全文获取类型
收费全文 | 8193篇 |
免费 | 1463篇 |
国内免费 | 818篇 |
专业分类
化学 | 152篇 |
晶体学 | 7篇 |
力学 | 952篇 |
综合类 | 330篇 |
数学 | 7331篇 |
物理学 | 1702篇 |
出版年
2024年 | 46篇 |
2023年 | 131篇 |
2022年 | 177篇 |
2021年 | 193篇 |
2020年 | 134篇 |
2019年 | 162篇 |
2018年 | 113篇 |
2017年 | 190篇 |
2016年 | 167篇 |
2015年 | 246篇 |
2014年 | 471篇 |
2013年 | 394篇 |
2012年 | 430篇 |
2011年 | 508篇 |
2010年 | 512篇 |
2009年 | 568篇 |
2008年 | 533篇 |
2007年 | 525篇 |
2006年 | 494篇 |
2005年 | 523篇 |
2004年 | 564篇 |
2003年 | 422篇 |
2002年 | 317篇 |
2001年 | 340篇 |
2000年 | 297篇 |
1999年 | 259篇 |
1998年 | 254篇 |
1997年 | 252篇 |
1996年 | 217篇 |
1995年 | 205篇 |
1994年 | 161篇 |
1993年 | 150篇 |
1992年 | 139篇 |
1991年 | 133篇 |
1990年 | 129篇 |
1989年 | 94篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
电路过渡过程所列方程是微分方程,本文中采用的是方框图模型分析法,即将微分方程的复杂示解分解成最基本的加(减)、乘(除)、积分(微分)、增益等运算,采用VB设计用户界面产进行计算,并给出了一算例。 相似文献
4.
许明浩 《武汉大学学报(理学版)》1996,(1)
讨论如下Hilbert空间中的半线性随机发展方程的Cauchy问题 dy(t)=[Ay(t) f(t,y(t))]dt G(t,y(t))dw(t) y(O)=V_u的适度解的存在唯一性,在更一般的条件下,得到了该问题的适度解的存在唯一性。 相似文献
5.
邵永恒 《数学物理学报(A辑)》1991,11(4):396-403
本文引入随机收缩偶,讨论具有随机定义域的随机集值(单值)算子方程公共随机解的存在性,建立随机收缩理论与公共随机不动点理论的联系,统一和推广了这两个方向的主要结果。 关健词:随机算子;方程;公共不动点。 相似文献
6.
7.
一类生化反应数学模型的分析 总被引:1,自引:0,他引:1
本文讨论了生化反应中一类可逆两分子饱和反应,它的数学模型可近似表达为应用常微分方程定性和稳定性的方法分析了参数的所有情况,得到了正初值的正半轨线的有界性、正平衡点的稳定性及极限环的存在唯一性等结论。 相似文献
8.
Second-order random wave solutions for interfacial internal waves in N-layer density-stratified fluid
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper studies the random internal wave equations describing the density interface displacements and the velocity potentials of N-layer stratified fluid contained between two rigid walls at the top and bottom. The density interface displacements and the velocity potentials were solved to the second-order by an expansion approach used by Longuet-Higgins (1963) and Dean (1979) in the study of random surface waves and by Song (2004) in the study of second- order random wave solutions for internal waves in a two-layer fluid. The obtained results indicate that the first-order solutions are a linear superposition of many wave components with different amplitudes, wave numbers and frequencies, and that the amplitudes of first-order wave components with the same wave numbers and frequencies between the adjacent density interfaces are modulated by each other. They also show that the second-order solutions consist of two parts: the first one is the first-order solutions, and the second one is the solutions of the second-order asymptotic equations, which describe the second-order nonlinear modification and the second-order wave-wave interactions not only among the wave components on same density interfaces but also among the wave components between the adjacent density interfaces. Both the first-order and second-order solutions depend on the density and depth of each layer. It is also deduced that the results of the present work include those derived by Song (2004) for second-order random wave solutions for internal waves in a two-layer fluid as a particular case. 相似文献
9.
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
10.
Abstract
In this note, we consider a Frémond model of shape memory alloys. Let us imagine a piece of a shape memory alloy which is
fixed on one part of its boundary, and assume that forcing terms, e.g., heat sources and external stress on the remaining
part of its boundary, converge to some time-independent functions, in appropriate senses, as time goes to infinity. Under
the above assumption, we shall discuss the asymptotic stability for the dynamical system from the viewpoint of the global
attractor. More precisely, we generalize the paper [12] dealing with the one-dimensional case. First, we show the existence
of the global attractor for the limiting autonomous dynamical system; then we characterize the asymptotic stability for the
non-autonomous case by the limiting global attractor.
* Project supported by the MIUR-COFIN 2004 research program on “Mathematical Modelling and Analysis of Free Boundary Problems”. 相似文献