全文获取类型
收费全文 | 208篇 |
免费 | 0篇 |
专业分类
系统科学 | 7篇 |
理论与方法论 | 1篇 |
现状及发展 | 50篇 |
研究方法 | 29篇 |
综合类 | 115篇 |
自然研究 | 6篇 |
出版年
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2012年 | 6篇 |
2011年 | 18篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 11篇 |
1999年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1981年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 5篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1966年 | 7篇 |
1965年 | 4篇 |
1964年 | 4篇 |
1962年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有208条查询结果,搜索用时 15 毫秒
21.
22.
J R Blair-West J P Coghlan D A Denton J F Nelson E Orchard B A Scoggins R D Wright K Myers C L Junqueira 《Nature》1968,217(5132):922-928
23.
24.
Hereditary deficiency of pseudocholinesterase in Eskimos 总被引:6,自引:0,他引:6
25.
B M Wright 《Nature》1968,218(5148):1263-1264
26.
27.
28.
Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode 总被引:1,自引:0,他引:1
Seafloor spreading centres show a regular along-axis segmentation thought to be produced by a segmented magma supply in the passively upwelling mantle. On the other hand, continental rifts are segmented by large offset normal faults, and many lack magmatism. It is unclear how, when and where the ubiquitous segmented melt zones are emplaced during the continental rupture process. Between 14 September and 4 October 2005, 163 earthquakes (magnitudes greater than 3.9) and a volcanic eruption occurred within the approximately 60-km-long Dabbahu magmatic segment of the Afar rift, a nascent seafloor spreading centre in stretched continental lithosphere. Here we present a three-dimensional deformation field for the Dabbahu rifting episode derived from satellite radar data, which shows that the entire segment ruptured, making it the largest to have occurred on land in the era of satellite geodesy. Simple elastic modelling shows that the magmatic segment opened by up to 8 m, yet seismic rupture can account for only 8 per cent of the observed deformation. Magma was injected along a dyke between depths of 2 and 9 km, corresponding to a total intrusion volume of approximately 2.5 km3. Much of the magma appears to have originated from shallow chambers beneath Dabbahu and Gabho volcanoes at the northern end of the segment, where an explosive fissural eruption occurred on 26 September 2005. Although comparable in magnitude to the ten year (1975-84) Krafla events in Iceland, seismic data suggest that most of the Dabbahu dyke intrusion occurred in less than a week. Thus, magma intrusion via dyking, rather than segmented normal faulting, maintains and probably initiated the along-axis segmentation along this sector of the Nubia-Arabia plate boundary. 相似文献
29.
It is important that migration is measured accurately, for example to inform population estimates and projections. However, current sources of information present challenges in producing robust estimates of emigration from Great Britain. This article reports on work carried out by the Office for National Statistics to investigate the potential for using administrative data sources to contribute to the measurement of emigration. 相似文献
30.
Periodic circadian (24-h) cycles play an important role in daily hormonal and behavioural rhythms. Usually our sleep/wake
cycle, temperature and melatonin rhythms are internally synchronized with a stable phase relationship. When there is a desynchrony
between the sleep/wake cycle and circadian rhythm, sleep disorders such as advanced and delayed sleep phase syndrome can arise
as well as transient chronobiologic disturbances, for example from jet lag and shift work. Appropriately timed bright light
is effective in re-timing the circadian rhythm and sleep pattern to a more desired time, ameliorating these disturbances.
Other less potent retiming effects may also be obtained from the judicious use of melatonin and exercise. 相似文献