全文获取类型
收费全文 | 3661篇 |
免费 | 448篇 |
国内免费 | 430篇 |
专业分类
化学 | 126篇 |
晶体学 | 3篇 |
力学 | 283篇 |
综合类 | 133篇 |
数学 | 3291篇 |
物理学 | 703篇 |
出版年
2024年 | 9篇 |
2023年 | 50篇 |
2022年 | 58篇 |
2021年 | 96篇 |
2020年 | 122篇 |
2019年 | 108篇 |
2018年 | 104篇 |
2017年 | 123篇 |
2016年 | 165篇 |
2015年 | 112篇 |
2014年 | 228篇 |
2013年 | 250篇 |
2012年 | 176篇 |
2011年 | 169篇 |
2010年 | 187篇 |
2009年 | 206篇 |
2008年 | 259篇 |
2007年 | 262篇 |
2006年 | 211篇 |
2005年 | 200篇 |
2004年 | 174篇 |
2003年 | 169篇 |
2002年 | 188篇 |
2001年 | 144篇 |
2000年 | 124篇 |
1999年 | 124篇 |
1998年 | 89篇 |
1997年 | 99篇 |
1996年 | 68篇 |
1995年 | 47篇 |
1994年 | 49篇 |
1993年 | 22篇 |
1992年 | 22篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 20篇 |
1988年 | 8篇 |
1987年 | 16篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1957年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有4539条查询结果,搜索用时 8 毫秒
991.
Fernando Dobarro Bülent Ünal 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(11):5476-5490
In the framework of standard static space–times, we state a family of sufficient or necessary conditions for a set of physically reasonable energy and convergence conditions in relativity and related theories. We concentrate our study on questions about the sub-harmonicity of the warping function, the scalar curvature map, conformal hyperbolicity, conjugate points and the time-like diameter of this class of space–times. 相似文献
992.
GAO Hong-ya~ 《高校应用数学学报(英文版)》2008,23(1):43-50
A new kind of weight-Ar^λ3 (λ1, λ2, Ω)-weight is used to prove the local and global integral inequalities for conjugate A-harmonic tensors, which can be regarded as generalizations of the classical results. Some applications of the above results to quasiregular mappings are given. 相似文献
993.
简单平均法预测误差平方和的进一步研究 总被引:1,自引:0,他引:1
邓雪 《数学的实践与认识》2008,38(12):60-65
用数学归纳法对简单平均法与简单加权平均法的预测误差平方和的上界进行了比较,对简单平均法的有效性进行了分析.与相关文献的证明方法相比较,本文所采用的方法简单,直观而易懂.同时也得到了简单平均法就是最优组合预测方法的几个等价条件. 相似文献
994.
We develop the optimal transportation approach to modified log-Sobolev inequalities and to isoperimetric inequalities. Various
sufficient conditions for such inequalities are given. Some of them are new even in the classical log-Sobolev case. The idea
behind many of these conditions is that measures with a non-convex potential may enjoy such functional inequalities provided
they have a strong integrability property that balances the lack of convexity. In addition, several known criteria are recovered
in a simple unified way by transportation methods and generalized to the Riemannian setting.
The research of A.V. Kolesnikov was supported by RFBR 07-01-00536, DFG Grant 436 RUS 113/343/0 and GFEN 06-01-39003. 相似文献
995.
An important component of protein–nucleic acid interactions is the formation of salt bridges between cationic amino acid
side chains and the anionic phosphate groups of the nucleic acid. We have used molecular mechanics to study the energetic
and conformational impact of such interactions. Firstly, crystallographic protein–nucleic acid complexes from the Protein
Data Bank were analysed in terms of DNA curvature and the presence of salt bridges. For complexes where the DNA is significantly
bent, the contribution of salt bridges to this curvature was modelled by studying the effect of neutralising the appropriate
phosphate groups. The number and the distribution of salt bridges vary widely for different DNA binding motifs and appear
to have very different effects on DNA. In the case of homeodomain, bZIP and helix–loop–helix proteins, salt bridges induce
DNA bending, whereas for prokaryotic helix–turn–helix proteins the number of salt bridges is much smaller and little bending
is found. By analysing the components of the DNA deformation energy involved in protein binding we show that salt bridges
consistently increase the flexibility of the DNA backbone.
Received: 1 September 2000 / Accepted: 5 January 2001 / Published online: 3 May 2001 相似文献
996.
本利用几何不等式和曲率估计的方法,证明了黎曼流形N^n+p,上的具有平行平均曲率的紧子流形M^n上的一个拼挤定理。若N上的截曲率KN满足- 1≤ KN≤δ≤0,且‖S- nH2‖n/2, ‖ S-nH^2‖n/n-s满足一些不等式,则δ= - 1。 相似文献
997.
Jan Ámos Víšek 《Annals of the Institute of Statistical Mathematics》2009,61(3):543-578
A robust version of method of Instrumental Variables accommodating the idea of an implicit weighting the residuals is proposed
and its properties studied. Firstly, it is shown that all solutions of the corresponding normal equations are bounded in probability.
Then the weak consistency of them is proved. The algorithm, evaluating the estimate, is described and results of small MC
study discussed.
Research was supported by grant of GA ČR number 402/06/0408. 相似文献
998.
Mats Boman 《BIT Numerical Mathematics》2006,46(2):249-260
We consider the orthogonal L2-projection P onto continuous finite element spaces. We prove estimates for P in a weighted Lp-norm and use these to prove corresponding approximation properties.
AMS subject classification (2000) 65N60, 35K85 相似文献
999.
曲率二次衰减的完备流形的基本群 总被引:1,自引:0,他引:1
本文研究曲率二次衰减的完备黎曼流形,证明了若它的直径增长满足小的线性增长条件,则其基本群是有限生成的. 相似文献
1000.
JianQuan Ge 《中国科学A辑(英文版)》2008,51(6):1127-1134
By using moving frame theory,first we introduce 2p-th mean curvatures and(2p 1)-th mean curvature vector fields for a submanifold.We then give an integral expression of them that characterizes them as mean values of symmetric functions of principle curvatures.Next we apply it to derive directly the celebrated Weyl-Gray tube formula in terms of integrals of the 2p-th mean curvatures and some Minkowski-type integral formulas. 相似文献