全文获取类型
收费全文 | 97750篇 |
免费 | 5373篇 |
国内免费 | 12617篇 |
专业分类
化学 | 78912篇 |
晶体学 | 1214篇 |
力学 | 2410篇 |
综合类 | 863篇 |
数学 | 12814篇 |
物理学 | 19527篇 |
出版年
2024年 | 126篇 |
2023年 | 787篇 |
2022年 | 2049篇 |
2021年 | 1995篇 |
2020年 | 2506篇 |
2019年 | 2414篇 |
2018年 | 2069篇 |
2017年 | 2956篇 |
2016年 | 3075篇 |
2015年 | 2567篇 |
2014年 | 3691篇 |
2013年 | 7486篇 |
2012年 | 6547篇 |
2011年 | 5337篇 |
2010年 | 4488篇 |
2009年 | 6104篇 |
2008年 | 6358篇 |
2007年 | 6656篇 |
2006年 | 6050篇 |
2005年 | 5186篇 |
2004年 | 4833篇 |
2003年 | 3990篇 |
2002年 | 5076篇 |
2001年 | 2964篇 |
2000年 | 2763篇 |
1999年 | 2586篇 |
1998年 | 2243篇 |
1997年 | 1742篇 |
1996年 | 1485篇 |
1995年 | 1414篇 |
1994年 | 1291篇 |
1993年 | 1054篇 |
1992年 | 993篇 |
1991年 | 676篇 |
1990年 | 554篇 |
1989年 | 538篇 |
1988年 | 401篇 |
1987年 | 318篇 |
1986年 | 291篇 |
1985年 | 239篇 |
1984年 | 253篇 |
1983年 | 143篇 |
1982年 | 229篇 |
1981年 | 183篇 |
1980年 | 200篇 |
1979年 | 189篇 |
1978年 | 171篇 |
1977年 | 125篇 |
1976年 | 110篇 |
1973年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
82.
阐述检测物体是否产生了电场的方法;通过实际检测证实立方体永磁体既产生了负静电场,也产生了正静电场,并测定了具体的场强. 相似文献
83.
meso-Tetra(n-hexyloxycarbonyl)porphyrin was found to be converted into porphine, the mother compound of porphyrins, in a 77% yield when heated in aqueous sulfuric acid at 180 °C over 30 min under an inert atmosphere. The observation demonstrates that the substituted porphyrin serves as a novel and useful precursor for porphine. 相似文献
84.
A practical access to alkyl- and aryl-substituted (E)-2-(azidomethyl)alkenoates and related azido compounds from the corresponding allylic bromides in aqueous acetone is described. An alternative method to obtain the starting bromides based on heterogeneous catalysis under mild conditions was also investigated. 相似文献
85.
Atsuo Nakazaki 《Tetrahedron》2006,62(26):6264-6271
The stereoselective total syntheses of (±)-α-vetispirene, (±)-hinesol, and (±)-β-vetivone were accomplished based on a Claisen rearrangement in an alkenyl bicyclic dihydropyran system. The most striking feature of this approach is that the Claisen rearrangement of bicyclic dihydropyran proceeds stereoselectively to provide a multi-functionalized spiro[4.5]decane, which is an efficient precursor for the synthesis of the vetivane sesquiterpenes. 相似文献
86.
87.
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
88.
89.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
90.