全文获取类型
收费全文 | 3633篇 |
免费 | 303篇 |
国内免费 | 396篇 |
学科分类
数理化 | 4332篇 |
出版年
2024年 | 4篇 |
2023年 | 46篇 |
2022年 | 63篇 |
2021年 | 120篇 |
2020年 | 104篇 |
2019年 | 121篇 |
2018年 | 134篇 |
2017年 | 131篇 |
2016年 | 141篇 |
2015年 | 76篇 |
2014年 | 206篇 |
2013年 | 372篇 |
2012年 | 163篇 |
2011年 | 214篇 |
2010年 | 165篇 |
2009年 | 214篇 |
2008年 | 218篇 |
2007年 | 242篇 |
2006年 | 210篇 |
2005年 | 199篇 |
2004年 | 172篇 |
2003年 | 162篇 |
2002年 | 138篇 |
2001年 | 99篇 |
2000年 | 104篇 |
1999年 | 87篇 |
1998年 | 93篇 |
1997年 | 51篇 |
1996年 | 64篇 |
1995年 | 37篇 |
1994年 | 31篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 18篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1959年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有4332条查询结果,搜索用时 22 毫秒
41.
A review of the analysis of petroleum fuels, oils, tars and engine exhaust particulate extracts by on-line coupled LC-GC is presented. 相似文献
42.
Manuel Fernández-López Eduardo García-Río Demir N. Kupeli 《Annals of Global Analysis and Geometry》2002,21(1):1-13
A characterization of time functions on a spacetime is made by using theMöbius equation. It is shown that a time function characterized in this wayyields past timelike geodesic incompleteness and local Lorentzian warpedproduct decomposition of spacetime, provided that the stress-energy tensoris a fluid. Also, by imposing additional assumptions on the stress-energytensor and global analytic structure of the spacetime, more restrictivedecompositions closer to Robertson–Walker spacetimes are obtained. 相似文献
43.
A new collectively fixed point theorem for a family of set-valued mappings defined on product spaces of non-compact topological spaces without linear structure is proved and some special cases are also discussed. As applications, some non-empty intersection theorems of sets with convex sections and equilibrium existence theorem of abstract economies are obtained under much weaker assumptions. Our results includes a number of known results as many special cases. 相似文献
44.
We introduce a generalized notion of semiring and prove that all known properties that semirings have according to the old definition are preserved. 相似文献
45.
设G是有限群,|G|-1∈R.本文证明了与强G-分次环R,R#k[G]*,非分次R-模和Re-模有关的两个Maschke-型定理. 相似文献
46.
For each infinite cardinal κ, we give examples of 2κ many non‐isomorphic vertex‐transitive graphs of order κ that are pairwise isomorphic to induced subgraphs of each other. We consider examples of graphs with these properties that are also universal, in the sense that they embed all graphs with smaller orders as induced subgraphs. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 99–106, 2003 相似文献
47.
48.
The wreath product of finite association schemes is a natural generalization of the notion of the wreath product of finite permutation groups. We determine all irreducible representations (the Jacobson radical) of a wreath product of two finite association schemes over an algebraically closed field in terms of the irreducible representations (Jacobson radicals) of the two factors involved. 相似文献
49.
Nessan J. Kerrigan 《Tetrahedron letters》2004,45(49):9087-9090
The samarium(II) iodide-mediated coupling of ketones with β-alkoxyacrylates gives β-hydroxy-γ-butyrolactones in moderate yield. The process has been applied to the asymmetric synthesis of an antifungal, γ-butyrolactone natural product. 相似文献
50.
Nicolas Victoir 《Journal of Functional Analysis》2004,208(1):107-121
This note extends the work of Capitaine (J. Funct. Anal. 179 (1) (2001) 153) on the Levy area process for the free Brownian motion in two directions. First, we reprove that a Levy area for the Free Brownian motion exists in the Von Neumann tensor product, by exhibiting a non-commutative Burkholder-Davis-Gundy type inequality. Then, we show that there does not exist a Levy area in the projective tensor product. 相似文献