全文获取类型
收费全文 | 2647篇 |
免费 | 107篇 |
国内免费 | 23篇 |
专业分类
化学 | 1849篇 |
晶体学 | 6篇 |
力学 | 78篇 |
数学 | 417篇 |
物理学 | 427篇 |
出版年
2023年 | 26篇 |
2022年 | 22篇 |
2021年 | 99篇 |
2020年 | 71篇 |
2019年 | 59篇 |
2018年 | 38篇 |
2017年 | 44篇 |
2016年 | 122篇 |
2015年 | 96篇 |
2014年 | 91篇 |
2013年 | 133篇 |
2012年 | 181篇 |
2011年 | 193篇 |
2010年 | 124篇 |
2009年 | 121篇 |
2008年 | 156篇 |
2007年 | 144篇 |
2006年 | 169篇 |
2005年 | 151篇 |
2004年 | 137篇 |
2003年 | 97篇 |
2002年 | 91篇 |
2001年 | 58篇 |
2000年 | 44篇 |
1999年 | 25篇 |
1998年 | 19篇 |
1997年 | 16篇 |
1996年 | 36篇 |
1995年 | 20篇 |
1994年 | 20篇 |
1993年 | 23篇 |
1992年 | 18篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1959年 | 2篇 |
1908年 | 2篇 |
排序方式: 共有2777条查询结果,搜索用时 312 毫秒
1.
2.
3.
4.
5.
6.
The paper deals with the riskiness analysis for a large portfolio of life annuities. By means of the limiting distribution of the present value of the portfolio, in the first part of the paper a model for evaluating the investment and the projection risks is presented. In the second part, with regard to the investment risk's effects, the insolvency risk is measured considering the cumulative probability distribution function of the discounted average cost per policy. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
7.
J.-F. Pascual-Sánchez A. San Miguel F. Vicente 《General Relativity and Gravitation》2004,36(9):2075-2083
We analyze the geometry of a rotating disk with a tangential acceleration in the framework of the theory of Special Relativity, using the kinematic linear differential system that verifies the relative position vector of time-like curves in a Fermi reference. A numerical integration of these equations for a generic initial value problem is made up and the results are compared with those obtained in other works. 相似文献
8.
Differential cross sections of nucleons excited in photonuclear reactions in medium and heavy nuclei are studied by considering all relevant reaction mechanisms leading to the excitation of protons or neutrons. We take advantage of previous microscopic studies for the absorption and scattering of photons and photoproduced pions, and implement a simulation code in order to take into account the propagation of the nucleons as well as their collisions with other nucleons in the nuclear medium, which generate secondary excited nucleons. Comparison with experimental data is done. Cross sections for nucleon emission in coincidence with one pion are also calculated, and some coincidence observables are discussed. 相似文献
9.
10.
Giovanni Tartarini Alessandra Lena Davide Passaro Lorenzo Rosa Stefano Selleri Pier Faccin Enrico Maria Fabbri 《Optical and Quantum Electronics》2006,38(9-11):869-876
A comprehensive numerical tool has been developed for the evaluation of the performances of Radio over Fiber (RoF) links intended for wireless signal distribution.At the transmitter end an appropriate set of rate equations allows to model the optical source as a solitary laser or as an appropriately injection locked laser. The optical channel is modeled putting into account the combined effect of fiber dispersion, laser source non ideal performances (e.g. non-linear effects, frequency chirp), and quadratic detection of the receiving photodiode. The simulation model developed can be a useful tool at the design stage allowing a preliminary evaluation of the characteristics of real RoF links. 相似文献