全文获取类型
收费全文 | 2039篇 |
免费 | 63篇 |
国内免费 | 210篇 |
专业分类
化学 | 1091篇 |
力学 | 205篇 |
综合类 | 3篇 |
数学 | 183篇 |
物理学 | 830篇 |
出版年
2016年 | 6篇 |
2015年 | 17篇 |
2014年 | 2篇 |
2013年 | 16篇 |
2012年 | 31篇 |
2011年 | 451篇 |
2010年 | 235篇 |
2009年 | 235篇 |
2008年 | 40篇 |
2007年 | 24篇 |
2006年 | 55篇 |
2005年 | 121篇 |
2004年 | 385篇 |
2003年 | 195篇 |
2002年 | 152篇 |
2001年 | 107篇 |
2000年 | 31篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 23篇 |
1992年 | 35篇 |
1991年 | 14篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1964年 | 2篇 |
1925年 | 2篇 |
排序方式: 共有2312条查询结果,搜索用时 15 毫秒
21.
22.
YU Ming XU Qiang School of Materials Science Engineering East China University of Science Technology Shanghai China 《Chinese Journal of Reactive Polymers》2006,(1)
1. INTRODUCTIONThese years, HCFC-141b may be the most used blowing agent for its useful properties. But, because of its high global warming effect leading to the destruction of the ozone layer, production of HCFC141b has been forbidden. However, there are… 相似文献
23.
24.
25.
XinYingZHANG XueSenFAN JianJiWANG YanZhenLI 《中国化学快报》2004,15(10):1170-1172
Quinoline derivatives were efficiently prepared through acid-catalyzed Friedlander reaction in ionic liquid ([bmim] [BF4]). It is shown that the proposed method is operationally simple and environmentally benign in that the reaction media and the catalyst can be recovered and be reused effectively for at least four times. 相似文献
26.
Introduction As an important type of fungicides, triazole compounds are highly efficient, low poisonous and inward absorbent.1-3 At present, the studies on triazole derivatives are mainly concentrated on compounds with triazole as the only active group. The report of triazole compounds that contain both triazole group and other active group in a single molecule has rarely been found. Dialkyl-substituted dithiocarbamate salts have also shown interesting biological effects.4 N,N-Dialkyldithio-… 相似文献
27.
28.
The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step. 相似文献
29.
FuShengWANG BingKuiSONG XiaoLiHAN BaoGuiZHANG 《中国化学快报》2004,15(12):1487-1490
Black lead, Ti-Ru and Ti-PbO2 were used as anode and stainless steel was used as cathode The electrolytic process of producing hypophosphorous acid with four-compartment electrodialytic cell was studied. The comparison of some factors, such as anodic voltage, product concentration and current efficiency, of black lead, Ti-Ru, and Ti-PbO2 electrodes was conducted. As a result, theTi-PbO2 electrode is the optimal anode material used, it can be in electrolytic process for producing hypophosphorous acid. 相似文献
30.
HongBingJI DuGuiHE JunSONG YuQIAN 《中国化学快报》2004,15(10):1241-1244
Clean liquid oxidation of aldehydes can be accomplished using solid catalyst in the presence of molecular oxygen at room temperature, which is a valuable alternative to traditional counterparts. 相似文献