全文获取类型
收费全文 | 157篇 |
免费 | 6篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 17篇 |
地球物理 | 39篇 |
地质学 | 31篇 |
海洋学 | 19篇 |
天文学 | 35篇 |
综合类 | 1篇 |
自然地理 | 19篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 18篇 |
2009年 | 10篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 12篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 15 毫秒
21.
Development and verification of deep-water blowout models 总被引:2,自引:0,他引:2
Johansen Ø 《Marine pollution bulletin》2003,47(9-12):360-368
Modeling of deep-water releases of gas and oil involves conventional plume theory in combination with thermodynamics and mass transfer calculations. The discharges can be understood in terms of multiphase plumes, where gas bubbles and oil droplets may separate from the water phase of the plume and rise to the surface independently. The gas may dissolve in the ambient water and/or form gas hydrates––a solid state of water resembling ice. All these processes will tend to deprive the plume as such of buoyancy, and in stratified water the plume rise will soon terminate. Slick formation will be governed by the surfacing of individual oil droplets in a depth and time variable current. This situation differs from the conditions observed during oil-and-gas blowouts in shallow and moderate water depths. In such cases, the bubble plume has been observed to rise to the surface and form a strong radial flow that contributes to a rapid spreading of the surfacing oil. The theories and behaviors involved in deepwater blowout cases are reviewed and compared to those for the shallow water blowout cases. 相似文献
22.
Challenges in global ballast water management 总被引:3,自引:0,他引:3
Endresen Ø Lee Behrens H Brynestad S Bjørn Andersen A Skjong R 《Marine pollution bulletin》2004,48(7-8):615-623
Ballast water management is a complex issue raising the challenge of merging international regulations, ship's specific configurations along with ecological conservation. This complexity is illustrated in this paper by considering ballast water volume, discharge frequency, ship safety and operational issues aligned with regional characteristics to address ecological risk for selected routes. A re-estimation of ballast water volumes gives a global annual level of 3500 Mton. Global ballast water volume discharged into open sea originating from ballast water exchange operations is estimated to approximately 2800 Mton. Risk based decision support systems coupled to databases for different ports and invasive species characteristics and distributions can allow for differentiated treatment levels while maintaining low risk levels. On certain routes, the risk is estimated to be unacceptable and some kind of ballast water treatment or management should be applied. 相似文献
23.
S. Solberg T. Krognes F. Stordal OØ Hov H. J. Beine D. A. Jaffe K. C. Clemitshaw S. A. Penkett 《Journal of Atmospheric Chemistry》1997,28(1-3):209-225
Simultaneousindependent measurements of NOy and NOx(NOx= NO + NO2) by high-sensitivitychemiluminescence systems and of PAN (peroxyacetylnitrate) and PPN (peroxypropionyl nitrate) by GC-ECDwere made at Spitsbergen in the Norwegian Arcticduring the first half year of 1994. The average mixingratio of the sum of PAN and PPN (denoted PANs)increased from around 150 pptv in early winter to amaximum of around 500 pptv in late March, whereasepisodic peak values reached 800 pptv. This occurredsimultaneously with a maximum in ozone which increasedto 45–50 ppbv in March–April. The average NOxmixing ratio was 27 pptv and did not show any cyclethrough the period. The NOy mixing ratio showeda maximum in late March, while the difference betweenNOy and PAN decreased during spring. This is anindication of the dominance of PAN in the NOybudget in the Arctic, but possible changes in theefficiency of the NOy converter could alsocontribute to this. Although most PAN in theArctic is believed to be due to long range transport,the observations indicate local loss and formationrates of up to 1–2 pptv h-1 in April–May.Measurements of carbonyl compounds suggest thatacetaldehyde was the dominant, local precursor ofPAN.Now at 1. 相似文献
24.
25.
Øystein Dalland 《Geoforum》1983,14(2):193-203
This paper explores the historical, geographical and human ecology aspects of an extreme conflict between development and conservation in northern Scandinavia. Development of hydro-power projects not only affects the physical environment but also conflicts with the culture of a distinct ethnic community, the Sami Lapps. Over one hundred power and mining projects have now been constructed in Sami territory, the cumulative effects of which have focused opposition to the Alta—Kautokeino Waterway. The long- and short-term origins of the conflict are analysed in the light of Sami ecology and Norwegian administrative principles. How the Sami ecology has affected the national frontiers and recent resource management issues are described. Finally, the importance of environmental protests and public hearings in the resolution of fundamental resource/land use conflicts is discussed. The author concludes that the basic aspects of land use conflict may be analysed by using a symbiotic ecology model and applying this to technical human activities. 相似文献
26.
This paper reviews the exploration history of the Barents Sea part of the Norwegian continental shelf. The main structural elements which so far have been identified in the Troms/Finnmark/Barents Sea region are outlined and discussed. Special attention is given to the selected Area I outside Troms, where according to latest government plans, drilling will start in 1978. At least two different fault systems are discribed in Area I. The salt diapirs in the Tromsø Basin and their location relative to the fault pattern are discussed. A schematic structural model for Area I is suggested. 相似文献
27.
Two years of individual nonmethane hydrocarbon (NMHC) measurements at a rural site close to the south coast of Norway show that there was a distinct annual cycle with a late winter maximum and late summer minimum in the slowly reacting NMHCs acetylene, ethane, propane and i- and n-butane. The average January—March concentrations were a factor 2–4 higher than the July-September concentrations. Also ethene, propene and the pentanes show a similar annual cycle, but the individual scatter in the measurements in particular of propene, is large. The highest concentrations of NMHC were found in winter for easterly transport on a regional scale (out to 1500 km from the site), and for southeasterly transport in the summer. 相似文献
28.
PETER STRØMGAARD M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):6-12
Stromgaard, Peter: Potential Crop Production—illustrated by an example from West Africa, Geografisk Tidsskrift, 77: 6—12, København, June 1, 1978. Different ways of describing and modelling the process of primary production are compared, and the concept of potential crop production is elaborated. Two mathematical models are suggested, converted into FORTRAN IV, and used for an estimation of potential productivity in Ghana. 相似文献
29.
30.
We explore flat ΛCDM models with bulk viscosity, and study the role of the bulk viscosity in the evolution of these universe
models. The dynamical equations for these models are obtained and solved for some cases of bulk viscosity. We obtain differential
equations for the Hubble parameter H and the energy density of dark matter ρ
m
, for which we give analytical solutions for some cases and for the general case we give a numerical solution. Also we calculate
the statefinder parameters for these models and display them in the s–r-plane. 相似文献