全文获取类型
收费全文 | 5140篇 |
免费 | 535篇 |
国内免费 | 536篇 |
专业分类
化学 | 682篇 |
晶体学 | 10篇 |
力学 | 530篇 |
综合类 | 162篇 |
数学 | 3829篇 |
物理学 | 998篇 |
出版年
2024年 | 6篇 |
2023年 | 32篇 |
2022年 | 72篇 |
2021年 | 82篇 |
2020年 | 121篇 |
2019年 | 92篇 |
2018年 | 112篇 |
2017年 | 141篇 |
2016年 | 177篇 |
2015年 | 107篇 |
2014年 | 219篇 |
2013年 | 376篇 |
2012年 | 266篇 |
2011年 | 296篇 |
2010年 | 279篇 |
2009年 | 359篇 |
2008年 | 364篇 |
2007年 | 363篇 |
2006年 | 335篇 |
2005年 | 312篇 |
2004年 | 237篇 |
2003年 | 248篇 |
2002年 | 189篇 |
2001年 | 196篇 |
2000年 | 168篇 |
1999年 | 161篇 |
1998年 | 160篇 |
1997年 | 136篇 |
1996年 | 100篇 |
1995年 | 70篇 |
1994年 | 63篇 |
1993年 | 44篇 |
1992年 | 41篇 |
1991年 | 35篇 |
1990年 | 16篇 |
1989年 | 22篇 |
1988年 | 25篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 26篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 17篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1936年 | 2篇 |
排序方式: 共有6211条查询结果,搜索用时 15 毫秒
1.
2.
在完备的度量空间中,讨论了一类新型的非线性压缩映射ρ(Tx,Ty)≤a(ρ(x,y))ρ(x,Tx)+b(ρ(x,y))ρ(y,Ty)+c(ρ(x,y))ρ(x,y)通过构造迭代序列,指出该映射的不动点的存在性和唯一性,并给出相应的误差估计式,拓展和改进了有关文献的范围. 相似文献
3.
In this paper, the authors discuss a generalization of Lappan’s theorem to higher dimensional complex projective space and get the following result: Let f be a holomorphic mapping of ? into Pn(C), and let H1, · · · , Hq be hyperplanes in general position in Pn(C).Assume that sup {(1 ? |z|2)f?(z) : z ∈ q[ j=1 f?1(Hj )o < ∞,if q ≥ 2n2 + 3, then f is normal. 相似文献
4.
We introduce a new flexible mesh adaptation approach to efficiently compute a quantity of interest by the finite element method. Efficiently, we mean that the method provides an evaluation of that quantity up to a predetermined accuracy at a lower computational cost than other classical methods. The central pillar of the method is our scalar error estimator based on sensitivities of the quantity of interest to the residuals. These sensitivities result from the computation of a continuous adjoint problem. The mesh adaptation strategy can drive anisotropic mesh adaptation from a general scalar error contribution of each element. The full potential of our error estimator is then reached. The proposed method is validated by evaluating the lift, the drag, and the hydraulic losses on a 2D benchmark case: the flow around a cylinder at a Reynolds number of 20. 相似文献
5.
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
6.
7.
Juan Luis García Guirao Jaume Llibre Wei Gao 《Journal of Difference Equations and Applications》2020,26(2):203-208
The objective of this work is to present sufficient conditions for having positive topological entropy for continuous self-maps defined on a closed surface by using the action of this map on the homological groups of the closed surface. 相似文献
8.
9.
Kai Tao 《Journal of Differential Equations》2019,266(6):3559-3579
We first study the discrete Schrödinger equations with analytic potentials given by a class of transformations. It is shown that if the coupling number is large, then the Lyapunov exponent equals approximately to the logarithm of this coupling number. When the transformation becomes the skew-shift mapping, we prove that the Lyapunov exponent is weak Hölder continuous, and the spectrum satisfies Anderson Localization and contains large intervals. Moreover, all of these conclusions are non-perturbative. 相似文献
10.
基于Hilbert空间标架理论,借助算子工具,用己有连续广义标架构造了新连续广义标架,并给出了有限个连续广义标架和构成新连续广义标架的充要条件,为构造连续广义标架提供了新方法。 相似文献