全文获取类型
收费全文 | 517973篇 |
免费 | 4099篇 |
国内免费 | 1177篇 |
专业分类
化学 | 244745篇 |
晶体学 | 7817篇 |
力学 | 28149篇 |
综合类 | 14篇 |
数学 | 75323篇 |
物理学 | 167201篇 |
出版年
2021年 | 4198篇 |
2020年 | 4436篇 |
2019年 | 5138篇 |
2018年 | 12621篇 |
2017年 | 13179篇 |
2016年 | 12471篇 |
2015年 | 5866篇 |
2014年 | 9383篇 |
2013年 | 20796篇 |
2012年 | 18807篇 |
2011年 | 27303篇 |
2010年 | 19231篇 |
2009年 | 19517篇 |
2008年 | 24486篇 |
2007年 | 26750篇 |
2006年 | 16095篇 |
2005年 | 17892篇 |
2004年 | 15096篇 |
2003年 | 14023篇 |
2002年 | 12838篇 |
2001年 | 13914篇 |
2000年 | 10497篇 |
1999年 | 7994篇 |
1998年 | 6818篇 |
1997年 | 6575篇 |
1996年 | 6256篇 |
1995年 | 5488篇 |
1994年 | 5389篇 |
1993年 | 5272篇 |
1992年 | 5646篇 |
1991年 | 6068篇 |
1990年 | 5812篇 |
1989年 | 5788篇 |
1988年 | 5476篇 |
1987年 | 5654篇 |
1986年 | 5298篇 |
1985年 | 6689篇 |
1984年 | 6755篇 |
1983年 | 5703篇 |
1982年 | 5789篇 |
1981年 | 5494篇 |
1980年 | 5300篇 |
1979年 | 5783篇 |
1978年 | 5924篇 |
1977年 | 5889篇 |
1976年 | 5994篇 |
1975年 | 5606篇 |
1974年 | 5543篇 |
1973年 | 5734篇 |
1972年 | 4264篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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
992.
993.
994.
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
995.
Recently, the theory of sortability of partition property has been shown to be an effective tool to prove the existence of an optimal partition with that property. In this paper, we extend the theory to multi-partition where the partition is on t types of components. We apply our results to settle an optimal assignment problem whose proof was incomplete as given in the literature. 相似文献
996.
997.
998.
T Yamakawa H Matsukura Y Nomura M Yoshioka M Masaki H Igata S Okabe 《Chemical & pharmaceutical bulletin》1991,39(7):1746-1752
A series of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines (3) was synthesized and evaluated for its biological activity against gastric H+/K(+)-ATPase prepared from rabbit stomach and gastric acid secretions in Heidenhain pouch dogs. Monoalkyl substituents on the nitrogen atom of the aniline moiety markedly inhibited the enzyme activity to the same degree as omeprazole, a representative H+/K(+)-ATPase inhibitor. Most of these compounds, administered at 3 mg/kg i.v. inhibited histamine-stimulated gastric acid secretion. The inhibitory activity of these derivatives on the enzymes at pH 6.0 was more potent than that at pH 7.4, and was distinctly correlated to stability in aqueous solution at pH 5.0. 相似文献
999.
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
1000.