全文获取类型
收费全文 | 402篇 |
免费 | 25篇 |
国内免费 | 16篇 |
专业分类
航空 | 203篇 |
航天技术 | 10篇 |
综合类 | 131篇 |
航天 | 99篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 33篇 |
2013年 | 36篇 |
2012年 | 30篇 |
2011年 | 41篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 44篇 |
2007年 | 30篇 |
2006年 | 19篇 |
2005年 | 31篇 |
2004年 | 22篇 |
2003年 | 19篇 |
2002年 | 32篇 |
2001年 | 13篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
排序方式: 共有443条查询结果,搜索用时 15 毫秒
441.
通过反应熔渗(RMI)方式,以缝合碳纤维预制体和Si-Zr合金作为反应物,制备得到Cf/C-ZrC-SiC复合材料,并利用SEM-EDS和XRD系统分析了复合材料的微观结构,可以明确SiC-ZrC陶瓷基体在材料内部分布比较均匀且致密度较高。得益于上述基体结构,Cf/C-ZrC-SiC复合材料的弯曲强度和模量分别达到323.2 MPa和46.6 GPa,表现为韧性断裂。采用氧乙炔实验进行抗烧蚀测试,在表面温度为18 00~1 900 ℃下,ZrC含量较多的Cf/C-ZrC-SiC复合材料质量烧蚀率和线烧蚀率分别为1.263 mg/s和2.367 μm/s,ZrC含量较少的Cf/C-SiC-ZrC复合材料分别为2.056 mg/s和5.067 μm/s,Cf/C-ZrC-SiC复合材料表现出更加优异的抗烧蚀性能。 相似文献
442.
443.
《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