全文获取类型
收费全文 | 710697篇 |
免费 | 6154篇 |
国内免费 | 1861篇 |
专业分类
化学 | 344146篇 |
晶体学 | 10113篇 |
力学 | 38186篇 |
综合类 | 16篇 |
数学 | 114528篇 |
物理学 | 211723篇 |
出版年
2021年 | 5796篇 |
2020年 | 6424篇 |
2019年 | 7249篇 |
2018年 | 19500篇 |
2017年 | 19213篇 |
2016年 | 19580篇 |
2015年 | 8676篇 |
2014年 | 13409篇 |
2013年 | 28738篇 |
2012年 | 25737篇 |
2011年 | 36381篇 |
2010年 | 25298篇 |
2009年 | 25766篇 |
2008年 | 31389篇 |
2007年 | 32805篇 |
2006年 | 23182篇 |
2005年 | 21485篇 |
2004年 | 20455篇 |
2003年 | 18874篇 |
2002年 | 18143篇 |
2001年 | 18708篇 |
2000年 | 14552篇 |
1999年 | 11163篇 |
1998年 | 9696篇 |
1997年 | 9326篇 |
1996年 | 8886篇 |
1995年 | 7974篇 |
1994年 | 7893篇 |
1993年 | 7688篇 |
1992年 | 8240篇 |
1991年 | 8615篇 |
1990年 | 8327篇 |
1989年 | 8171篇 |
1988年 | 7968篇 |
1987年 | 7926篇 |
1986年 | 7440篇 |
1985年 | 9333篇 |
1984年 | 9559篇 |
1983年 | 7796篇 |
1982年 | 8043篇 |
1981年 | 7746篇 |
1980年 | 7257篇 |
1979年 | 7956篇 |
1978年 | 8159篇 |
1977年 | 8146篇 |
1976年 | 8135篇 |
1975年 | 7519篇 |
1974年 | 7370篇 |
1973年 | 7497篇 |
1972年 | 5739篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
901.
M. Okumura K. Fukushi S. N. Willie R. E. Sturgeon 《Fresenius' Journal of Analytical Chemistry》1993,345(8-9):570-574
Summary Atomic fluorescence (AFS), absorption (AAS) and emission (AES) systems were evaluated for the determination of inorganic mercury. Identical vapour generation and amalgamation procedures were used to permit direct comparison of the performance of a commercial long-path AAS instrument to laboratory constructed non-dispersive AFS as well as He-MIP based AES instruments. Instrumental noise-limited detection limits (LOD) were 0.94, 2.4, 2.8 pg for AAS, AES and AFS techniques, respectively. Methodological LOD's were found to be blank controlled and similar for all three instruments, viz. 9, 25 and 16 pg for AAS, AFS and AES, respectively. All three systems produced accurate results at the low ng/l concentration, as verified by the analysis of a certified river water reference material (NRCC ORMS-1). 相似文献
902.
903.
904.
Surface-wave gas discharges sustained under the conditions of a diffusion controlled regime are studied on the basis of the fluid plasma model. The self-consistent behaviour of the plasma density and of the field intensity along the discharge length is obtained. It is shown that the nonlinearity in the particle balance equation due to stepwise ionisation determines the plasma density in terms of the field intensity and ensures self-consistent behaviour of the wave ? discharge characteristics in a diffusion controlled regime. 相似文献
905.
906.
This paper surveys applications of dynamic programming to decisionproblems faced by active participants in sports. 相似文献
907.
Vortex-sheet growth is considered. Broken symmetry bifurcations are found in the growth process. The collective elasticity theory for a well-developed vortex sheet is presented, which is similar to that of smectic liquid crystals. The bifurcations in the limit of a much folded vortex sheet correspond to the Helfrich instability in smectics and cholesterics. 相似文献
908.
P. Tekely V. G rardy P. Palmas D. Canet A. Retournard 《Solid state nuclear magnetic resonance》1995,4(6):361-367
A simple modification of the standard cross-polarization method designed for quenching the proton T1ρ dependence when studying polarization transfer is presented. It is demonstrated that by using this simple procedure, new and subtle details of cross-polarization dynamics, previously hidden by the T1ρ(1H) effect, can be observed in dipolar-coupled spin systems. 相似文献
909.
M. J. Gaylard G. C. MacLeod D. P. Smits M. E. West D. J. Walt 《Journal of chemical crystallography》1993,23(9):763-763
Future contributions toJournal of Crystallographic and Spectroscopic Research 相似文献
910.
The Lie symmetries of nonlinear diffusion equations with convection term are completely described. The Lie ansatzes and exact solutions of a certain nonlinear generalization of the Murray equation are constructed. An example of the family of non-Lie solutions of the Murray equation is given. 相似文献