全文获取类型
收费全文 | 366813篇 |
免费 | 4312篇 |
国内免费 | 1063篇 |
专业分类
化学 | 203590篇 |
晶体学 | 6432篇 |
力学 | 14985篇 |
综合类 | 15篇 |
数学 | 36397篇 |
物理学 | 110769篇 |
出版年
2019年 | 3000篇 |
2018年 | 3378篇 |
2017年 | 3444篇 |
2016年 | 5595篇 |
2015年 | 3745篇 |
2014年 | 5772篇 |
2013年 | 15953篇 |
2012年 | 11252篇 |
2011年 | 13846篇 |
2010年 | 9540篇 |
2009年 | 9437篇 |
2008年 | 12367篇 |
2007年 | 12362篇 |
2006年 | 11717篇 |
2005年 | 10622篇 |
2004年 | 9727篇 |
2003年 | 8788篇 |
2002年 | 8494篇 |
2001年 | 10488篇 |
2000年 | 8059篇 |
1999年 | 6291篇 |
1998年 | 5030篇 |
1997年 | 4975篇 |
1996年 | 4849篇 |
1995年 | 4530篇 |
1994年 | 4340篇 |
1993年 | 4096篇 |
1992年 | 5097篇 |
1991年 | 4902篇 |
1990年 | 4761篇 |
1989年 | 4789篇 |
1988年 | 4761篇 |
1987年 | 4803篇 |
1986年 | 4532篇 |
1985年 | 5987篇 |
1984年 | 6009篇 |
1983年 | 4854篇 |
1982年 | 5132篇 |
1981年 | 5169篇 |
1980年 | 4864篇 |
1979年 | 5263篇 |
1978年 | 5495篇 |
1977年 | 5462篇 |
1976年 | 5237篇 |
1975年 | 4873篇 |
1974年 | 4813篇 |
1973年 | 4790篇 |
1972年 | 3226篇 |
1968年 | 3385篇 |
1967年 | 3459篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
M. W. Alexejewa A. G. Pukirew A. Tschetajew J. A. Feldman E. Allisson D. A. Webb Sh. Murahashi S. Sabetay M. Nicloux H. Kreipe E. Flotow L. Malaprade und Y. R. Naves 《Fresenius' Journal of Analytical Chemistry》1940,120(7-8):271-275
Ohne Zusammenfassung 相似文献
992.
K. Wolf 《Archive of Applied Mechanics (Ingenieur Archiv)》1941,12(4):259-264
Ohne Zusammenfassung 相似文献
993.
K. K. Kadyrzhanov S. Khazhekber S. N. Lukashenko V. P. Solodukhin I. V. Kazachevskiy V. L. Poznyak B. B. Knyazev Ch. Rofer 《Czechoslovak Journal of Physics》2003,53(1):A39-A44
Data on the spatial distribution of radionuclides (241Am, 239Pu, 137Cs and 152Eu) formed during nuclear explosions of different types near P2 SNTS test site are presented. Radionuclide contamination induced by the explosions varies in the concentrations of individual radionuclides, their proportions and species. Examination of the variations is a crucial task to plan remediation activities as well as those aimed at decrease of radiation risk for population and prevention of repeated contamination. Concentrations of 241Am and 239+240Pu that are the most toxic radionuclides in the area lie in hundred thousands of Bqkg?1. The most contaminated areas are classified by the radionuclide concentration, ratio and form present in soil. 相似文献
994.
The aim of this paper is to investigate homomorphisms which reserve square-free languages or primitive languages. A characterization of square-free-preserving homomorphisms is presented. We show that every square-free-preserving homomorphism is primitive-preserving. Strongly cube-free-preserving homomorphisms are also studied. 相似文献
995.
996.
A non-fused fiber coupler for side-pumping of double-clad fiber lasers 总被引:17,自引:0,他引:17
A non-fused fiber coupler is demonstrated for side-pumping of the double-clad fiber (DCF) lasers by adhesive techniques. The fiber coupler is fabricated by adhering an angularly polished single-clad fiber (SCF) to the inner cladding of the DCF. The pumping light is launched from the SCF by total inner reflection. Coupling coefficient as a function of coupling angle, bend distance, and backward scattering is investigated. The field distribution in DCF is also discussed. 相似文献
997.
Pyroelectric effect in lead-magnoniobate-based solid solutions 总被引:1,自引:0,他引:1
E. P. Smirnova S. E. Aleksandrov K. A. Sotnikov A. A. Kapralov A. V. Sotnikov 《Physics of the Solid State》2003,45(7):1305-1309
A coordinated study of the dielectric, electrostriction, and pyroelectric properties of the lead-magnoniobate-based ceramic solid solutions 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 and 0.55PbMg1/3Nb2/3O3-0.45PbSc1/2Nb1/2O3 conducted at the relaxor transition temperatures is reported. Electromechanical coupling stimulated by the giant electrostriction effect is shown to play an essential part in the pyroelectric effect. 相似文献
998.
Cao H. P. Chen G. Grechkoseeva M. A. Mazurov V. D. Shi W. J. Vasil'ev A. V. 《Siberian Mathematical Journal》2004,45(6):1031-1035
The spectrum of a finite group is the set of its element orders. A finite group G is said to be recognizable by spectrum, if every finite group with the same spectrum as G is isomorphic to G. The purpose of the paper is to prove that for every natural m the finite simple Chevalley group F
4(2
m
) is recognizable by spectrum. 相似文献
999.
H. Katsurada 《Journal of Number Theory》2004,104(1):100-117
We introduce a formula for the p-adic Siegel-Eisenstein series which demonstrates a connection with the genus theta series and the twisted Eisenstein series with level p. We then prove a generalization of Serre's formula in the elliptic modular case. 相似文献
1000.
Ledzewicz U. Nowakowski A. Schättler H. 《Journal of Optimization Theory and Applications》2004,122(2):345-370
It is shown that, if a parametrized fämily of extremals F can be stratified in a way compatible with the flow map generated by F, then those trajectories of the family which realize the minimal values of the cost in F are indeed optimal in comparison with all trajectories which lie in the region R covered by the trajectories of F. It is not assumed that F is a field covering the state space injectively. As illustration, an optimal synthesis is constructed for a system where the flow of extremals exhibits a simple cusp singularity. 相似文献