全文获取类型
收费全文 | 8881篇 |
免费 | 769篇 |
国内免费 | 813篇 |
专业分类
化学 | 611篇 |
晶体学 | 26篇 |
力学 | 762篇 |
综合类 | 212篇 |
数学 | 7954篇 |
物理学 | 898篇 |
出版年
2024年 | 14篇 |
2023年 | 69篇 |
2022年 | 106篇 |
2021年 | 158篇 |
2020年 | 163篇 |
2019年 | 190篇 |
2018年 | 195篇 |
2017年 | 267篇 |
2016年 | 283篇 |
2015年 | 172篇 |
2014年 | 389篇 |
2013年 | 646篇 |
2012年 | 389篇 |
2011年 | 484篇 |
2010年 | 445篇 |
2009年 | 542篇 |
2008年 | 591篇 |
2007年 | 654篇 |
2006年 | 534篇 |
2005年 | 472篇 |
2004年 | 444篇 |
2003年 | 416篇 |
2002年 | 395篇 |
2001年 | 322篇 |
2000年 | 305篇 |
1999年 | 264篇 |
1998年 | 265篇 |
1997年 | 250篇 |
1996年 | 185篇 |
1995年 | 124篇 |
1994年 | 102篇 |
1993年 | 85篇 |
1992年 | 66篇 |
1991年 | 67篇 |
1990年 | 57篇 |
1989年 | 33篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 21篇 |
1985年 | 34篇 |
1984年 | 30篇 |
1983年 | 34篇 |
1982年 | 25篇 |
1981年 | 27篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1978年 | 16篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
Marcus Carlsson 《Expositiones Mathematicae》2021,39(1):149-157
von Neumann’s inequality in matrix theory refers to the fact that the Frobenius scalar product of two matrices is less than or equal to the scalar product of the respective singular values. Moreover, equality can only happen if the two matrices share a joint set of singular vectors, and this latter part is hard to find in the literature. We extend these facts to the separable Hilbert space setting, and provide a self-contained proof of the “latter part”. 相似文献
4.
基于时变Copula模型,获得预测方差,确定单个基金收益率序列的边缘分布.利用常见的静态Copula和时变Copula模型对基金收益率序列间两两相依关系进行建模并进行对比分析.应用研究表明,基于MCMC方法的时变Copula模型能更有效地度量基金收益率序列的风险. 相似文献
5.
Qi Yongcheng 《数学年刊B辑(英文版)》1998,19(4):499-510
1.IntroductionLet{X.,n21}beasequenceoflidry'swithanondegeneratedistributionfunctionF(x).Supposethereexistsomeconstantsan>0,b.6RandsomeacERsuchthatwhereG.standsforoneoftheextremevaluedistributions:Heretheindex7ERisarealparameter(interpret(1 box)--'/ryase--"for7~0).Theestimationoftheextreme-valueindex7isveryimportantbothintheextremevaluetheoryandinpractice.Manystatistics,suchasHillestimator(forcaseac>0),PickandsestimatorandDekkers-EinmahLdeHaan'smomentestimatorwhicharebasedonafinitesample,… 相似文献
6.
Boundedness of commutators on homogeneous Herz spaces 总被引:9,自引:0,他引:9
The boundedness on homogeneous Herz spaces is established for a large class of linear commutators generated by BMO(R
n
) functions and linear operators of rough kernels which include the Calderón-Zygmund operators and the Ricci-Stein oRfiUatory
singular integrals with rough kernels.
Project supponed in pan by the National h’atural Science Foundation of China (Grant No. 19131080) and the NEDF of China. 相似文献
7.
We study spectral properties of discrete Schrödinger operators with potentials obtained via dimerization of a class of aperiodic sequences. It is shown that both the nature of the autocorrelation measure of a regular sequence and the presence of generic (full probability) singular continuous spectrum in the hull of primitive and palindromic (four block substitution) potentials are robust under dimerization. Generic results also hold for circle potentials. We illustrate these results with numerical studies of the quantum mean square displacement as a function of time. The numerical techniques provide a very fast algorithm for the time evolution of wave packets. 相似文献
8.
We discuss an error estimation procedure for the global error of collocation schemes applied to solve singular boundary value problems with a singularity of the first kind. This a posteriori estimate of the global error was proposed by Stetter in 1978 and is based on the idea of Defect Correction, originally due to Zadunaisky. Here, we present a new, carefully designed modification of this error estimate which not only results in less computational work but also appears to perform satisfactorily for singular problems. We give a full analytical justification for the asymptotical correctness of the error estimate when it is applied to a general nonlinear regular problem. For the singular case, we are presently only able to provide computational evidence for the full convergence order, the related analysis is still work in progress. This global estimate is the basis for a grid selection routine in which the grid is modified with the aim to equidistribute the global error. This procedure yields meshes suitable for an efficient numerical solution. Most importantly, we observe that the grid is refined in a way reflecting only the behavior of the solution and remains unaffected by the unsmooth direction field close to the singular point. 相似文献
9.
本文给出了混合型多项式Hammerstein积分方程正解的迭代求法,并将所得结果应用到二阶非线性常微分方程的边值问题 相似文献
10.
Lin Surong 《Annals of Differential Equations》2006,22(4):517-523
The singularly perturbed boundary value problem for nonlinear higher order ordinary differential equation involving two small parameters has been considered. Under appropriate assumptions, for the three cases:ε/μ2→0(μ→0),μ2/ε→0 (ε→0) andε=μ2, the uniformly valid asymptotic solution is obtained by using the expansion method of two small parameters and the theory of differential inequality. 相似文献