全文获取类型
收费全文 | 94267篇 |
免费 | 7824篇 |
国内免费 | 8篇 |
出版年
2023年 | 537篇 |
2022年 | 602篇 |
2021年 | 1246篇 |
2020年 | 1025篇 |
2019年 | 1086篇 |
2018年 | 2324篇 |
2017年 | 2163篇 |
2016年 | 2978篇 |
2015年 | 4047篇 |
2014年 | 4095篇 |
2013年 | 5398篇 |
2012年 | 6524篇 |
2011年 | 5887篇 |
2010年 | 3714篇 |
2009年 | 3015篇 |
2008年 | 4727篇 |
2007年 | 4503篇 |
2006年 | 4162篇 |
2005年 | 3687篇 |
2004年 | 3577篇 |
2003年 | 3297篇 |
2002年 | 3058篇 |
2001年 | 2355篇 |
2000年 | 2326篇 |
1999年 | 1873篇 |
1998年 | 875篇 |
1997年 | 721篇 |
1996年 | 715篇 |
1995年 | 645篇 |
1994年 | 564篇 |
1993年 | 573篇 |
1992年 | 1224篇 |
1991年 | 1094篇 |
1990年 | 1030篇 |
1989年 | 1069篇 |
1988年 | 973篇 |
1987年 | 959篇 |
1986年 | 821篇 |
1985年 | 912篇 |
1984年 | 838篇 |
1983年 | 626篇 |
1982年 | 614篇 |
1981年 | 525篇 |
1980年 | 507篇 |
1979年 | 656篇 |
1978年 | 593篇 |
1975年 | 533篇 |
1974年 | 607篇 |
1973年 | 587篇 |
1972年 | 491篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
2.
3.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
4.
T Smith 《BMJ (Clinical research ed.)》1984,289(6449):909-910
5.
6.
7.
M del Mar Medina-Puerta A Garrido-Pertierra 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(1):215-220
The enzyme 6-phosphogluconate dehydrogenase (6-phospho-D-gluconate: NADP+ oxidoreductase, decarboxylating EC 1.1.1.44) from bass liver has been purified to over 95% of homogeneity by gel filtration, affinity and ion exchange chromatographies. The apparent molecular weight was estimated by gel filtration chromatography to about 100,000. Analysis of the enzyme on sodium dodecyl sulphate polyacrylamide gel electrophoresis showed to be a dimeric protein. The effect of pH and kinetic properties were studied. 相似文献
8.
"Pertussis toxin induces tachycardia and impairs the increase in blood pressure produced by alpha 2-adrenergic agonists" 总被引:4,自引:0,他引:4
Administration of purified pertussis toxin to rats induced persistent tachycardia, (observed in conscious rats but not after pithing); as little as 0.05 microgram/100 g produced a significant effect. Pertussis toxin-treatment did not affected the pressor response produced in the pithed rats by the alpha 2-adrenergic agonist methoxamine but markedly diminished the pressor effect of the alpha 2-adrenergic agonists clonidine and azepexole. A role of adenylate cyclase inhibition in the action of postsynaptic vascular alpha 2-adrenergic receptors is suggested. 相似文献
9.
Andrew C Smith 《BMJ (Clinical research ed.)》1981,283(6306):1596-1597
10.
Escherichia coli RecBC pseudorevertants lacking chi recombinational hotspot activity 总被引:24,自引:7,他引:17
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pseudorevertants of an Escherichia coli exonuclease V (RecBC enzyme)-negative mutant have been isolated after ethyl methane sulfonate mutagenesis of a recC73 (presumed missense) mutant. The remedial mutations in each of the four pseudorevertants studied in detail map and complement as recC mutations. By several criteria, such as recombination proficiency, support of phage growth, RecBC nuclease activity, and cell viability, the pseudorevertants appear to have regained partially or completely various aspects of RecBC activity. However, chi recombinational hotspots, which stimulate exclusively the RecBC pathway of recombination, have no detectable activity in lambda vegetative crosses in the pseudorevertants. The properties of these mutants, in which the RecBC pathway of recombination is active yet in which chi is not active, are consistent with the hypothesis that wild-type RecBC enzyme directly interacts with chi sites; alternatively, the mutants may block or bypass the productive interaction of another recombinational enzyme with chi. 相似文献