全文获取类型
收费全文 | 18321篇 |
免费 | 2883篇 |
国内免费 | 2378篇 |
专业分类
化学 | 14445篇 |
晶体学 | 149篇 |
力学 | 1482篇 |
综合类 | 101篇 |
数学 | 642篇 |
物理学 | 6763篇 |
出版年
2024年 | 30篇 |
2023年 | 180篇 |
2022年 | 335篇 |
2021年 | 552篇 |
2020年 | 690篇 |
2019年 | 561篇 |
2018年 | 465篇 |
2017年 | 565篇 |
2016年 | 742篇 |
2015年 | 800篇 |
2014年 | 995篇 |
2013年 | 1485篇 |
2012年 | 1152篇 |
2011年 | 1395篇 |
2010年 | 1127篇 |
2009年 | 1208篇 |
2008年 | 1311篇 |
2007年 | 1259篇 |
2006年 | 1220篇 |
2005年 | 1037篇 |
2004年 | 963篇 |
2003年 | 767篇 |
2002年 | 748篇 |
2001年 | 503篇 |
2000年 | 465篇 |
1999年 | 411篇 |
1998年 | 360篇 |
1997年 | 329篇 |
1996年 | 289篇 |
1995年 | 264篇 |
1994年 | 216篇 |
1993年 | 185篇 |
1992年 | 176篇 |
1991年 | 138篇 |
1990年 | 114篇 |
1989年 | 80篇 |
1988年 | 89篇 |
1987年 | 49篇 |
1986年 | 55篇 |
1985年 | 42篇 |
1984年 | 45篇 |
1983年 | 15篇 |
1982年 | 41篇 |
1981年 | 21篇 |
1980年 | 25篇 |
1979年 | 24篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 15篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
O.P. Hasekamp J. Landgraf 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,75(2):221-238
We present a plane parallel radiative transfer model for polarized light, that provides the intensity vector as well as the derivatives of the four Stokes parameters with respect to atmospheric trace gas profiles. These derivatives are essential for retrieval of height resolved trace gas information from satellite measurements of backscattered sunlight. The model uses the Gauss-Seidel iteration technique for solving the radiative transfer equation. For the first time, the forward-adjoint radiative perturbation theory is applied for the linearization of a radiative transfer model including polarization. The accuracy of the model is better than 0.025% for all four Stokes parameters and better than 0.03% for the derivatives. 相似文献
152.
Eugene A. Ustinov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(6):683-696
An analytic approach is proposed for the evaluation of weighting functions for remote sensing of a blackbody planetary atmosphere based on straightforward, general linearization. In the present paper, this approach is applied to the case of remote sensing with the nadir (down-looking) geometry. Expressions for weighting functions for various atmospheric parameters are derived. It is demonstrated that in a realistic case of temperature-dependent atmospheric absorption, an additional term appears in the expression for the temperature weighting function which contains the temperature derivative of the atmospheric absorption coefficient. The approach is applied to the case of a semi-infinite atmosphere and then, to the atmosphere of a finite optical depth with the underlying surface. In this, latter case, the expressions are also obtained for partial derivatives of observed radiances with respect to surface parameters: surface pressure, temperature and emissivity. 相似文献
153.
Hui-Ling Li De-Jiang Qi Qing-Quan Jiang Shu-Zheng Yang 《International Journal of Theoretical Physics》2006,45(12):2428-2436
An extension of the Parikh-Wilczek's semi-classical quantum tunneling method, the tunneling radiation of the charged particle from a torus-like black hole is investigated. Difference from the uncharged mass-less particle, the geodesics of the charged massive particle tunneling from the black hole is not light-like, but determined by the phase velocity. The derived result shows that the tunneling rate depends on the emitted particle's energy and electric charge, and takes the same functional form as uncharged particle. It proves also that the exact emission spectrum is not strictly pure thermal, but is consistent with the underlying unitary theory.
PACS Numbers: 04.70.Dy, 97.60.Lf, 05.30.Ch. 相似文献
154.
Noriko SUTO Makoto HARADA Jun IZUTSU Toshiyasu NAGAO 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2006,82(5):175-180
In order to accurately estimate the geomagnetic transfer functions in the area of the volcano Mt. Iwate (IWT), we applied the interstation transfer function (ISTF) method to the three-component geomagnetic field data observed at Mt. Iwate station (IWT), using the Kakioka Magnetic Observatory, JMA (KAK) as remote reference station. Instead of the conventional Fourier transform, in which temporary transient noises badly degrade the accuracy of long term properties, continuous wavelet transform has been used. The accuracy of the results was as high as that of robust estimations of transfer functions obtained by the Fourier transform method. This would provide us with possibilities for routinely monitoring the transfer functions, without sophisticated statistical procedures, to detect changes in the underground electrical conductivity structure. 相似文献
155.
本文介绍了兰州重离子加速器(HIRFL)的注入器(SFC)所用PIG离子源的研制和改进工作,使用新研制的PIG源,已在注人器SFC上获得了5μA的O_(16)~(5+)及10μA的C_(16)~(4+)的离子束。 相似文献
156.
Kefu Fu Kevin Henbest Yufen J. Zhang Shane Valentin Ya-Ping Sun 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):143-152
Dimeric fullerene macromolecules were prepared via the complexation of two fullerenylated 2,2′:6′,2″-terpyridine ligands with Fe(II) and Co(II) ions. The solubility of these macromolecules in some organic solvents allowed both their structural characterization and a study of their optical properties. The electronic absorption and emission of the macromolecules in solution were evaluated; and the results indicated no meaningful ground-state and excited singlet state intramolecular charge transfer interactions. However, the laser flash photolysis results could be explained in terms of the electron transfer quenching of the excited triplet methanofullerene moiety by the center metal–ligand complex in the macromolecules. The optical limiting properties of the macromolecules in solution were also investigated in comparison with those of the ligands for an evaluation of the complexation effects. 相似文献
157.
提出了核双电荷交换反应的双重子共振态的反应机制,成功地解释了长期以来一直困惑着人们的共振区反应的角分布的实验结果.说明了共振区核双电荷交换反应是寻找双重子共振态的一个可能的途径. 相似文献
158.
The features of interaction of a spherical metallic particle with a rarefied thermal plasma flow due to the presence o charges-electrons and ions in the gaseous phase-are considered. Analytical expressions describing charge, momentum, and energy exchange between the plasma and the particle für the cases of strong and weak Debye screening are obtained. It is illustrated that the efficiency of particle heating in the plasma considerably grows as compared with a hot molecular gas due to participation of electrons and ions in file transfer processes. 相似文献
159.
唐瑞平 《高等学校化学学报》1991,12(4):532-536
通过测定平带电位,澄清了OH~-离子在CdSe电极上的吸附情况,发现在S、S~(2-)、OH~-溶液中S~(2-)离子优先吸附,结合旋转环盘电极测量,证明n-CdSe电极在多硫溶液界面上的电荷转移过程。 相似文献
160.
本文导出了考虑外场和束流效应后束流均方根发射度平方变化方程的一般表达式,并就仅考虑外场,仅考虑空间电荷场和仅考虑尾场等三种特殊情况进行了分析。 相似文献