全文获取类型
收费全文 | 143537篇 |
免费 | 7550篇 |
国内免费 | 84篇 |
出版年
2021年 | 750篇 |
2018年 | 1637篇 |
2017年 | 1753篇 |
2016年 | 3919篇 |
2015年 | 7991篇 |
2014年 | 7901篇 |
2013年 | 8347篇 |
2012年 | 8513篇 |
2011年 | 5800篇 |
2010年 | 4566篇 |
2009年 | 4330篇 |
2008年 | 3915篇 |
2007年 | 4087篇 |
2006年 | 3981篇 |
2005年 | 9693篇 |
2004年 | 8450篇 |
2003年 | 6618篇 |
2002年 | 4015篇 |
2001年 | 1709篇 |
2000年 | 742篇 |
1999年 | 2169篇 |
1998年 | 1190篇 |
1997年 | 797篇 |
1992年 | 2458篇 |
1991年 | 2464篇 |
1990年 | 2517篇 |
1989年 | 2438篇 |
1988年 | 2392篇 |
1987年 | 2247篇 |
1986年 | 2060篇 |
1985年 | 2150篇 |
1984年 | 1697篇 |
1983年 | 1387篇 |
1982年 | 1127篇 |
1981年 | 1145篇 |
1980年 | 1046篇 |
1979年 | 1489篇 |
1978年 | 1219篇 |
1977年 | 1055篇 |
1976年 | 1018篇 |
1975年 | 1217篇 |
1974年 | 1398篇 |
1973年 | 1357篇 |
1972年 | 1191篇 |
1971年 | 1148篇 |
1970年 | 1062篇 |
1969年 | 1055篇 |
1968年 | 935篇 |
1967年 | 931篇 |
1966年 | 720篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Robert C. Tait Byron E. Froman Debbie L. Laudencia-Chingcuanco Leslie D. Gottlieb 《Plant molecular biology》1988,11(4):381-388
Nuclear genes that appear to encode both cytosolic and plastid isozymes of phosphoglucose isomerase (PGI), an essential glycolytic enzyme, have been isolated from three diploid species of the annual wild flower genus Clarkia (Onagraceae). The genes do not contain introns and are expressed to varying degrees in Escherichia coli when cloned in either Charon 35 phage or pUC plasmid vectors. The PGI proteins synthesized in E. coli form dimers, are catalytically active, and their electrophoretic mobilities are similar to those of appropriate Clarkia PGIs. The nucleotide sequence of a gene encoding a plastid isozyme of C. unguiculata is described. 相似文献
102.
Robert Layton 《The journal of the Royal Anthropological Institute》2003,9(3):447-464
In his book, Art and agency , Alfred Gell presents a theory of art based neither on aesthetics nor on visual communication. Art is defined by the distinctive function it performs in advancing social relationships through 'the abduction of agency'. Art objects are indexes of the artist's or model's agency. This article examines Gell's use of agency, particularly in relation to the ritual art that is central to his argument. Focusing on Gell's employment of Peirce's term 'index' (out of his triad of index, icon, and symbol), I note that Peirce's approach deflects attention from signification towards the link between art works and the things to which they refer. I consider what Peirce meant by abduction, and conclude that while Gell makes a good case for the agency of art objects he does not explain the distinctive ways in which art objects extend their maker's or user's agency. Gell lacked the time to make detailed revisions before publication and I acknowledge that, given more time, he might have revised some parts of the book. 相似文献
103.
104.
105.
Protoplasts of Schizosaccharomyces pombe, grown on a rich nutrient medium, were treated with a peptide factor isolated from cultures of the protozoan Tetrahymena pyriformis. The peptide factor is known to inhibit RNA synthesis in Tetrahymena. It has now been shown that the peptide factor also inhibits RNA synthesis in yeast protoplasts without affecting protein synthesis. 相似文献
106.
107.
108.
109.
110.
The cytotoxic and radiosensitizing effects of hyperthermia was shown on Ehrlich ascites tumor cells heated in vitro. The effect of hyperthermia resulted in the formation of local lesions in membranes of dying cells. 相似文献