全文获取类型
收费全文 | 300208篇 |
免费 | 2329篇 |
国内免费 | 527篇 |
专业分类
化学 | 144124篇 |
晶体学 | 5034篇 |
力学 | 14808篇 |
综合类 | 11篇 |
数学 | 43406篇 |
物理学 | 95681篇 |
出版年
2020年 | 1743篇 |
2019年 | 1971篇 |
2018年 | 10859篇 |
2017年 | 11747篇 |
2016年 | 7516篇 |
2015年 | 3068篇 |
2014年 | 3704篇 |
2013年 | 9297篇 |
2012年 | 10890篇 |
2011年 | 20442篇 |
2010年 | 12736篇 |
2009年 | 12838篇 |
2008年 | 17643篇 |
2007年 | 21138篇 |
2006年 | 7004篇 |
2005年 | 12877篇 |
2004年 | 8968篇 |
2003年 | 8511篇 |
2002年 | 6353篇 |
2001年 | 6329篇 |
2000年 | 4960篇 |
1999年 | 3578篇 |
1998年 | 2813篇 |
1997年 | 2740篇 |
1996年 | 2772篇 |
1995年 | 2545篇 |
1994年 | 2429篇 |
1993年 | 2260篇 |
1992年 | 2915篇 |
1991年 | 2818篇 |
1990年 | 2774篇 |
1989年 | 2788篇 |
1988年 | 2819篇 |
1987年 | 2817篇 |
1986年 | 2683篇 |
1985年 | 3411篇 |
1984年 | 3449篇 |
1983年 | 2712篇 |
1982年 | 2823篇 |
1981年 | 2876篇 |
1980年 | 2653篇 |
1979年 | 3003篇 |
1978年 | 3003篇 |
1977年 | 3032篇 |
1976年 | 2896篇 |
1975年 | 2623篇 |
1974年 | 2578篇 |
1973年 | 2570篇 |
1972年 | 1754篇 |
1968年 | 1809篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
P.S Erdman M Fajardo K.M Sando W.C Stwalley 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,88(4):447-481
Experimental results are reported for a unique spectroscopic device called the Plasma Spectroscopy Cell. Optical absorption of lithium metal vapor was observed at high density and temperature. Absorption spectra are analyzed using theoretical calculations of absorption cross sections for lithium-helium interactions, and singlet and triplet state transitions of diatomic lithium in the visible spectral range. This is believed to be the most complex example yet calculated in which absolute bound-bound, bound-free, free-bound, and free-free contributions for all possible optically allowed transitions are all included, in quite respectable agreement with experiment. 相似文献
973.
974.
975.
The construction of non-Abelian affine Toda models is discussed in terms of its underlying Lie algebraic structure. It is shown that a subclass of such non-conformal two-dimensional integrable models naturally leads to the construction of a pair of actions, which share the same spectra and are related by canonical transformations. 相似文献
976.
L. K. Seah U. S. Dinish S. K. Ong Z. X. Chao V. M. Murukeshan 《Optics & Laser Technology》2004,36(5):371-376
Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed. 相似文献
977.
Theory and experiment of spatially and temporally partially coherent speckle shearing interferometry
The theory and experiment of spatially and temporally partially coherent speckle shearing interferometry is reported in this rapid communication for the first time. The general requirements for the surface roughness and coherence area of a diffuse object surface in spatially and temporally partially coherent speckle shearing interferometry are discussed. An experimental verification is presented and the results of theory and experiment are in good agreement. 相似文献
978.
979.
The IR absorption spectrum of polycrystalline 4-amyloxy-4′-cyanobiphenyl (5OCB) is measured in a KBr pellet over the range 400–4000 cm?1. The structure of the molecule and the frequencies and intensities of the bands in the spectrum are calculated in the approximation of the B3LYP hybrid density functional with the 6-31G(d) and 6-31+G(d) basis sets. With the method of linear scaling of frequencies, 39 bands of the experimental IR spectrum are assigned. On the basis of calculations for related compounds, the vibrations belonging to the substituents and the biphenyl fragment are ascertained. It is shown that the IR absorption spectra of polycrystalline 4-hydroxypropyl-4′-cyanobiphenyl and 5OCB are almost identical and differ by the occurrence of three bands associated with vibrations localized on the oxyamyl radical. 相似文献
980.