全文获取类型
收费全文 | 494071篇 |
免费 | 19545篇 |
国内免费 | 1304篇 |
专业分类
化学 | 293407篇 |
晶体学 | 6140篇 |
力学 | 21862篇 |
综合类 | 27篇 |
数学 | 60865篇 |
物理学 | 132619篇 |
出版年
2023年 | 5209篇 |
2021年 | 5335篇 |
2020年 | 7983篇 |
2019年 | 5959篇 |
2018年 | 8453篇 |
2017年 | 6833篇 |
2016年 | 13570篇 |
2015年 | 10723篇 |
2014年 | 12472篇 |
2013年 | 23755篇 |
2012年 | 20316篇 |
2011年 | 20643篇 |
2010年 | 16709篇 |
2009年 | 15867篇 |
2008年 | 17616篇 |
2007年 | 17616篇 |
2006年 | 15825篇 |
2005年 | 17918篇 |
2004年 | 15990篇 |
2003年 | 13183篇 |
2002年 | 11347篇 |
2001年 | 11448篇 |
2000年 | 8874篇 |
1999年 | 6888篇 |
1998年 | 5967篇 |
1997年 | 5939篇 |
1996年 | 5640篇 |
1995年 | 5218篇 |
1994年 | 5313篇 |
1993年 | 5036篇 |
1992年 | 5700篇 |
1991年 | 5690篇 |
1990年 | 5433篇 |
1989年 | 5308篇 |
1988年 | 5322篇 |
1987年 | 5112篇 |
1986年 | 4813篇 |
1985年 | 6417篇 |
1984年 | 6739篇 |
1983年 | 5605篇 |
1982年 | 5988篇 |
1981年 | 5821篇 |
1980年 | 5732篇 |
1979年 | 5849篇 |
1978年 | 6267篇 |
1977年 | 6159篇 |
1976年 | 6379篇 |
1975年 | 6022篇 |
1974年 | 6152篇 |
1973年 | 6140篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
V. V. Kondrat'ev E. G. Tolstopyatova V. V. Malev 《Russian Journal of Electrochemistry》2002,38(6):589-595
The charge transfer in poly-3-methylthiophene films in 0.05–0.5 M LiClO4 solutions in acetonitrile is studied by cyclic voltammetry and chronoamperometry. An analysis of data on the current relaxation following a film perturbation by a low-voltage pulse reveals two constituents of the current relaxation, both exponentially dependent on time. Dependence of parameters of the empirical equation derived for the current relaxation on experimental variables is studied. 相似文献
992.
The coupling of visible nanosecond laser pulses to metallic targets irradiated in vacuum is studied. The expressions of the vapour and plasma ignition times are obtained. Two cases for vapour breakdown in the plasma ignition process are considered. The first case is that 40 generations of new electrons are born in vapour generation time before plasma formation as assumed in the literature. The second case is that 10 generations of new electrons are born in vapour generation time. Molybdenum (Mo), niobium (Nb) and aluminium (Al) targets are considered for illustrations of our results. The expression of the plasma ignition time for the Al target is substantially different from that reported in the literature. The vapour and plasma ignition threshold laser intensities are calculated and compared with those reported in the literature. Reasons for disagreement are discussed. The plasma ignition threshold estimated in the second case is noted to be in good agreement with the reported experimental result. 相似文献
993.
994.
995.
We prove global existence of solutions to the continuous nonhomogeneous Smoluchowski equation for coagulation rates satisfying a more general structure condition than the Galkin–Tupchiev monotony hypothesis considered in (Ph. Laurençot, S. Mischler, Arch. Rational Mech. Anal. 162 (1) (2002) 45–99). The Smoluchowski coagulation rate fulfils this condition as well as some rates which vanish on the diagonal. Under the condition of positivity of the coagulation rate outside of the diagonal we prove that solutions tend to 0 in the large time asymptotic. These results depend on a new estimate from below for the dissipation rate of the Lp-norm, p>1. To cite this article: S. Mischler, M. Rodriguez Ricard, C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献
996.
997.
We construct a three-parameter family of contact metric structures on the unit tangent sphere bundle T
1
M of a Riemannian manifold M and we study some of their special properties related to the Levi-Civita connection. More precisely, we give the necessary
and sufficient conditions for a constructed contact metric structure to be K-contact, Sasakian, to satisfy some variational conditions or to define a strongly pseudo-convex CR-structure. The obtained
results generalize classical theorems on the standard contact metric structure of T
1
M. 相似文献
998.
999.
Dorota G?azowska Janusz Matkowski 《Journal of Mathematical Analysis and Applications》2007,331(2):1187-1199
The invariance of the geometric mean G with respect to the Lagrangian mean-type mapping (Lf,Lg), i.e. the equation G○(Lf,Lg)=G, is considered. We show that the functions f and g must be of high class regularity. This fact allows to reduce the problem to a differential equation and determine the second derivatives of the generators f and g. 相似文献
1000.
In the paper we indicate an error made in the proof of the main result of the paper [M.A. Darwish, On quadratic integral equation of fractional orders, J. Math. Anal. Appl. 311 (2005) 112-119]. Moreover, we provide correct proof of a slightly modified version of the mentioned result. The main tool used in our proof is the technique associated with the Hausdorff measure of noncompactness. 相似文献