全文获取类型
收费全文 | 271篇 |
免费 | 25篇 |
国内免费 | 46篇 |
专业分类
航空 | 160篇 |
航天技术 | 128篇 |
综合类 | 22篇 |
航天 | 32篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 21篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 13篇 |
2010年 | 15篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 3篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 0 毫秒
341.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(2):1293-1306
We report results of an experimental and theoretical study of complex UV line shapes of Ne II 369.421 nm, Ne II 370.962 nm, Ne II 371.308 nm, and.Ne II 372.711 nm lines in the cathode sheath (CS) region of an abnormal DC glow discharge in pure neon. Two sets of experimental profiles and electric field distributions, one for discharge with tungsten and the other with titanium cathode, were obtained by means of the optical emission spectroscopy (OES) and theoretically studied by the iterative CS kinetic model. It is shown that our theoretical model enables the determination of the most important CS parameters (e.g. the thickness of the CS region, and the theoretical distributions of electric field and gas temperature) and thereupon based accurate theoretical predictions of the experimentally observed profiles of the studied lines. 相似文献
342.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(4):1907-1914
Classic solar atmospheric models put the Chromosphere-Corona Transition Region (CCTR) at Mm above the level, whereas radiative MHD (rMHD) models place the CCTR in a wider range of heights. However, observational verification is scarce. In this work we review and discuss recent results from various instruments and spectral domains. In SDO and TRACE images spicules appear in emission in the 1600, 1700 and 304 Å bands and in absorption in the EUV bands; the latter is due to photo-ionization of H i and He i, which increases with wavelength. At the shortest available AIA wavelength and taking into account that the photospheric limb is Mm above the level, we found that CCTR emission starts at Mm; extrapolating to , where there is no chromospheric absorption, we deduced a height of Mm, which is above the value of 2.14 Mm of the Avrett and Loeser model. Another indicator of the extent of the chromosphere is the height of the network structures. Height differences produce a limbward shift of features with respect to the position of their counterparts in magnetograms. Using this approach, we measured heights of Mm (at 1700 Å), Mm (at 1600 Å) and Mm (at 304 Å) for the center of the solar disk. A previously reported possible solar cycle variation is not confirmed. A third indicator is the position of the limb in the UV, where IRIS observations of the Mg ii triplet lines show that they extend up to Mm above the 2832 Å limb, while AIA/SDO images give a limb height of Mm (1600 Å) and Mm (304 Å). Finally, ALMA mm- full-disk images provide useful diagnostics, though not very accurate, due to their relatively low resolution; values of Mm at 1.26 mm and Mm at 3 mm were obtained. Putting everything together, we conclude that the average chromosphere extends higher than homogeneous models predict, but within the range of rMHD models.. 相似文献