全文获取类型
收费全文 | 1410578篇 |
免费 | 40584篇 |
国内免费 | 17574篇 |
专业分类
化学 | 713064篇 |
晶体学 | 21043篇 |
力学 | 80327篇 |
综合类 | 623篇 |
数学 | 250590篇 |
物理学 | 403089篇 |
出版年
2021年 | 16857篇 |
2020年 | 19049篇 |
2019年 | 19574篇 |
2018年 | 15198篇 |
2017年 | 13320篇 |
2016年 | 31747篇 |
2015年 | 24694篇 |
2014年 | 35390篇 |
2013年 | 80680篇 |
2012年 | 45190篇 |
2011年 | 41949篇 |
2010年 | 41812篇 |
2009年 | 44080篇 |
2008年 | 38422篇 |
2007年 | 33493篇 |
2006年 | 39700篇 |
2005年 | 30867篇 |
2004年 | 31663篇 |
2003年 | 29595篇 |
2002年 | 30534篇 |
2001年 | 29000篇 |
2000年 | 25613篇 |
1999年 | 23980篇 |
1998年 | 22499篇 |
1997年 | 22361篇 |
1996年 | 22684篇 |
1995年 | 20442篇 |
1994年 | 19837篇 |
1993年 | 19082篇 |
1992年 | 18828篇 |
1991年 | 19090篇 |
1990年 | 18135篇 |
1989年 | 17990篇 |
1988年 | 17448篇 |
1987年 | 17376篇 |
1986年 | 16308篇 |
1985年 | 22676篇 |
1984年 | 23858篇 |
1983年 | 20015篇 |
1982年 | 21703篇 |
1981年 | 20915篇 |
1980年 | 20227篇 |
1979年 | 20316篇 |
1978年 | 21648篇 |
1977年 | 21225篇 |
1976年 | 20954篇 |
1975年 | 19651篇 |
1974年 | 19286篇 |
1973年 | 19773篇 |
1972年 | 14281篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
36.
Nasirizadeh Navid Dehghani Mohammad Yazdanshenas Mohammad E. 《Journal of Sol-Gel Science and Technology》2015,73(1):14-21
Journal of Sol-Gel Science and Technology - In this paper, a simple method is presented for making a conductive and hydrophobic cotton fabric using a multi-walled carbon nanotube (MWCNT). The... 相似文献
37.
38.
39.
Qin Yin Shou-Guo Wang Xiao-Wei Liang De-Wei Gao Jun Zheng Shu-Li You 《Chemical science》2015,6(7):4179-4183
An organocatalytic asymmetric chlorinative dearomatization of naphthols was realized for the first time, providing chiral naphthalenones with a Cl-containing all-substituted stereocenter in excellent yields and enantioselectivity (up to 97% yield and 96% ee). The reaction features mild reaction conditions, good tolerance of diverse functional groups and simple reaction operation. 相似文献
40.
Triesterase and Promiscuous Diesterase Activities of a Di‐CoII‐Containing Organophosphate Degrading Enzyme Reaction Mechanisms 下载免费PDF全文
Dr. Marta E. Alberto Gaspar Pinto Prof. Nino Russo Dr. Marirosa Toscano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3736-3745
The reaction mechanism for the hydrolysis of trimethyl phosphate and of the obtained phosphodiester by the di‐CoII derivative of organophosphate degrading enzyme from Agrobacterium radiobacter P230(OpdA), have been investigated at density functional level of theory in the framework of the cluster model approach. Both mechanisms proceed by a multistep sequence and each catalytic cycle begins with the nucleophilic attack by a metal‐bound hydroxide on the phosphorus atom of the substrate, leading to the cleavage of the phosphate‐ester bond. Four exchange‐correlation functionals were used to derive the potential energy profiles in protein environments. Although the enzyme is confirmed to work better as triesterase, as revealed by the barrier heights in the rate‐limiting steps of the catalytic processes, its promiscuous ability to hydrolyze also the product of the reaction has been confirmed. The important role played by water molecules and some residues in the outer coordination sphere has been elucidated, while the binuclear CoII center accomplishes both structural and catalytic functions. To correctly describe the electronic configuration of the d shell of the metal ions, high‐ and low‐spin arrangement jointly with the occurrence of antiferromagnetic coupling, have been herein considered. 相似文献