全文获取类型
收费全文 | 10822篇 |
免费 | 1034篇 |
国内免费 | 732篇 |
专业分类
化学 | 1679篇 |
晶体学 | 26篇 |
力学 | 735篇 |
综合类 | 128篇 |
数学 | 8356篇 |
物理学 | 1664篇 |
出版年
2024年 | 16篇 |
2023年 | 94篇 |
2022年 | 119篇 |
2021年 | 185篇 |
2020年 | 298篇 |
2019年 | 311篇 |
2018年 | 282篇 |
2017年 | 289篇 |
2016年 | 348篇 |
2015年 | 266篇 |
2014年 | 493篇 |
2013年 | 1004篇 |
2012年 | 532篇 |
2011年 | 570篇 |
2010年 | 496篇 |
2009年 | 666篇 |
2008年 | 618篇 |
2007年 | 713篇 |
2006年 | 625篇 |
2005年 | 520篇 |
2004年 | 484篇 |
2003年 | 462篇 |
2002年 | 447篇 |
2001年 | 355篇 |
2000年 | 364篇 |
1999年 | 337篇 |
1998年 | 274篇 |
1997年 | 277篇 |
1996年 | 174篇 |
1995年 | 126篇 |
1994年 | 110篇 |
1993年 | 65篇 |
1992年 | 92篇 |
1991年 | 46篇 |
1990年 | 49篇 |
1989年 | 37篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 33篇 |
1985年 | 47篇 |
1984年 | 54篇 |
1983年 | 24篇 |
1982年 | 40篇 |
1981年 | 38篇 |
1980年 | 37篇 |
1979年 | 36篇 |
1978年 | 18篇 |
1977年 | 24篇 |
1976年 | 23篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
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
12.
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
13.
设f是非常数亚纯函数,g是f的线性微分多项式.a和b是f的两个不同的小函数.本文证明如果f和g几乎CM分担a和b,则f≡g;此外,若f是非常数整函数,且f和f(k)(k≥1)IM分担a和b,b-a≠Peλz,测f≡g. 相似文献
14.
方程w"-w+f(t,w)=O的Dirichlet边值问题的正解存在性与多解性 总被引:1,自引:0,他引:1
姚庆六 《应用泛函分析学报》2002,4(1):4-9
考察了下列常微分方程的Dirichlet边值问题的正解[w″(t)-w(t) f(t,w(t))=0,0≤t≤1 w(0)=w(1)=0建立了n正解的存在性,其中n是一个任意的自然数。 相似文献
15.
In this work, the natural convection in a concentric annulus between a cold outer square cylinder and a heated inner circular cylinder is simulated using the differential quadrature (DQ) method. The vorticity‐stream function formulation is used as the governing equation, and the coordinate transformation technique is introduced in the DQ computation. It is shown in this paper that the outer square boundary can be approximated by a super elliptic function. As a result, the coordinate transformation from the physical domain to the computational domain is set up by an analytical expression, and all the geometrical parameters can be computed exactly. Numerical results for Rayleigh numbers range from 104 to 106 and aspect ratios between 1.67 and 5.0 are presented, which are in a good agreement with available data in the literature. It is found that both the aspect ratio and the Rayleigh number are critical to the patterns of flow and thermal fields. The present study suggests that a critical aspect ratio may exist at high Rayleigh number to distinguish the flow and thermal patterns. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
16.
The angular variations of the five-fold differential cross section obtained by using different wave functions of helium are
compared with experimental data. It is found that in the coplanar geometry two kinematical arrangements, (i) equal energy
sharing between the two ejected electrons with one of them ejected along the momentum transfer direction and the other along
varying direction and (ii) the Bethe ridge condition with fixed sum of ejected electron energies and varying angle between
them, are very sensitive to e-e correlations contained in the target wave function. This comparison has been used to show
that open-shell class of wave functions better incorporate e-e correlations than the closed-shell class. 相似文献
17.
本文对具有有限时滞的泛函微分方程建立了关于依照两种测度的实际稳定性的Razumikhin型判定定理,其中未采用通常的辅助函数,且可运用多个含有状态变量x的部分变元的Lyapunov函数,得出部分变远实际稳定性的判定定理,从而改进了已有的结果。 相似文献
18.
19.
20.
Mehdi Dehghan 《Numerical Methods for Partial Differential Equations》2002,18(2):193-202
Developement of numerical methods for obtaining approximate solutions to the three dimensional diffusion equation with an integral condition will be carried out. The numerical techniques discussed are based on the fully explicit (1,7) finite difference technique and the fully implicit (7,1) finite difference method and the (7,7) Crank‐Nicolson type finite difference formula. The new developed methods are tested on a problem. Truncation error analysis and numerical examples are used to illustrate the accuracy of the new algorithms. The results of numerical testing show that the numerical methods based on the finite difference techniques discussed in the present article produce good results. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 193–202, 2002; DOI 10.1002/num.1040 相似文献