全文获取类型
收费全文 | 333154篇 |
免费 | 6164篇 |
国内免费 | 4899篇 |
专业分类
化学 | 157070篇 |
晶体学 | 4591篇 |
力学 | 20306篇 |
综合类 | 329篇 |
数学 | 53102篇 |
物理学 | 108819篇 |
出版年
2022年 | 2663篇 |
2021年 | 3504篇 |
2020年 | 3813篇 |
2019年 | 4376篇 |
2018年 | 12415篇 |
2017年 | 12862篇 |
2016年 | 10100篇 |
2015年 | 4562篇 |
2014年 | 6592篇 |
2013年 | 11197篇 |
2012年 | 13330篇 |
2011年 | 21168篇 |
2010年 | 14546篇 |
2009年 | 14893篇 |
2008年 | 18597篇 |
2007年 | 21290篇 |
2006年 | 8813篇 |
2005年 | 12425篇 |
2004年 | 9584篇 |
2003年 | 9335篇 |
2002年 | 7957篇 |
2001年 | 7109篇 |
2000年 | 5556篇 |
1999年 | 4180篇 |
1998年 | 3859篇 |
1997年 | 3516篇 |
1996年 | 3459篇 |
1995年 | 3023篇 |
1994年 | 3008篇 |
1993年 | 2975篇 |
1992年 | 2959篇 |
1991年 | 3281篇 |
1990年 | 3190篇 |
1989年 | 3200篇 |
1988年 | 2988篇 |
1987年 | 2997篇 |
1986年 | 2799篇 |
1985年 | 3348篇 |
1984年 | 3400篇 |
1983年 | 2970篇 |
1982年 | 2996篇 |
1981年 | 2827篇 |
1979年 | 3026篇 |
1978年 | 3180篇 |
1977年 | 3179篇 |
1976年 | 3396篇 |
1975年 | 3085篇 |
1974年 | 3047篇 |
1973年 | 3266篇 |
1972年 | 2665篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Yu. V. Brezhnev 《Theoretical and Mathematical Physics》2002,133(3):1657-1662
We construct Dubrovin equations and trace formulas for finite-band operators with trigonal curves and present some examples. 相似文献
102.
We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch. 相似文献
103.
104.
The structural evolution in amorphous silicon and germanium thin films has been investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with autocorrelation function (ACF) analysis. The results established that the structure of as-deposited semiconductor films is of a high density of nanocrystallites embedded in the amorphous matrix. In addition, from ACF analysis, the structure of a-Ge is more ordered than that of a-Si. The density of embedded nanocrystallites in amorphous films was found to diminish with annealing temperature first, then to increase. The conclusions also corroborate well with the results of diminished medium-range order in annealed amorphous films determined previously by a variable coherence microscopy method. 相似文献
105.
Guofen Yu Yuanci Gao Shenggang Liu Wenxiang Wang Jin Wu 《International Journal of Infrared and Millimeter Waves》2002,23(8):1261-1269
Analysis of the field distributions in a single biological cell under electromagnetic wave is given. With Debye approximation, the dielectric relaxation of each part of the cell, including the extracellular and cellular media, the cell membrane and the nuclear membrane, was taken into account. Making use of some typical parameters for a cell, the voltage across nuclear and cytoplasma membranes under electromagnetic waves are calculated up to millimeter wave frequency range. The calculated result indicates that it is unlikely to generate electroporation by present available millimeter wave sources. 相似文献
106.
A. E. Angervaks S. A. Dimakov S. I. Kliment’ev A. I. Ryskin A. S. Shcheulin 《Optics and Spectroscopy》2002,93(2):307-314
The diffraction efficiency and the recording and relaxation times of dynamic reflection holograms, recorded in CdF2 crystals with bistable centers are studied experimentally in the temperature range 20–100°C. In the model experiments which measured the quality of the wave reflected from the hologram, the dynamic wavefront distortions are demonstrated to be efficiently compensated using a holographic corrector based on these crystals. CdF2 crystals with bistable centers are likely to be useful in solving problems of correction of laser light wavefront and image correction in observation telescopes with nonideal primary mirrors. 相似文献
107.
Purification and some properties of squalene-2,3-epoxide: lanosterol cyclase from rat liver 总被引:1,自引:0,他引:1
Squalene-2,3-epoxide: lanosterol cyclase was purified from rat liver in five steps as a soluble and homogeneous protein. The purified enzyme showed a single band on SDS-polyacrylamide gel electrophoresis with a molecular weight of 75 kD. In its native state it behaved as a homo-dimer. The isoelectric point of 5.5 and the apparent Km value for (3S)-squalene-epoxide of 55 microM were estimated for the cyclase. 相似文献
108.
A. I. Bril' V. P. Kabashnikov N. V. Kuz'mina Yu. V. Khodyko 《Journal of Applied Spectroscopy》1991,55(3):934-939
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 478–484, September, 1991. 相似文献
109.
In this paper, we consider a class of functional equations and prove three theorems which give the approximation properties
and error estimates of the optimal polynomial approximation of slution of those functional equations. 相似文献
110.
A. P. Prudnikov Yu. A. Brychkov O. I. Marichev 《Journal of Mathematical Sciences》1991,54(6):1239-1341
Translated from Itogi Nauki i Tekhniki, Seriya Matematicheskii Analiz, Vol. 27, pp. 3–146, 1989. 相似文献