全文获取类型
收费全文 | 4879篇 |
免费 | 169篇 |
国内免费 | 19篇 |
专业分类
化学 | 3703篇 |
晶体学 | 81篇 |
力学 | 44篇 |
数学 | 197篇 |
物理学 | 1042篇 |
出版年
2022年 | 22篇 |
2021年 | 39篇 |
2020年 | 45篇 |
2019年 | 53篇 |
2018年 | 53篇 |
2017年 | 46篇 |
2016年 | 91篇 |
2015年 | 83篇 |
2014年 | 90篇 |
2013年 | 244篇 |
2012年 | 255篇 |
2011年 | 284篇 |
2010年 | 181篇 |
2009年 | 174篇 |
2008年 | 273篇 |
2007年 | 297篇 |
2006年 | 301篇 |
2005年 | 305篇 |
2004年 | 243篇 |
2003年 | 225篇 |
2002年 | 199篇 |
2001年 | 99篇 |
2000年 | 77篇 |
1999年 | 78篇 |
1998年 | 43篇 |
1997年 | 60篇 |
1996年 | 85篇 |
1995年 | 41篇 |
1994年 | 41篇 |
1993年 | 37篇 |
1992年 | 62篇 |
1991年 | 50篇 |
1990年 | 38篇 |
1989年 | 33篇 |
1988年 | 40篇 |
1987年 | 35篇 |
1986年 | 37篇 |
1985年 | 83篇 |
1984年 | 85篇 |
1983年 | 46篇 |
1982年 | 57篇 |
1981年 | 62篇 |
1980年 | 51篇 |
1979年 | 56篇 |
1978年 | 42篇 |
1977年 | 34篇 |
1976年 | 37篇 |
1975年 | 30篇 |
1974年 | 18篇 |
1973年 | 18篇 |
排序方式: 共有5067条查询结果,搜索用时 31 毫秒
101.
The reaction of [(trimethylsilyl)imino]methyldiphenylphosphorane: Ph2MePNSiMe3 (I) with several acid anhydrides or alkyl isocyanates took place by the simple cleavage of silicon-nitrogen bond. In contrast the interaction of (I) with phenyl isocyanate, isothiocyanate or carbon disulphide led to addition-elimination reactions of the Wittig type. Detailed investigation in the case of phenyl isocyanate indicated the usual elimination of Ph2MePO is suppressed by the strong affinity of the trimethylsilyl group for anionic oxygen atom. 相似文献
102.
103.
(?)-Terrecyclic acid A () was synthesized from (+)-fenchone (). The absolute configuration of terrecyclic acid A and quadrone was established. 相似文献
104.
Keiichi Kimura Ryoko Mizutani Tatsuya Suzuki Masaaki Yokohama 《Journal of inclusion phenomena and macrocyclic chemistry》1998,32(2-3):295-310
Design of two types of ion-conducting systems using photochromic crown ethers as the photocontrol agents is described; one type is based on the phase transition of azobenzene derivatives induced by their photoisomerization and the other based on the molecular control of metal ion complexation by crowned spirobenzopyrans. The photoresponsive ion-conducting systems are applicable to electrostatic imaging and photorefractive materials. 相似文献
105.
106.
Yatsuhisa Nagano Yuhji Achiba Kenji Sato Katsumi Kimura 《Chemical physics letters》1982,93(5):510-514
Kenetic energies and angular distributions of photoelectrons emitted by three-photon ionization fo atomic iron through two-photon resonant state e7DJ and e5 DJ, were measured, by using visible lasers. J-resolved photoelectron bands attributab to the a6DJ and a4Fj ionic states are reported. 相似文献
107.
Rapid method for preparing a beta-glucan-specific sensitive fraction from Limulus (Tachypleus tridentatus) amebocyte lysate 总被引:1,自引:0,他引:1
By separating Limulus amebocyte lysate by cation-exchange chromatography with an SP-Toyopearl 650C column, a fraction insensitive to endotoxin, yet specifically sensitive to beta-glucan, was successfully obtained in the unadsorbed portion. This fraction showed beta-glucan dose-dependent clotting enzyme activity, although no sensitivity to endotoxin. This beta-glucan-dependent reaction showed no interference in the presence of endotoxin, with the fraction also showing sensitivity towards various kinds of beta-glucan, i.e. curdlan, pachyman, laminaran and lichenan. The sensitivity towards curdlan was approximately 10(-10) g/ml. 相似文献
108.
109.
110.