全文获取类型
收费全文 | 5359篇 |
免费 | 363篇 |
国内免费 | 731篇 |
专业分类
化学 | 69篇 |
晶体学 | 3篇 |
力学 | 187篇 |
综合类 | 77篇 |
数学 | 5759篇 |
物理学 | 358篇 |
出版年
2024年 | 7篇 |
2023年 | 102篇 |
2022年 | 42篇 |
2021年 | 71篇 |
2020年 | 108篇 |
2019年 | 151篇 |
2018年 | 160篇 |
2017年 | 163篇 |
2016年 | 150篇 |
2015年 | 130篇 |
2014年 | 228篇 |
2013年 | 416篇 |
2012年 | 163篇 |
2011年 | 259篇 |
2010年 | 252篇 |
2009年 | 364篇 |
2008年 | 391篇 |
2007年 | 406篇 |
2006年 | 382篇 |
2005年 | 361篇 |
2004年 | 276篇 |
2003年 | 270篇 |
2002年 | 231篇 |
2001年 | 178篇 |
2000年 | 192篇 |
1999年 | 190篇 |
1998年 | 152篇 |
1997年 | 167篇 |
1996年 | 109篇 |
1995年 | 52篇 |
1994年 | 51篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 19篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 22篇 |
1984年 | 20篇 |
1983年 | 13篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 21篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1974年 | 4篇 |
排序方式: 共有6453条查询结果,搜索用时 15 毫秒
91.
We introduce left central and right central functions and left and right leaves in quasi-Poisson geometry, generalizing central (or Casimir) functions and symplectic leaves from Poisson geometry. They lead to a new type of (quasi-)Poisson reduction, which is both simpler and more general than known quasi-Hamiltonian reductions. We study these notions in detail for moduli spaces of flat connections on surfaces, where the quasi-Poisson structure is given by an intersection pairing on homology. 相似文献
92.
In recent years, Landweber iteration has been extended to solve linear inverse problems in Banach spaces by incorporating non-smooth convex penalty functionals to capture features of solutions. This method is known to be slowly convergent. However, because it is simple to implement, it still receives a lot of attention. By making use of the subspace optimization technique, we propose an accelerated version of Landweber iteration with non-smooth convex penalty which significantly speeds up the method. Numerical simulations are given to test the efficiency. 相似文献
93.
Helmut Rudolph 《Optimization》2015,64(8):1739-1757
94.
95.
96.
The nonlinear propagation of modified electron‐acoustic (mEA) shock waves in an unmagnetized, collisionless, relativistic, degenerate quantum plasma (containing non‐relativistic degenerate inertial cold electrons, both nonrelativistic and ultra‐relativistic degenerate hot electron and inertial positron fluids, and positively charged static ions) has been investigated theoretically. The well‐known Burgers type equation has been derived for both planar and nonplanar geometry by employing the reductive perturbation method. The shock wave solution has also been obtained and numerically analyzed. It has been observed that the mEA shock waves are significantly modified due to the effects of degenerate pressure and other plasma parameters arised in this investigation. The properties of planar Burgers shocks are quite different from those of nonplanar Burgers shocks. The basic features and the underlying physics of shock waves, which are relevant to some astrophysical compact objects (viz. non‐rotating white dwarfs, neutron stars, etc.), are briefly discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
97.
丁协平 《应用数学和力学(英文版)》2005,26(12):1547-1555
A new notion of finite continuous topological space (in short, FC-space) with out convexity structure was introduced. A new continuous selection theorem was established in FC-spaces. By applying the continuous selection theorem, some new coincidence theorems for two families of set-valued mappings defined on product space of noncompact FC-spaces are proved under much weak assumptions. These results generalize many known results in recent literature. Some applications will be given in a follow-up paper. 相似文献
98.
Based on the successive iteration in the Taylor series expansion method,a three-point explicit compact difference scheme with arbitrary order of accuracy is derived in this paper.Numerical characteristics of the scheme are studied by the Fourier analysis. Unlike the conventional compact difference schemes which need to solve the equation to obtain the unknown derivatives in each node,the proposed scheme is explicit and can achieve arbitrary order of accuracy in space.Application examples for the convection- diffusion problem with a sharp front gradient and the typical lid-driven cavity flow are given.It is found that the proposed compact scheme is not only simple to implement and economical to use,but also is effective to simulate the convection-dominated problem and obtain high-order accurate solution in coarse grid systems. 相似文献
99.
Based on the successive iteration in the Taylor series expansion method, a three-point explicit compact difference scheme with arbitrary order of accuracy is derived in this paper. Numerical characteristics of the scheme are studied by the Fourier analysisl Unlike the conventional compact difference schemes which need to solve the equation to obtain the unknown derivatives in each node, the proposed scheme is explicit and can achieve arbitrary order of accuracy in space. Application examples for the convectiondiffusion problem with a sharp front gradient and the typical lid-driven cavity flow are given. It is found that the proposed compact scheme is not only simple to implement and economical to use, but also is effective to simulate the convection-dominated problem and obtain high-order accurate solution in coarse grid systems. 相似文献
100.
高精度非线性格式WCNS的分析研究与其应用 总被引:1,自引:0,他引:1
首先将Fourier方法推广于高维方向研究了五阶精度WCNS的特性,并与其他高阶格式进行比较。分析结果表明WCNS的高精度特性普遍接近甚至好于迎风偏置五阶显式格式EUW-5与Pade′标准格式。然后开展了WCNS的应用研究,采用高效率的WCNS-E-5数值模拟了含强激波的高维复杂流场。算例包括二维高超声速边界层对自由流扰动波的吸收问题以及三维球头绕流问题。计算结果反映出WCNS-E-5对激波等间断的良好捕捉能力,图像清晰光滑,数据准确可靠。 相似文献