全文获取类型
收费全文 | 15952篇 |
免费 | 730篇 |
国内免费 | 145篇 |
专业分类
化学 | 10363篇 |
晶体学 | 87篇 |
力学 | 334篇 |
综合类 | 1篇 |
数学 | 2982篇 |
物理学 | 3060篇 |
出版年
2023年 | 137篇 |
2022年 | 214篇 |
2021年 | 349篇 |
2020年 | 425篇 |
2019年 | 503篇 |
2018年 | 383篇 |
2017年 | 296篇 |
2016年 | 609篇 |
2015年 | 576篇 |
2014年 | 560篇 |
2013年 | 947篇 |
2012年 | 1100篇 |
2011年 | 1297篇 |
2010年 | 694篇 |
2009年 | 587篇 |
2008年 | 924篇 |
2007年 | 866篇 |
2006年 | 857篇 |
2005年 | 794篇 |
2004年 | 617篇 |
2003年 | 482篇 |
2002年 | 457篇 |
2001年 | 253篇 |
2000年 | 181篇 |
1999年 | 191篇 |
1998年 | 166篇 |
1997年 | 175篇 |
1996年 | 180篇 |
1995年 | 156篇 |
1994年 | 123篇 |
1993年 | 111篇 |
1992年 | 92篇 |
1991年 | 86篇 |
1990年 | 73篇 |
1989年 | 47篇 |
1988年 | 50篇 |
1987年 | 56篇 |
1986年 | 61篇 |
1985年 | 82篇 |
1984年 | 61篇 |
1983年 | 50篇 |
1982年 | 66篇 |
1981年 | 55篇 |
1980年 | 51篇 |
1979年 | 45篇 |
1978年 | 62篇 |
1977年 | 61篇 |
1976年 | 57篇 |
1974年 | 44篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
71.
72.
Alexander G. Stepanov Sergei S. Arzumanov Horst Ernst Dieter Freude 《Chemical physics letters》2006,420(4-6):574-576
It has been demonstrated that 1H MAS NMR spectroscopy can be used as a tool for in situ monitoring the reaction kinetics of 13C-labeled carbon scrambling in alkane molecules adsorbed on zeolite catalysts at the reaction temperature of 540–570 K. The accuracy of the results and the time resolution are improved compared to 13C MAS NMR spectroscopy. 相似文献
73.
Alexander O. Smirnov 《Letters in Mathematical Physics》2006,76(2-3):297-316
We find a new class of Fuchsian equations, with algebro-geometric solutions associated to a hyperelliptic curve. A method for calculating its arithmetic genus and branching points is suggested. Numerous examples are given. 相似文献
74.
75.
The ternary system CsCl?NaCl?LaCl3 was investigated by means of differential thermal analysis and X-ray powder diffraction analysis. There exists one congruently melting compound, Cs2NaLaCl6, crystallizing with the cubic elpasolite structure. No quasi-binary section exists for the whole system, however three binaries range from the ternary compound Cs2NaLaCl6 to NaCl, CsLa2Cl7 and Cs3LaCl6 resp., dividing the system in three areas of composition: one triangle, Cs3LaCl6?Cs2NaLaCl6?CsLa2Cl7, containing additionally a compound Cs2LaCl5 below 510°C, and the two areas CsCl?NaCl?Cs2NaLaCl6?Cs3LaCl6 and Cs2NaLaCl6?NaCl?LaCl3?CsLa2Cl7, containing a mixed crystal range between LaCl3 and Na3La5Cl18. These areas could be further divided in five triangles, so that the whole system contains six Alkemade triangles. 相似文献
76.
77.
78.
79.
80.
For classical solutions of the incompressible Navier-Stokes equations (NSE) the energybalance between kinetic energy, work done by external forces, and viscous dissipation holds rigorously true. It is shown in this paper that standard Galerkin approximations violate energy balance in the case of plane Couette flow, whereas Poiseuille flow turns out to be energy consistent at any cutoff. The main reason for this discrepancy is seen in the different boundary conditions between the stationary linear shear flow and its disturbances. In our analysis, essentially, we introduce an auxiliary external force field which enforces the finite dimensional Galerkin approximation to fulfil the NSE. It is exemplarily demonstrated how the energy discrepancy decreases when the number of disturbed modes is increased which couple to the stationary shear flow. 相似文献