全文获取类型
收费全文 | 2406篇 |
免费 | 49篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 73篇 |
大气科学 | 70篇 |
地球物理 | 1186篇 |
地质学 | 557篇 |
海洋学 | 25篇 |
天文学 | 446篇 |
综合类 | 5篇 |
自然地理 | 97篇 |
出版年
2019年 | 26篇 |
2018年 | 52篇 |
2017年 | 53篇 |
2016年 | 67篇 |
2015年 | 54篇 |
2014年 | 54篇 |
2013年 | 77篇 |
2012年 | 79篇 |
2011年 | 70篇 |
2010年 | 62篇 |
2009年 | 70篇 |
2008年 | 58篇 |
2007年 | 74篇 |
2006年 | 65篇 |
2005年 | 45篇 |
2004年 | 53篇 |
2003年 | 52篇 |
2002年 | 46篇 |
2001年 | 34篇 |
2000年 | 36篇 |
1999年 | 28篇 |
1997年 | 29篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 33篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 47篇 |
1990年 | 25篇 |
1989年 | 56篇 |
1988年 | 33篇 |
1987年 | 48篇 |
1986年 | 40篇 |
1985年 | 43篇 |
1984年 | 36篇 |
1983年 | 42篇 |
1982年 | 44篇 |
1981年 | 39篇 |
1980年 | 41篇 |
1979年 | 39篇 |
1978年 | 48篇 |
1977年 | 38篇 |
1976年 | 27篇 |
1975年 | 33篇 |
1974年 | 29篇 |
1973年 | 29篇 |
1972年 | 32篇 |
1971年 | 46篇 |
1969年 | 28篇 |
1968年 | 30篇 |
排序方式: 共有2459条查询结果,搜索用时 15 毫秒
91.
92.
Summary The atmospheric mean energetic level and corresponding flow pattern are studied theoretically in terms of the prescribed divergence of the horizontal wind vector. The divergence field may reflect the diabatic effect due to particles of extraterrestrial origin. 相似文献
93.
94.
The Pond of Dvorec, used for a final treatment of waste waters and at the same time for fish breeding, has been observed working in an assimilation and later on in a stabilization mode (SVOBODA and KOUBEK) . The data on the chemical composition and microbiological properties of its sediments are given. A comparative analysis of the stabilization pond sediments and the sediments of the second stabilization pond have shown a high purification function. An influence of temperature, aeration and thickness of the layer upon a microbial activity and a release of the substance into the water environment were verified in laboratory experiments. A higher layer of sediments can, above all at increased temperatures, negatively influence the water quality for fish breeding. After composting the drawn pond sediments can be recommended for the fertilization of an agricultural land in near surroundings. 相似文献
95.
96.
97.
98.
99.
Summary The paper is intended as a contribution to the quantitative analysis of travel-time curves of seismic events recorded in the Ostrava-Karviná District (OKD). The input data represent a set of 2621 seismic events, recorded by the local seismological network of 26 mine stations DSLA and a regional diagnostic polygon consisting of five surface Lennartz stations. All the events were processed automatically in the Operational Seismological Centre of the Czechoslovak Army Mine in Karviná and stored in the seismological data base. The results are presented in the form of graphs of arrival times versus distance for the whole OKD, for two mines and one tectonic block.Travel-time curves of direct P and S waves, as well as of reflected and refracted waves are given. The direct P and S waves propagate well practically throughout the whole region studied, but their apparent velocities of propagation are affected by the properties of the rock medium.As a result of the complicated geological conditions, the recorded wave image is quite complicated. Methods of mathematical modelling, using kinematic and dynamic parameters of seismic waves, will have to be applied to identify the separate wave groups uniquely. 相似文献
100.
Radan Květ 《GeoJournal》1994,34(4):365-370