全文获取类型
收费全文 | 19695篇 |
免费 | 4432篇 |
国内免费 | 2047篇 |
专业分类
化学 | 4297篇 |
晶体学 | 271篇 |
力学 | 1715篇 |
综合类 | 269篇 |
数学 | 4065篇 |
物理学 | 15557篇 |
出版年
2024年 | 40篇 |
2023年 | 199篇 |
2022年 | 412篇 |
2021年 | 517篇 |
2020年 | 610篇 |
2019年 | 474篇 |
2018年 | 533篇 |
2017年 | 667篇 |
2016年 | 797篇 |
2015年 | 707篇 |
2014年 | 1027篇 |
2013年 | 1857篇 |
2012年 | 1246篇 |
2011年 | 1380篇 |
2010年 | 1290篇 |
2009年 | 1350篇 |
2008年 | 1336篇 |
2007年 | 1303篇 |
2006年 | 1234篇 |
2005年 | 1164篇 |
2004年 | 1093篇 |
2003年 | 936篇 |
2002年 | 888篇 |
2001年 | 712篇 |
2000年 | 673篇 |
1999年 | 553篇 |
1998年 | 532篇 |
1997年 | 421篇 |
1996年 | 362篇 |
1995年 | 257篇 |
1994年 | 243篇 |
1993年 | 208篇 |
1992年 | 182篇 |
1991年 | 140篇 |
1990年 | 135篇 |
1989年 | 121篇 |
1988年 | 82篇 |
1987年 | 73篇 |
1986年 | 79篇 |
1985年 | 64篇 |
1984年 | 50篇 |
1983年 | 26篇 |
1982年 | 45篇 |
1981年 | 30篇 |
1980年 | 26篇 |
1979年 | 25篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1976年 | 10篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
The behavior of a two-level entangled atom in an optical field with circular polarization is studied in this paper. The interaction of an optical field and one of the entangled atoms is analyzed in detail. A general solution of the SchrAo¨Gdinger equation about the motion of the entangled atom is obtained. The properties of the action are dependent on the initial state of the atom. By detecting the entangled atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field will influence the energies of the split-levels of the atom in the field. 相似文献
52.
Summary We study the integration theory for general integral metrics when restricted to upper integrals q, finding improvements in the relation between the classes of the q-integrable and the ql-integrable functions. We give new results and notions which lead to the desirable characterizations of q-integrable functions as ql-integrable f with q(|f|) < ∞, and of ql-integrable functions via the integrability of their upper truncations, under natural conditions which are fulfilled in most
finitely additive integration theories. 相似文献
53.
54.
The values of the Higgs mass are obtained for two possibilities of extending the standard model in a way compatible with the existence of a noncommutative structure at high energies. We assume the existence of a big desert between the low energy electroweak scale and the high energy scale Λ=1.1×1017 GeV, where noncommutative features become relevant. We conclude that it is extremely difficult to depart from the Higgs mass value obtained from noncommutative geometry for the standard model with three generations only. 相似文献
55.
脉冲中立型时滞抛物方程的振动性 总被引:6,自引:0,他引:6
本文研究了一类脉冲中立型时滞抛物方程解的振动性及强振动性,获得了此类脉冲中立型时滞抛物方程解振动和强振动的代数判据. 相似文献
56.
对Hajek-Renyi不等式进行了推广,利用推广的不等式给出了随机变量序列绝对平均意义下的强大数定律的一个条件. 相似文献
57.
引进了随机环境中多物种分枝随机游动的一般模型.在分枝过程非灭绝的情况下,讨论了系统的状态分类,得到了系统暂留及强常返的充要条件是存在k个定义在整数集上的函数分别满足某种性质.最后给出了系统强暂留的充分条件. 相似文献
58.
Boniface Nkemzi 《Mathematical Methods in the Applied Sciences》2006,29(9):1053-1080
This paper is concerned with the structure of the singular and regular parts of the solution of time‐harmonic Maxwell's equations in polygonal plane domains and their effective numerical treatment. The asymptotic behaviour of the solution near corner points of the domain is studied by means of discrete Fourier transformation and it is proved that the solution of the boundary value problem does not belong locally to H2 when the boundary of the domain has non‐acute angles. A splitting of the solution into a regular part belonging to the space H2, and an explicitly described singular part is presented. For the numerical treatment of the boundary value problem, we propose a finite element discretization which combines local mesh grading and the singular field methods and derive a priori error estimates that show optimal convergence as known for the classical finite element method for problems with regular solutions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
59.
利用关于乘积分布密度的相对熵和相对熵率的概念,建立了相依连续型随机变量序列关于参考微分熵的一类强偏差定理,证明中给出了将Laplace变换应用于微分熵强偏差定理的研究的一种途径. 相似文献
60.
A nonclassical problem is considered for the transport equation with coefficients depending on the energy of radiation. The task is to find the discontinuity surfaces for the coefficients of the equation from measurements of the radiation flux leaving the medium. For this tomography problem, an optimization problem is stated and numerically analyzed. The latter consists in determining the radiation energy that ensures the best reconstruction of the unknown medium. A simplified optimization problem is solved analytically. 相似文献