全文获取类型
收费全文 | 19035篇 |
免费 | 1605篇 |
国内免费 | 1163篇 |
专业分类
化学 | 1068篇 |
晶体学 | 65篇 |
力学 | 3481篇 |
综合类 | 263篇 |
数学 | 14077篇 |
物理学 | 2849篇 |
出版年
2024年 | 22篇 |
2023年 | 192篇 |
2022年 | 207篇 |
2021年 | 292篇 |
2020年 | 423篇 |
2019年 | 447篇 |
2018年 | 433篇 |
2017年 | 518篇 |
2016年 | 592篇 |
2015年 | 452篇 |
2014年 | 771篇 |
2013年 | 1564篇 |
2012年 | 809篇 |
2011年 | 988篇 |
2010年 | 855篇 |
2009年 | 1122篇 |
2008年 | 1221篇 |
2007年 | 1207篇 |
2006年 | 1030篇 |
2005年 | 924篇 |
2004年 | 847篇 |
2003年 | 776篇 |
2002年 | 729篇 |
2001年 | 636篇 |
2000年 | 621篇 |
1999年 | 517篇 |
1998年 | 550篇 |
1997年 | 439篇 |
1996年 | 363篇 |
1995年 | 273篇 |
1994年 | 257篇 |
1993年 | 207篇 |
1992年 | 198篇 |
1991年 | 170篇 |
1990年 | 152篇 |
1989年 | 98篇 |
1988年 | 90篇 |
1987年 | 82篇 |
1986年 | 84篇 |
1985年 | 83篇 |
1984年 | 91篇 |
1983年 | 57篇 |
1982年 | 76篇 |
1981年 | 59篇 |
1980年 | 66篇 |
1979年 | 59篇 |
1978年 | 40篇 |
1977年 | 33篇 |
1976年 | 36篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
1.
2.
3.
This paper infers from a generalized Picone identity the uniqueness of the stable positive solution for a class of semilinear equations of superlinear indefinite type, as well as the uniqueness and global attractivity of the coexistence state in two generalized diffusive prototypes of the symbiotic and competing species models of Lotka–Volterra. The optimality of these uniqueness theorems reveals the tremendous strength of the Picone identity. 相似文献
4.
5.
In this article, we construct and analyze a residual-based a posteriori error estimator for a quadratic finite volume method (FVM) for solving nonlinear elliptic partial differential equations with homogeneous Dirichlet boundary conditions. We shall prove that the a posteriori error estimator yields the global upper and local lower bounds for the norm error of the FVM. So that the a posteriori error estimator is equivalent to the true error in a certain sense. Numerical experiments are performed to illustrate the theoretical results. 相似文献
6.
7.
An approach of dynamic mesh adaptation for simulating 3‐dimensional unsteady moving‐immersed‐boundary flows 下载免费PDF全文
In this paper, we present an approach of dynamic mesh adaptation for simulating complex 3‐dimensional incompressible moving‐boundary flows by immersed boundary methods. Tetrahedral meshes are adapted by a hierarchical refining/coarsening algorithm. Regular refinement is accomplished by dividing 1 tetrahedron into 8 subcells, and irregular refinement is only for eliminating the hanging points. Merging the 8 subcells obtained by regular refinement, the mesh is coarsened. With hierarchical refining/coarsening, mesh adaptivity can be achieved by adjusting the mesh only 1 time for each adaptation period. The level difference between 2 neighboring cells never exceeds 1, and the geometrical quality of mesh does not degrade as the level of adaptive mesh increases. A predictor‐corrector scheme is introduced to eliminate the phase lag between adapted mesh and unsteady solution. The error caused by each solution transferring from the old mesh to the new adapted one is small because most of the nodes on the 2 meshes are coincident. An immersed boundary method named local domain‐free discretization is employed to solve the flow equations. Several numerical experiments have been conducted for 3‐dimensional incompressible moving‐boundary flows. By using the present approach, the number of mesh nodes is reduced greatly while the accuracy of solution can be preserved. 相似文献
8.
9.
10.