全文获取类型
收费全文 | 498206篇 |
免费 | 5416篇 |
国内免费 | 2190篇 |
专业分类
化学 | 259004篇 |
晶体学 | 7638篇 |
力学 | 22865篇 |
综合类 | 68篇 |
数学 | 60206篇 |
物理学 | 156031篇 |
出版年
2021年 | 4189篇 |
2020年 | 4646篇 |
2019年 | 5109篇 |
2018年 | 6917篇 |
2017年 | 7093篇 |
2016年 | 9942篇 |
2015年 | 5999篇 |
2014年 | 9545篇 |
2013年 | 22662篇 |
2012年 | 18135篇 |
2011年 | 21766篇 |
2010年 | 15991篇 |
2009年 | 15708篇 |
2008年 | 19889篇 |
2007年 | 19885篇 |
2006年 | 18459篇 |
2005年 | 16370篇 |
2004年 | 14974篇 |
2003年 | 13253篇 |
2002年 | 13149篇 |
2001年 | 15123篇 |
2000年 | 11334篇 |
1999年 | 8701篇 |
1998年 | 7288篇 |
1997年 | 7093篇 |
1996年 | 6809篇 |
1995年 | 5914篇 |
1994年 | 5953篇 |
1993年 | 5719篇 |
1992年 | 6318篇 |
1991年 | 6504篇 |
1990年 | 6150篇 |
1989年 | 6022篇 |
1988年 | 5746篇 |
1987年 | 5791篇 |
1986年 | 5613篇 |
1985年 | 7223篇 |
1984年 | 7332篇 |
1983年 | 6104篇 |
1982年 | 6344篇 |
1981年 | 5929篇 |
1980年 | 5737篇 |
1979年 | 6128篇 |
1978年 | 6291篇 |
1977年 | 6308篇 |
1976年 | 6308篇 |
1975年 | 5888篇 |
1974年 | 5933篇 |
1973年 | 6042篇 |
1972年 | 4487篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
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
5.
6.
An optimal control model of exhaustible resources is used to clarify the long run relationship between mineral rent and depletion cost at the industry level. A standard first order condition of the time rate of change of rents is reformulated to reveal that rent data may be used to help forecast the rise in extraction costs resulting from resource depletion. This application of the theory of exhaustible resources is illustrated using historical mineral industry rent and extraction cost data. A forecast of U.S. coal extraction costs, following the method proposed in this paper, suggests that future rates of extraction cost increases will be similar to rates experienced in the past. 相似文献
7.
Open circuit voltage (OCV) measurements in H2O/air concentration cells at T<580 K using Yb-doped SrCeO3 electrolyte indicate that under these conditions, protons are transported through the electrolyte as -ve ions, possibly as
hydroxyl (OH−) ions. The H+ ionic transport, which is generally reported, becomes the dominant mode for H2O/air concentration cells at temperatures greater than 750 K or when H2O/air electrodes are replaced by H2/Ar, and the anomalous OCV sign disappears. The combination of low temperature and the presence of hydrogen and oxygen as
provided by the H2O/air system appears to be necessary for the postulated hydroxyl ion electrode reactions to take place.
In addition to OCV measurements, results from impedance spectroscopy are used to provide evidence in support of the suggested
hydroxyl ion mode of protonic transport under the specified conditions. These findings are directly relevant in the development
of novel humidity sensors in the temperature range 450–580K and is reported in a separate paper in this conference.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996 相似文献
8.
S. A. Gurevich T. A. Zaraiskaya S. G. Konnikov V. M. Mikushkin S. Yu. Nikonov A. A. Sitnikova S. E. Sysoev V. V. Khorenko V. V. Shnitov Yu. S. Gordeev 《Physics of the Solid State》1997,39(10):1691-1695
The concentration and chemical state of copper in the subsurface region of Cu/SiO2 composite films obtained by simultaneous magnetron sputtering from two sources (Cu and SiO2) are determined by x-ray photoelectron spectroscopy (XPS). It is established that copper in the as-grown film is primarily in the form of unoxidized atoms dispersed in a SiO2 matrix. Annealing of the film results in practically no oxidation, but about 70% of the copper atoms condense into metallic clusters with sizes below 10 Å in the subsurface region and about 50 Å in the bulk of the film. The changes in the binding energy of core electrons, and especially in the energies of Auger electrons, are so large in this situation that photoelectron and Auger spectroscopy are efficient methods for monitoring the chemical state of this composite material. 相似文献
9.
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
10.
L. K. Aminov I. N. Kurkin D. A. Lukoyanov K. P. Chernov 《Physics of the Solid State》1997,39(8):1184-1186
Results are reported for measurements of the spin-lattice relaxation times of E′1 centers in quartz glass, produced by neutron irradiation, with the measurements made at two frequencies 9.25 and 24.0 GHz
over a wide temperature interval 1.5–300 K. The experimental data are interpreted on the basis of interaction mechanisms of
the spins with two-level systems with excitation energies ∼6, ∼26, and ∼420 cm−1. A small modification of the existing theory allows us to explain a number of features of the observed temperature and frequency
dependence of the relaxation rate. The results are compared with the data available in the literature on spin-lattice relaxation
of irradiation centers in crystalline quartz and quartz glass.
Fiz. Tverd. Tela (St. Petersburg) 39, 1335–1337 (August 1997) 相似文献