全文获取类型
收费全文 | 1388651篇 |
免费 | 129244篇 |
国内免费 | 1495篇 |
出版年
2021年 | 17996篇 |
2019年 | 16209篇 |
2018年 | 17730篇 |
2017年 | 16324篇 |
2016年 | 28170篇 |
2015年 | 42750篇 |
2014年 | 50849篇 |
2013年 | 77103篇 |
2012年 | 39359篇 |
2011年 | 28067篇 |
2010年 | 43948篇 |
2009年 | 45262篇 |
2008年 | 26309篇 |
2007年 | 24280篇 |
2006年 | 29088篇 |
2005年 | 30111篇 |
2004年 | 29341篇 |
2003年 | 26792篇 |
2002年 | 24709篇 |
2001年 | 37941篇 |
2000年 | 35283篇 |
1999年 | 34107篇 |
1998年 | 25948篇 |
1997年 | 25800篇 |
1996年 | 25270篇 |
1995年 | 23365篇 |
1994年 | 23201篇 |
1993年 | 22333篇 |
1992年 | 28866篇 |
1991年 | 26969篇 |
1990年 | 25586篇 |
1989年 | 26348篇 |
1988年 | 24031篇 |
1987年 | 22834篇 |
1986年 | 21565篇 |
1985年 | 23238篇 |
1984年 | 23057篇 |
1983年 | 20376篇 |
1982年 | 20797篇 |
1981年 | 20026篇 |
1980年 | 18660篇 |
1979年 | 19176篇 |
1978年 | 17896篇 |
1977年 | 17210篇 |
1976年 | 16434篇 |
1975年 | 15729篇 |
1974年 | 16206篇 |
1973年 | 16530篇 |
1972年 | 13889篇 |
1971年 | 12845篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
The fish pathogenVibrio anguillarum causes significant economic losses in commercially cultured fish species worldwide. At present, identification ofV. anguillarum requires conventional isolation and culturing techniques. Using differential hybridization, a 310 base pairV. anguillarum-specific DNA fragment was isolated for use as a probe. In specificity studies against 19 different bacterial species, including twoVibrio sp. and fish pathogens, and 223 marine bacterial isolates, the probe hybridized exclusively toV. anguillarum strains. The probe also strongly hybridizes to 7 of 9 serotypes tested, with serotype 09 giving a weak probe reaction and serotype O7 negative. The probe allows rapid and accurate detection of both pathogenic and environmental strains ofV. anguillarum. 相似文献
152.
153.
S-adenosyl-L-homocysteine (S-AH), a potent inhibitor of biological transmethylation, decreased the response of rat retina adenylate cyclase to dopamine and to 2-amino-6, 7-dihydroxytetrahydronaphtalene (ADTN). This effect appeared for 10?7M of S-adenosyl-L-homocysteine and was linear for concentration ranging to 10?4M. S-adenosyl-L-homocysteine did not decrease the cyclic AMP accumulation with sodium fluoride, a non specific adenylate cyclase activator. On the other hand, the incorporation of methyl group was reduced in rat retina homogenates by S-adenosyl-L-homocysteine. These findings suggest that the activity of the dopamine dependent adenylate cyclase is linked to a methylation process. 相似文献
154.
Scott M. Montgomery 《CMAJ》2010,182(11):1157-1158
155.
156.
157.
Nonintegrative transformation in the filamentous fungus Podospora anserina: stabilization of a linear vector by the chromosomal ends of Tetrahymena thermophila. 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The effect of the chromosomal ends of Tetrahymena thermophila on the stability of linear transforming molecules in the filamentous fungus Podospora anserina was tested. A derivative of an integrative vector for this fungus has been constructed, so that after linearization, the ends of the plasmid are the telomeric sequences of T. thermophila. After transformation, this linear molecule was maintained as an extrachromosomal plasmid with no integrated copies in about 50% of the transformants. Under selective conditions, there was approximately one linear molecule per 5 to 10 nuclei, and these extrachromosomal molecules were rapidly lost under nonselective conditions. The circular plasmid carrying an inverted repeat of T. thermophila telomeres could be linearized and processed in vivo. 相似文献
158.
159.
Vernon Shattuck Frank R. Katterman 《Biochemical and biophysical research communications》1982,109(3):1017-1025
When cotyledonary tissue of cotton are treated with the mutagen ethyl methanesulfonate and then germinated, an enhanced, unscheduled DNA synthesis response is observed, along with a concomitant increase in the thymidine triphosphate precursor pool size. The implications of these results are discussed in this paper. 相似文献
160.