全文获取类型
收费全文 | 7127篇 |
免费 | 650篇 |
国内免费 | 732篇 |
专业分类
化学 | 787篇 |
晶体学 | 11篇 |
力学 | 623篇 |
综合类 | 225篇 |
数学 | 5719篇 |
物理学 | 1144篇 |
出版年
2024年 | 13篇 |
2023年 | 47篇 |
2022年 | 112篇 |
2021年 | 111篇 |
2020年 | 164篇 |
2019年 | 142篇 |
2018年 | 150篇 |
2017年 | 188篇 |
2016年 | 231篇 |
2015年 | 136篇 |
2014年 | 296篇 |
2013年 | 601篇 |
2012年 | 344篇 |
2011年 | 386篇 |
2010年 | 365篇 |
2009年 | 482篇 |
2008年 | 517篇 |
2007年 | 501篇 |
2006年 | 459篇 |
2005年 | 411篇 |
2004年 | 320篇 |
2003年 | 339篇 |
2002年 | 253篇 |
2001年 | 255篇 |
2000年 | 244篇 |
1999年 | 213篇 |
1998年 | 224篇 |
1997年 | 184篇 |
1996年 | 144篇 |
1995年 | 92篇 |
1994年 | 93篇 |
1993年 | 54篇 |
1992年 | 49篇 |
1991年 | 48篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 28篇 |
1987年 | 23篇 |
1986年 | 20篇 |
1985年 | 33篇 |
1984年 | 33篇 |
1983年 | 20篇 |
1982年 | 31篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1936年 | 2篇 |
排序方式: 共有8509条查询结果,搜索用时 15 毫秒
1.
2.
Transformation hydrodynamics and the corresponding metamaterials have been proposed as a means to exclude the drag force acting on an object. Here, we report a strategy to deploy the hydrodynamic cloaks in a more practical manner by assembling different-shaped cloaking parts. Our strategy is to first model a square-shaped cloak and a carpet cloak and then combine them to conceal a more complex-shaped space in the three-dimensional hydrodynamic flow. With the derivation of transformation hydrodynamics, the coordinate transformations for each hydrodynamic cloaking are demonstrated with the calculated viscosity tensors. The pressure and velocity fields of the square, triangular (carpet), and exemplary three-dimensional house-shaped cloaks are numerically simulated, thus showing a cloaking effect and reduced drag. This study suggests an efficient way of cloaking complex architectures from fluid-dynamic forces. 相似文献
3.
We study spectral properties of discrete Schrödinger operators with potentials obtained via dimerization of a class of aperiodic sequences. It is shown that both the nature of the autocorrelation measure of a regular sequence and the presence of generic (full probability) singular continuous spectrum in the hull of primitive and palindromic (four block substitution) potentials are robust under dimerization. Generic results also hold for circle potentials. We illustrate these results with numerical studies of the quantum mean square displacement as a function of time. The numerical techniques provide a very fast algorithm for the time evolution of wave packets. 相似文献
4.
The Schwinger representation of the SO(8) fermion pair algebra in terms ofd and quasispin vector (u, s, v) bosons is used in deriving a microscopic boson coherent state having both particle-hole and pair excitations. The coherent
state is the exact boson image of the HFB variational solution. We can study the shape phase transition and pairing behaviour
of the nuclear ground states using the coherent states. 相似文献
5.
Paul Bankston 《Archive for Mathematical Logic》2006,45(1):97-112
The Chang-Łoś-Suszko theorem of first-order model theory characterizes universal-existential classes of models as just those
elementary classes that are closed under unions of chains. This theorem can then be used to equate two model-theoretic closure
conditions for elementary classes; namely unions of chains and existential substructures. In the present paper we prove a
topological analogue and indicate some applications. 相似文献
6.
Michel Weber 《Transactions of the American Mathematical Society》2006,358(2):911-936
We apply a majorizing measure theorem of Talagrand to obtain uniform bounds for sums of random variables satisfying increment conditions of the type considered in Gál-Koksma Theorems. We give some applications.
7.
The present paper devotes to the long-time behavior of a class of reaction diffusion equations with delays under Dirichlet boundary conditions. The stability and global attractability for the zero solution are provided, and the existence, stability and attractability for the positive stationary solution are also obtained. 相似文献
8.
9.
本文应用上、下解方法和 Leray-Schauder不动点定理 ,证明了一类拟线性椭圆方程边值问题弱解的存在性 ,并且给出了一个应用实例 相似文献
10.
曾六川 《数学物理学报(A辑)》2002,22(1):99-106
该文研究Banach空间中一类强增生型变分包含解的存在性及其具误差的Ishikawa迭代程序的收敛性问题.该文结果是几位作者早期与最近的相应结果的改进和推广. 相似文献