全文获取类型
收费全文 | 18842篇 |
免费 | 1633篇 |
国内免费 | 1篇 |
出版年
2023年 | 104篇 |
2022年 | 154篇 |
2021年 | 571篇 |
2020年 | 307篇 |
2019年 | 395篇 |
2018年 | 497篇 |
2017年 | 397篇 |
2016年 | 689篇 |
2015年 | 1068篇 |
2014年 | 1146篇 |
2013年 | 1400篇 |
2012年 | 1559篇 |
2011年 | 1547篇 |
2010年 | 965篇 |
2009年 | 810篇 |
2008年 | 1127篇 |
2007年 | 1107篇 |
2006年 | 895篇 |
2005年 | 819篇 |
2004年 | 818篇 |
2003年 | 675篇 |
2002年 | 638篇 |
2001年 | 266篇 |
2000年 | 185篇 |
1999年 | 223篇 |
1998年 | 169篇 |
1997年 | 142篇 |
1996年 | 111篇 |
1995年 | 120篇 |
1994年 | 109篇 |
1993年 | 80篇 |
1992年 | 101篇 |
1991年 | 108篇 |
1990年 | 103篇 |
1989年 | 98篇 |
1988年 | 89篇 |
1987年 | 78篇 |
1986年 | 72篇 |
1985年 | 62篇 |
1984年 | 78篇 |
1983年 | 48篇 |
1982年 | 39篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 30篇 |
1978年 | 31篇 |
1977年 | 35篇 |
1976年 | 26篇 |
1973年 | 28篇 |
1970年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
1.
Zhaolin Wang Cara Fraley Adam R. Mezo 《Bioorganic & medicinal chemistry letters》2013,23(5):1253-1256
The neonatal Fc receptor, FcRn, prolongs the half-life of IgG in the serum and represents a potential therapeutic target for the treatment of autoimmune disease. Small molecules that block the protein–protein interactions of human IgG–human FcRn may lower pathogenic autoantibodies and provide effective treatment. A novel class of quinoxalines has been discovered as antagonists of the IgG:FcRn protein–protein interaction through optimization of a hit derived from a virtual ligand-based screen. 相似文献
2.
Winnie W.Y. Lau Marlene M. Martinez 《Journal of experimental marine biology and ecology》2003,295(1):1-21
Hydrodynamic forces can affect survival as well as limit the movement of motile benthic animals. An animal's danger of dislodgement depends on the hydrodynamic forces it experiences in its microhabitat relative to the force required to dislodge it (tenacity) from the substratum. We measured water flow and substratum characteristics in two different habitats of the shore crab Pachygrapsus crassipes: a wave-swept rocky shore and an intertidal mudflat. The maximum water velocities and accelerations in the microhabitats of the crabs at the wave-swept site were three times and two times greater, respectively, than at the mudflat site. In the laboratory, we measured the tenacity of crabs of various sizes on different substrata, and also measured their drag, lift and added-mass coefficients. Using these data, we calculated the flow conditions under which crabs would be overturned or sheared off the substratum in their two habitats. The net horizontal force (drag plus acceleration reaction) required to dislodge a crab on a rugose rock substratum was an order of magnitude greater than on smooth rock and two orders of magnitude greater than on mud. Our calculations indicate that, under non-storm conditions, crabs will not be dislodged from the substratum in either the mudflat or the wave-swept habitat when grasping the substratum with maximum tenacity. Moving crabs have lower tenacity and our calculations predict that hydrodynamic forces will restrict the mobility of large crabs more than that of small ones on smooth, but not on rugose rock. 相似文献
3.
4.
Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research... 相似文献
5.
6.
7.
8.
Hierarchy and monophyly 总被引:1,自引:0,他引:1
9.
Eliot C. Bush Anne E. Clark Chris M. DeBoever Lillian E. Haynes Sidra Hussain Singer Ma Matthew M. McDermott Adam M. Novak John S. Wentworth 《PloS one》2012,7(11)
A significant proportion of enzymes display cooperativity in binding ligand molecules, and such effects have an important impact on metabolic regulation. This is easiest to understand in the case of positive cooperativity. Sharp responses to changes in metabolite concentrations can allow organisms to better respond to environmental changes and maintain metabolic homeostasis. However, despite the fact that negative cooperativity is almost as common as positive, it has been harder to imagine what advantages it provides. Here we use computational models to explore the utility of negative cooperativity in one particular context: that of an inhibitor binding to an enzyme. We identify several factors which may contribute, and show that acting together they can make negative cooperativity advantageous. 相似文献
10.