全文获取类型
收费全文 | 9494篇 |
免费 | 1852篇 |
国内免费 | 607篇 |
专业分类
化学 | 2161篇 |
晶体学 | 79篇 |
力学 | 861篇 |
综合类 | 146篇 |
数学 | 4317篇 |
物理学 | 4389篇 |
出版年
2024年 | 12篇 |
2023年 | 92篇 |
2022年 | 221篇 |
2021年 | 278篇 |
2020年 | 294篇 |
2019年 | 330篇 |
2018年 | 305篇 |
2017年 | 408篇 |
2016年 | 433篇 |
2015年 | 371篇 |
2014年 | 501篇 |
2013年 | 857篇 |
2012年 | 564篇 |
2011年 | 607篇 |
2010年 | 540篇 |
2009年 | 574篇 |
2008年 | 636篇 |
2007年 | 568篇 |
2006年 | 508篇 |
2005年 | 466篇 |
2004年 | 396篇 |
2003年 | 405篇 |
2002年 | 356篇 |
2001年 | 304篇 |
2000年 | 267篇 |
1999年 | 256篇 |
1998年 | 187篇 |
1997年 | 205篇 |
1996年 | 156篇 |
1995年 | 130篇 |
1994年 | 96篇 |
1993年 | 74篇 |
1992年 | 67篇 |
1991年 | 57篇 |
1990年 | 49篇 |
1989年 | 45篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 32篇 |
1985年 | 49篇 |
1984年 | 30篇 |
1983年 | 18篇 |
1982年 | 27篇 |
1981年 | 24篇 |
1980年 | 9篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
12.
LI Yu-qiong SUN Zhen-rong ZHANG Shi-an YANG Xi-hua WANG Zu-geng. Key Laboratory of Optical Magnetic Resonance Spectroscopy 《光谱学与光谱分析》2006,26(8):1395-1395
The authors achieved the temporal coherent control in an Er^3+ doped telluride glass, one kind of disordered solids. The upconversion at 670 nm was modulated and the dephasing time was simulated as 300 fs. Moreover, the photon echo signal gave the dephasing time due to the phonon interaction. The agreement between the two data indicates that the interaction between the wavepacket and the phonon leads to the fast disappearance of wavepackets interference, which is helpful for the tech- nique to be applied to the disordered solids. 相似文献
13.
14.
15.
带干扰的多险种风险模型 总被引:2,自引:0,他引:2
由于保险公司风险经营规模不断扩大,用单一险种的模型来描述风险过程存在局限性,本文讨论了带干扰多险种风险模型,应用鞅论方法,得出伦德伯格不等式和最终破产概率公式。 相似文献
16.
Blaise Faugeras Jé rô me Pousin Franck Fontvieille. 《Mathematics of Computation》2006,75(253):209-222
A numerical scheme based on an operator splitting method and a dense output event location algorithm is proposed to integrate a diffusion-dissolution/precipitation chemical initial-boundary value problem with jumping nonlinearities. The numerical analysis of the scheme is carried out and it is proved to be of order 2 in time. This global order estimate is illustrated numerically on a test case.
17.
Claudio Simeone 《General Relativity and Gravitation》2002,34(11):1887-1893
A consistent quantization with a clear notion of time and evolution is given for the anisotropic Kantowski–Sachs cosmological model. It is shown that a suitable coordinate choice allows to obtain a solution of the Wheeler–DeWitt equation in the form of definite energy states, and that the results can be associated to two disjoint equivalent theories, one for each sheet of the constraint surface. 相似文献
18.
可变抽样区间的非参数控制图 总被引:1,自引:1,他引:0
最近几年一些学者研究了可变抽样区间的质量控制图。Amin等提出了可变抽样区间(VSI)的非参数控制图———符号 (Sign)统计量图〔1〕。本文在此基础上研究位置VSI符号控制图的制定方法 ,并设计离散VSI符号控制图。符号控制图的优点是对非正态总体亦可应用 ,并且不需要过程方差的信息。本文将所设计的VSI符号控制图同固定抽样区间 (FSI)的常规图作比较 ,并举实例说明符号控制图的应用 相似文献
19.
A Dirac picture perturbation theory is developed for the time evolution operator in classical dynamics in the spirit of the Schwinger–Feynman–Dyson perturbation expansion and detailed rules are derived for computations. Complexification formalisms are given for the time evolution operator suitable for phase space analyses, and then extended to a two-dimensional setting for a study of the geometrical Berry phase as an example. Finally a direct integration of Hamilton's equations is shown to lead naturally to a path integral expression, as a resolution of the identity, as applied to arbitrary functions of generalized coordinates and momenta. 相似文献
20.
Evolutionary algorithms are applied as problem-independent optimization algorithms. They are quite efficient in many situations. However, it is difficult to analyze even the behavior of simple variants of evolutionary algorithms like the (1+1) EA on rather simple functions. Nevertheless, only the analysis of the expected run time and the success probability within a given number of steps can guide the choice of the free parameters of the algorithms. Here static (1+1) EAs with a fixed mutation probability are compared with dynamic (1+1) EAs with a simple schedule for the variation of the mutation probability. The dynamic variant is first analyzed for functions typically chosen as example-functions for evolutionary algorithms. Afterwards, it is shown that it can be essential to choose the suitable variant of the (1+1) EA. More precisely, functions are presented where each static (1+1) EA has exponential expected run time while the dynamic variant has polynomial expected run time. For other functions it is shown that the dynamic (1+1) EA has exponential expected run time while a static (1+1) EA with a good choice of the mutation probability has polynomial run time with overwhelming probability. 相似文献