全文获取类型
收费全文 | 47篇 |
免费 | 0篇 |
专业分类
大气科学 | 14篇 |
地球物理 | 4篇 |
地质学 | 1篇 |
海洋学 | 3篇 |
天文学 | 12篇 |
自然地理 | 13篇 |
出版年
2020年 | 1篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 4篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有47条查询结果,搜索用时 15 毫秒
41.
The 30 MHz absorption observed by a network of wide-beam riometers in Scandinavia is compared to the expected absorption calcvlated on the basis of simultaneously observed fluxes of precipitating electrons in the 10–80 keV energy band at geostationary distance and in magnetic coincidence with the riometer network. By choosing a reasonable altitude profile of the effective recombination coefficient, it is found to be possible to match the observed and calculated absorptions. Further calculations indicate that precipitating electrons of higher energy may be responsible for some of the observed absorption. An empirical law is given which relates the observed absorption to the energy flux of 40–80 keV electrons incident on the atmosphere. 相似文献
42.
43.
Juha E. P. Heikkinen Marja Maljanen Mika Aurela Ken J. Hargreaves Pertti J. Martikainen 《Polar research》2002,21(1):49-62
We studied carbon dynamics on various surface parts of a highly patterned fen, typical in northern Finland, to examine the importance of different microsites to the areal carbon fluxes. The studies were carried out in June-September 1995 on a mesotrophic flark fen (an aapa mire) in Kaamanen (69°08'N, 27° 17'E). Wet flarks, moist lawns and dry strings accounted for 60%, 10% and 30% of the surface area, respectively. A static chamber technique was applied to measure the CH4 exchange, the instantaneous net ecosystem exchange (NEE, transparent chamber) and the ecosystem respiration (Rtot' opaque chamber) in several microsites. The static chamber results were compared with those obtained by the eddy covariance technique. The mean daytime areal net ecosystem CO2 exchange rate measurement in conditions where photosynthesis was light saturated (PAR>400 μmol m-2 s-1 ) varied during the measurement period from −59 mg CO2 -C m−2 h−1 (release) to 250 (uptake). The mean CH4 emission during the measuring period was 78 mg CH4- Cm−2 d−1 on the flarks, 68 mg on the lawn and 6.0 mg on the strings. The strings without shrubs (mainly Betula nana ) were in general net sources of CO2 , even during the middle of the growing season, whereas the lawns, flarks and also strings growing B. nana showed a daytime net uptake of CO2 . Areally integrated chamber results showed lower CO2 and higher CH4 fluxes than predicted from the eddy covariance measurements. 相似文献
44.
45.
Tom Hargreaves 《Geoforum》2012,43(2):315-324
Drawing on Flyvbjerg’s (2001) call for the development of phronetic social science, this paper argues that much current research into pro-environmental behaviour (PEB) is misguided, and even potentially dangerous. After outlining Flyvbjerg’s argument, it reviews existing work on PEB and argues that, to date, it has predominantly sought after the Aristotelian intellectual virtues of either episteme or techne, and has neglected phronesis which Aristotle himself saw as most important. It then explores the ways in which aspects of a phronetic approach are being developed in cultural geography and environmental sociology, before offering a brief empirical case study of a PEB-change initiative to illustrate what a phronetic approach to research might look like. It concludes by calling for an improved and more reflexive dialogue between PEB researchers regarding the purpose and approach of their work, both in order to improve the relevance and impact of their research, and in order to help individuals and communities understand and confront the significant environmental challenges they currently face. 相似文献
46.
47.