全文获取类型
收费全文 | 3785篇 |
免费 | 137篇 |
国内免费 | 9篇 |
专业分类
化学 | 2438篇 |
晶体学 | 18篇 |
力学 | 69篇 |
数学 | 357篇 |
物理学 | 1049篇 |
出版年
2021年 | 39篇 |
2020年 | 71篇 |
2019年 | 60篇 |
2018年 | 30篇 |
2017年 | 30篇 |
2016年 | 103篇 |
2015年 | 83篇 |
2014年 | 115篇 |
2013年 | 154篇 |
2012年 | 171篇 |
2011年 | 201篇 |
2010年 | 114篇 |
2009年 | 106篇 |
2008年 | 158篇 |
2007年 | 139篇 |
2006年 | 137篇 |
2005年 | 140篇 |
2004年 | 103篇 |
2003年 | 90篇 |
2002年 | 94篇 |
2001年 | 96篇 |
2000年 | 81篇 |
1999年 | 55篇 |
1998年 | 63篇 |
1997年 | 29篇 |
1996年 | 59篇 |
1995年 | 57篇 |
1994年 | 53篇 |
1993年 | 51篇 |
1992年 | 67篇 |
1991年 | 49篇 |
1990年 | 45篇 |
1989年 | 39篇 |
1988年 | 44篇 |
1987年 | 41篇 |
1986年 | 49篇 |
1985年 | 51篇 |
1984年 | 50篇 |
1983年 | 33篇 |
1982年 | 39篇 |
1981年 | 48篇 |
1980年 | 43篇 |
1979年 | 52篇 |
1978年 | 49篇 |
1977年 | 43篇 |
1976年 | 32篇 |
1975年 | 38篇 |
1974年 | 36篇 |
1973年 | 32篇 |
1970年 | 25篇 |
排序方式: 共有3931条查询结果,搜索用时 15 毫秒
991.
Kikuchi Y de Bock MF Finken KH Jakubowski M Jaspers R Koslowski HR Kraemer-Flecken A Lehnen M Liang Y Matsunaga G Reiser D Wolf RC Zimmermann O;TEXTOR-team 《Physical review letters》2006,97(8):085003
The magnetic field penetration process into a magnetized plasma is of basic interest both for plasma physics and astrophysics. In this context special measurements on the field penetration and field amplification are performed by a Hall probe on the dynamic ergodic divertor (DED) on the TEXTOR tokamak and the data are interpreted by a two-fluid plasma model. It is observed that the growth of the forced magnetic reconnection by the rotating DED field is accompanied by a change of the plasma fluid rotation. The differential rotation frequency between the DED field and the plasma plays an important role in the process of the excitation of tearing modes. The momentum input from the rotating DED field to the plasma is interpreted by both a ponderomotive force at the rational surface and a radial electric field modified by an edge ergodization. 相似文献
992.
Reinhard Wolf 《Arkiv f?r Matematik》2010,48(2):395-403
Let X be a compact Hausdorff space. A kernel function on X×X, enjoying additional properties, naturally defines a semi-inner product structure on certain subspaces of all finite signed
Borel measures on X. This paper discusses the question of completeness of such spaces. 相似文献
993.
994.
Wolf Kohn Vladimir Brayman Zelda B. Zabinsky Yanfang Shen 《Nonlinear Analysis: Hybrid Systems》2010,4(4):736-742
We develop a chattering approach to solve variational problems that lack traditional properties such as differentiable everywhere and convexity conditions. We prove that our chattering approximation approaches the true relaxed solution as the intervals get smaller. Our chattering approach suggests a nonlinear optimization problem that can be easily solved to recover the optimal trajectory. A numerical example demonstrates our approach. 相似文献
995.
Stefanie Wolf 《Journal of organometallic chemistry》2010,695(22):2418-2422
The utility of [(NHC)(PPh3)RuCl2(CHPh)] for the facile and efficient synthesis of ten complexes of the type [(NHC)(NHCewg)RuCl2(CHR)] with saturated and unsaturated NHC ligands in 85-94% isolated yield via a simple one step synthesis utilizing [AgI(NHCewg)] as NHCewg transfer reagents was demonstrated. 相似文献
996.
997.
Towards future reference systems for GM analysis 总被引:1,自引:0,他引:1
Stefanie Trapmann Philippe Corbisier Heinz Schimmel Hendrik Emons 《Analytical and bioanalytical chemistry》2010,396(6):1969-1975
Despite the fact that the measurement unit for the quantification of GMOs in food and feed products has not yet been unambiguously agreed upon in Europe, international trade requires reliable GMO analysis measuring comparably the GMO content of products. The two reference systems, based either on mass fractions or on copy number ratios, and their metrological traceability chains are presented and discussed. It is concluded that, properly established and expressed, measurement results in copy number ratios can provide a metrologically sound reference system. In this case, certified reference materials used for calibration and quality control can be independent of each other and the uncertainty derived from calibration can correctly be included in the overall uncertainty of the GMO measurement. However, further efforts are required to establish this metrological system. 相似文献
998.
Claudio C. Silveira Samuel R. Mendes Lucas Wolf Guilherme M. Martins 《Tetrahedron letters》2010,51(15):2014-3697
Anhydrous CeCl3 was successfully used as a catalyst for the synthesis of several 3-sulfenyl indoles in good to excellent yields through the reaction of indole with N-(alkylthio) and N-(arylthio)phthalimides in DMF. 相似文献
999.
The stable benzylazido-boronate ester 1 is presented as an example of a dual-functional linker that allows the synthetically valuable boronate motif to be clicked onto other molecules under mild conditions. The utility of the azido-boronate motif as a modular building block is demonstrated in the rapid synthesis of drug-like structures employing sequential catalytic azide-alkyne cycloaddition and Suzuki coupling reactions. 相似文献
1000.