全文获取类型
收费全文 | 110984篇 |
免费 | 7888篇 |
国内免费 | 6459篇 |
专业分类
化学 | 66030篇 |
晶体学 | 1463篇 |
力学 | 6237篇 |
综合类 | 478篇 |
数学 | 13375篇 |
物理学 | 37748篇 |
出版年
2023年 | 976篇 |
2022年 | 1683篇 |
2021年 | 2362篇 |
2020年 | 2875篇 |
2019年 | 3109篇 |
2018年 | 3305篇 |
2017年 | 3193篇 |
2016年 | 4131篇 |
2015年 | 3022篇 |
2014年 | 4188篇 |
2013年 | 5802篇 |
2012年 | 6211篇 |
2011年 | 6535篇 |
2010年 | 5096篇 |
2009年 | 5042篇 |
2008年 | 5334篇 |
2007年 | 4963篇 |
2006年 | 4486篇 |
2005年 | 4006篇 |
2004年 | 3562篇 |
2003年 | 3230篇 |
2002年 | 3447篇 |
2001年 | 3113篇 |
2000年 | 2346篇 |
1999年 | 1910篇 |
1998年 | 1718篇 |
1997年 | 1492篇 |
1996年 | 1423篇 |
1995年 | 1197篇 |
1994年 | 1233篇 |
1993年 | 1162篇 |
1992年 | 1140篇 |
1991年 | 1204篇 |
1990年 | 1184篇 |
1989年 | 1076篇 |
1988年 | 952篇 |
1987年 | 935篇 |
1986年 | 906篇 |
1985年 | 943篇 |
1984年 | 930篇 |
1983年 | 830篇 |
1982年 | 802篇 |
1979年 | 803篇 |
1978年 | 812篇 |
1977年 | 806篇 |
1976年 | 919篇 |
1975年 | 811篇 |
1974年 | 839篇 |
1973年 | 843篇 |
1972年 | 751篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
我们对多电子束契伦柯夫自由电子激光进行了首次实验研究。280A,500kV的电子束被引入一多介质矩形谐振腔,在频率为33.4GHz处产生了1.7MW的契伦柯夫相干受激辐射。互作用效率为1.2%。 相似文献
992.
V. L. Rusinov A. Yu. Petrov O. N. Chupakhin 《Chemistry of Heterocyclic Compounds》1992,28(11):1335-1339
Two variants of a synthesis for nitropyrazolopyridines from aminopyrazoles and two- or three-carbon nitrosynthons are examined.For Communication 19 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1560–1564, November, 1992. 相似文献
993.
The stable quasistationary mixing of ternary gas mixtures in a system of two chambers connected by a capillary is described
by a theoretical model which predicts the density distribution of the mixture along the length of the diffusion channel. It
is demonstrated that inversion of the density gradient can occur due to a nonlinear concentration distribution of the heavy
component in a diffusion “gate” effect. The results obtained using this model are compared with the experimental data.
Zh. Tekh. Fiz. 68, 14–17 (May 1998) 相似文献
994.
The stable site of Si substitutional impurities in GaAs and AlAs at T=0 K is determined on the basis of an analysis of the energy of solution of silicon, and of the energies of formation of intrinsic
defects and the reaction energies of their interaction obtained by calculating the total energy of the disordered compounds.
These calculations indicate that amphotericity and vacancies have an effect on the distribution of Si. At low Si concentrations,
Si in GaAs is located on the sublattice of the group III element, and in AlAs, on the sublattice of the group V element.
Fiz. Tverd. Tela (St. Petersburg) 39, 264–266 (February 1997) 相似文献
995.
We consider a nonlinear system of difference equations. This system corresponds to chains of N symmetrically connected oscillators with sufficiently general type of connection, which includes, among others, local and global connection. We prove a theorem on the existence and stability of space-time periodic solutions of such systems for sufficiently small values of the parameter of connection ?. 相似文献
996.
997.
998.
999.
Using high-dimensional quantum error-avoiding code, we present two new quantum key distribution protocols over a collective noisy channel, i.e. six-photon and five-photon quantum error-avoiding codes. Compared with the previous protocols using four-photon and three-photon quantum error-avoiding code, the qubit efficiencies of the new protocols have increases of 16.67% and 5% respectively. In addition, the security of these protocols is analysed with a conclusion that the new protocols are much more secure than the four-photon and three-photon ones. 相似文献
1000.
C. Scheidenberger K. Beckert P. Beller F. Bosch C. Brandau D. Boutin L. Chen B. Franzke H. Geissel R. Knöbel C. Kozhuharov J. Kurcewicz S. A. Litvinov Yu. A. Litvinov M. Mazzocco G. Münzenberg F. Nolden W. R. Plaß M. Steck B. Sun H. Weick M. Winkler 《Hyperfine Interactions》2006,173(1-3):61-66
One important goal of the ILIMA project at FAIR is the study of masses and decay properties of relativistic isomeric beams
stored and cooled in the planned storage-ring complex. A new scheme is described, where a storage-cooler ring is used for
high-resolution mass separation. Experimental results on the separation of the isobaric pair 140Pr-140Ce are presented.
P. Beller, deceased. 相似文献