全文获取类型
收费全文 | 201篇 |
免费 | 12篇 |
国内免费 | 33篇 |
专业分类
测绘学 | 4篇 |
地球物理 | 1篇 |
地质学 | 77篇 |
海洋学 | 8篇 |
天文学 | 151篇 |
综合类 | 3篇 |
自然地理 | 2篇 |
出版年
2023年 | 3篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 13篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 14篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
排序方式: 共有246条查询结果,搜索用时 79 毫秒
161.
162.
Jun MaNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2003,3(6):499-504
In the first paper of this series, we directly studied the mathematical forms, symmetry of spiral structure, and the projection of galactic discs on the images, and measured the pitch angles of the spiral arms and inclination angles of the galactic discs for 60 spiral galaxies. In this second paper, we estimate the vertical scale parameters of 48 non-edge-on spiral galaxies based on the method proposed by Peng et al. and on the results given in Paper Ⅰ. As we know, for edge-on disc galaxies we can obtain the vertical scale parameter from the photometry, once a mathematical form is specified for the vertical light distribution. For non-edgeon galaxies, some other methods have to be used. The statistical result was that the vertical scale parameter is comparable for edge-on and non-edge-on galaxies, although it is obtained from two very different methods. 相似文献
163.
164.
基于NASA/IPAC河外星系数据库(NASA/IPAC Extragalactic Database,NED)和Sloan数字巡天(Sloan Digital Sky Survey,SDSS)第8次释放的数据(The Eighth Data Release,DR8),对星系团Abell 85(以下简称A85)的2倍动力学特征半径2r_(200)内的光度函数(Luminosity Function,LF)进行了研究.研究表明,A85的光度函数在Sloan巡天5个波段用Schechter函数均能拟合得很好.在u、g和z波段光度函数都显示出1个下凹.早型星系r波段的两个最佳拟合参数(r波段特征绝对星等和暗端的陡度)分别为M_r~*=-21.14_(-0.17)~(+0.17)mag,α=-0.83_(-0.14)~(+0.12),晚型星系为M_r~*=-21.98_(-0.98)~(+0.84)mag,α=-1.5_(-0.35)~(+0.24).早型星系的特征星等暗于晚型星系,而暗端比晚型星系要平坦得多.早型星系的光度函数在-20.5~-20.0 mag下凹.将1.5r_(200)范围内的星系按距离团中心的远近划分为3个环状区域,发现距离团中心越近,光度函数的暗端越陡,特征星等越亮. 相似文献
165.
Lu-Lu Fan Andrea Lapi Alessandro Bressan Mario Nonino Gianfranco De Zotti Luigi Danese 《中国天文和天体物理学报》2014,(1):15-34
We build a sample of 298 spectroscopically-confirmed galaxies at redshift z - 2, selected in the z850-band from the GOODS-MUSIC catalog. By utilizing the rest frame 8 p.m luminosity as a proxy of the star formation rate (SFR), we check the accuracy of the standard SED-fitting technique, finding it is not accurate enough to provide reliable estimates of the physical parameters of galaxies. We then develop a new SED-fitting method that includes the IR luminosity as a prior and a generalized Calzetti law with a variable Rv. Then we exploit the new method to re-analyze our galaxy sample, and to robustly determine SFRs, stellar masses and ages. We find that there is a general trend of increasing attenuation with the SFR. Moreover, we find that the SFRs range between a few to 103 M~ yr-1, the masses from 109 to 4 ~ 1011 Mo, and the ages from a few tens of Myr to more than 1 Gyr. We discuss how individual age measurements of highly attenuated objects indicate that dust must have formed within a few tens of Myr and already been copious at 〈 100 Myr. In addition, we find that low luminosity galaxies harbor, on average, significantly older stellar populations and are also less massive than brighter ones; we discuss how these findings and the well known 'downsizing' scenario are consistent in a framework where less massive galaxies form first, but their star formation lasts longer. Finally, we find that the near-IR attenuation is not scarce for luminous objects, contrary to what is customarily assumed; we discuss how this affects the interpretation of the observed M,/L ratios. 相似文献
166.
168.
169.
Tao Hu Zheng-Yi Shao Qiu-He Peng Department of Astronomy Nanjing University Nanjing Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Joint Institute for Galaxies Cosmology Chinese Academy of Sciences Shanghai Joint Astrophysics Center of Chinese Academy of Sciences-Peking University Beijing The Open Laboratory of Cosmic Ray High Energy Astrophysics Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(2):175-180
We have studied some properties including surface brightness in the u, g, r, i, and z bands of the nearly face-on galaxy PGC 35105. By subtracting a model surface brightness distribution from the observed image we obtain the residual image that shows only the spiral arms freed from the contamination by the bulge. From this we measured the the inclination, pitch angle, and forbidden radius (identified with the innermost point of the arm) for each of the two arms; and that for each of the five observing bands. We found these three parameters are largely independent of the observing band. 相似文献
170.
白矮星演化与宇宙纪年学 总被引:2,自引:0,他引:2
近几年白矮星研究在理论与观测方面都取得了很大进展,这推动了白矮星宇宙纪年学的应用和发展。白矮星宇宙纪年学,即利用白矮星的演化结果计算白矮星理论光度函数,并通过与现测光度函数的对比来确定天体年龄。简要描述了白矮星的基本性质,回顾了白矮星演化研究的历史和基本方法;介绍了白矮星宇宙纪年学研究的基本原理及其在银盘、球状星团、疏散星团以及银晕年龄确定方面的应用现状。白矮星宇宙纪年学是一个很新的研究领域,但它已经在确定天体年龄方面显示出很大的潜力。最后讨论了目前研究中存在的问题,并提出今后需要进一步研究的几项工作。 相似文献