全文获取类型
收费全文 | 3413篇 |
免费 | 263篇 |
国内免费 | 245篇 |
专业分类
化学 | 402篇 |
晶体学 | 36篇 |
力学 | 295篇 |
综合类 | 67篇 |
数学 | 2188篇 |
物理学 | 933篇 |
出版年
2025年 | 4篇 |
2024年 | 24篇 |
2023年 | 46篇 |
2022年 | 61篇 |
2021年 | 51篇 |
2020年 | 74篇 |
2019年 | 84篇 |
2018年 | 82篇 |
2017年 | 92篇 |
2016年 | 103篇 |
2015年 | 71篇 |
2014年 | 144篇 |
2013年 | 242篇 |
2012年 | 154篇 |
2011年 | 131篇 |
2010年 | 175篇 |
2009年 | 233篇 |
2008年 | 219篇 |
2007年 | 231篇 |
2006年 | 181篇 |
2005年 | 184篇 |
2004年 | 173篇 |
2003年 | 141篇 |
2002年 | 136篇 |
2001年 | 122篇 |
2000年 | 121篇 |
1999年 | 105篇 |
1998年 | 102篇 |
1997年 | 85篇 |
1996年 | 75篇 |
1995年 | 50篇 |
1994年 | 58篇 |
1993年 | 24篇 |
1992年 | 30篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有3921条查询结果,搜索用时 15 毫秒
201.
根据物理量的可测实在性,应用二次型理论,一般地解决了3个质量与3个频率均不相同、坐标和动量各自具有全耦合谐振子系统的哈密顿量的可对角化问题,并具体给出了哈密顿量对角化的标准形. 相似文献
202.
203.
M.L. Dubernet V. Boudon M.S. Dimitrijevic C. Joblin G. Leto P.A. Loboda N.J. Mason G. Mulas L.A. Nuñez N. Piskunov G. Rixon E. Roueff A. Ryabtsev B. Schmitt J. Tennyson N.A. Walton C.J. Zeippen 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2151-2159
The Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu) is a European Union funded collaboration between groups involved in the generation, evaluation, and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. The project will cover establishing the core consortium, the development and deployment of the infrastructure and the development of interfaces to the existing atomic and molecular databases. It will also provide a forum for training potential users and dissemination of expertise worldwide. This review describes the scope of the VAMDC project; it provides a survey of the atomic and molecular data sets that will be included plus a discussion of how they will be integrated. Some applications of these data are also discussed. 相似文献
204.
Elastic electron scattering on the exotic light nucleus28S is investigated in the plane wave Born approximation. The variation of the squared form factors of28S with momentum transfer is compared with that of32S. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive
to the alteration of the charge density distribution of halo protons in28S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei. 相似文献
205.
Whilst the space volume of muffler in noise control system is often constrained for maintenance in practical engineering work, the maximization on muffler’s performance becomes important and essential. In this paper, a novel approach genetic algorithms (GAs) based on the principles of natural biological evolution will be used to tackle this optimization of muffler design [M. Mitchell, An Introduction to Genetic Algorithms, The MIT Press, Cambridge, MA, 1996]. Here, the shape optimization of multi-segments muffler coupled with the GA searching technique is presented. The techniques of binary genetic algorithms (BGA) together with the commercial MATLAB package [G. Lindfield, J. Penny, Numerical Method Using Matlab, second ed., Prentice Hall, Englewood Cliffs, NJ, 2000] are applied in GA searching. In addition, a numerical case of pure tone elimination with 2-5 segments on muffler is introduced and fully discussed. To achieve the best optimization in GA, several GA parameters are on trial in various values. Results show that the GA operators, including crossover mutation and elitism, are essential in accuracy. Consequently, results verify that the optimal sound transmission loss at the designed frequency of 500 Hz is exactly maximized. The GA optimization on multi-segments muffler proposed in this study surely provides a quick and correct approach. 相似文献
206.
DONGYu-Bing LIUJian 《理论物理通讯》2004,42(1):87-89
Point form relativistic dynamics of relativistic quantum mechanics is employed to estimate the photon and electroproduction amplitudes of A(1232) resonance. Results are compared with the non-relativistic work, and the differences between the two frame works are discussed. 相似文献
207.
208.
Filtering for linear systems with noise correlation and its application to singular systems
下载免费PDF全文

In this paper, an optimal filter for a stochastic linear system with previous stage noise correlation is designed.Based on this result, together with the decomposition techniques of the stochastic singular linear system, the design ofan optimal filter for a stochastic singular linear system is given. 相似文献
209.
Non-Noether conserved quantity constructed by using form invariance for Birkhoffian system 总被引:6,自引:0,他引:6
下载免费PDF全文

Based on the invariance of Birkhoffian equations under the infinitesimal transformations of groups, the definition and the criterion of a form invariance for a Birkhoffian system are established. The condition under which the form invariance can lead to a non-Noether conserved quantity and the form of the conserved quantity are deduced by relyingon the total time derivative along the trajectory of the equations, and two corollaries in special cases are presented. An example is finally given to illustrate the application of the results. 相似文献
210.