全文获取类型
收费全文 | 13108篇 |
免费 | 1460篇 |
国内免费 | 854篇 |
专业分类
化学 | 441篇 |
晶体学 | 46篇 |
力学 | 4455篇 |
综合类 | 170篇 |
数学 | 7481篇 |
物理学 | 2829篇 |
出版年
2024年 | 15篇 |
2023年 | 139篇 |
2022年 | 195篇 |
2021年 | 210篇 |
2020年 | 366篇 |
2019年 | 323篇 |
2018年 | 347篇 |
2017年 | 391篇 |
2016年 | 443篇 |
2015年 | 325篇 |
2014年 | 560篇 |
2013年 | 1190篇 |
2012年 | 600篇 |
2011年 | 697篇 |
2010年 | 611篇 |
2009年 | 713篇 |
2008年 | 671篇 |
2007年 | 789篇 |
2006年 | 719篇 |
2005年 | 711篇 |
2004年 | 628篇 |
2003年 | 605篇 |
2002年 | 545篇 |
2001年 | 498篇 |
2000年 | 475篇 |
1999年 | 459篇 |
1998年 | 408篇 |
1997年 | 316篇 |
1996年 | 270篇 |
1995年 | 194篇 |
1994年 | 174篇 |
1993年 | 118篇 |
1992年 | 150篇 |
1991年 | 128篇 |
1990年 | 86篇 |
1989年 | 50篇 |
1988年 | 37篇 |
1987年 | 43篇 |
1986年 | 33篇 |
1985年 | 47篇 |
1984年 | 32篇 |
1983年 | 32篇 |
1982年 | 17篇 |
1981年 | 18篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1974年 | 3篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Hsien-Chung Wu 《Fuzzy Optimization and Decision Making》2003,2(1):61-73
The concept of fuzzy scalar (inner) product that will be used in the fuzzy objective and inequality constraints of the fuzzy primal and dual linear programming problems with fuzzy coefficients is proposed in this paper. We also introduce a solution concept that is essentially similar to the notion of Pareto optimal solution in the multiobjective programming problems by imposing a partial ordering on the set of all fuzzy numbers. We then prove the weak and strong duality theorems for fuzzy linear programming problems with fuzzy coefficients. 相似文献
82.
杨青 《高等学校计算数学学报(英文版)》2003,12(2)
The mathematical model of semiconductor devices is described by the initial boundary value problem of a system of three nonlinear partial differential equations. One equation in elliptic form is for the electrostatic potential; two equations of convection-dominated diffusion type are for the electron and hole concentrations. Finite volume element procedure are put forward for the electrostatic potential, while upwind 相似文献
83.
84.
A time-dependent model corresponding to an Oldroyd-B viscoelastic fluid is considered, the convective terms being disregarded.
Global existence in time is proved in Banach spaces provided the data are small enough, using the implicit function theorem
and a maximum regularity property for a three fields Stokes problem. A finite element discretization in space is then proposed.
Existence of the numerical solution is proved for small data, so as a priori error estimates, using again an implicit function
theorem.
Supported by the Swiss National Science Foundation. Fellowship PBEL2–114311. 相似文献
85.
In this paper we consider a class of nonlinear delay partial difference equations and a class of linear delay partial difference equations with variable coefficients, which may change sign. We obtain oscillation criteria for these equations. There are no results for the oscillation of these equations up to now. 相似文献
86.
A finite element solution of the Navier-Stokes equations for steady flow under the magnetic effect through a double-branched two-dimensional section of a three-dimensional model of the canine aorta is discussed. The numerical scheme involves transforming the physical co-ordinates to a curvilinear boundary-fitted co-ordinate system. The shear stress at the wall is calculated for a Reynolds number of 1000 with the branch-to-main aortic flow rate ratio as a parameter. The results are compared with earlier works involving experimental data and found to be in reasonable qualitative agreement. The steady flow, shear stress and branch flow under the effect of a magnetic field have been discussed in detail. 相似文献
87.
George Stoica 《Journal of Mathematical Analysis and Applications》2007,336(2):1489-1492
We obtain a Baum-Katz-Nagaev type theorem for bounded martingale difference sequences that have more than a second moment, and prove that the celebrated Hsu-Robbins-Erd?s theorem fails for martingales. 相似文献
88.
汪巍 《数学的实践与认识》2004,34(3):103-109
首先引入了差分系统基于两种度量的极端稳定性概念 ,然后建立了一些关于差分系统 ( h0 ,h)极端稳定性 (极端一致稳定性 ,极端渐近稳定性 ,极端一致渐近稳定性 )的判定准则 .在所得到的定理中 ,对△ V的限制较弱 ,特别地 ,△V甚至可以恒为正 ,从而便于实际应用 . 相似文献
89.
杨青 《高校应用数学学报(A辑)》2002,17(3):353-362
热传导型半导体器件的瞬时状态由四个方程的非线性偏微分方程组的初边值问题所决定,其中电子位势方程是椭圆型的,电子和空穴浓度方程是对流扩散型的,温度方程为热传导型的。本文提出解这类问题的特征变网格有限元法,并进行了理论分析,在一定条件下,得到了某种意义下的最佳L^2误差估计结果。 相似文献
90.
Piotr Biler 《Reports on Mathematical Physics》2003,52(2):205-225
We study asymptotic properties of solutions to an extension to arbitrary dimensions of the astrophysical model proposed by Chavanis et al. to explain phenomena of gravitational collapse in clouds of self-gravitating particles. In particular, we show that in the two-dimensional case the solutions can be continued to global ones, while in three space dimensions large data of negative energy blow up in a finite time. Relations between isothermal, Streater's energy-transport and the present models are also studied. 相似文献