全文获取类型
收费全文 | 2133篇 |
免费 | 47篇 |
国内免费 | 7篇 |
专业分类
化学 | 1523篇 |
晶体学 | 29篇 |
力学 | 26篇 |
数学 | 139篇 |
物理学 | 470篇 |
出版年
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 32篇 |
2019年 | 20篇 |
2018年 | 27篇 |
2017年 | 23篇 |
2016年 | 31篇 |
2015年 | 29篇 |
2014年 | 41篇 |
2013年 | 93篇 |
2012年 | 88篇 |
2011年 | 146篇 |
2010年 | 78篇 |
2009年 | 70篇 |
2008年 | 123篇 |
2007年 | 129篇 |
2006年 | 117篇 |
2005年 | 84篇 |
2004年 | 82篇 |
2003年 | 99篇 |
2002年 | 73篇 |
2001年 | 54篇 |
2000年 | 35篇 |
1999年 | 29篇 |
1998年 | 17篇 |
1997年 | 35篇 |
1996年 | 26篇 |
1995年 | 13篇 |
1994年 | 32篇 |
1993年 | 36篇 |
1992年 | 29篇 |
1991年 | 23篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 47篇 |
1984年 | 30篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1981年 | 15篇 |
1980年 | 33篇 |
1979年 | 28篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 26篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 11篇 |
排序方式: 共有2187条查询结果,搜索用时 125 毫秒
41.
M. Yoshikuni M. Asami S. Iwabuchi K. Kojima 《Journal of polymer science. Part A, Polymer chemistry》1973,11(12):3115-3124
The polymerization of methyl methacrylate (MMA) initiated by tri-n-butylborane (TBB) was studied in the presence of various organic halides (R′X). It was found that R′X accelerated the polymerization of MMA. Aliphatic halides were more effective than aromatic halides. Cocatalytic effects of butyl halides decreased in the order: n -BuI > n -BuBr > n -BuCl; n -BuBr ? sec-BuBr > i-BuBr > tert-BuBr. In the polymerization of MMA by TBB- n -BuI, the initial rate of polymerization was found to be proportional to the concentration of MMA and to the square root of the concentration of TBB-n-BuI. The apparent activation energy was 5.3 kcal/mole. From this and other results, it was assumed that the polymerization of MMA by this initiator system proceeds by a radical mechanism via a weak complex between TBB and R′X; alkyl radicals are formed by the interaction of R′X with TBB. The TBB–R′X system can initiate the polymerization of MMA and AN, but is ineffective in the polymerization of styrene. 相似文献
42.
43.
44.
45.
46.
Kenji Kojima Kusuo Nishiyama Kanetada Nagamine Hironobu Ikeda 《Hyperfine Interactions》1993,78(1-4):429-433
The site diluted finite spin cluster system Rb2CO
x
Mg1–x
F4 (x=0.15, 0.4, 0.5) has been investigated by the +SR technique. Muon spin relaxation was observed in these diluted magnetic systems in a weak longitudinal field of 100 G. By reducing temperature below 100 K, the experimental data show features of slowing down phenomena of the Co electron moments in the finite spin clusters. 相似文献
47.
48.
Masanori Yamaguchi Kaoru Kojima Ikuko Kakizaki Keiichi Takagaki 《Tetrahedron letters》2006,47(42):7455-7458
Efficient constructions of two types of neo-proteoglycan are described. Enzymatically prepared alkyne containing chondroitin 6-sulfate chains and chemically synthesized azido group having compounds are linked by utilizing the copper(I) catalyzed 1,3-dipolar cycloaddition. 相似文献
49.
50.
Toru Tachihara Susumu Ishizaki Yoshiko Kurobayashi Hiroshi Tamura Youichi Ikemoto Atsushi Onuma Keisuke Yoshikawa Tetsuya Yanai Takeshi Kitahara 《Helvetica chimica acta》2003,86(2):274-279
All possible stereoisomers of imine derivatives 1 – 4 , which have the characteristic roast odor of seafood, were synthesized. As a result of odor evaluation of all isomers, we found that each isomer has a different and characteristic odor of roasted seafood. 相似文献