全文获取类型
收费全文 | 304篇 |
免费 | 35篇 |
国内免费 | 5篇 |
专业分类
航空 | 139篇 |
航天技术 | 75篇 |
综合类 | 56篇 |
航天 | 74篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 26篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 11篇 |
2008年 | 18篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 21篇 |
2004年 | 22篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
排序方式: 共有344条查询结果,搜索用时 15 毫秒
341.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(1):654-675
Space law education has an essential role in the space capacity building of a country because of its importance for human resources development in space law. Comparisons between Canada and China, the European Union and China and the United States of America (USA) and China in space law degree education, course, teaching methodology, institute and practice and communication platform are provided in an attempt to review some issues which exist within the Chinese space law educational system and to seek a better choice for China’s space law education reform. Chinese space law education has achieved noticeable progress over the past two decades. However, it is still limited in comparison to its counterparts in Europe and Northern America. The range of the space law degree education programmes and space-law-related courses is comparatively limited. A gap remains between space law education and practice in China. Chinese space law classes are still dominated by the teacher-centred teaching methodology, although several universities have some new teaching practices. The establishment of seven space law-related research institutes plays an increasingly important role in Chinese space law education, space law and policy research and legal advisory services for the Chinese government and non-governmental sectors. However, these institutes still have a long way to go in comparison with their counterparts in Europe and Northern America. While China has established domestic research platforms for space law communication through international cooperation, it does not provide space law practice platforms for space law education. While international space law does not provide a direct legal foundation for space law education in China, Chinese educational laws can lay a profound legal foundation for Chinese space law education. To promote its national expertise and capacity in space law, based on the three-pillar model and the experiences of its counterparts in North America and Europe, China should adopt a systematic and sustainable regime for its space law education. 相似文献
342.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(6):2909-2923
Coastal marine gravity modeling faces challenges due to the degradation of the quality and poor coverage of altimeter data in coastal regions. The effective fusion of shipborne gravity data and altimeter-derived marine gravity data can make shipborne gravity data more useful for the accurate estimation of altimeter-derived coastal marine gravity. A mean sea surface height constraint factor (MSSHCF) method based on the ordinary kriging method and the remove-restore technique is proposed to fuse altimeter-derived gravity model with shipborne gravity data. In this method, all data are standardized during the interpolation process to reduce the error and mean sea surface as a vertical variable is added to the semi-variance function in ordinary kriging to obtain the residual shipborne gravity as corrected data source. The coastal marine gravity models V2.1 and V3.1 which fused altimeter-derived gravity data with shipborne gravity data and V1.1 without shipborne gravity data at a spatial resolution of 1′×1′ can be obtained. Validation experiments show that the accuracy of the gravity model V3.1 obtained by the MSSHCF method more closely agrees with the validated gravity model DTU17 and SS V31 than the model V2.1 obtained by the ordinary kriging interpolation method and the V1.1 model. Our results were validated against shipborne gravity data; the accuracy of model V3.1 was 4.95 % higher than the model V1.1 in South China Sea area A and 2.48 % higher in South China Sea area B. Meanwhile, the accuracy of model V3.1 was 2.07 % higher than model V2.1 in South China Sea area A and 2.42 % higher in South China Sea area B. The effects of distance from the coast and sea depth on the marine gravity model were also evaluated. The results show that the gravity model V3.1 has higher accuracy with the change in ocean distance and depth than the V2.1 and V1.1 gravity models. Thus, our study shows that the MSSHCF method effectively refines coastal altimeter-derived gravity using shipborne gravity data. 相似文献
343.
344.