全文获取类型
收费全文 | 7130篇 |
免费 | 164篇 |
国内免费 | 19篇 |
专业分类
化学 | 5238篇 |
晶体学 | 81篇 |
力学 | 80篇 |
综合类 | 1篇 |
数学 | 352篇 |
物理学 | 1561篇 |
出版年
2022年 | 45篇 |
2021年 | 75篇 |
2020年 | 84篇 |
2019年 | 86篇 |
2018年 | 64篇 |
2017年 | 51篇 |
2016年 | 101篇 |
2015年 | 111篇 |
2014年 | 111篇 |
2013年 | 315篇 |
2012年 | 276篇 |
2011年 | 366篇 |
2010年 | 173篇 |
2009年 | 194篇 |
2008年 | 340篇 |
2007年 | 355篇 |
2006年 | 360篇 |
2005年 | 373篇 |
2004年 | 359篇 |
2003年 | 267篇 |
2002年 | 267篇 |
2001年 | 220篇 |
2000年 | 195篇 |
1999年 | 105篇 |
1998年 | 58篇 |
1997年 | 77篇 |
1996年 | 101篇 |
1995年 | 84篇 |
1994年 | 91篇 |
1993年 | 104篇 |
1992年 | 123篇 |
1991年 | 118篇 |
1990年 | 89篇 |
1989年 | 102篇 |
1988年 | 97篇 |
1987年 | 72篇 |
1986年 | 77篇 |
1985年 | 117篇 |
1984年 | 136篇 |
1983年 | 67篇 |
1982年 | 76篇 |
1981年 | 70篇 |
1980年 | 83篇 |
1979年 | 96篇 |
1978年 | 83篇 |
1977年 | 86篇 |
1976年 | 65篇 |
1975年 | 62篇 |
1974年 | 55篇 |
1973年 | 54篇 |
排序方式: 共有7313条查询结果,搜索用时 15 毫秒
121.
Israel Goldberg Zafra Stein Koichi Tanaka Fumio Toda 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(1):97-107
The crystal structures of the 2,2-di(p-hydroxyphenyl)propane host and its 1:1 adducts withm-andp-cresol guests have been studied. The preferential complexation of this host withp-cresol overm-cresol is related to the opposite trend exhibited by 1,1-di(p-hydroxyphenyl)cyclohexane; both hosts can separate effectively the two cresols from their liquid mixture by crystalline inclusion. A plausible explanation of the different inclusion features is provided by examining the intermolecular association in the corresponding solids. The analysed structures are stabilized by strong and continuous H-bonding between the constituent entities along two dimensions, and by weak van der Waals forces along the third axis. The p-cresol complex of the title host reveals a unique arrangement within and a more efficient packing of the layered structure, and thus represents a more stable and less soluble crystal lattice than itsm-cresol analog.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82099 (8 pages). 相似文献
122.
Hiroki Nakamura Jiro Tanaka Nobuaki Nakashima Keitaro Yoshihara 《Chemical physics letters》1981,77(2):419-421
The photoionization of 8-anilino-1-naphthalenesulfonate in polar solvents occurs through a biphotonic process, as proved by nanosecond flash photolysis. A transient absorption of a charge transfer to solvent (CTTS) state is found with ≈10 ns life-time. The state is shown to be an intermediate of the photoionization process. 相似文献
123.
Kô Kaneko Mikako Tanaka Kimiaki Haruki Nobuaki Naruse Hiroshi Mitsuhashi 《Tetrahedron letters》1979,20(39):3737-3740
The 13C-NMR spectra of seven cavanine alkaloids isolated from Veratrum and Fritillaria plants were measured and their signals were assigned, and these results were applicated for structure elucidation of two new cevanine alkaloids, baimonidine and isoverticine, isolated from mature Fritillaria verticillata. 相似文献
124.
Masakazu Uramoto Kimie Kobinata Kiyoshi Isono Tsutomu Higashijima Tatsuo Miyazawa Ellen E. Jenkins James A. McCloskey 《Tetrahedron》1982,38(11):1599-1608
New chitin synthetase inhibitors, neopolyoxins A, B, and C were isolated from the culture filtrate of Streptomyces cacaoi subsp. asoensis. Their absolute structures have been established on the basis of chemical and spectroscopic evidence. They are structural analogs of the polyoxins. As a nucleobase, neopolyoxin C possesses uracil, while neopolyoxins A and B contain the imidazoline moiety. A ring contraction reaction of pyrimidine nucleoside into imidazoline nucleoside played a key role in the structure determination of the nucleoside moiety. A similar transformation was suggested for the biosynthesis of neopolyoxins A and B. 相似文献
125.
126.
127.
128.
129.
130.