全文获取类型
收费全文 | 117篇 |
免费 | 4篇 |
国内免费 | 4篇 |
专业分类
化学 | 121篇 |
晶体学 | 2篇 |
物理学 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有125条查询结果,搜索用时 0 毫秒
1.
2.
3.
5.
Study on the oligomerization of cyclopentadiene and dicyclopentadiene to tricyclopentadiene through diels-alder reaction 总被引:3,自引:0,他引:3
Zhongqiang Xiong Zhentao Mi Xiangwen Zhang 《Reaction Kinetics and Catalysis Letters》2005,85(1):89-97
Summary The oligomerization of cyclopentadiene (CPD) and its dimer, dicyclopentadiene (DCPD), to tricyclopentadiene (TCPD) through Diels-Alder reaction at temperatures between 120 and 150°C was investigated. The results show that reaction temperature, pressure and solvent influence the product yield; at 150°C up to 50% yield of TCPD was obtained in the absence of solvents. The ratios of isomers A to B in the product can be adjusted by using different solvents. The kinetics indicate that the rate is more sensitive to the concentration of CPD than to that of DCPD. 相似文献
6.
7.
R. Lalrempuia Patrick J. Carroll K.A. Kreisel 《Journal of organometallic chemistry》2005,690(17):3990-3996
The reactions of [(ind)Ru(PPh3)2CN] (ind = η5-C9H7) (1) and [CpRu(PPh3)2CN] (Cp = η5-C5H5) (2) with [(η6-p-cymene)Ru(bipy)Cl]Cl (bipy = 2,2′-bipyridine) (3) in the presence of AgNO3/NH4BF4 in methanol, respectively, yielded dicationic cyano-bridged complexes of the type [(ind)(PPh3)2Ru(μ-CN)Ru(bipy)(η6-p-cymene)](BF4)2 (4) and [Cp(PPh3)2Ru(μ-CN)Ru(bipy)(η6-p-cymene)](BF4)2 (5). The reaction of [CpRu(PPh3)2CN] (2), [CpOs(PPh3)2CN] (6) and [CpRu(dppe)CN] (7) with the corresponding halide complexes and [(η6-p-cymene)RuCl2]2 formed the monocationic cyano-bridge complexes [Cp(PPh3)2Ru(μ-CN)Os(PPh3)2Cp](BF4) (8), [Cp(PPh3)2Os(μ- CN)Ru(PPh3)2Cp](BF4) (9) and [Cp(dppe)Ru(μ-CN)Os(PPh3)2Cp](BF4) (10) along with the neutral complexes [Cp(PPh3)2Ru(μ-CN)Ru (η6-p-cymene)Cl2] (11), [Cp(PPh3)2Os(μ-CN)Ru(η6-p-cymene)Cl2] (12), and [Cp(dppe) Ru(μ-CN)Ru(η6-p-cymene)Cl2] (13). These complexes were characterized by FT IR, 1H NMR, 31P{1H} NMR spectroscopy and the molecular structures of complexes 4, 8 and 11 were solved by X-ray diffraction studies. 相似文献
8.
Chris J. Adams Michael I. Bruce Brian W. Skelton Allan H. White 《Journal of Cluster Science》1994,5(3):419-441
The reactions between Ru5(
5-C2PPh2)(gm-PPh2(CO)13 (1) and cyclopentadienes afforded the hexanuclear clusters Ru6(
6-C)(
3-PPh2)2(CO)10(-C5
R
5) [R
5 = H5 (2), H4Me (3), Me5 (4)] which contain an encapsulated carbide and a face-capping
3-CH group, formed by cleavage of CC and CP bonds of the C2PPh2 moiety in1. In the reaction with cyclopentadiene, the unusual ligand C13H12O, formed by combination of C2, CO and two molecules of C5H6 (or one molecule of dicyclopentadien), was characterized in the complex Ru5(
4-PPh) (
4-C13H12O)(-PPh2(CO)11(-C5H5) (5). In the reaction with pentamethylcyclopentadiene, the vinylidene complex Ru5(
3-CCHPh)(
4-PPh)(
4-PPh) (-PPh2)(CO)9(-C5Me5) (6) was also formed. 相似文献
9.
Claudia G. Avila-Ortiz 《Tetrahedron》2005,61(35):8372-8381
β2-(3,4-Dihydroxybenzyl)-β-alanine [β2-Homo-Dopa, 1] is a novel β-amino acid homologue of Dopa, the most successful therapeutic agent in the treatment of Parkinson's disease. Enantioenriched (R)-1 and (S)-1 were obtained via the diastereoselective alkylation of enantiopure pyrimidinone (R)- and (S)-3, chiral derivatives of β-alanine, with veratryl iodide. The major diastereomeric products (2S,5R)-4 and (2R,5S)-4 were hydrolyzed with 57% HBr, and the desired β-amino acids were purified by silica gel chromatography. Alternatively, enantioenriched (R)- and (S)-1 were prepared by means of the highly diastereoselective alkylation (3,4-dimethoxybenzyl iodide) of open-chain β-aminopropionic acid derivatives (R,R,S)-8 and (S,S,R)-8 containing the chiral auxiliary α-phenylethylamine. Finally, nearly enantiopure (R)- and (S)-1 were obtained by resolution of racemic N-benzyloxycarbonyl-2-(3,4-dibenzyloxybenzyl)-3-aminopropionic acid, rac-12, with (R)- or (S)-α-phenylethylamine, followed by catalytic hydrogenolysis. 相似文献
10.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):971-981
Several mononuclear transition metal cations stabilized by acetonitrile molecules act as initiators for the polymerization of cyclopentadiene. The highest yield is reached with Cr, Mn, Fe, and Zn complexes, all of them in the oxidation state +II. The analogous V and Ni complexes, however, are completely or nearly inactive. In general, the observed activity of the examined monomeric complexes correlates well with the ligand field stabilization energy as a function of the number of d electrons for octahedrally coordinated transition metals in the oxidation state +II. The counter ions have a pronounced influence on the catalytic activity: the less coordinating they are, the higher is the activity of the cations. The reaction temperature also has a significant influence: above 50°C the complex activity is on decline, possibly due to initiator decomposition or com-petitive inhibition by dicyclopentadiene. 相似文献