全文获取类型
收费全文 | 12531篇 |
免费 | 1099篇 |
国内免费 | 798篇 |
专业分类
化学 | 2600篇 |
晶体学 | 54篇 |
力学 | 4605篇 |
综合类 | 158篇 |
数学 | 3664篇 |
物理学 | 3347篇 |
出版年
2024年 | 35篇 |
2023年 | 144篇 |
2022年 | 245篇 |
2021年 | 256篇 |
2020年 | 325篇 |
2019年 | 259篇 |
2018年 | 275篇 |
2017年 | 376篇 |
2016年 | 426篇 |
2015年 | 348篇 |
2014年 | 622篇 |
2013年 | 892篇 |
2012年 | 549篇 |
2011年 | 681篇 |
2010年 | 592篇 |
2009年 | 697篇 |
2008年 | 646篇 |
2007年 | 676篇 |
2006年 | 637篇 |
2005年 | 591篇 |
2004年 | 548篇 |
2003年 | 557篇 |
2002年 | 503篇 |
2001年 | 497篇 |
2000年 | 424篇 |
1999年 | 434篇 |
1998年 | 365篇 |
1997年 | 303篇 |
1996年 | 259篇 |
1995年 | 261篇 |
1994年 | 186篇 |
1993年 | 139篇 |
1992年 | 172篇 |
1991年 | 112篇 |
1990年 | 119篇 |
1989年 | 68篇 |
1988年 | 39篇 |
1987年 | 32篇 |
1986年 | 12篇 |
1985年 | 25篇 |
1984年 | 27篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 13篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1973年 | 3篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
Investigators have viewed the stress rate in two different ways: the material (body-fixed) point of view and the Eulerian point of view. We discuss the Zaremba–Jaumann rate and Oldroyd’s rate from the material viewpoint and apply them to the material formulation of a theory of plasticity for materials undergoing anisotropic plastic deformation. Significant advantages of the material formulation are that the derivation of equations is straight forward, the distortion of yield surface can be easily accounted for, and the issue of self-consistent elastic equation does not arise. 相似文献
973.
In this paper, a fully discrete format of nonlinear Galerkin mixed element method with two-step discretization of time for the non stationary conduction-convection problems is presented. The existence and the convergence of the fully discrete mixed element solution are shown. On the basis of [9] and [10], we have proved that the schemes have second-order convergence accuracy for the time discretization. 相似文献
974.
非线性对流扩散方程沿特征线的多步有限体积元格式 总被引:4,自引:1,他引:3
对于二维非线性对流扩散方程构造了沿特征线方向的多步有限体积元格式.关于空间采用二次有限体积元方法离散,关于时间采用多步法进行离散,获得了O(Δt^2 h^2)形式的误差估计.本文最后给出的数值算例表明了方法的有效性. 相似文献
975.
THE UPWIND FINITE ELEMENT SCHEME AND MAXIMUM PRINCIPLE FOR NONLINEAR CONVECTION-DIFFUSION PROBLEM 总被引:3,自引:0,他引:3
Zhi-yongZhao Jian-weiHu 《计算数学(英文版)》2004,22(5):699-718
In this paper, a kind of partial upwind finite element scheme is studied for twodimensional nonlinear convection-diffusion problem. Nonlinear convection term approximated by partial upwind finite element method considered over a mesh dual to the triangular grid, whereas the nonlinear diffusion term approximated by Galerkin method. A linearized partial upwind finite element scheme and a higher order accuracy scheme are constructed respectively. It is shown that the numerical solutions of these schemes preserve discrete maximum principle. The convergence and error estimate are also given for both schemes under some assumptions. The numerical results show that these partial upwind finite element scheme are feasible and accurate. 相似文献
976.
Z. Li T. Lin Y. Lin R. C. Rogers 《Numerical Methods for Partial Differential Equations》2004,20(3):338-367
This article discusses an immersed finite element (IFE) space introduced for solving a second‐order elliptic boundary value problem with discontinuous coefficients (interface problem). The IFE space is nonconforming and its partition can be independent of the interface. The error estimates for the interpolation of a function in the usual Sobolev space indicate that this IFE space has an approximation capability similar to that of the standard conforming linear finite element space based on body‐fit partitions. Numerical examples of the related finite element method based on this IFE space are provided. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 338–367, 2004 相似文献
977.
978.
Chiung‐Chiou Tsai Suh‐Yuh Yang 《Numerical Methods for Partial Differential Equations》2004,20(6):831-842
In this article we analyze the L2 least‐squares finite element approximations to the incompressible inviscid rotational flow problem, which is recast into the velocity‐vorticity‐pressure formulation. The least‐squares functional is defined in terms of the sum of the squared L2 norms of the residual equations over a suitable product function space. We first derive a coercivity type a priori estimate for the first‐order system problem that will play the crucial role in the error analysis. We then show that the method exhibits an optimal rate of convergence in the H1 norm for velocity and pressure and a suboptimal rate of convergence in the L2 norm for vorticity. A numerical example in two dimensions is presented, which confirms the theoretical error estimates. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2004 相似文献
979.
Larry J. Gerstein 《Linear and Multilinear Algebra》2004,52(5):381-383
Characteristic elements have been useful in the classification of unimodular lattices over the integers. This article gives an explicit formula for characteristic elements of a lattice in terms of a basis for the lattice and the dual of that basis. 相似文献
980.
本文提出了Pr_6O_(11)样品ICP摄谱分析时干扰系数法校正光谱干扰的方法和相应的计算机软件系统。建立了Pr基体对14种稀土杂质元素24条灵敏分析线的干扰系数表(KCT),利用所提出的方法分析了Pr_6O_(11)合成样品,由91个实验点所得回收结果可知,回收率在90~110%之间的占93.4%。可见校正是相当有效和十分必要的。 相似文献