全文获取类型
收费全文 | 478361篇 |
免费 | 4621篇 |
国内免费 | 1343篇 |
专业分类
化学 | 248085篇 |
晶体学 | 7838篇 |
力学 | 21627篇 |
综合类 | 16篇 |
数学 | 54569篇 |
物理学 | 152190篇 |
出版年
2021年 | 4116篇 |
2020年 | 4537篇 |
2019年 | 5098篇 |
2018年 | 6675篇 |
2017年 | 6923篇 |
2016年 | 9785篇 |
2015年 | 5712篇 |
2014年 | 9447篇 |
2013年 | 22452篇 |
2012年 | 17007篇 |
2011年 | 20440篇 |
2010年 | 14901篇 |
2009年 | 14819篇 |
2008年 | 18273篇 |
2007年 | 18121篇 |
2006年 | 16868篇 |
2005年 | 14858篇 |
2004年 | 13769篇 |
2003年 | 12318篇 |
2002年 | 12133篇 |
2001年 | 14433篇 |
2000年 | 10860篇 |
1999年 | 8399篇 |
1998年 | 6944篇 |
1997年 | 6772篇 |
1996年 | 6394篇 |
1995年 | 5715篇 |
1994年 | 5560篇 |
1993年 | 5284篇 |
1992年 | 6193篇 |
1991年 | 6312篇 |
1990年 | 6054篇 |
1989年 | 6043篇 |
1988年 | 5800篇 |
1987年 | 5916篇 |
1986年 | 5570篇 |
1985年 | 7129篇 |
1984年 | 7187篇 |
1983年 | 5854篇 |
1982年 | 6051篇 |
1981年 | 5865篇 |
1980年 | 5575篇 |
1979年 | 6113篇 |
1978年 | 6151篇 |
1977年 | 6247篇 |
1976年 | 6088篇 |
1975年 | 5665篇 |
1974年 | 5539篇 |
1973年 | 5581篇 |
1972年 | 3933篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Experimental data on the effect of thallium and sodium impurities on the lattice heat conductivity of PbTe at room temperature
are reported. Because the lattice of lead chalcogenides is strongly polarized near charged impurities, the effect of impurities
on the lattice heat conductivity depends substantially on their charge state. This property of the material has been used
to determine the charge state of the thallium impurity in PbTe. The results obtained argue for a model of quasi-local thallium-impurity
states which assumes low electron-correlation energy at an impurity center.
Fiz. Tverd. Tela (St. Petersburg) 40, 1206–1208 (July 1998) 相似文献
12.
13.
E. Jackiewicz M. Lukasiak M. Kopcewicz K. Szpila N. Bakun-Czubarow 《Hyperfine Interactions》1992,70(1-4):993-996
Terrestrial basalt rocks considered to be a good analogues of the Martian regolith were studied by using the Mössbauer spectroscopy and X-ray diffraction. The weathering of basalts was followed by the changes of the Fe2+/Fe3+ ratio. The basalt rock undergoes alteration from primary mineral composition (olivine+pyroxene+plagioclase) through smectite to kaolinite clay with oxides and hydroxides with the increase of the Fe2+/Fe3+ ratio. 相似文献
14.
15.
16.
Myagchenkov V. A. Chichkanov S. V. Proskurina V. E. Myagchenkov A. V. 《Russian Journal of Applied Chemistry》2002,75(9):1485-1488
The Thoms effect observed with water-soluble cationic copolymer of acrylamide was studied in relation to the concentration, molecular weight, and molecular weight polydispersity of the polymeric additive, with its composition and composition polydispersity being constant. 相似文献
17.
18.
A. K. Lopatin 《Ukrainian Mathematical Journal》1997,49(1):51-74
We consider the method of normal forms, the Bogolyubov averaging method, and the method of asymptotic decomposition proposed by Yu. A. Mitropol’skii and the author of this paper. Under certain assumptions about group-theoretic properties of a system of zero approximation, the results obtained by the method of asymptotic decomposition coincide with the results obtained by the method of normal forms or the Bogolyubov averaging method. We develop a new algorithm of asymptotic decomposition by a part of the variables and its partial case — the algorithm of averaging on a compact Lie group. For the first time, it became possible to consider asymptotic expansions of solutions of differential equations on noncommutative compact groups. 相似文献
19.
A. J. Parsons S. D. J. Inglethorpe D. J. Morgan A. C. Dunham 《Journal of Thermal Analysis and Calorimetry》1997,48(1):49-62
Using a system based on non-dispersive infrared (NDIR) detectors, evolved gas analysis (EGA) was able to identify and quantify the principal volatiles produced by heating powdered samples of UK brick clays. From these results, atmospheric emissions likely to result from brick production can be predicted. In addition, EGA results for extruded brick clay test pieces are significantly different from those of powdered samples. Within an extruded brick clay body, evolved gases are contained within a pore system and evolved gas-solid phase reactions also occur. This EGA study provides further evidence on the nature of firing reactions within brick clay bodies. The qualitative and quantitative influence of heating rate — a key process condition in brick manufacture — on gas release is also outlined.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday 相似文献
20.