全文获取类型
收费全文 | 798636篇 |
免费 | 7778篇 |
国内免费 | 2280篇 |
专业分类
化学 | 414416篇 |
晶体学 | 11328篇 |
力学 | 38581篇 |
综合类 | 28篇 |
数学 | 106059篇 |
物理学 | 238282篇 |
出版年
2021年 | 7230篇 |
2020年 | 7782篇 |
2019年 | 8714篇 |
2018年 | 11353篇 |
2017年 | 11280篇 |
2016年 | 16511篇 |
2015年 | 9732篇 |
2014年 | 15442篇 |
2013年 | 36188篇 |
2012年 | 27918篇 |
2011年 | 33642篇 |
2010年 | 24490篇 |
2009年 | 24215篇 |
2008年 | 31449篇 |
2007年 | 31191篇 |
2006年 | 28788篇 |
2005年 | 25750篇 |
2004年 | 23866篇 |
2003年 | 21248篇 |
2002年 | 21048篇 |
2001年 | 22718篇 |
2000年 | 17567篇 |
1999年 | 13700篇 |
1998年 | 11590篇 |
1997年 | 11309篇 |
1996年 | 10823篇 |
1995年 | 9798篇 |
1994年 | 9715篇 |
1993年 | 9379篇 |
1992年 | 10145篇 |
1991年 | 10496篇 |
1990年 | 10162篇 |
1989年 | 9826篇 |
1988年 | 9688篇 |
1987年 | 9529篇 |
1986年 | 9061篇 |
1985年 | 11713篇 |
1984年 | 12110篇 |
1983年 | 9937篇 |
1982年 | 10318篇 |
1981年 | 9915篇 |
1980年 | 9309篇 |
1979年 | 10010篇 |
1978年 | 10307篇 |
1977年 | 10190篇 |
1976年 | 10076篇 |
1975年 | 9554篇 |
1974年 | 9422篇 |
1973年 | 9595篇 |
1972年 | 6917篇 |
排序方式: 共有10000条查询结果,搜索用时 1 毫秒
231.
232.
We show that there are close relations between extremal problems in dual Brunn-Minkowski theory and isotropic-type properties for some Borel measures on the sphere. The methods we use allow us to obtain similar results in the context of Firey-Brunn-Minkowski theory. We also study reverse inequalities for dual mixed volumes which are related with classical positions, such as ?-position or isotropic position. 相似文献
233.
A homologous series of azomesogens, 2″-[4-(4′-n-alkoxybenzoyloxy)-2-chlorophenylazo] naphthalenes, with lateral chloro groups was synthesised. All the homologues synthesized
exhibit enantiotropic nematic mesophase. The mesomorphic properties of the present series are compared with other structurally
related series to evaluate the effect of lateral chloro group and its position on mesomorphism
This paper was presented at the 10th National Conference on Liquid Crystals held at Bangalore, India during 9–11 October 2003. 相似文献
234.
Yu. M. Dyukarev 《Mathematical Notes》2004,75(1-2):66-82
In this paper, we obtain criteria for the indeterminacy of the Stieltjes matrix moment problem. We obtain explicit formulas for Stieltjes parameters and study the multiplicative structure of the resolvent matrix. In the indeterminate case, we study the analytic properties of the resolvent matrix of the moment problem. We describe the set of all matrix functions associated with the indeterminate Stieltjes moment problem in terms of linear fractional transformations over Stieltjes pairs. 相似文献
235.
236.
Rhodium catalysts have been prepared on palygorskite and montmorillonite (clay) supports by reduction with hydrogen (1 atmosphere) at room temperature of a cationic organometallic rhodium compound anchored to the support. The activity of these catalysts for the hydrogenation of liquid-phase 1-hexene remains constant with increase of prehydrogenation time and with re-use for several runs. No rhodium leaching is observed. 相似文献
237.
238.
We show that, in dimensions equal or greater than three, classical strings do not join or split. This is part of a no-interaction theorem that is also proved. The quantum theory is considered. 相似文献
239.
240.
D. N. Karimov E. A. Krivandina Z. I. Zhmurova B. P. Sobolev V. A. Bezhanov S. P. Chernov G. M. Shapochkin 《Crystallography Reports》2006,51(6):1009-1015
Crystalline materials that are transparent in the vacuum UV spectral region and currently used have been reviewed. Transmission of crystals of solid solutions with the fluorite structure Ca1?x R xF2+x (R = Sc, Y, La, Yb, Lu) in the UV and vacuum UV spectral regions has been investigated. It is shown that application of different methods of purification of fluorides from some impurities can significantly improve the optical quality of fluoride multicomponent crystals in the short-wavelength spectral region. 相似文献