全文获取类型
收费全文 | 50502篇 |
免费 | 8761篇 |
国内免费 | 11634篇 |
专业分类
测绘学 | 4660篇 |
大气科学 | 5196篇 |
地球物理 | 10515篇 |
地质学 | 31749篇 |
海洋学 | 5605篇 |
天文学 | 2254篇 |
综合类 | 3415篇 |
自然地理 | 7503篇 |
出版年
2024年 | 276篇 |
2023年 | 769篇 |
2022年 | 1642篇 |
2021年 | 1732篇 |
2020年 | 1844篇 |
2019年 | 2025篇 |
2018年 | 1589篇 |
2017年 | 1808篇 |
2016年 | 2004篇 |
2015年 | 2186篇 |
2014年 | 2659篇 |
2013年 | 2590篇 |
2012年 | 2950篇 |
2011年 | 3134篇 |
2010年 | 2701篇 |
2009年 | 3191篇 |
2008年 | 3173篇 |
2007年 | 3538篇 |
2006年 | 3442篇 |
2005年 | 3040篇 |
2004年 | 2826篇 |
2003年 | 2694篇 |
2002年 | 2433篇 |
2001年 | 2143篇 |
2000年 | 1978篇 |
1999年 | 1856篇 |
1998年 | 1612篇 |
1997年 | 1455篇 |
1996年 | 1314篇 |
1995年 | 1101篇 |
1994年 | 1134篇 |
1993年 | 970篇 |
1992年 | 752篇 |
1991年 | 541篇 |
1990年 | 477篇 |
1989年 | 379篇 |
1988年 | 287篇 |
1987年 | 187篇 |
1986年 | 119篇 |
1985年 | 83篇 |
1984年 | 35篇 |
1983年 | 31篇 |
1982年 | 31篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 29篇 |
1978年 | 35篇 |
1977年 | 24篇 |
1974年 | 4篇 |
1954年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
81.
Szilárd Csizmadia Zsolt Kővári Péter Klagyivik 《Astrophysics and Space Science》2006,304(1-4):355-357
We carried out optical and Hα photometry of two contact binaries (V861 Herculis, EQ Tauri). The light curve modeling revealed stellar spots in both contact systems and strong Hα excess in the position of the observed stellar spots. A correlation was found between the V−R and R−Hα colour indices of V861 Her. 相似文献
82.
83.
84.
尚永亮 《广东海洋大学学报》2003,23(2):27-29
古代荆湘之地域的特殊性使其成为朝廷贬官吏的首选之地和贬官的中转之地。在此 ,这些被贬官首创了大量关于贬谪的文学作品。其作品物色鲜明 ,楚地风情突出 ,具有近乎凝固化了的悲怨传统 ,早期逐臣、作品及谪地成为凝定的贬谪代码和符号 ,生成并积淀了深厚的人文精神。 相似文献
85.
A calculation formula on spherical pattern of Qinghai-Tibet plateau moving model is established. Tibet massif moves norward by east in speed of 28 mm/a, Ganshu-Qinghai massif moves to northeast in speed of 15 mm/a, Qomolangma Feng moves northward by a few east in speed of 35 ~42 mm/a. The low latitude perimeter is longer than the nigh latitude perimeter. When the Tibet massif moves northward, its latitude perimeter must be contracted and the Tibet massif must move eastward by Coriolis. Coriolis force is inertial in earth rotation. It makes the fall body turning to east and the rising block turning westward. In the Northern Hemisphere, it makes the northward body turning to east and the southward block turning to west.This is the reason why the tectonic zones of western Pacific are different from those of eastern Pacific. 相似文献
86.
Variables related to urban park awareness are identified and methods for relaxing assumptions of perfect information in park use models are discussed. Park awareness is related to park characteristics (age and degree of development of the park), population characteristics (race, age, length of residence, recreation participation), and distance. Park attributes are stronger predictors of both park awareness and use than is distance. These findings parallel similar research on the cognitive aspects of shopping decisions. 相似文献
87.
《The Professional geographer》1987,39(1):85-94
Reviews of geographic software in this article: DEMO-GRAPHICS: WORLD POPULATIONS AND PROJECTIONS. ESP GAUSS. CEMODEL S. Damus LIMDEP. William H. Greene MICROSTAT 4.1 OTIS PCIPS. (Personal Computer Image Processing System) . H.J. Meyers and R. Bernstein. REGRESSION ANALYSIS OF TIME SERIES (RATS) SPSS/PC+ URBAN DATA MANAGEMENT SOFTWARE (UDMS) 相似文献
88.
卞菊梅 《地球科学与环境学报》1995,(1)
本文主要依据地形图和航空照片解译,并经已有地质、钻孔资料验证及野外实地考察的方法来研究地形面及其变形特征,由此确定渭河盆地活断层的分布、最新活动特征及活动规律,为地震预报及地震危险性分析提供依据。 相似文献
89.
90.
Results of a single group participating in an international experiment are analyzed. The experiment served to verify computational predictions of the ground-motion variations due to near-surface geological effects at a site established for that purpose by the California Department of Conservation. Based on an acceleration record at a rock location, and geotechnical model of medium, records at the other locations of a nearby sedimentary deposit were predicted. A 2-D finite-difference sensitivity analysis suggested that the lateral wave-propagation effects are negligibly small, and locally 1-D computations are sufficient for the present site. Those computations are compared with observations not available to the authors during the blind prediction. Peak accelerations, peak velocities and RMS accelerations were predicted with errors less than 159%, 114% and 62%, respectively. Maxima of the response spectra were fitted within a factor of 2. The predicted and observed Husid's plots (i.e., the normalized cumulative plots of the acceleration squared) have the correlation coefficients 0.98. The detected misfits do not show any simple relation to the instrument location, component, frequency, or time. 相似文献