全文获取类型
收费全文 | 400008篇 |
免费 | 7750篇 |
国内免费 | 5399篇 |
专业分类
化学 | 192545篇 |
晶体学 | 6203篇 |
力学 | 21949篇 |
综合类 | 323篇 |
数学 | 58823篇 |
物理学 | 133314篇 |
出版年
2021年 | 3373篇 |
2020年 | 3889篇 |
2019年 | 4300篇 |
2018年 | 12554篇 |
2017年 | 12998篇 |
2016年 | 10330篇 |
2015年 | 5228篇 |
2014年 | 7167篇 |
2013年 | 14549篇 |
2012年 | 15764篇 |
2011年 | 24809篇 |
2010年 | 16519篇 |
2009年 | 16532篇 |
2008年 | 21657篇 |
2007年 | 24481篇 |
2006年 | 11752篇 |
2005年 | 15847篇 |
2004年 | 12210篇 |
2003年 | 11394篇 |
2002年 | 9809篇 |
2001年 | 9451篇 |
2000年 | 7402篇 |
1999年 | 5690篇 |
1998年 | 4953篇 |
1997年 | 4642篇 |
1996年 | 4590篇 |
1995年 | 4072篇 |
1994年 | 4059篇 |
1993年 | 4069篇 |
1992年 | 4156篇 |
1991年 | 4363篇 |
1990年 | 4096篇 |
1989年 | 3981篇 |
1988年 | 3884篇 |
1987年 | 3804篇 |
1986年 | 3598篇 |
1985年 | 4655篇 |
1984年 | 4851篇 |
1983年 | 3937篇 |
1982年 | 4150篇 |
1981年 | 3992篇 |
1980年 | 3856篇 |
1979年 | 4089篇 |
1978年 | 4199篇 |
1977年 | 4025篇 |
1976年 | 4249篇 |
1975年 | 3838篇 |
1974年 | 3858篇 |
1973年 | 3959篇 |
1972年 | 2891篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
971.
L.-Q. Han S.-Y. Zhao Y.-D. Zhou P.-L. Zhang 《Applied physics. B, Lasers and optics》1997,65(3):399-402
Received: 18 June 1996/Revised version: 3 January 1997 相似文献
972.
该文讨论了形变诺振子相干态的一些有意义的性质,利用量子代数SUq(3)的形变谐振子实现,构造了SU3(q)在玻色、费米两种情况下的相干态. 相似文献
973.
A free-piston driver that employs entropy-raising shock processes with diaphragm rupture has been constructed, which promises
significant theoretical advantages over isentropic compression. Results from a range of conditions with helium and argon driver
gases are reported. Significant performance gains were achieved in some test cases. Heat losses are shown to have a strong
effect on driver processes. Measurements compare well with predictions from a quasi-one-dimensional numerical code.
Received 7 September 1996 / Accepted 5 October 1996 相似文献
974.
It has been shown by Yu. M. Golubev, M. I. Kolobov, and I. V. Sokolov, Zh. éksp. Teor. Fiz. 111, 1579 (1997) [JETP 84, 864 (1997)], that when an optical cavity is excited by external radiation from a sub-Poisson laser the cavity mode may be
in either a sub-Poisson or a Poisson stationary state. This is not important for a resonant medium which is excited into the
upper laser level while interacting with this mode inside the cavity. The degree of regularity of the excitation will be identical
to that of the initial light flux incident on the cavity, and this ultimately ensures the same sub-Poisson lasing as for strictly
regular pumping of the resonant medium.
Zh. éksp. Teor. Fiz. 113, 1223–1234 (April 1998) 相似文献
975.
A complete study of the spectrum of a finite-dimensional Bose operator is carried out in the paper. The cases in which the
spectrum is discrete or continuous are studied.
Translated fromMatematicheskie Zametki, Vol. 61, No. 6, pp. 835–854, June, 1997.
Translated by A. M. Chebotarev 相似文献
976.
977.
L.-H. Tang P. Smilauer D.D. Vvedensky 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(3):409-412
Two types of mechanisms are proposed for mound coarsening during unstable epitaxial growth: stochastic, due to deposition
noise, and deterministic, due to mass currents driven by surface energy differences. Both yield the relation H=(RWL)2 between the typical mound height W, mound size L, and the film thickness H. An analysis of simulations and experimental data shows that the parameter R saturates to a value which discriminates sharply between stochastic () and deterministic () coarsening. We derive a scaling relation between the coarsening exponent 1/z and the mound-height exponent which, for a saturated mound slope, yields .
Received: 11 November 1997 / Revised in final form: 28 November 1997 /
Accepted: 28 November 1997 相似文献
978.
设F(p,q)和G(p,q)在无穷远点的邻域内是分别关于p和q的近似凸函数,且具有二次增长.考虑由F和G构成的一对定义在Soblev空间中的泛函.本文利用blowup技巧,证明了这样一对泛函的Nash平衡点实际上是Lipschitz连续的. 相似文献
979.
A. Bonilla F. Pérez-González A. Stray R. Trujillo-González 《Journal d'Analyse Mathématique》1997,73(1):65-89
This paper is concerned with several approximation problems in the weighted Hardy spacesH
p(Ω) of analytic functions in the open unit disc D of the complex plane ℂ. We prove that ifX is a relatively closed subset of D, the class of uniform limits onX of functions inH
p(Ω) coincides, moduloH
p(Ω), with the space of uniformly continuous functions on a certain hull ofX which are holomorphic on its interior. We also solve the simultaneous approximation problems of describing Farrell and Mergelyan
sets forH
p(Ω), giving geometric characterizations for them. By replacing approximating polynomials by polynomial multipliers of outer
functions, our results lead to characterizations of the same sets with respect to cyclic vectors in the classical Hardy spacesH
p(D), 1 ⪯p < ∞.
Dedicated to Professor Nácere Hayek on the occasion of his 75th birthday. 相似文献
980.
V. I. Grafutin V. L. Grishkin G. G. Myasishcheva Yu. V. Funtikov Yu. A. Novikov 《Physics of the Solid State》1998,40(4):549-551
The empirical relation θ
p
6
/I
p=aK (where θ
p is the limiting angle of the parabolic component in the angular distributions of annihilation photons in metals, I
p is the integrated contribution of this component, K=1, 2, 3, ... is an integer, and a is a constant independent of the type of metal) observed earlier has been tested on magnesium, aluminum, copper, zinc, lead,
and bismuth samples. The validity of this relation has been substantiated. The value of the dimensionless constant a has been determined and was found to coincide within experimental error with the result obtained in previous measurements.
It is shown that the value of K for the same metal but for different samples may be different. It is conjectured that this may be due to different defect
concentrations in samples.
Fiz. Tverd. Tela (St. Petersburg) 40, 600–602 (April 1998) 相似文献