全文获取类型
收费全文 | 83701篇 |
免费 | 7303篇 |
国内免费 | 43篇 |
出版年
2022年 | 463篇 |
2021年 | 1004篇 |
2020年 | 601篇 |
2019年 | 759篇 |
2018年 | 984篇 |
2017年 | 923篇 |
2016年 | 1557篇 |
2015年 | 2573篇 |
2014年 | 2920篇 |
2013年 | 4015篇 |
2012年 | 4916篇 |
2011年 | 5104篇 |
2010年 | 3355篇 |
2009年 | 3028篇 |
2008年 | 4499篇 |
2007年 | 4605篇 |
2006年 | 4421篇 |
2005年 | 4387篇 |
2004年 | 4518篇 |
2003年 | 4074篇 |
2002年 | 4097篇 |
2001年 | 996篇 |
2000年 | 740篇 |
1999年 | 1046篇 |
1998年 | 1326篇 |
1997年 | 920篇 |
1996年 | 848篇 |
1995年 | 831篇 |
1994年 | 810篇 |
1993年 | 753篇 |
1992年 | 731篇 |
1991年 | 705篇 |
1990年 | 681篇 |
1989年 | 703篇 |
1988年 | 606篇 |
1987年 | 589篇 |
1986年 | 542篇 |
1985年 | 680篇 |
1984年 | 824篇 |
1983年 | 712篇 |
1982年 | 847篇 |
1981年 | 867篇 |
1980年 | 805篇 |
1979年 | 581篇 |
1978年 | 624篇 |
1977年 | 612篇 |
1976年 | 598篇 |
1975年 | 467篇 |
1974年 | 587篇 |
1973年 | 532篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
101.
102.
103.
104.
Charles E. Wenner John C. Cheney L. David Tomei 《Journal of cellular biochemistry》1981,15(2):161-168
The introduction of either PGF2α (10?7 M) or TPA (10?7 M) stimulated, ouabain-sensitive 86Rb+ influx at 30 min in postconfluent 3T3-4 mouse fibroblast cultures by 117% and 124%, respectively. Both TPA and PGF2α at these concentrations stimulated the incorporation of 3H-TdR into DNA. TPA had the greatest stimulatory effect, which was similar to that obtained with 10% fetal calf serum. In accord with the idea that modulation of membrane processes such as Na+/K+ pump activity in fibroblasts may reflect important events related to the initiation of DNA synthesis, it was observed that in both 3T3-4 and C3H-1 0T½ cells there were parallel increases in 3H-TdR incorporation and ouabain-sensitive 86Rb+ influxes with 10?7 M TPA, whereas PGF2α stimulated a significant increase in 3H-TdR incorporation in 3T3-4 but not C3H-10T½ cells and only marginal increases in ouabain-sensitive 86Rb+ influx in both. Therefore, although there appears to be a close correlation between Na+/K+ pump activation and subsequent S-phase entry following TPA stimulation, a similar correlation for PGF2α cannot be confirmed. 相似文献
105.
The Devonian cemented brachiopod Schuchertellopsis durbutensis has proved difficult to classify and its possible taxonomic relationships are unknown. Morphologically Schuchertellopsis resembles more closely members of the Orthotetidina than the Davidsoniidina. Examination of the shell structure, a key diagnostic feature of the Orthotetidina, shows that Schuchertellopsis has the cross laminar secondary shell typical of all orthotetidines. However, the presence of both pseudopunctate and incipient an extropunctate fabric within the ventral valve is unique amongst orthotetidine brachiopods and is thought to represent a phase of shell fabric experimentation. Schuchertellopsis probably fits most comfortably within the Schuchertellidae, and is the earliest representative of that family. 相似文献
106.
John Warden 《BMJ (Clinical research ed.)》1986,293(6561):1583
107.
108.
109.
110.