全文获取类型
收费全文 | 23012篇 |
免费 | 913篇 |
国内免费 | 1281篇 |
专业分类
化学 | 9503篇 |
晶体学 | 202篇 |
力学 | 399篇 |
综合类 | 63篇 |
数学 | 11270篇 |
物理学 | 3769篇 |
出版年
2024年 | 35篇 |
2023年 | 365篇 |
2022年 | 267篇 |
2021年 | 290篇 |
2020年 | 444篇 |
2019年 | 555篇 |
2018年 | 486篇 |
2017年 | 393篇 |
2016年 | 468篇 |
2015年 | 553篇 |
2014年 | 785篇 |
2013年 | 1371篇 |
2012年 | 912篇 |
2011年 | 1626篇 |
2010年 | 1253篇 |
2009年 | 1618篇 |
2008年 | 1791篇 |
2007年 | 1576篇 |
2006年 | 1229篇 |
2005年 | 937篇 |
2004年 | 863篇 |
2003年 | 786篇 |
2002年 | 1068篇 |
2001年 | 543篇 |
2000年 | 501篇 |
1999年 | 539篇 |
1998年 | 409篇 |
1997年 | 333篇 |
1996年 | 399篇 |
1995年 | 374篇 |
1994年 | 328篇 |
1993年 | 258篇 |
1992年 | 229篇 |
1991年 | 180篇 |
1990年 | 151篇 |
1989年 | 166篇 |
1988年 | 110篇 |
1987年 | 114篇 |
1986年 | 101篇 |
1985年 | 130篇 |
1984年 | 107篇 |
1983年 | 63篇 |
1982年 | 99篇 |
1981年 | 100篇 |
1980年 | 49篇 |
1979年 | 39篇 |
1978年 | 39篇 |
1977年 | 51篇 |
1976年 | 43篇 |
1971年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
31.
32.
Summary. We present a simple proof, based on modified logarithmic Sobolev inequalities, of Talagrand’s concentration inequality for
the exponential distribution. We actually observe that every measure satisfying a Poincaré inequality shares the same concentration
phenomenon. We also discuss exponential integrability under Poincaré inequalities and its consequence to sharp diameter upper
bounds on spectral gaps.
Received: 10 June 1996 / In revised form: 9 August 1996 相似文献
33.
S. A. Denisov 《Integral Equations and Operator Theory》2002,42(2):166-173
We consider the Krein systems. For the set of Stummel class coefficients, we establish the criterion in terms of these coefficients for the system to satisfy the Szegö-type estimate on the spectral measure. 相似文献
34.
35.
本文通过对大量的黄酮类化合物13C NMR图谱的分析和研究,总结了不同类型的黄酮类化合物的13C NMR图谱特征及化学位移规律.对影响黄酮类化合物结构骨架上不同位置碳原子化学位移的因素进行了分析,建立了用于黄酮类天然产物13C NMR图谱智能解析的知识库. 相似文献
36.
Tatsien Li 《Mathematical Methods in the Applied Sciences》2006,29(13):1543-1553
By means of a direct and constructive method based on the theory of semi‐global C2 solution, the local exact boundary observability and an implicit duality between the exact boundary controllability and the exact boundary observability are shown for 1‐D quasilinear wave equations with various boundary conditions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
37.
Let Λ be a smooth Lagrangian submanifold of a complex symplectic manifold X. We construct twisted simple holonomic modules along Λ in the stack of deformation-quantization modules on X. 相似文献
38.
The main results of the paper are as follows: covering characterizations of wQN-spaces, covering characterizations of QN-spaces and a theorem saying that Cp(X) has the Arkhangel'ski?ˇ property (α1) provided that X is a QN-space. The latter statement solves a problem posed by M. Scheepers [M. Scheepers, Cp(X) and Arhangel'ski?ˇ's αi-spaces, Topology Appl. 89 (1998) 265-275] and for Tychonoff spaces was independently proved by M. Sakai [M. Sakai, The sequence selection properties of Cp(X), Preprint, April 25, 2006]. As the most interesting result we consider the equivalence that a normal topological space X is a wQN-space if and only if X has the property S1(Γshr,Γ). Moreover we show that X is a QN-space if and only if Cp(X) has the property (α0), and for perfectly normal spaces, if and only if X has the covering property (β3). 相似文献
39.
We propose a new scheme for the long time approximation of a diffusion when the drift vector field is not globally Lipschitz. Under this assumption, a regular explicit Euler scheme–with constant or decreasing step–may explode and implicit Euler schemes are CPU-time expensive. The algorithm we introduce is explicit and we prove that any weak limit of the weighted empirical measures of this scheme is a stationary distribution of the stochastic differential equation. Several examples are presented including gradient dissipative systems and Hamiltonian dissipative systems. 相似文献
40.
Pál Sohár Gábor Bernáth Géza Stájer Angela E. Szabo 《Magnetic resonance in chemistry : MRC》1989,27(9):872-876
Pentacyclic isoxazolines were obtained by the cycloaddition of benzonitrile oxide to norbornene-azetidinone-fused 3,1-oxazines. The constitutions of two of the isomers obtained, and the configurations and conformations of all products, were determined by means of 1H and 13C NMR spectroscopy and DNOE experiments. 相似文献