全文获取类型
| 收费全文 | 64篇 |
| 免费 | 0篇 |
专业分类
| 测绘学 | 3篇 |
| 大气科学 | 3篇 |
| 地球物理 | 10篇 |
| 地质学 | 4篇 |
| 海洋学 | 8篇 |
| 天文学 | 32篇 |
| 综合类 | 1篇 |
| 自然地理 | 3篇 |
出版年
| 2022年 | 1篇 |
| 2020年 | 1篇 |
| 2017年 | 4篇 |
| 2016年 | 2篇 |
| 2015年 | 1篇 |
| 2013年 | 8篇 |
| 2011年 | 1篇 |
| 2010年 | 1篇 |
| 2009年 | 1篇 |
| 2008年 | 1篇 |
| 2007年 | 2篇 |
| 2006年 | 6篇 |
| 2005年 | 5篇 |
| 2004年 | 1篇 |
| 2003年 | 1篇 |
| 2002年 | 6篇 |
| 2001年 | 5篇 |
| 2000年 | 3篇 |
| 1998年 | 2篇 |
| 1997年 | 1篇 |
| 1995年 | 1篇 |
| 1992年 | 1篇 |
| 1991年 | 2篇 |
| 1990年 | 1篇 |
| 1988年 | 1篇 |
| 1987年 | 1篇 |
| 1985年 | 2篇 |
| 1978年 | 1篇 |
| 1972年 | 1篇 |
排序方式： 共有64条查询结果，搜索用时 15 毫秒
61.
An approximate expression for the spreading by charge-exchange of a fine proton beam precipitating into the atmosphere is obtained. It shows the dependence on atmospheric structure, collision data and primary particle energy and pitch angle in a simple way. 相似文献
62.
A. C. Fabian J. S. Sanders S. Ettori G. B. Taylor S. W. Allen C. S. Crawford K. Iwasawa R. M. Johnstone P. M. Ogle 《Monthly notices of the Royal Astronomical Society》2000,318(4):L65-L68
We report subarcsec-resolution X-ray imaging of the core of the Perseus cluster around the galaxy NGC 1275 with the Chandra X-ray Observatory . The ROSAT -discovered holes associated with the radio lobes have X-ray bright rims which are cooler than the surrounding gas and not a result of shocks. The holes themselves may contain some hotter gas. We map strong photoelectric absorption across the northern lobe and rim owing to a small infalling irregular galaxy, known as the high-velocity system. Two outer holes, one of which was previously known, are identified with recently found spurs of low-frequency radio emission. The spiral appearance of the X-ray cooler gas and the outer optical parts of NGC 1275 may be due to angular momentum in the cooling flow. 相似文献
63.
Ecosystem-based management of marine fisheries requires the use of simulation modelling to investigate the system-level impact of candidate fisheries management strategies. However, testing of fundamental assumptions such as system structure or process formulations is rarely done. In this study, we compare the output of three different ecosystem models (Atlantis, Ecopath with Ecosim, and OSMOSE) applied to the same ecosystem (the southern Benguela), to explore which ecosystem effects of fishing are most sensitive to model uncertainty. We subjected the models to two contrasting fishing pressure scenarios, applying high fishing pressure to either small pelagic fish or to adult hake. We compared the resulting model behaviour at a system level, and also at the level of model groups. We analysed the outputs in terms of various commonly used ecosystem indicators, and found some similarities in the overall behaviour of the models, despite major differences in model formulation and assumptions. Direction of change in system-level indicators was consistent for all models under the hake pressure scenario, although discrepancies emerged under the small-pelagic-fish scenario. Studying biomass response of individual model groups was key to understanding more integrated system-level metrics. All three models are based on existing knowledge of the system, and the convergence of model results increases confidence in the robustness of the model outputs. Points of divergence in the model results suggest important areas of future study. The use of feeding guilds to provide indicators for fish species at an aggregated level was explored, and proved to be an interesting alternative to aggregation by trophic level. 相似文献
64.
Denitrification was measured over an 8-month period in the Bothnian Bay and the Bothnian Sea, the two northernmost basins of the Baltic Sea. The recorded rates varied between 0 and 0·94 mmol N m−2day−1. In the Bothnian Sea, a seasonal pattern could be discerned with high rates in spring, no rate in summer and a moderate rate in winter. In the Bothnian Bay, no such seasonality was observed. It is suggested that denitrification in the Gulf of Bothnia is regulated by sediment nitrification. Calculation of annual mean rates of denitrification gave that the amount of nitrogen consumed by denitrification corresponded to 1·45×104tons N year−1for the Bothnian Bay and 3·45×104tons N year−1for the Bothnian Sea. A comparison with total N input (river runoff, point sources and atmospheric deposition) to the two basins showed that the proportion of N removed through denitrification amounted to 23% for the Bothnian Bay and 31% for the Bothnian Sea. 相似文献