全文获取类型
收费全文 | 422篇 |
免费 | 6篇 |
专业分类
化学 | 300篇 |
力学 | 7篇 |
数学 | 28篇 |
物理学 | 93篇 |
出版年
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 22篇 |
2012年 | 12篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 22篇 |
2007年 | 29篇 |
2006年 | 18篇 |
2005年 | 21篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1943年 | 2篇 |
1907年 | 2篇 |
排序方式: 共有428条查询结果,搜索用时 15 毫秒
1.
Gordon W. Rewcastle Hamish S. Sutherland Claudette A. Weir Adrian G. Blackburn William A. Denny 《Tetrahedron letters》2005,46(50):8719-8721
A novel two-step synthesis of isonitrosoacetanilides [2-(hydroxyimino)-N-phenylacetamides] has been developed, involving the initial acylation of aniline derivatives with 2,2-diacetoxyacetyl chloride, followed by reaction with hydroxylamine hydrochloride. The method works equally well with a variety of different aniline derivatives, including those with poor aqueous solubility and those containing electron rich ortho-substituents, neither of which react well under traditional conditions. 相似文献
2.
3.
4.
5.
Diaper CM Sutherland A Pillai B James MN Semchuk P Blanchard JS Vederas JC 《Organic & biomolecular chemistry》2005,3(24):4402-4411
Aziridine analogues of diaminopimelic acid (DAP) have been prepared stereoselectively for the first time and evaluated as inhibitors of DAP epimerase. (2R,3S,3'S)-3-(3'-Aminopropane)aziridine-2,3'-dicarboxylate was synthesised and shown to be a reversible inhibitor of DAP epimerase with an IC(50) value of 2.88 mM. (2S,4S)- and (2S,4R)-2-(4-Amino-4-carboxybutyl)aziridine-2-carboxylic acid (ll-azi-DAP and dl-azi-DAP ) were made as pure diastereomers, and both were shown to be irreversible inhibitors of DAP epimerase. ll-Azi-DAP selectively binds to Cys-73 of the enzyme active site whereas dl-azi-DAP binds to Cys-217 via attack of sulfhydryl on the methylene of the inhibitor aziridine ring. These observations are consistent with the two base mechanism proposed for the epimerization of ll-DAP and meso-DAP by DAP epimerase. 相似文献
6.
ALFALFA SEEDLINGS GROWN OUTDOORS ARE MORE RESISTANT TO UV-INDUCED DNA DAMAGE THAN PLANTS GROWN IN A UV-FREE ENVIRONMENTAL CHAMBER 总被引:4,自引:0,他引:4
Shinnosuke Takayanagi John G. Trunk John C. Sutherland Betsy M. Sutherland † 《Photochemistry and photobiology》1994,60(4):363-367
Abstract The relative UV sensitivities of alfalfa seedlings grown outdoors versus plants grown in a growth chamber under UV-filtered cool white fluorescent bulbs have been determined using three criteria: (1) level of endogenous DNA damage as sites for the UV endonuclease from Micrococcus luteus . (2) susceptibility to pyrimidine dimer induction by a UV challenge exposure and (3) ability to repair UV-induced damage. We find that outdoor-grown plants contain approximately equal frequencies of endogenous DNA damages, are less susceptible to dimer induction by a challenge exposure of broad-spectrum UV and photorepair dimers more rapidly than plants grown in an environmental chamber under cool white fluorescent lamps plus a filter that removes most UV radiation. These data suggest that plants grown in a natural environment would be less sensitive to UVB-induced damage than would be predicted on the basis of studies on plants grown under minimum UV. 相似文献
7.
C.C. Lee K.J. Demchuk W.J. Pannekoek R.G. Sutherland 《Journal of organometallic chemistry》1978,162(2):253-269
Ligand exchange reactions between phenanthrene or 9,10-dimethylphenanthrene with ferrocene effected in the presence of AlCl3-Al were carried out under a variety of conditions. With phenanthrene (I), hydrogenation at the C-9 and C-10 positions could take place during the reaction and the cationic products obtained were the η6-phenanthrene-η5-cyclopentadienyliron and η6-9,10-dihydro-phenanthrene-η5-cyclopentadienyliron moncations (II and III), and the η6-phenanthrene---η5-cyclopentadienyliron and η6-9,10-dihydrophenanthrene---η5-cyclopentadienyliron dications (IV and V). With 9,10-dimethylphenanthrene (VI), reactions carried out in refluxing cyclohexane gave the non-hydrogenated η6-9,10-dimethylphenanthrene-η5-cyclopentadienyliron monocation (VII) and η6-9,10-dimethylphenanthrene---η5-cyclopentadienyliron dication (VIII). When higher temperatures were used in an attempt to promote hydrogenation, decomposition predominated and no cationic product could be obtained. These finding are discussed and contrasted with previous results obtained from similar reactions using anthracene or 9,10-dimethylanthracene. 相似文献
8.
Several enones are converted into their alpha-iodo derivatives in excellent yields and carbonylated with palladium catalysis in the presence of alcohol or amines to the alpha-carbonyl enones in satisfactory yields. 相似文献
9.
Reactions of various η6-arene-η5-cyclopentadienyliron or substituted cyclopentadienyliron cations with trimethyl, triethyl or triphenyl phosphite under either thermal or photochemical conditions all resulted in the replacement of the arene ligand with three phosphite ligands to give η5-tris(trimethyl, triethyl or triphenyl phosphite)-η5-cyclopentadienyliron or substituted cyclopentadienyliron cations. The yields of the phosphite complexes were higher from photolysis than from the analogous thermolysis. Photolysis of the η6-chlorobenzene-η5-cyclopentadienyliron cation (IX) carried out in the presence of a more basic or more electron-rich aromatic ligand resulted in the exchange of the chlorobenzene of IX with the more basic arene, thus providing synthetic routes to cyclopentadienyliron complexes that may be difficult to prepare by other means. New complexes synthesized in this way are the η6-2-phenylethyl tosylate-η5-cyclopentadienyliron cation and the CpFe+ complexes of thiophene, 2-methylthiophene, 3-methylthiophene and 2,5-dimethylthiophene. 相似文献
10.
Ronald G. Sutherland Adam Pirko Udai S. Gill Choi Chuck Lee 《Journal of heterocyclic chemistry》1982,19(4):801-803
A method for the synthesis of heterocylic systems related to 9,10-dihydroanthracene with two hetero-atoms at the 9,10-positions is described. It involves the nucleophilic substitution reaction of η6-o-dichlorobenzene-η5-cyclopentadienyliron hexafluorophosphate with two nucleophilic groups (OH, SH and/or NH2) located in the 1,2-positions of a benzene ring to give a cyclopentadienyliron complexed heterocycle. Upon pyrolytic sublimation of the complex, the free heterocyclic compound is then obtained. 相似文献