全文获取类型
收费全文 | 714篇 |
免费 | 14篇 |
国内免费 | 42篇 |
专业分类
化学 | 760篇 |
晶体学 | 4篇 |
综合类 | 2篇 |
物理学 | 4篇 |
出版年
2023年 | 19篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 22篇 |
2018年 | 39篇 |
2017年 | 36篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 67篇 |
2013年 | 89篇 |
2012年 | 33篇 |
2011年 | 51篇 |
2010年 | 28篇 |
2009年 | 47篇 |
2008年 | 51篇 |
2007年 | 43篇 |
2006年 | 31篇 |
2005年 | 41篇 |
2004年 | 52篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有770条查询结果,搜索用时 390 毫秒
701.
Ahmed Kamal B. Rajendra Prasad A. Venkata Ramana A. Hari Babu K. Srinivasa Reddy 《Tetrahedron letters》2004,45(17):3507-3509
The tetrahydroquinoline moiety is an important structural component of a number of natural products. The reaction of aryl azides with 3,4-dihydro-2H-pyran in the presence of FeCl3-NaI affords the corresponding tetrahydroquinoline derivatives in an efficient manner. Most of the cyclizations exhibited cis selectivity. 相似文献
702.
Warren J. Grigsby Lyndsay Main Brian K. Nicholson 《Journal of organometallic chemistry》1997,540(1-2):185-187
Orthomanganated aryl ketones undergo NiBr2(PPh3)2-promoted reactions with activated alkenes to give indanol products with higher specificity than similar Pd(II)- or Me3NO-promoted reactions. 相似文献
703.
Chigusa Yamada 《Tetrahedron letters》2007,48(24):4223-4227
Aryl C-glycosylation of several glycosyl donors, including unprotected sugars, with phenol and naphthol derivatives in an ionic liquid containing a protic acid proceeded effectively and stereoselectively to give the corresponding aryl C-glycosides in good to high yields. Because the ionic liquid was nonvolatile, the reaction could be carried out under reduced pressure; in addition, the ionic liquid could be reused without loss of effectiveness. These features contribute to the significant advantages of this novel aryl C-glycosylation reaction. 相似文献
704.
Mingzhong Cai Qiuhua Xu Pingping Wang 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):199-202
A novel MCM-41-supported sulfur palladium(0) complex was conveniently prepared from commercially available and cheap γ-mercaptopropyltriethoxysilane via immobilization on MCM-41, followed by reacting with palladium chloride and then the reduction with hydrazine hydrate. This complex exhibited excellent performance in Sonogashira coupling reaction. 相似文献
705.
The conjugate reduction of aryl acrylates performed with tributyltin hydride in the presence of magnesium bromide diethyl etherate in dichloromethane gave the corresponding saturated esters in moderate to high yields. The reduction of α-methylene-γ-benzyloxycarboxylic acid esters proceeded syn-selectively, but α-methylene-β-oxycarboxylic acid esters afforded reductive elimination products under the reaction conditions. 相似文献
706.
707.
Reactions of alkyl halides with arylmagnesium bromides in the presence of cobalt(II)(diphosphine) complexes are discussed. Treatment of 1-bromooctane with phenylmagnesium bromide with the aid of a catalytic amount of CoCl2(dppp) [DPPP=1,3-bis(diphenylphosphino)propane] yielded octylbenzene in good yield. The reaction mechanism would include single electron transfer from an electron-rich cobalt complex to alkyl halide to generate the corresponding alkyl radical. The mechanism was justified by CoCl2(dppe)-catalyzed [DPPE=1,2-bis(diphenylphosphino)ethane] sequential radical cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives that yielded benzyl-substituted cyclopentane skeletons. 相似文献
708.
Chenyi Yi 《Tetrahedron letters》2006,47(15):2573-2576
Catalyst system PdCl2(PCy3)2/Cs2CO3 in dioxane was found to be the efficient catalyst system for Heck cross-coupling reactions of deactivated, neutral, and activated aryl chlorides with a variety of alkenes under mild conditions to afford selectively E-arylated alkenes in good to excellent yields. 相似文献
709.
Fatma Çetin 《Journal of organometallic chemistry》2004,689(1):154-157
Metal-halogen exchange between Ph2CuLi · LiCN and ortho-substituted aryl iodides or bromides may be used to conveniently afford substituted metallated aryls which can subsequently undergo reaction with electrophiles. 相似文献
710.
Ka Young Lee 《Tetrahedron letters》2005,46(1):69-74
We found a suitable condition for the effective alkynylation of N-tosylimines with aryl acetylenes. The reaction of N-tosylimines and aryl acetylenes in the presence of ZnBr2 and DIEA (N,N-diisopropylethylamine) in CH3CN afforded the desired N-tosyl propargylamines in moderate to good yields. 相似文献