全文获取类型
收费全文 | 7647篇 |
免费 | 757篇 |
国内免费 | 714篇 |
专业分类
化学 | 832篇 |
晶体学 | 29篇 |
力学 | 551篇 |
综合类 | 204篇 |
数学 | 6158篇 |
物理学 | 1344篇 |
出版年
2024年 | 11篇 |
2023年 | 61篇 |
2022年 | 119篇 |
2021年 | 169篇 |
2020年 | 158篇 |
2019年 | 167篇 |
2018年 | 163篇 |
2017年 | 243篇 |
2016年 | 254篇 |
2015年 | 169篇 |
2014年 | 354篇 |
2013年 | 595篇 |
2012年 | 355篇 |
2011年 | 451篇 |
2010年 | 385篇 |
2009年 | 480篇 |
2008年 | 521篇 |
2007年 | 563篇 |
2006年 | 465篇 |
2005年 | 404篇 |
2004年 | 375篇 |
2003年 | 349篇 |
2002年 | 326篇 |
2001年 | 286篇 |
2000年 | 263篇 |
1999年 | 197篇 |
1998年 | 210篇 |
1997年 | 184篇 |
1996年 | 156篇 |
1995年 | 104篇 |
1994年 | 83篇 |
1993年 | 56篇 |
1992年 | 41篇 |
1991年 | 54篇 |
1990年 | 46篇 |
1989年 | 33篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 15篇 |
1985年 | 27篇 |
1984年 | 24篇 |
1983年 | 31篇 |
1982年 | 21篇 |
1981年 | 27篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 13篇 |
1977年 | 4篇 |
1973年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有9118条查询结果,搜索用时 78 毫秒
1.
2.
3.
Rong Yin Jihui Zhang Xudong Shang 《Mathematical Methods in the Applied Sciences》2020,43(15):8736-8752
This paper is dedicated to studying the following Schrödinger–Poisson system Under some different assumptions on functions V(x), K(x), a(x) and f(u), by using the variational approach, we establish the existence of positive ground state solutions. 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.
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
7.
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
8.
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
9.
本文定义了二阶微分方程的弱 Carathéodory解 ,在不涉及紧型条件的情形下 ,直接用迭代法证明了 Banach空间二阶非线性常微分方程两点边值问题存在唯一解 ,并给出逼近解迭代序列的误差估计 ,对周期边值问题得到类似的结果 相似文献
10.
A. Mielke 《Journal of statistical physics》1991,62(3-4):509-528
The magnetic properties of the one-dimensional Hubbard model with a hardcore interaction on a ring (periodic boundary conditions) are investigated. At finite temperatures it is shown to behave up to exponentially small corrections as a pure paramagnet. An explicit expression for the ground-state degeneracies is derived. The eigenstates of this model are used to perform a perlurbational treatment for large but finite interactions. In first order inU
1 an effective Hamiltonian for the one-dimensional Hubbard model is derived. It is the Hamiltonian of the one-dimensional Hcisenberg model with antiferromagnetic couplings between nearest neighbor spins. An asymptotic expansion for the ground-state energy is given. The results are valid for arbitrary densities of electrons. 相似文献