全文获取类型
收费全文 | 2411篇 |
免费 | 141篇 |
国内免费 | 1篇 |
专业分类
化学 | 1591篇 |
晶体学 | 25篇 |
力学 | 53篇 |
数学 | 292篇 |
物理学 | 592篇 |
出版年
2024年 | 6篇 |
2023年 | 18篇 |
2022年 | 43篇 |
2021年 | 90篇 |
2020年 | 81篇 |
2019年 | 121篇 |
2018年 | 118篇 |
2017年 | 102篇 |
2016年 | 152篇 |
2015年 | 99篇 |
2014年 | 121篇 |
2013年 | 174篇 |
2012年 | 158篇 |
2011年 | 193篇 |
2010年 | 113篇 |
2009年 | 85篇 |
2008年 | 144篇 |
2007年 | 124篇 |
2006年 | 128篇 |
2005年 | 93篇 |
2004年 | 75篇 |
2003年 | 59篇 |
2002年 | 60篇 |
2001年 | 30篇 |
2000年 | 22篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1968年 | 2篇 |
1965年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有2553条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
For the first time a comparative study of holographic recording in planarly oriented films of nematic and cholesteric azobenzene-containing polymers was performed. The influence of temperature and light intensity on the values of diffraction efficiencies of holographic gratings was investigated. The kinetics of grating relaxation at different temperatures was studied. It was shown that the helical supramolecular structure of cholesteric copolymer causes a significant decrease of the diffraction efficiency in comparison with the one observed for the nematic state of the homopolymer. 相似文献
5.
Low-lying energy states of the [Fe3S4]0 cluster have been calculated by taking into account the double exchange, superexchange and vibronic interaction. It was found that the adiabatic potential of the excited state withS=0 corresponds to the full delocalization of the “excess” charge. From the analysis of experimental data of Mössbauer spectroscopy and the temperature dependence of the magnetic susceptibility the double exchange parametert≥4000 cm?1 and the vibronic interaction parameter λ2/2k cm?1 have been estimated. 相似文献
6.
Alexey Yurasov Alexander Granovsky Sergey Tarapov Jean-Pierre Clerc 《Journal of magnetism and magnetic materials》2006
The transmission of millimeter-range electromagnetic waves (30–50 GHz) through a magnetic nanocomposite thin film exhibiting tunnel magnetoresistance (TMR) is calculated. The relative change of transmission coefficient in an applied magnetic field due to the magnetorefractive effect is approximately linear with TMR and strongly depends on nanocomposite resistivity and film thickness. The obtained results are in a good agreement with experiment. 相似文献
7.
Based on an analysis of the signal of an interferometric intensity autocorrelator, we demonstrate theoretically and experimentally a simple technique for retrieving the temporal distributions of the amplitude and phase of an ultrashort light pulse. Assuming that a phase-modulated wave packet has a Gaussian envelope, we derive an analytical expression for the autocorrelator signal in the cases of linear- and quadratic-chirp optical pulses. The experimental and theoretical results are in excellent agreement. In particular, we show that a linear chirp (quadratic phase modulation) can be measured with a good experimental accuracy of no worse than 10%. This yields the possibility of measuring the parameter k2, which describes the dispersion characteristics of a medium in the second order of the dispersion theory, with the same accuracy. Measuring a quadratic chirp by the proposed method is possible only if such a chirp is sufficiently large. 相似文献
8.
9.
A. N. Aleev N. S. Amaglobeli V. P. Balandin O. V. Bulekov I. M. Geshkov T. S. Grigalashvili E. A. Goudzovski D. K. Guriev D. D. Emelianov S. V. Eremin A. I. Zinchenko Z. M. Ivanchenko I. M. Ivanchenko M. N. Kapishin A. A. Loktionov V. D. Kekelidze Z. I. Kozhenkova V. V. Korenkov I. G. Kosarev N. A. Kuzmin A. L. Ljubimov D. T. Madigozhin V. G. Maznyj A. S. Mestvirishvili N. A. Molokanova A. N. Morozov R. E. Pismenyj V. D. Poze I. A. Polenkevich A. K. Ponosov T. Ponta Yu. K. Potrebenikov F. M. Sergeev L. A. Slepets V. N. Spaskov 《Physics of Atomic Nuclei》2004,67(8):1513-1522
The features of the associated production of φ mesons with Λ0 hyperons in neutron-carbon interactions were investigated. The experiment was performed with the aid of the EXCHARM spectrometer at the Serpukhov accelerator in a neutron beam of energy in the interval 20–70 GeV. The differential cross section for inclusive associated φΛ0 production was measured. 相似文献
10.
Vladimir B. Arion Alexey A. Nazarov Christian G. Hartinger Gerald Giester Bernhard K. Keppler 《应用有机金属化学》2003,17(9):723-724
For the unsymmetrical title compound, 1‐bromo‐1′‐[(2S)‐N‐(1‐hydroxy‐3‐methylbutane‐2‐yl)]‐ferroceneamide, two independent molecules were found in the asymmetric unit. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献