全文获取类型
收费全文 | 737篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
化学 | 545篇 |
晶体学 | 5篇 |
力学 | 1篇 |
数学 | 53篇 |
物理学 | 159篇 |
出版年
2023年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 40篇 |
2012年 | 48篇 |
2011年 | 39篇 |
2010年 | 30篇 |
2009年 | 35篇 |
2008年 | 39篇 |
2007年 | 45篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 29篇 |
2003年 | 21篇 |
2002年 | 29篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1979年 | 4篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1972年 | 5篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 4篇 |
排序方式: 共有763条查询结果,搜索用时 15 毫秒
761.
Noboru Matsumura Yasuyo Shimizu Yoshio Yagyu Hiroo Inoue Kazuhiko Mizuno Tomohiro Adachi 《Heteroatom Chemistry》1998,9(4):387-397
The reaction of tetrachlorocyclopropene (1) with arenethiols (2a–e), followed by treatmentwith perchloric acid, gave tris(arylthio)cyclopropenylium perchlorates (3a–c and e), 1,1,2,3,3-pentakis(arylthio)-1-propenes (4a–d), and 2,3,3-tris(arylthio)propenals (5a–d). The structures of tris(phenylthio)cyclopropenylium perchlorate (3a), 1,1,2,3,3-pentakis(phenylthio)-1-propene (4a), and 2,3,3-tris(o-tolylthio)propenal (5b) were analyzed by single-crystal X-ray diffraction studies. The yields depended significantly on the electron-withdrawing property of the substituents of the arenethiols and the molar ratio of 2 to 1. The reaction with 2,6-dimethylbenzenethiol (2e) gave only tris(2,6-dimethylphenylthio)cyclopropenylium perchlorate (3e) without the formation of 4e and 5e. Compounds 5a–d were produced by acid hydrolysis of 4a–d. Pyrolysis of 4a–d gave (3R,4S)-1,1,2,3,4,5,6,6-octakis(arylthio)-1,5-hexadienes (9a–d) and 1,1,2,5,6,6-hexakis(arylthio)-(3E)-1,3,5-hexatrienes (10a–d) together with diaryl disulfides (11a–d). Compound 10a was also produced by photolysis. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:387–397, 1998 相似文献
762.
Masanori Okamoto Hidekazu Doe Kazuhiko Mizuno Tsuyoshi Fukuo Ryuichi Arakawa 《Journal of the American Society for Mass Spectrometry》1998,9(9):966-969
Electrospray ionization mass spectrometry was used to study chemical electron-transfer reactions of 1,2-diarylcyclopropanes by Cu(II) salt in acetonitrile. The ion [M ? H]+ with a hydrogen atom loss and the solvent adduct ions, [M+42]+, etc., were detected as the initial reaction products, where [M+42]+ represents the ion whose mass is 42 u greater than the parent molecule M. From the study of deuterated derivatives, the hydrogen abstraction was revealed to occur at the 3 position of the cyclopropanes, and the mechanism of the hydrogen abstraction reaction and of the solvent addition were discussed. 相似文献
763.
Prof. Dr. Toshikazu Takata Prof. Dr. Koji Yamamoto Kazuki Higuchi Dr. Masahiro Ogawa Ayumi Kawasaki Shunya Mizuno Hikaru Iwasaki Masaki Nagashima Prof. Dr. Yoshihiro Hayashi Prof. Dr. Susumu Kawauchi Prof. Dr. Kazuko Nakazono Prof. Dr. Yasuhito Koyama 《Angewandte Chemie (International ed. in English)》2023,62(24):e202303494
Post-synthesis modification of polymers streamlines the synthesis of functionalized polymers, but is often incomplete due to the negative polymer effects. Developing efficient polymer reactions in artificial systems thus represents a long-standing objective in the fields of polymer and material science. Here, we show unprecedented macrocycle-metal-complex-catalyzed systems for efficient polymer reaction that result in 100 % transformation of the main chain functional groups presumably via a processive mode reaction. The complete polymer reactions were confirmed in not only intramolecular reaction (hydroamination) but also intermolecular reaction (hydrosilylation) by using Pd- and Pt-macrocycle-catalyzed systems. The most fascinating feature of the both reactions is that higher-molecular-weight polymers reach completion faster. Various studies suggested that the reactions occur in the catalyst cavity via the formation of a supramolecular complex between the macrocycle catalyst and polymer substrate like pseudorotaxane, which should be of characteristic of the efficient polymer reactions progressing in a processive mode. 相似文献