全文获取类型
收费全文 | 8216篇 |
免费 | 216篇 |
国内免费 | 1篇 |
专业分类
化学 | 4758篇 |
晶体学 | 43篇 |
力学 | 241篇 |
数学 | 1261篇 |
物理学 | 2130篇 |
出版年
2023年 | 44篇 |
2021年 | 47篇 |
2020年 | 105篇 |
2019年 | 73篇 |
2018年 | 94篇 |
2017年 | 70篇 |
2016年 | 166篇 |
2015年 | 167篇 |
2014年 | 186篇 |
2013年 | 368篇 |
2012年 | 463篇 |
2011年 | 508篇 |
2010年 | 250篇 |
2009年 | 212篇 |
2008年 | 409篇 |
2007年 | 426篇 |
2006年 | 406篇 |
2005年 | 410篇 |
2004年 | 346篇 |
2003年 | 279篇 |
2002年 | 274篇 |
2001年 | 170篇 |
2000年 | 133篇 |
1999年 | 102篇 |
1998年 | 73篇 |
1997年 | 100篇 |
1996年 | 67篇 |
1995年 | 91篇 |
1994年 | 60篇 |
1993年 | 63篇 |
1992年 | 77篇 |
1991年 | 51篇 |
1990年 | 57篇 |
1989年 | 54篇 |
1988年 | 73篇 |
1987年 | 66篇 |
1986年 | 58篇 |
1985年 | 73篇 |
1984年 | 77篇 |
1983年 | 68篇 |
1982年 | 100篇 |
1981年 | 97篇 |
1980年 | 77篇 |
1979年 | 75篇 |
1978年 | 88篇 |
1977年 | 77篇 |
1976年 | 70篇 |
1975年 | 62篇 |
1974年 | 67篇 |
1973年 | 66篇 |
排序方式: 共有8433条查询结果,搜索用时 15 毫秒
21.
An acoustic pulse propagating on a two-mode fiber can act as a beam splitter in a scanning interferometer. When this device
is employed in white-light interferometry, the effects of distributed coupling and dispersive interferometer arms need to
be considered. A theory suitable for treating acousto-optic interaction of partially coherent light in a moving interaction
region was developed. It was found that differential optical dispersion should be negligible and the acoustic pulse length
short. Also the coherence time should be short but long compared to the intermodal group delay difference over a pulse length.
Experiments with long acoustic pulses were performed, and fairly good agreement with theory was obtained. 相似文献
22.
Steen Mørup 《Hyperfine Interactions》1994,90(1):171-185
Interactions between magnetic nanoparticles can lead to superferromagnetic ordering, i.e. ordering of their magnetic moments at low temperatures. The use of a simple mean field theory, describing the temperature dependence of the order parameter is discussed. This model is found to give excellent fits to experimental results. In systems of particles with pure dipole interactions, the degree of ordering depends critically on the geometrical configuration of the particles. The application of superferromagnetic nanostructures for magnetic refrigeration is also discussed. 相似文献
23.
24.
Martin E. V. Pedersen Lars S. Rishøj Henrik Steffensen Sanshui Xiao Niels Asger Mortensen 《Optical and Quantum Electronics》2007,39(10-11):903-911
Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner–Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light–matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized absorbance cells for optical detection in lab-on-a-chip systems. 相似文献
25.
Microarrays are a popular technology to study genes that are differentially expressed between two conditions. In this Note, we propose an iterative procedure to determine the biggest subset of non-differentially expressed genes. We prove a pseudo Markov relationship that allows practical computations. We obtain explicit expressions for FDR and the level of the proposed test at each step. To cite this article: A. Bar-Hen, S. Robin, C. R. Acad. Sci. Paris, Ser. I 337 (2003). 相似文献
26.
27.
In multivariate statistical analysis, several authors have studied the total positivity properties of the generalized (0 F 1) hypergeometric function of two real symmetric matrix arguments. In this paper, we make use of zonal polynomial expansions to obtain a new proof of a result that these 0 F 1functions fail to satisfy certain pairwise total positivity properties; this proof extends both to arbitrary generalized ( r F s ) functions of two matrix arguments and to the generalized hypergeometric functions of Hermitian matrix arguments. In the case of the generalized hypergeometric functions of two Hermitian matrix arguments, we prove that these functions satisfy certain modified pairwise TP2properties; the proofs of these results are based on Sylvester's formula for compound determinants and the condensation formula of C. L. Dodgson [Lewis Carroll] (1866). 相似文献
28.
29.
30.