全文获取类型
收费全文 | 1546篇 |
免费 | 33篇 |
国内免费 | 7篇 |
专业分类
化学 | 934篇 |
晶体学 | 6篇 |
力学 | 31篇 |
数学 | 202篇 |
物理学 | 413篇 |
出版年
2022年 | 16篇 |
2021年 | 11篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 12篇 |
2016年 | 24篇 |
2015年 | 19篇 |
2014年 | 27篇 |
2013年 | 44篇 |
2012年 | 77篇 |
2011年 | 110篇 |
2010年 | 52篇 |
2009年 | 54篇 |
2008年 | 69篇 |
2007年 | 98篇 |
2006年 | 84篇 |
2005年 | 80篇 |
2004年 | 51篇 |
2003年 | 56篇 |
2002年 | 59篇 |
2001年 | 39篇 |
2000年 | 35篇 |
1999年 | 16篇 |
1997年 | 12篇 |
1996年 | 32篇 |
1995年 | 24篇 |
1994年 | 11篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 23篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 25篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1973年 | 15篇 |
1969年 | 14篇 |
1904年 | 11篇 |
排序方式: 共有1586条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
25.
26.
27.
28.
Jerald S. Bradshaw Ralph B. Nielsen Pui-Kwan Tse Giuseppi Arena Bruce E. Wilson N. Kent Dalley John D. Lamb James J. Christensen Reed M. Izatt 《Journal of heterocyclic chemistry》1986,23(2):361-368
A series of macrocyclic polyether (crown) ligands containing the proton-ionizable s-triazole subcyclic unit were prepared by reacting the 1-THP blocked 3,5-bis(chloromethyl)-1H-1,2,4-triazole with various oligoethylene glycols. The starting bis(chloromethyl)triazole is a vessicant and must be used with caution. Triazolo-18-crown-6 ( 5 ) formed stable complexes with barium, strontium, copper and benzylammonium cations but not with potassium or lithium. The crystal structure of 5 showed the triazole proton to be on nitrogen 3 which is outside the macroring cavity. 相似文献
29.
Nielsen MB Moonen NN Boudon C Gisselbrecht JP Seiler P Gross M Diederich F 《Chemical communications (Cambridge, England)》2001,(18):1848-1849
Novel extended tetrathiafulvalenes (TTFs) with hexa-2,4-diyne-1,6-diylidene spacers between the two 1,3-dithiole rings and laterally appended alkynyl moieties for one- and two-dimensional scaffolding were synthesised and investigated for their electronic properties. 相似文献
30.
Spin-exchange experiments are useful for improving the resolution and establishment of sequential assignments in solid-state NMR spectra of uniformly (15)N-labeled proteins oriented macroscopically in phospholipid bilayers. To exploit this advantage fully, it is crucial that the diagonal peaks in the two-dimensional exchange spectra are suppressed. This may be accomplished using the recent pure-exchange (PUREX) experiments, which, however, suffer from up to a threefold reduction of the cross-peak intensity relative to experiments without diagonal-peak suppression. This loss in sensitivity may severely hamper the applicability for the study of membrane proteins. In this paper, we present a two-dimensional exchange experiment (iPUREX) which improves the PUREX sensitivity by 50%. The performance of iPUREX is demonstrated experimentally by proton-mediated (15)N-(15)N spin-exchange experiments for a (15)N-labeled N-acetyl-L-valyl-L-leucine dipeptide. The relevance of exchange experiments with diagonal-peak suppression for large, uniformly (15)N-labeled membrane proteins in oriented phospholipid bilayers is demonstrated numerically for the G-protein coupled receptor rhodopsin. 相似文献