全文获取类型
收费全文 | 3869篇 |
免费 | 701篇 |
国内免费 | 519篇 |
专业分类
化学 | 2596篇 |
晶体学 | 66篇 |
力学 | 260篇 |
综合类 | 23篇 |
数学 | 582篇 |
物理学 | 1562篇 |
出版年
2024年 | 12篇 |
2023年 | 91篇 |
2022年 | 137篇 |
2021年 | 161篇 |
2020年 | 184篇 |
2019年 | 149篇 |
2018年 | 169篇 |
2017年 | 181篇 |
2016年 | 181篇 |
2015年 | 185篇 |
2014年 | 224篇 |
2013年 | 295篇 |
2012年 | 339篇 |
2011年 | 357篇 |
2010年 | 225篇 |
2009年 | 261篇 |
2008年 | 262篇 |
2007年 | 221篇 |
2006年 | 256篇 |
2005年 | 181篇 |
2004年 | 119篇 |
2003年 | 106篇 |
2002年 | 104篇 |
2001年 | 86篇 |
2000年 | 71篇 |
1999年 | 76篇 |
1998年 | 68篇 |
1997年 | 51篇 |
1996年 | 61篇 |
1995年 | 38篇 |
1994年 | 39篇 |
1993年 | 31篇 |
1992年 | 26篇 |
1991年 | 31篇 |
1990年 | 26篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1957年 | 2篇 |
1929年 | 2篇 |
1926年 | 2篇 |
排序方式: 共有5089条查询结果,搜索用时 15 毫秒
111.
Zhen‐Feng Zhang Dong‐Chao Wang Jian‐Ge Wang Gui‐Rong Qu 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(9):o524-o527
The molecules of 2,2,2‐trichloro‐N,N′‐diphenylethane‐1,1‐diamine, C14H13Cl3N2, are linked into (040) sheets by a combination of C—H...Cl and C—H...π(arene) hydrogen bonds. In 2,2,2‐trichloro‐N,N′‐bis(4‐methylphenyl)ethane‐1,1‐diamine, C16H17Cl3N2, the molecules are linked into C(7) chains by two independent C—H...Cl hydrogen bonds and one Cl...Cl contact. 相似文献
112.
113.
114.
115.
116.
117.
Yi Yuan Zong-Lin Jiang Jia-Ming Yan Ge Gao Albert S. C. Chan Ru-Gang Xie 《合成通讯》2013,43(24):4555-4561
Two new macrobicyclic imidazolium and benzimidazolium phanes were synthesized by direct quaternization of the corresponding tripodal azacycles with tribromide under high dilution condition in excellent yields. The cyclophanes were identified by 1H-NMR, 13C-NMR, FAB-MS, IR, elemental analysis and X-ray diffraction analysis. 相似文献
118.
119.
120.
Chen He Ban‐Kun Jin Wei‐Dong He Xue‐Song Ge Jing Tao Jing Yang Sheng‐Qi Chen 《Journal of polymer science. Part A, Polymer chemistry》2013,51(10):2142-2149
Long‐subchain hyperbranched polystyrene (lsc‐hp PSt) with uniform subchain length was obtained through copper‐catalyzed azide‐alkyne cycloaddition click chemistry from seesaw macromonomer of PSt having one alkynyl group anchored at the chain centre and two azido group attached to both chain ends [alkynyl‐(PSt‐N3)2]. After precipitation fraction, different portions of lsc‐hp PSt having narrow overall molecular weight distribution were obtained for further grafting with alkynyl‐capped poly(N‐isopropylacrylamide) (alkynyl‐PNIPAM), which was obtained via single‐electron transfer living radical polymerization of NIPAM with propargyl 2‐bromoisobutyrate as the initiator and grafted onto the peripheral azido groups of lsc‐hp PSt via click chemistry. Thus, amphiphilic lsc‐hp PSt grafted with PNIPAM chains (lsc‐hp PSt‐g‐PNIPAM) was obtained and would have star‐like conformation in tetrahydrofuran (THF). By replacing THF with water, lsc‐hp PSt‐g‐PNIPAM was dissolved at molecular level in aqueous solution due to the hydrophilicity of PNIPAM and exhibited thermal induced shrinkage of PNIPAM arms. The water‐insoluble lsc‐hp PSt would collapse densely and could be served as a reservoir to absorb hydrophobic chemicals in aqueous solution. The influence of overall molecular weight of lsc‐hp PSt on the absorption of pyrene was studied. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献