全文获取类型
收费全文 | 77篇 |
免费 | 1篇 |
专业分类
系统科学 | 2篇 |
现状及发展 | 21篇 |
研究方法 | 10篇 |
综合类 | 44篇 |
自然研究 | 1篇 |
出版年
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有78条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
The recreational use of amphetamine-type stimulants can produce a marked and sometimes lethal increase in body temperature. Here we show that mice deficient in a mitochondrial protein known as UCP-3 (for 'uncoupling protein-3') have a diminished thermogenic response to the drug MDMA (3,4-methylenedioxymethamphetamine, nicknamed 'ecstasy') and so are protected against this dangerously toxic effect. Our findings indicate that UCP-3 is important in MDMA-induced hyperthermia and point to a new therapeutic direction for solving an increasing public-health problem. 相似文献
55.
Population dynamics of Canada lynx (Lynx canadensis) have been of interest to ecologists for nearly sixty years. Two competing hypotheses concerning lynx population dynamics and large-scale spatial synchrony are currently debated. The first suggests that dispersal is substantial among lynx populations, and the second proposes that lynx at the periphery of their range exist in small, isolated patches that maintain cycle synchrony via correlation with extrinsic environmental factors. Resolving the nature of lynx population dynamics and dispersal is important both to ecological theory and to the conservation of threatened lynx populations: the lack of knowledge about connectivity between populations at the southern periphery of the lynx's geographic range delayed their legal listing in the United States. We test these competing hypotheses using microsatellite DNA markers and lynx samples from 17 collection sites in the core and periphery of the lynx's geographic range. Here we show high gene flow despite separation by distances greater than 3,100 km, supporting the dispersal hypothesis. We therefore suggest that management actions in the contiguous United States should focus on maintaining connectivity with the core of the lynx's geographic range. 相似文献
56.
57.
58.
Luo G Santoro IM McDaniel LD Nishijima I Mills M Youssoufian H Vogel H Schultz RA Bradley A 《Nature genetics》2000,26(4):424-429
Bloom syndrome is a disorder associated with genomic instability that causes affected people to be prone to cancer. Bloom cell lines show increased sister chromatid exchange, yet are proficient in the repair of various DNA lesions. The underlying cause of this disease are mutations in a gene encoding a RECQ DNA helicase. Using embryonic stem cell technology, we have generated viable Bloom mice that are prone to a wide variety of cancers. Cell lines from these mice show elevations in the rates of mitotic recombination. We demonstrate that the increased rate of loss of heterozygosity (LOH) resulting from mitotic recombination in vivo constitutes the underlying mechanism causing tumour susceptibility in these mice. 相似文献
59.
60.
It is well documented that the generations born around 1930 are consistently exhibiting higher rates of mortality improvement than the generations either side of them. There is currently no evidence that these differentials are declining. In current ONS National Population Projections, it is assumed that these cohorts will continue to experience higher rates of improvement. However, it is not yet precisely clear why this is so. This article details preliminary research carried out using the ONS Longitudinal Study to try to understand better why the members of the generation born around 1930 have been enjoying higher rates of mortality improvement throughout their adult life. 相似文献