全文获取类型
收费全文 | 105篇 |
免费 | 0篇 |
专业分类
化学 | 64篇 |
数学 | 20篇 |
物理学 | 21篇 |
出版年
2020年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1966年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有105条查询结果,搜索用时 15 毫秒
71.
Treatment of the sulfones 1 or 2 with sodium phenylsulfinate in DMSO affords the head-to-tail coupled conjugated monoterpenoids 5–8 in comparable amounts. The corresponding reaction of 3 gives the isomers 16 and 17. The tail-to-tail homologation of 4 furnishes chiefly a 2E,4E/Z-mixture of the conjugated isoprenoids 18 and 19. The various isoprenoid mixtures are separated into their components and the configuration of the isomers is established by 1H NMR double resonance and the NMR/NOE technique. The head-to-tail and tail-to-tail coupled isoprenoid mixtures 5–8 and 18–21, respectively, are isomerized to 2E/Z, 4E-mixtures in a 2:1 ratio. The C15-sulfones 11 and 13 are obtained by treatment of 1 with the head-functionalized isoprene synthon 10. Some speculations on the stereochemical course of the MIRB-homologation are presented. 相似文献
72.
73.
74.
75.
76.
Trouwborst ML Huisman EH Bakker FL van der Molen SJ van Wees BJ 《Physical review letters》2008,100(17):175502
We study the interaction between single apex atoms in a metallic contact, using the break junction geometry. By carefully training our samples, we create stable junctions in which no further atomic reorganization takes place. This allows us to study the relation between the so-called jump out of contact (from contact to tunneling regime) and jump to contact (from tunneling to contact regime) in detail. Our data can be fully understood within a relatively simple elastic model, where the elasticity k of the electrodes is the only free parameter. We find 5相似文献
77.
The molecular structure of trifluoroethene was determined from electron diffraction data and the microwave rotational constants of the parent and deuterated molecule, corrected for zero-point vibrational motion. A GVFF adjusted to fit the vibrational frequencies was used for the correction. The molecule was found to be planar. Assuming equal geminal C1—F bond lengths, the following rg distances and rav angles are found: C1—F = 1.316 ± 0.011 Å, C2—F = 1.342 ± 0.024 Å, CC = 1.341 ± 0.012 Å, C—H = 1.100 ± 0.02 Å, ∠C—C—F1 = 123.1 ± 1.5°. ∠C—C—F2 = 124.0 ± 0.6°, ∠C—C—F3 = 120 ± 0.7° (Fl trans to F3) and ∠C—C—H = 124.0 ± 1.7°.The error limits include 3σ (σ = estimated standard deviation) and estimates of the systematic errors. The analysis suggests that all the C1—F distances are not equivalent, neither are the C2—C1—F angles, though the differences are not significant (10% level). 相似文献
78.
79.
80.
J. Huisman 《Mathematische Zeitschrift》1995,219(1):335-342
Supported by the Netherlands Organisation for Scientific Research (NWO) 相似文献