全文获取类型
收费全文 | 465593篇 |
免费 | 46736篇 |
国内免费 | 405篇 |
专业分类
512734篇 |
出版年
2016年 | 6108篇 |
2015年 | 10819篇 |
2014年 | 11330篇 |
2013年 | 13803篇 |
2012年 | 14098篇 |
2011年 | 11696篇 |
2010年 | 8426篇 |
2009年 | 8041篇 |
2008年 | 9309篇 |
2007年 | 9749篇 |
2006年 | 9322篇 |
2005年 | 14844篇 |
2004年 | 13527篇 |
2003年 | 11440篇 |
2002年 | 9132篇 |
2001年 | 18955篇 |
2000年 | 18950篇 |
1999年 | 15916篇 |
1998年 | 5136篇 |
1997年 | 5281篇 |
1996年 | 4881篇 |
1995年 | 4708篇 |
1994年 | 4654篇 |
1993年 | 4620篇 |
1992年 | 13488篇 |
1991年 | 13165篇 |
1990年 | 12878篇 |
1989年 | 12503篇 |
1988年 | 11851篇 |
1987年 | 11274篇 |
1986年 | 10579篇 |
1985年 | 10735篇 |
1984年 | 8668篇 |
1983年 | 7407篇 |
1982年 | 5694篇 |
1981年 | 5307篇 |
1980年 | 4801篇 |
1979年 | 8464篇 |
1978年 | 6748篇 |
1977年 | 6138篇 |
1976年 | 5862篇 |
1975年 | 6700篇 |
1974年 | 7427篇 |
1973年 | 7412篇 |
1972年 | 6885篇 |
1971年 | 6273篇 |
1970年 | 5460篇 |
1969年 | 5436篇 |
1968年 | 4926篇 |
1967年 | 4267篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
922.
923.
924.
925.
926.
927.
928.
Pinkerton K. E.; Lewis J.; Mulder A. M.; Ikegami M.; Jobe A. H. 《Journal of applied physiology》1993,74(3):1240-1247
929.
H Shibata F W Robinson T R Soderling T Kono 《The Journal of biological chemistry》1991,266(27):17948-17953
Okadaic acid, a potent inhibitor of Type 1 and Type 2A protein phosphatases, was used to investigate the mechanism of insulin action on membrane-bound low Km cAMP phosphodiesterase in rat adipocytes. Upon incubation of cells with 1 microM okadaic acid for 20 min, phosphodiesterase was stimulated 3.7- to 3.9-fold. This stimulation was larger than that elicited by insulin (2.5- to 3.0-fold). Although okadaic acid enhanced the effect of insulin, the maximum effects of the two agents were not additive. When cells were pretreated with 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), the level of phosphodiesterase stimulation by okadaic acid was rendered smaller, similar to that attained by insulin. In cells that had been treated with 2 mM KCN, okadaic acid (like insulin) failed to stimulate phosphodiesterase, suggesting that ATP was essential. Also, as reported previously, the effect of insulin on phosphodiesterase was reversed upon exposure of hormone-treated cells to KCN. This deactivation of previously-stimulated phosphodiesterase was blocked by okadaic acid, but not by insulin. The above KCN experiments were carried out with cells in which A-kinase activity was minimized by pretreatment with H-7. Okadaic acid mildly stimulated basal glucose transport and, at the same time, strongly inhibited the action of insulin thereon. It is suggested that insulin may stimulate phosphodiesterase by promoting its phosphorylation and that the hormonal effect may be reversed by a protein phosphatase which is sensitive to okadaic acid. The hypothetical protein kinase thought to be involved in the insulin-dependent stimulation of phosphodiesterase appears to be more H-7-resistant than A-kinase. 相似文献
930.
Role of different lymphoid tissues in the initiation and maintenance of DNA-raised antibody responses to the influenza virus H1 glycoprotein. 下载免费PDF全文
Antibody responses in mice immunized by a single gene gun inoculation of plasmid expressing the influenza virus H1 hemagglutinin and in mice immunized by a sublethal H1 influenza virus infection have been compared. Both immunizations raised long-lived serum responses that were associated with the localization of antibody-secreting cells (ASC) to the bone marrow. However, the kinetics of these responses were 4 to 8 weeks slower in the DNA-immunized than in the infection-primed mice. Following a gene gun booster, the presence of ASC in the inguinal lymph nodes, but not in other lymph nodes, revealed gene gun responses being initiated in the nodes that drain the skin target site. Both pre- and postchallenge, the DNA-immunized mice had 5- to 10-times-lower levels of antibody and ASC than the infection-primed mice. 相似文献