全文获取类型
收费全文 | 1826篇 |
免费 | 376篇 |
国内免费 | 510篇 |
专业分类
测绘学 | 82篇 |
大气科学 | 496篇 |
地球物理 | 535篇 |
地质学 | 794篇 |
海洋学 | 272篇 |
天文学 | 126篇 |
综合类 | 198篇 |
自然地理 | 209篇 |
出版年
2024年 | 5篇 |
2023年 | 32篇 |
2022年 | 66篇 |
2021年 | 74篇 |
2020年 | 67篇 |
2019年 | 70篇 |
2018年 | 79篇 |
2017年 | 78篇 |
2016年 | 83篇 |
2015年 | 81篇 |
2014年 | 84篇 |
2013年 | 89篇 |
2012年 | 94篇 |
2011年 | 109篇 |
2010年 | 103篇 |
2009年 | 112篇 |
2008年 | 100篇 |
2007年 | 136篇 |
2006年 | 102篇 |
2005年 | 70篇 |
2004年 | 56篇 |
2003年 | 68篇 |
2002年 | 45篇 |
2001年 | 48篇 |
2000年 | 77篇 |
1999年 | 109篇 |
1998年 | 101篇 |
1997年 | 82篇 |
1996年 | 86篇 |
1995年 | 60篇 |
1994年 | 55篇 |
1993年 | 58篇 |
1992年 | 33篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 20篇 |
1988年 | 32篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2712条查询结果,搜索用时 171 毫秒
61.
Zhengqiang Li Philippe Goloub Claude Devaux Xingfa Gu Yanli Qiao Fengsheng Zhao Hongbin Chen 《Atmospheric Research》2004,71(4):233-241
Aerosol optical parameters, polarized phase function and single-scattering albdeo, have been retrieved from ground-based sun photometer measurements in Beijing 2003. The measured aerosol optical thickness varies from 0.12 to 0.77 with an average value of 0.39. The measured Ångström coefficient ranges from 0.75 to 1.47 with an average value of 1.21. The retrieved single-scattering albedo at 870 nm is within the 0.76–0.94 range and the average value is 0.85, suggests there are considerable aerosol absorptions in Beijing. The maximum value of retrieved polarized phase function at 870 nm ranges from 0.068 to 0.225 with an average value of 0.16, and it illustrates good correlations with the Ångström coefficient, i.e. the relative size of aerosol particles. Analyses of measurements and theoretical calculations show the polarized phase function is sensitive to aerosol size distribution and complex refractive index, especially the imaginary part of the refractive index which denotes aerosol light absorbing effects. These results suggest that the polarized phase function is an effective and unique aerosol optical parameter and is able to improve the retrieval of aerosol physical properties. 相似文献
62.
63.
The paper introduces the horizontal crustal movement obtained from GPS observations in the regional networks (including the
basic network and the fiducial network) of the Crustal Movement Observation Network of China (CMONOC) carried out in 1999
and 2001. This paper is characterized by the acquisition of the horizontal displacement velocities during the period from
1999 to 2001 at the observation stations in the regional networks with datum definition of a group of stable stations with
small mutual displacements in east China. Based on the most detailed map of horizontal crustal movement in Chinese mainland,
the division of blocks, their displacements and deformations are studied. An approach to analysis of the intensity of the
horizontal crustal deformation is proposed. The general characteristics of the recent horizontal crustal movement in Chinese
mainland and that before the Kunlunshan earthquake of M=8.1 on November 14, 2001 are analyzed.
Foundation item: The National Development and Programming Project for Key Basic Research (95-13-03-07). 相似文献
64.
65.
66.
67.
68.
69.
70.
Although Eddy Covariance (EC) technique is one of the best methods for estimating the energy and mass exchanges between underlying surface and atmosphere in micrometeorology, errors and uncertainties still exist without necessary corrections. In this paper, we will focus on the effect of coordinate system on the eddy fluxes. Based on the data observed over four sites (one farmland site, one grassland site and two forest sites), the effects of three coordinate system transforming methods (Double Rotation-DR, Triple Rotation-TR and Planar Fit-PF)on the turbulent fluxes are analyzed. It shows that (i) the corrected fluxes are more or less than the uncorrected fluxes, which is related mainly to the sloping degree of surface, wind speed and wind direction; and (ii) pitch angle has a sinusoidal dependence on wind direction, especially in the regular sloping terrain; and (iii) PF method is something like the simplification of TR or DR,and there are not obvious distinctions in correction in sloping grassland and flat farmland, but PF method is not suitable for uneven and irregular forest sites. 相似文献