approximant increases, the spectrum becomes singular throughout the entire energy scale.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 8, 557–562 (25 April 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
164.
The anomalous proximity effect between a d-wave superconductor and a thin disordered normal layer is studied theoretically in the framework of Eilenberger equations.
It is shown that disorder of the quasiparticle reflection from this thin layer leads to the formation of an s-wave component localized near the boundary. The angular and spatial structure of the pair potential near the interface is
studied.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 478–483 (10 April 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
165.
Space time-index plots for probing dynamical nonstationarity 总被引:3,自引:0,他引:3
We propose a simple method to efficiently probe dynamical nonstationarity in observed time series. In a space time-index plot, the density distributions as a function of normalized time-index are V-shaped due to nonstationarity. We show that this method is workable for short data sets and typical examples are illustrated. 相似文献
166.
1.RecentlytherearesomegoodliteraturesconcerningtheuniquenesoflimitcyclesforgeneralizedLiénardsystemsx=φ(y)-F(x),y=-g(x),(F(x)... 相似文献
167.
It is found that, in the spherical coordinate system, the fundamental solution of the Helmholtz equation in a wedge satisfies the Sommerfeld radiation conditions at infinity uniformly in angle coordinates.Deceased.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 9, pp. 1312–1314, September, 1993. 相似文献
168.
169.
V. D. Dyachenko S. G. Krivokolysko Yu. A. Sharanin V. P. Litvinov 《Chemistry of Heterocyclic Compounds》1997,33(7):793-798
Ammonium 6-amino-4-aryl-3,5-dicyano-1,4-dihydropyridine-2-thiolates were synthesized by recyclization of 4-aryl-2,6-diamino-3,5-dicyano-4H-thiopyranes in the presence of organic bases. On acidification of the products, the corresponding substituted 3,4-dihydropyridine-2(1H)-thiones were obtained which were used in the synthesis of 2-alkylthio-1,4-dihydropyridines, bis-(pyridyl-2)disulfides and thieno[2,3-b]pyridines.Deceased.T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 909–914, July, 1997. 相似文献
170.