全文获取类型
收费全文 | 434篇 |
免费 | 14篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 17篇 |
地球物理 | 91篇 |
地质学 | 188篇 |
海洋学 | 12篇 |
天文学 | 63篇 |
综合类 | 1篇 |
自然地理 | 65篇 |
出版年
2023年 | 3篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 16篇 |
2011年 | 15篇 |
2010年 | 12篇 |
2009年 | 30篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 21篇 |
2001年 | 6篇 |
2000年 | 13篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1955年 | 3篇 |
1949年 | 2篇 |
排序方式: 共有452条查询结果,搜索用时 15 毫秒
451.
The celestial mechanics approach: theoretical foundations 总被引:4,自引:3,他引:1
Gravity field determination using the measurements of Global Positioning receivers onboard low Earth orbiters and inter-satellite
measurements in a constellation of satellites is a generalized orbit determination problem involving all satellites of the
constellation. The celestial mechanics approach (CMA) is comprehensive in the sense that it encompasses many different methods
currently in use, in particular so-called short-arc methods, reduced-dynamic methods, and pure dynamic methods. The method
is very flexible because the actual solution type may be selected just prior to the combination of the satellite-, arc- and
technique-specific normal equation systems. It is thus possible to generate ensembles of substantially different solutions—essentially
at the cost of generating one particular solution. The article outlines the general aspects of orbit and gravity field determination.
Then the focus is put on the particularities of the CMA, in particular on the way to use accelerometer data and the statistical
information associated with it. 相似文献
452.
Gert Finger Frank Eisenhauer Reinhard Genzel Christopher Mandla Ian Baker Domingo Alvarez Antonio Amorim Wolfgang Brandner Christophe Dupuy Casey Deen Derek Ives Leander Mehrgan Manfred Meyer Karin Perraut Guy Perrin Jörg Stegmeier Christian Straubmeier Harald J. Weller Vincent Isgar 《Astronomische Nachrichten》2023,344(8-9):e20230069
Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e−APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is mk = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10−3 e−/s have been demonstrated with 1Kx1K e−APD arrays and 2Kx2K e−APD arrays have already been developed, the possibilities and adaptations of e−APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed. 相似文献