全文获取类型
收费全文 | 536篇 |
免费 | 21篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 42篇 |
地球物理 | 90篇 |
地质学 | 129篇 |
海洋学 | 37篇 |
天文学 | 230篇 |
综合类 | 1篇 |
自然地理 | 34篇 |
出版年
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 31篇 |
2012年 | 8篇 |
2011年 | 19篇 |
2010年 | 21篇 |
2009年 | 29篇 |
2008年 | 16篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 18篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 12篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1969年 | 8篇 |
1968年 | 4篇 |
排序方式: 共有564条查询结果,搜索用时 5 毫秒
561.
562.
Andy J. Howard John N. Carney Malcolm T. Greenwood David H. Keen Tim Mighall Charlotte O’Brien Emma Tetlow 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(3):419-431
This paper provides the first detailed, multi-proxy environmental record for the character of Lateglacial conditions in the lowest Pleistocene terrace of the main valley floor of the River Trent at Holme Pierrepont near Nottingham. The analysis of pollen, plant, insect and mollusc remains preserved within organic channels near the base of the terrace, named the Holme Pierrepont Sand and Gravel by the British Geological Survey (historically known as the Floodplain Terrace), provided evidence of cool, though not fully arctic climatic conditions and a largely treeless landscape, roamed by large herbivores. Radiocarbon dating indicates that these sediments were deposited during the Loch Lomond Stadial (Younger Dryas GS-1). Comparison of these dates from Holme Pierrepont with those from morphostratigraphically similar deposits in the wider Trent catchment suggests that the Holme Pierrepont Sand and Gravel may have been laid down in two separate pulses of braidplain aggradation either side of the ‘Last Glacial Maximum’. It has been demonstrated from historical documentation and riverine archaeological evidence that the middle Trent has been particularly sensitive to changing flood frequency and magnitude associated with climatic oscillations during the late Holocene; this study demonstrates that such sensitivity appears to extend back into the late Pleistocene. The timing of fluvial aggradation recorded at Holme Pierrepont agrees broadly with that recorded from other sites across England and north-west Europe. 相似文献
563.
564.
Integration of a record of Holocene landscape evolution with the cultural record from a multicomponent archaeological site in northern Minnesota has fostered the development of a regional model of human interaction with the changing physical environment. Excavation of 21-CA-169 near Nushka Lake revealed two components, an aceramic Archaic zone where processing of large mammals was the major activity and an upper zone with artifacts suggestive of wild rice processing. Seasonal occupation of the lower zone occurred during a period of falling regional lake levels resulting from natural stream network evolution. The upper zone represents human occupation in a physical and biological setting that was quite different than during earlier occupation. Integration of the geomorphic history of the region along with an interpretation of the types of cultural activities occurring on the changing landscape have provided a model to understand land use and to predict the location of other sites. © 1993 John Wiley & Sons, Inc. 相似文献