全文获取类型
收费全文 | 70篇 |
免费 | 4篇 |
专业分类
化学 | 60篇 |
数学 | 1篇 |
物理学 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1896年 | 1篇 |
排序方式: 共有74条查询结果,搜索用时 15 毫秒
1.
MM. J. Duflos D. Letouz G. Queguiner P. Pastour 《Journal of heterocyclic chemistry》1973,10(6):1083-1084
This communication describes the synthesis of l-methyl-2,3-diformylpyrrole. This new compound is used to prepare a new heterocycle, l-methylcyclohepta[b]pyrrol-6-one and thus allows a new synthesis of l-methylpyrrolo[2,3-d]pyridazine. 相似文献
2.
Paul RL Argent SP Jeffery JC Harding LP Lynam JM Ward MD 《Dalton transactions (Cambridge, England : 2003)》2004,(21):3453-3458
Reaction of the bis-bidentate bridging ligand L(3), in which two bidentate chelating 3(2-pyridyl)pyrazole units are separated by a 3,3'-biphenyl spacer, with Co(II) salts affords tetranuclear cage complexes of composition [Co(4)(L(3))(6)]X(8)(X =[BF(4)](-), [ClO(4)](-), [PF(6)](-) or I(-)) in which four 6-coordinate Co(II) ions in an approximately tetrahedral array are connected by six bis-bidentate bridging ligands, one spanning each of the six edges of the Co(4) tetrahedron. In every case, X-ray crystallography reveals that the 'apical' Co(II) ion has a fac tris-chelate geometry, whereas the other three Co(II) ions have mer tris-chelate geometries, resulting in (non-crystallographic)C(3) symmetry for the cages; that this structure is retained in solution is confirmed by (1)H NMR spectroscopy of the paramagnetic cages. In every case one of the anions is located inside the central cavity of the cage, with the remaining seven outside. We found no clear evidence for an anion-based templating effect. The cage superstructure is sufficiently large to leave gaps in the centres of the faces through which the internal and external anions can exchange. Variable-temperature (19)F NMR spectroscopy was used to investigate the dynamic behaviour of the cages with X =[BF(4)](-) and [PF(6)](-) in MeCN solution: in both cases two separate signals, corresponding to external and internal anions, are clear at 233 K which have coalesced to a single signal at room temperature. Analysis of the linewidth of the minor signal (for the internal anion) at various temperatures below coalescence gave an activation energy for anion exchange of ca. 50 kJ mol(-1) in each case, a figure which suggests that anion exchange can occur via a conformational rearrangement of the cage superstructure in solution rather than opening of the cavity by cleavage of metal-ligand bonds. 相似文献
3.
4.
5.
6.
Ian J.S. Fairlamb Anant R. Kapdi Jason M. Lynam Richard J.K. Taylor Adrian C. Whitwood 《Tetrahedron》2004,60(27):5711-5718
A new palladium(II) precatalyst for Suzuki cross-coupling of aryl halides and organoboronic acids has been identified, namely bis(triphenylphosphine)palladium(II)succinimide [(Ph3P)2Pd(N-Succ)2] 2. The precatalyst is easily prepared from palladium(0) precursors, such as (Ph3P)4Pd or Pd2dba3·CHCl3/Ph3P and succinimide, is air, light and moisture stable, and may be employed with a variety of substrates to give the cross-coupled products, in good yields and in reasonable time, at relatively low catalyst loadings. 相似文献
7.
8.
Emer Lahiff Carol Lynam Niamh Gilmartin Richard O’Kennedy Dermot Diamond 《Analytical and bioanalytical chemistry》2010,398(4):1575-1589
The growing need for analytical devices requiring smaller sample volumes, decreased power consumption and improved performance
have been driving forces behind the rapid growth in nanomaterials research. Due to their dimensions, nanostructured materials
display unique properties not traditionally observed in bulk materials. Characteristics such as increased surface area along
with enhanced electrical/optical properties make them suitable for numerous applications such as nanoelectronics, photovoltaics
and chemical/biological sensing. In this review we examine the potential that exists to use nanostructured materials for biosensor
devices. By incorporating nanomaterials, it is possible to achieve enhanced sensitivity, improved response time and smaller
size. Here we report some of the success that has been achieved in this area. Many nanoparticle and nanofibre geometries are
particularly relevant, but in this paper we specifically focus on organic nanostructures, reviewing conducting polymer nanostructures
and carbon nanotubes. 相似文献
9.
10.
MM. P. Duballet A. Godard G. Queguiner P. Pastour 《Journal of heterocyclic chemistry》1973,10(6):1079-1080
This article describes the synthesis of a new heterocycle, pyrido[2,3,f]phtalazine and three new diformylquinolincs. 相似文献