全文获取类型
收费全文 | 465276篇 |
免费 | 2293篇 |
国内免费 | 928篇 |
专业分类
化学 | 204917篇 |
晶体学 | 6592篇 |
力学 | 28912篇 |
综合类 | 9篇 |
数学 | 87095篇 |
物理学 | 140972篇 |
出版年
2020年 | 4162篇 |
2019年 | 5056篇 |
2018年 | 17511篇 |
2017年 | 17398篇 |
2016年 | 15331篇 |
2015年 | 5225篇 |
2014年 | 8701篇 |
2013年 | 16118篇 |
2012年 | 16454篇 |
2011年 | 25101篇 |
2010年 | 17983篇 |
2009年 | 18605篇 |
2008年 | 20897篇 |
2007年 | 22705篇 |
2006年 | 13064篇 |
2005年 | 12407篇 |
2004年 | 12264篇 |
2003年 | 11919篇 |
2002年 | 11283篇 |
2001年 | 10693篇 |
2000年 | 8385篇 |
1999年 | 6322篇 |
1998年 | 5849篇 |
1997年 | 5613篇 |
1996年 | 5194篇 |
1995年 | 4578篇 |
1994年 | 4578篇 |
1993年 | 4599篇 |
1992年 | 4639篇 |
1991年 | 5133篇 |
1990年 | 5047篇 |
1989年 | 5106篇 |
1988年 | 4750篇 |
1987年 | 4828篇 |
1986年 | 4518篇 |
1985年 | 5398篇 |
1984年 | 5589篇 |
1983年 | 4760篇 |
1982年 | 5013篇 |
1981年 | 4669篇 |
1980年 | 4331篇 |
1979年 | 4967篇 |
1978年 | 5137篇 |
1977年 | 5317篇 |
1976年 | 5466篇 |
1975年 | 5072篇 |
1974年 | 4896篇 |
1973年 | 5156篇 |
1972年 | 4320篇 |
1971年 | 3952篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
James V. Crivello Umut Bulut 《Journal of polymer science. Part A, Polymer chemistry》2005,43(21):5217-5231
Curcumin, a naturally occurring, intensely yellow dye extracted from the spice turmeric, is an efficient photosensitizer for diaryliodonium salt photoinitiators at wavelengths ranging from 340 to 535 nm. With curcumin as a photosensitizer, it is possible to carry out the cationic photopolymerization of a wide variety of epoxide, oxetane, and vinyl monomers with long‐wavelength UV and visible light. An example of the photopolymerization of an epoxide monomer with ambient solar irradiation is provided. Several other curcumin analogues were synthesized, and their use as photosensitizers is examined. With such photosensitizers, the range of spectral sensitivity can be extended well into the visible region of the electromagnetic spectrum. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5217–5231, 2005 相似文献
93.
94.
QUALITATIVE AND QUANTITATIVE ANALYSIS OF STOCHASTIC PROCESSES BASED ON MEASURED DATA, II: APPLICATIONS TO EXPERIMENTAL DATA 总被引:1,自引:0,他引:1
Analysis of stochastic processes governed by the Langevin equation is discussed. The analysis is based on a general method for non-parametric estimation of deterministic and random terms of the Langevin equation directly from given data. Separate estimation of the terms corresponds to the decomposition of process dynamics into deterministic and random components. Part I of the paper presented several possibilities for qualitative and quantitative analysis of process dynamics based on such decomposition. In Part II, some of these analysis possibilities are applied to experimental datasets from metal cutting and laser-beam welding. 相似文献
95.
A. I. Makarov 《Journal of Applied Mechanics and Technical Physics》2002,43(5):694-700
Aeroacoustic resonant oscillations (aeolian tones) are studied for flow past two plates forming a cross in a square cross section channel. Possible oscillation modes are classified on the basis of admissible symmetry groups and the existence of the modes is proved. The infinite linear system of equations for these modes obtained by the sewing method was simplified and studied numerically. Curves of eigenfrequency versus plate length are constructed. The form of the eigenfunctions is studied. 相似文献
96.
V. I. Bliznikas A. P. Norden B. N. Shapukov A. P. Shirokov 《Journal of Mathematical Sciences》1991,55(6):2091-2100
Biographical information on the eminent Soviet geometer Boris Lukich Laptev (4/23/05–1/15-89) is given as well as a survey of his research in the areas of differential geometry and history of mathematics.Translated from Itogi Nauki i Tekhniki, Seriya Problemy Geometrii, Vol. 21, pp.27–42, 1989. 相似文献
97.
98.
A. I. Khachaturov 《Technical Physics》2006,51(2):226-230
The contribution of electrons moving at large angles to the barrier junction plane to the tunnel current is calculated. This contribution turns out to be small only if the Fermi energy of the electrons equals several electron volts. Otherwise, specifically, when the Fermi energy is no higher than 1–2 eV, this contribution dominates in high and thin potential barriers. It is found that the tunnel magnetic resistance in ferromagnet-insulator-ferromagnet contacts correlates with this contribution. It is this correlation that is responsible for a decrease in this contribution as the potential barriers get lower and thicker. 相似文献
99.
V. B. Levenshtam 《Siberian Mathematical Journal》1989,30(4):554-559
Rostov-on-Don. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 30, No. 4, pp. 69–75, July–August, 1989. 相似文献
100.
An infinite row of periodically spaced, identical rigid circularcylinders is excited by an acoustic line source which is parallelto the generators of the cylinders. A method for calculatingthe scattered field accurately and efficiently is presented.When the cylinders are sufficiently close together, Rayleigh–Blochsurface waves that propagate energy to infinity along the arrayare excited. An expression is derived which enables the amplitudesof these surface waves to be computed without requiring thesolution to the full scattering problem. 相似文献