全文获取类型
收费全文 | 1393489篇 |
免费 | 124583篇 |
国内免费 | 2143篇 |
出版年
2021年 | 18034篇 |
2019年 | 16302篇 |
2018年 | 18133篇 |
2017年 | 16849篇 |
2016年 | 28408篇 |
2015年 | 42841篇 |
2014年 | 50915篇 |
2013年 | 77240篇 |
2012年 | 39532篇 |
2011年 | 29087篇 |
2010年 | 44723篇 |
2009年 | 45845篇 |
2008年 | 26893篇 |
2007年 | 24939篇 |
2006年 | 29799篇 |
2005年 | 30771篇 |
2004年 | 30022篇 |
2003年 | 27346篇 |
2002年 | 25336篇 |
2001年 | 35030篇 |
2000年 | 32353篇 |
1999年 | 32190篇 |
1998年 | 25630篇 |
1997年 | 25553篇 |
1996年 | 24986篇 |
1995年 | 23170篇 |
1994年 | 22907篇 |
1993年 | 22018篇 |
1992年 | 28098篇 |
1991年 | 26659篇 |
1990年 | 25354篇 |
1989年 | 25996篇 |
1988年 | 23884篇 |
1987年 | 22533篇 |
1986年 | 21626篇 |
1985年 | 23342篇 |
1984年 | 23000篇 |
1983年 | 20350篇 |
1982年 | 20585篇 |
1981年 | 19779篇 |
1980年 | 18517篇 |
1979年 | 18999篇 |
1978年 | 18040篇 |
1977年 | 17160篇 |
1976年 | 16318篇 |
1975年 | 16136篇 |
1974年 | 16652篇 |
1973年 | 16961篇 |
1972年 | 14406篇 |
1971年 | 13290篇 |
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
971.
972.
973.
974.
C-Type Virus Released from Cultured Human Rhabdomyosarcoma Cells 总被引:44,自引:0,他引:44
R. M. McALLISTER M. NICOLSON M. B. GARDNER R. W. RONGEY S. RASHEED P. S. SARMA R. J. HUEBNER M. HATANAKA S. OROSZLAN R. V. GILDEN A. KABIGTING L. VERNON 《Nature: New biology》1972,235(53):3-6
RD-114 virus, released from human rhabdomyosarcoma cells, has all the characteristics of a mammalian C-type virus. Immunological tests indicate that it differs from all known C-type viruses and is the most likely candidate for a human C-type virus yet described. 相似文献
975.
L V Melendez M D Daniel H H Barahona C E Fraser R D Hunt F G Garcia 《Laboratory animal science》1971,21(6):1050-1054
976.
977.
978.
Effect of freezing on dehydrogenase activity and reduction of triphenyl tetrazolium chloride 总被引:5,自引:0,他引:5
P L Steponkus 《Cryobiology》1971,8(6):570-573
979.
980.
WEHI-231 cells have been used extensively as a model of tolerance induction in B cells. Recent evidence has shown that anti-IgM treatment of WEHI-231 cells resulted in the induction of apoptosis. In this study, using acridine orange staining and flow cytometric analysis, we demonstrated that apoptotic cells are detected as a distinct population of cells separate from the cells in normal cell cycle progression. The validity of analysis gates was confirmed by cell sorting of the apoptotic population versus normal cells and subsequent gel analysis. Using this technique, we have demonstrated that F(ab')2 anti-mu, A23187, or PMA induced apoptosis in the WEHI-231 cells. The addition of LPS reversed apoptotic induction as seen previously with the WEHI-231 cell line. In contrast, however, PMA did not prevent the induction of apoptosis in anti-mu-treated cells. Additionally, we were interested in determining if the induction of apoptosis was restricted to a specific phase of cell cycle. Since growth inhibition results in most cells arresting in the G1 phase of cell cycle, we wanted to demonstrate apoptosis as a G1-dependent event. This was examined with WEHI-231 cells treated with known cell cycle inhibitors. Interestingly, inhibition of cells in each phase of cycle resulted in the induction of apoptosis. LPS was able to inhibit the induction of apoptosis with each of the cell cycle inhibitors except actinomycin D. Furthermore, we have demonstrated that the WEHI-231 cells contain a Ca(2+)-Mg(2+)-dependent preexisting endonuclease. 相似文献