全文获取类型
收费全文 | 203933篇 |
免费 | 2045篇 |
国内免费 | 655篇 |
专业分类
化学 | 106423篇 |
晶体学 | 2903篇 |
力学 | 9535篇 |
综合类 | 15篇 |
数学 | 19637篇 |
物理学 | 68120篇 |
出版年
2021年 | 1412篇 |
2020年 | 1506篇 |
2019年 | 1549篇 |
2018年 | 1966篇 |
2017年 | 1889篇 |
2016年 | 3253篇 |
2015年 | 2092篇 |
2014年 | 3293篇 |
2013年 | 8506篇 |
2012年 | 6898篇 |
2011年 | 8735篇 |
2010年 | 6064篇 |
2009年 | 6145篇 |
2008年 | 8023篇 |
2007年 | 7948篇 |
2006年 | 7436篇 |
2005年 | 6786篇 |
2004年 | 6069篇 |
2003年 | 5372篇 |
2002年 | 5294篇 |
2001年 | 6953篇 |
2000年 | 5183篇 |
1999年 | 3948篇 |
1998年 | 3193篇 |
1997年 | 3120篇 |
1996年 | 2765篇 |
1995年 | 2585篇 |
1994年 | 2498篇 |
1993年 | 2287篇 |
1992年 | 2838篇 |
1991年 | 2962篇 |
1990年 | 2664篇 |
1989年 | 2597篇 |
1988年 | 2508篇 |
1987年 | 2488篇 |
1986年 | 2281篇 |
1985年 | 3007篇 |
1984年 | 3076篇 |
1983年 | 2435篇 |
1982年 | 2570篇 |
1981年 | 2448篇 |
1980年 | 2339篇 |
1979年 | 2586篇 |
1978年 | 2803篇 |
1977年 | 2681篇 |
1976年 | 2636篇 |
1975年 | 2468篇 |
1974年 | 2559篇 |
1973年 | 2475篇 |
1972年 | 1559篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron... 相似文献
3.
NaY zeolite samples loaded with sodium metal by vapor phase deposition have been investigated using129Xe NMR spectroscopy. At low sodium concentration, the129Xe NMR spectrum showed three resonance lines which clearly indicate the existence of distinct domains in the zeolite sample. Such an observation suggests that the diffusion of the xenon atoms into each domain only occurs with respect to the NMR time scale (2.9 ms). As the sodium concentration increases, observation of a single broad line indicate a macroscopic homogenization of the system. The shift of this line is explained in part due to a paramagnetic interaction between the xenon atoms and the unpaired electrons of particles containing an odd number of sodium atoms. The linewidth is due to the distribution of the local magnetic fields partially averaged by the rapid motion of the xenon atoms and to the statistical distribution of the sodium particles in the supercage cavities. The paramagnetic interaction vanishes with the oxidation of the sample leading to a narrowing and a shift of the line to higher magnetic fields. 相似文献
4.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献
5.
F. G. Vagizov 《Hyperfine Interactions》1995,95(1):85-95
We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field. 相似文献
6.
7.
A.-S. F. Obada M. Darwish H. H. Salah 《International Journal of Theoretical Physics》2002,41(9):1755-1768
In this paper a new state called odd-excited binomial state (OEBS) is introduced. It interpolates between the odd number state and the odd-excited coherent state. We discuss some statistical properties, such as the Glauber second-order correlation function and squeezing phenomenon (normal and amplitude-squared squeezing) for this state. The quasiprobability distribution functions (Husimi Q-function and Wigner W-function) are also examined. 相似文献
8.
The structural properties of polycrystalline silicon films, prepared by plasma enhanced chemical vapor deposition system, with different flow rates of SiH4/SiF4 mixtures at 300 °C were investigated. This study indicates that the low hydrogen coverage on the growing surface, under optimum fluorine radicals, will be leaded to an improvement of crystallized area as compared with case of high hydrogen coverage surface. Moreover, the studies of the role of SiH4 and SiF4 radicals show that the SiH4 radicals are important in the nucleation and growth of grains. However, SiF4 radicals are effective in the structural change of grain boundaries regions and by this way, in the present system, establish the growth of grains under the dominant 〈1 1 0〉 direction. The stress investigation indicates that addition of high flow rate of SiF4 in amorphous film, results in the nearly stress free films. Finally, we found that the changes in g-value reflect the changes in the intrinsic compressive and tensile stress in the both polycrystalline and amorphous silicon films. 相似文献
9.
A. R. Volkov B. V. Shul'gin T. I. Polupanova V. N. Lebedev A. A. Nagornyi V. L. Petrov Yu. F. Kargin 《Journal of Applied Spectroscopy》1991,54(6):585-590
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 970–975, June, 1991. 相似文献
10.
In a twisted nematic liquid crystal cell we report and study the self-transparency effect induced by the creation of an isotropic droplet. A simple theoretical model is presented and good agreement with experimental data is found. In a two beams configuration transistor-like behavior is observed and theoretically discussed. 相似文献