全文获取类型
收费全文 | 958篇 |
免费 | 30篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 21篇 |
大气科学 | 48篇 |
地球物理 | 263篇 |
地质学 | 290篇 |
海洋学 | 60篇 |
天文学 | 250篇 |
综合类 | 2篇 |
自然地理 | 58篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 20篇 |
2018年 | 30篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 39篇 |
2014年 | 33篇 |
2013年 | 34篇 |
2012年 | 52篇 |
2011年 | 58篇 |
2010年 | 45篇 |
2009年 | 69篇 |
2008年 | 56篇 |
2007年 | 59篇 |
2006年 | 44篇 |
2005年 | 47篇 |
2004年 | 43篇 |
2003年 | 35篇 |
2002年 | 38篇 |
2001年 | 30篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有992条查询结果,搜索用时 0 毫秒
991.
José Maria Filippini-Alba Carlos Roberto de Souza Filho 《Environmental Earth Sciences》2010,59(5):1139-1147
The Ribeira Valley region (State of Sao Paulo, Brazil) hosts the largest Brazilian Atlantic forest reserve. The region was
an important mineral district during the ‘60s, from where several tons of lead and other metals were exploited. Residual materials
produced by the mining are diffused in the environment until today. The area also encompasses a regional arsenium anomaly
associated with unexplored gold deposits. The population presently living in this region performs basic farming activities,
from which most of their food is yielded. These features coupled together imply in a complex relationship between natural
and anthropogenic factors that are likely to affect the life and health of the local communities. The aim of this paper is
to apply digital data integration techniques for environmental risk assessment in the Ribeira Valley using environmental geochemistry.
Geochemical, digital elevation and remote sensing data (Landsat Thematic Mapper) were merged and analyzed using a geographical
information system. The assumed model considered environmental mobilization through erosion and anomalous As–Pb areas. Data
were analyzed through Boolean and fuzzy logic techniques. Fuzzy logic proved superior in this case study as it allowed not
only the detection but also the distinction between low, moderate and high environmental risk areas. 相似文献
992.
Continental evaporites are deposits that originate from the evaporation of saline waters in the low areas of saline lakes from all continents, except Europe, and mainly consist of chloride, sulphate and potash minerals. In recent years, the discovery on the Martian surface of hydrated salt minerals, including sulphates and chlorides, interpreted as deriving from the desiccation of preexisting large bodies of water, such as lakes, has provided further convincing evidence of liquid water activity on the surface of Mars and, consequently, it has reinforced the plausibility of finding life. Because evaporites require short‐term aqueous processes for their formation, they can trap and preserve over geologic times a biological record made up of halophilic extremophiles—such as microalgae, bacteria, and their remains—that recent research on Earth has shown to be characterized by unexpectedly high biodiversity. This record may consist of varying types of fossils, including morphological fossils, chemofossils and biominerals. As a consequence, continental evaporite environments and their saline deposits are now a primary target for the near future astrobiology missions devoted to the search for fossil Martian life. Lacustrine evaporite deposits and minerals have, therefore, been identified as primary targets for the NASA–ESA joint programme of the Mars sample return, planned for the end of the current decade. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献