全文获取类型
收费全文 | 185544篇 |
免费 | 1050篇 |
国内免费 | 314篇 |
专业分类
化学 | 93196篇 |
晶体学 | 2684篇 |
力学 | 9503篇 |
综合类 | 7篇 |
数学 | 22195篇 |
物理学 | 59323篇 |
出版年
2020年 | 1956篇 |
2019年 | 2438篇 |
2018年 | 3545篇 |
2017年 | 3657篇 |
2016年 | 4370篇 |
2015年 | 2016篇 |
2014年 | 3765篇 |
2013年 | 7441篇 |
2012年 | 5909篇 |
2011年 | 7036篇 |
2010年 | 5844篇 |
2009年 | 5889篇 |
2008年 | 6750篇 |
2007年 | 6686篇 |
2006年 | 5947篇 |
2005年 | 5297篇 |
2004年 | 5098篇 |
2003年 | 4603篇 |
2002年 | 4709篇 |
2001年 | 5079篇 |
2000年 | 3781篇 |
1999年 | 2913篇 |
1998年 | 2674篇 |
1997年 | 2510篇 |
1996年 | 2327篇 |
1995年 | 2097篇 |
1994年 | 2049篇 |
1993年 | 2090篇 |
1992年 | 2113篇 |
1991年 | 2415篇 |
1990年 | 2331篇 |
1989年 | 2399篇 |
1988年 | 2273篇 |
1987年 | 2303篇 |
1986年 | 2136篇 |
1985年 | 2670篇 |
1984年 | 2683篇 |
1983年 | 2333篇 |
1982年 | 2383篇 |
1981年 | 2287篇 |
1980年 | 2081篇 |
1979年 | 2402篇 |
1978年 | 2560篇 |
1977年 | 2652篇 |
1976年 | 2735篇 |
1975年 | 2543篇 |
1974年 | 2469篇 |
1973年 | 2639篇 |
1972年 | 2157篇 |
1971年 | 1977篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
A. I. Artem’ev D. N. Klochkov K. Oganesyan Yu. V. Rostovtsev M. V. Fedorov 《Laser Physics》2007,17(10):1213-1216
The spatial amplification of a wave in a magnetostatic undulator with noncollinear electron and laser beams is studied in the framework of the dispersion relation for single-frequency and collective regimes. The dependence of the gain on the electron beam width is estimated with regard to the spatial boundedness of the beams. The laser power threshold at which the selection with respect to the transverse velocity is possible is obtained for a free-electron laser without inversion. 相似文献
922.
V. F. Shkar’ V. P. Denisenkov A. M. Grishin A. A. Yalali S. I. Khartsev E. I. Nikolaev V. N. Sayapin 《Physics of the Solid State》2003,45(12):2334-2337
Bismuth iron garnet films prepared through electron-beam and laser-induced evaporation on (001)-oriented substrates of scandium gallium gadolinium garnet are investigated using ferromagnetic resonance. It is assumed that the additional minima observed in the angular dependence of the resonance field can be associated with the magnetic moment of bismuth ions. 相似文献
923.
924.
M. G. Voronkov S. G. D’yachkova I. P. Lebedeva A. V. Evart L. G. Shagun 《Russian Journal of General Chemistry》2007,77(4):604-606
Alkylthiochloroacetylenes react with geminal (in ether) and vicinal (in THF) dithiols to form, respectively, functional 1,3-dithiolenes (yield 43%) or 1,3-dithiolanes (yield 34%). 相似文献
925.
The HERA - B Collaboration I. Abt et al. 《The European Physical Journal C - Particles and Fields》2003,26(3):345-355
Using the HERA - B detector, the production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The production was tagged via inclusive bottom quark decays into by exploiting the longitudinal separation of decay vertices from the primary proton-nucleus interaction. Both e
+
e
-
and channels have been reconstructed and the combined analysis yields the cross section .
Received: 6 June 2002 / Revised version: 2 September 2002 / Published online: 8 November 2002 相似文献
926.
In this paper, we examine a class of convex problems of Bolza type, involving a time delay in the state. It encompasses a variety of time-delay problems arising in the calculus of variations and optimal control. A duality analysis is carried out which, among other things, leads to a characterization of minimizers in terms of the Euler-Lagrange inclusion. The results obtained improve in significant respects on what is achievable by techniques previously employed, based on elimination of the time delay by introduction of an infinite-dimensional state space or on the method of steps. 相似文献
927.
Yu. I. Samoilenko 《Ukrainian Mathematical Journal》2007,59(11):1750-1767
We propose and investigate a mathematical model of an open bilinear control system for the conversion of heat energy in a
coherent form. We show that the use of a combinational parametric resonance formed by the control system in a one-temperature
ensemble of weakly dissipative elastic-gyroscopic subsystems enables one to obtain a positive energy output without using
any cooling device apart from the control system.
__________
Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 11, pp. 1557–1573, November, 2007. 相似文献
928.
In this paper, we prove that every automorphism of the semigroup of invertible matrices with nonnegative elements over a linearly
ordered associative ring on some specially defined subgroup coincides with the composition of an inner automorphism of the
semigroup, an order-preserving automorphism of the ring, and a central homothety.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 2, pp. 3–23, 2005. 相似文献
929.
930.