全文获取类型
收费全文 | 348篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 5篇 |
丛书文集 | 1篇 |
教育与普及 | 1篇 |
现状及发展 | 71篇 |
研究方法 | 34篇 |
综合类 | 227篇 |
自然研究 | 12篇 |
出版年
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 25篇 |
2011年 | 44篇 |
2010年 | 15篇 |
2009年 | 4篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1971年 | 4篇 |
1970年 | 9篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 7篇 |
1966年 | 1篇 |
1965年 | 5篇 |
排序方式: 共有351条查询结果,搜索用时 0 毫秒
41.
Marijuana and many of its constituent cannabinoids influence the central nervous system (CNS) in a complex and dose-dependent manner. Although CNS depression and analgesia are well documented effects of the cannabinoids, the mechanisms responsible for these and other cannabinoid-induced effects are not so far known. The hydrophobic nature of these substances has suggested that cannabinoids resemble anaesthetic agents in their action, that is, they nonspecifically disrupt cellular membranes. Recent evidence, however, has supported a mechanism involving a G protein-coupled receptor found in brain and neural cell lines, and which inhibits adenylate cyclase activity in a dose-dependent, stereoselective and pertussis toxin-sensitive manner. Also, the receptor is more responsive to psychoactive cannabinoids than to non-psychoactive cannabinoids. Here we report the cloning and expression of a complementary DNA that encodes a G protein-coupled receptor with all of these properties. Its messenger RNA is found in cell lines and regions of the brain that have cannabinoid receptors. These findings suggest that this protein is involved in cannabinoid-induced CNS effects (including alterations in mood and cognition) experienced by users of marijuana. 相似文献
42.
Renin was found in the submandibular glands of male Quackenbush mice in concentrations higher than has been reported for any tissue of any strain or species. However, no renin-like activity could e detected in glands from male and female Wistar rats using either pH 5.8 or 7.4 for assay and a radioimmunoassay specific for renin's reaction product, angiotensin I. Rabbit submandibular glands contained renin. 相似文献
43.
Eoin E. Kelly Conor P. Horgan Mary W. McCaffrey Paul Young 《Cellular and molecular life sciences : CMLS》2011,68(2):185-194
Long-term potentiation (LTP) defines persistent increases in neurotransmission strength at synapses that are triggered by
specific patterns of neuronal activity. LTP, the most widely accepted molecular model for learning, is best characterised
at glutamatergic synapses on dendritic spines. In this context, LTP involves increases in dendritic spine size and the insertion
of glutamate receptors into the post-synaptic spine membrane, which together boost post-synaptic responsiveness to neurotransmitters.
In dendrites, the material required for LTP is sourced from an organelle termed the endosomal-recycling compartment (ERC),
which is localised to the base of dendritic spines. When LTP is induced, material derived from the recycling compartment,
which contains α-amino-3-hydroxy-5-methyl-4-isoxazole propionate-type glutamate receptors (AMPARs), is mobilised into dendritic
spines feeding the increased need for receptors and membrane at the spine neck and head. In this review, we discuss the importance
of endosomal-recycling and the role of key proteins which control these processes in the context of LTP. 相似文献
44.
The ABCs of cholesterol efflux. 总被引:13,自引:0,他引:13
45.
46.
47.
D. A. B. Young 《Cellular and molecular life sciences : CMLS》1976,32(11):1389-1390
Summary Suspensions of isolated cells from rat heart were prepared and the data for viability and yield are given. Glucose uptake by the cells was mediated by a carrier system.The technical assistance of Mr.E. T. Potter, Mr.K. D. Patel and Mr.M. Griffin is gratefully acknowledged. 相似文献
48.
49.
50.
Summary Treatment of post-feeding larvae of the cabbage maggotDelia radicum with methoprene did not affect the capacity of the insect to pupate, but suppressed eclosion to the adult stage. The concentration of hemolymph trehalose was significantly decreased by methoprene treatment, although hemolymph protein and amino nitrogen levels were unaffected.19 December 1986The authors are grateful to D. C. Read of the Research Centre, Agriculture Canada, Charlottetown, P.E.I., Canada for supplying eggs ofD. radicum for the stock colony. TheD. radicum colony was maintained at the Agriculture Canada Research Station, St. John's West, Newfoundland, Canada. The sample of methoprene was donated by Zoecon Corp., Palo Alto, California, U.S.A. This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (Operating grant A6679). 相似文献