全文获取类型
收费全文 | 693445篇 |
免费 | 73917篇 |
国内免费 | 540篇 |
出版年
2018年 | 6325篇 |
2016年 | 8407篇 |
2015年 | 11885篇 |
2014年 | 13344篇 |
2013年 | 19256篇 |
2012年 | 21322篇 |
2011年 | 21022篇 |
2010年 | 13993篇 |
2009年 | 12595篇 |
2008年 | 18542篇 |
2007年 | 18821篇 |
2006年 | 18171篇 |
2005年 | 17226篇 |
2004年 | 17074篇 |
2003年 | 16209篇 |
2002年 | 15812篇 |
2001年 | 29066篇 |
2000年 | 29531篇 |
1999年 | 23409篇 |
1998年 | 8238篇 |
1997年 | 8565篇 |
1996年 | 8176篇 |
1995年 | 7556篇 |
1994年 | 7427篇 |
1993年 | 7449篇 |
1992年 | 19090篇 |
1991年 | 18551篇 |
1990年 | 18046篇 |
1989年 | 17720篇 |
1988年 | 16486篇 |
1987年 | 15880篇 |
1986年 | 14875篇 |
1985年 | 15097篇 |
1984年 | 12530篇 |
1983年 | 10787篇 |
1982年 | 8573篇 |
1981年 | 7946篇 |
1980年 | 7331篇 |
1979年 | 12296篇 |
1978年 | 9765篇 |
1977年 | 9163篇 |
1976年 | 8583篇 |
1975年 | 9607篇 |
1974年 | 10641篇 |
1973年 | 10478篇 |
1972年 | 9581篇 |
1971年 | 8808篇 |
1970年 | 7833篇 |
1969年 | 7728篇 |
1968年 | 7094篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
F Stephen Perry 《BMJ (Clinical research ed.)》1998,317(7156):481
982.
983.
Calcium channel blockers, verapamil, nitrendipin and nifedipin, and cyclosporin A inhibited growth of colonies ofBotrytis cinerea in a concentration-dependent manner and simultaneously induced morphological changes of its hyphal tips. Exogenous calcium
at the concentration of 100 mmol/L decreased the growth-inhibitory effects of channel blockers and cyclosporin A; however,
at the concentration of 500 mmol/L Ca2+ their inhibitory effects were increased. At the latter concentration, calcium partly reversed the morphogenic effects of
the blockers but not of cyclosporin A. 相似文献
984.
Human umbilical vein endothelial cells were grown to confluence, as first passage cells, on coverslips. Treatment with ionomycin or histamine caused a sustained rise in intracellular Ca2+ (measured by Fura-2 fluorescence), but after treatment with thrombin, only a transient rise in Ca2+ was observed. Furthermore, the addition of thrombin after ionomycin or histamine lowered the raised Ca2+ back to near control levels. This effect of thrombin was concentration dependent, with increasing concentrations producing increases in both the rate and extent of the lowering of Ca2+. A similar effect of thrombin was seen on video imaging of Fura-2-loaded cell monolayers. The Ca2(+)-lowering effect of thrombin was not mimicked by phorbol 12-myristate 13-acetate nor blocked by staurosporine, indicating a lack of involvement of protein kinase C; intracellular pH also does not appear to be involved. The mechanism by which thrombin lowers cytoplasmic Ca2+ is due mainly to inhibition of Ca2+ entry since thrombin prevented the stimulated influx of Mn2+ caused by histamine or ionomycin. It may therefore be that in vivo under certain physiological or pathological conditions, thrombin's effects on intracellular Ca2+ are more transient than those of histamine, and thrombin also may induce transience in histamine's actions. 相似文献
985.
A serum- and glucocorticoid-regulated 4-kilobase mRNA encodes a cyclooxygenase-related protein. 总被引:21,自引:0,他引:21
M K O'Banion H B Sadowski V Winn D A Young 《The Journal of biological chemistry》1991,266(34):23261-23267
986.
The involvement of gibberellins in the control of flowering of sunflower was studied by direct application of GA3 to the apex of the plants, analysis of the endogenous levels of gibberellin-like substances at different plant ages, and indirectly by the application of paclobutrazol, an inhibitor of gibberellin synthesis. GA3 speeded-up flower initiation and floral apex development. The time of GA3 application was more critical than the amount of GA3 applied. The endogenous levels of gibberellin-like compounds increased significantly by day 15 after sowing. The application of paclobutrazol markedly delayed floral initiation and this effect was also depedent on plant age. Both GA3 and paclobutrazol had their greatest effects between 10 and 20 days after sowing suggesting that an increase in gibberellins in that time period plays a role in floral initiation. 相似文献
987.
988.
989.
Preventing the establishment of ectoparasitic poultry red mite (Dermanyssus gallinae) populations is key in ensuring welfare and egg production of laying hens and absence of allergic reactions of workers in poultry facilities. Using the Hazard Analysis and Critical Control Point method, a panel of experts identified hazards and associated risks concerning the introduction and spread of this mite in poultry facilities. Together we provide an overview of possible corrective actions that can be taken to prevent population establishment. Additionally, a checklist of the most critical control points has been devised as management tool for poultry farmers. This list was evaluated by Dutch and British poultry farmers. They found the checklist feasible and useful. 相似文献
990.