全文获取类型
收费全文 | 641篇 |
免费 | 61篇 |
出版年
2022年 | 5篇 |
2021年 | 22篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 31篇 |
2016年 | 15篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 26篇 |
2012年 | 37篇 |
2011年 | 34篇 |
2010年 | 32篇 |
2009年 | 18篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1960年 | 3篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
651.
One-dimensional diffusion of microtubules bound to flagellar dynein 总被引:21,自引:0,他引:21
Dynein is a multisubunit ATPase that powers microtubule-based motility. We find that a dissociated dynein particle containing the beta heavy chain subunit translocates microtubules unidirectionally over a glass surface in the presence of ATP. However, after nucleotide hydrolysis is inhibited by vanadate, unidirectional translocation ceases, and microtubules instead undergo irregular back-and-forth motion along their longitudinal axes. Quantitative analysis reveals that this motion is due to thermal-driven diffusion, but, unlike a particle undergoing Brownian motion, the diffusion is restricted to one dimension. The properties of the diffusional movement indicate that dynein can interact with microtubules in a way that permits the latter to diffuse only along their longitudinal axes. This weak binding interaction may constitute an important intermediate state in dynein's force-generating cycle. 相似文献
652.
653.
Ronald D. Vale 《Molecular biology of the cell》2013,24(6):680-682
Science begins by asking questions and then seeking answers. Young children understand this intuitively as they explore and try to make sense of their surroundings. However, science education focuses upon the end game of “facts” rather than the exploratory root of the scientific process. Encouraging questioning helps to bring the true spirit of science into our educational system, and the art of asking good questions constitutes an important skill to foster for practicing scientists. 相似文献
654.
655.
R E Peter C S Nahorniak W W Vale J E Rivier 《The Journal of experimental zoology》1984,231(1):161-163
Synthetic human pancreatic growth hormone-releasing factor (hpGRF) was injected intraperitoneally in different dosages, either as one injection or two injections 3 hours apart, into goldfish. Serum GH levels were increased by certain dosages of hpGRF under both treatments. This is the first demonstration of GH-releasing activity of hpGRF in a teleost fish. 相似文献
656.
657.
658.
A homologous radioimmunoassay was used for measurement of porcine prolactin in blood plasma collected from sows during the periparturient period. The assay was able to detect prolactin over a range of 0.5 to 7.0 ng/assay tube. There was no significant cross reaction with growth hormone, luteinizing hormone, or follicle stimulating hormone at amounts up to 105 ng/assay tube while porcine ACTH gave 30% binding at 104 ng. Prolactin was not detected in plamsa from a hypophysectomized pig or 2 ergocryptine-treated sows when 100 μ l plasma were assayed. Prolactin concentration in plasma was then measured in 14 periparturient sows within a period extending from 7 days before farrowing to 7 days after farrowing. Samples were collected at 15 min intervals between 1330 and 1630 h each day. However, prolactin assays were done only on the even-numbered samples (30 min interval). Plasma prolactin concentrations (ng/ml, ) were 23.7 ± 2.0 on days ?7 to ?5 prepartum, began to rise by day ?3 prepartum (42.5 ± 5.9), and peaked at 127.5 ± 17.6 on day 1 prepartum. By day 3 postpartum, prolactin concentrations in plasma had decreased to 80.5 ± 12.6 and further declined to 51.6 ± 4.6 on day 7 postpartum. The mean prolactin concentration in plasma for all pigs on days ?1 to +2 was 116.8 ± 13.8. This mean concentration for days ?1 to +2 was different (P < 0.025) from the mean prolactin concentration for the period both prior and subsequent to these days (?8 to ?2 and +3 to +8 days). 相似文献
659.
660.