全文获取类型
收费全文 | 100篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 75篇 |
力学 | 2篇 |
数学 | 12篇 |
物理学 | 14篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1938年 | 2篇 |
1920年 | 1篇 |
1913年 | 4篇 |
1911年 | 2篇 |
排序方式: 共有103条查询结果,搜索用时 4 毫秒
101.
Hunt DM Carvalho LS Cowing JA Parry JW Wilkie SE Davies WL Bowmaker JK 《Photochemistry and photobiology》2007,83(2):303-310
Of the four classes of vertebrate cone visual pigments, the shortwave-sensitive SWS1 class shows some of the largest shifts in lambda(max), with values ranging in different species from 390-435 nm in the violet region of the spectrum to < 360 nm in the ultraviolet. Phylogenetic evidence indicates that the ancestral pigment most probably had a lambda(max) in the UV and that shifts between violet and UV have occurred many times during evolution. In violet-sensitive (VS) pigments, the Schiff base is protonated whereas in UV-sensitive (UVS) pigments, it is almost certainly unprotonated. The generation of VS pigments in amphibia, birds and mammals from ancestral UVS pigments must involve therefore the stabilization of protonation. Similarly, stabilization must be lost in the evolution of avian UVS pigments from a VS ancestral pigment. The key residues in the opsin protein for these shifts are at sites 86 and 90, both adjacent to the Schiff base and the counterion at Glu113. In this review, the various molecular mechanisms for the UV and violet shifts in the different vertebrate groups are presented and the changes in the opsin protein that are responsible for the spectral shifts are discussed in the context of the structural model of bovine rhodopsin. 相似文献
102.
We consider a system interacting with a chaotic thermodynamic bath. We derive an explicit and exact Kraus operator sum representation (OSR) for the open system reduced density. The OSR preserves the Hermiticity, complete positivity and norm. We show that it is useful as a numerical tool by testing it against exact results for a qubit interacting with an isolated flawed quantum computer. We also discuss some interesting qualitative aspects of the OSR. 相似文献
103.
Charles A. Wilkie Gong-Yu Lin Daniel T. Haworth 《Journal of solid state chemistry》1979,30(2):197-201
The solid state 13C nuclear magnetic resonance spectra of fluorinated graphites show two resonances, one of which is assigned to aromatic carbon and the other to aliphatic carbon. The resonances are very broad with the high-field resonance centered at about 35 ppm below tetramethylsilane (TMS) and a low-field resonance centered at about 160 ppm below tetramethylsilane. The high-field resonance is typical of an sp3-like carbon and the low-field resonance is assigned to sp2-like carbons. It is found that the aromatic resonance in graphite decreases with an increase in fluorination of the graphite fluorides examined in this study. The 19F nuclear magnetic resonance spectra of C4F and CF1 each show one resonance. The fluorine resonance in C4F is 180 ppm above CFCI3 whereas the fluorine resonance in CF1 is 55 ppm above CFCI3. These peaks are in the range for fluorine bonded to aromatic and aliphatic carbons, respectively. 相似文献