全文获取类型
收费全文 | 1963篇 |
免费 | 74篇 |
国内免费 | 23篇 |
专业分类
测绘学 | 84篇 |
大气科学 | 152篇 |
地球物理 | 705篇 |
地质学 | 681篇 |
海洋学 | 153篇 |
天文学 | 136篇 |
综合类 | 11篇 |
自然地理 | 138篇 |
出版年
2022年 | 12篇 |
2021年 | 25篇 |
2020年 | 49篇 |
2019年 | 34篇 |
2018年 | 60篇 |
2017年 | 51篇 |
2016年 | 80篇 |
2015年 | 71篇 |
2014年 | 69篇 |
2013年 | 115篇 |
2012年 | 89篇 |
2011年 | 117篇 |
2010年 | 101篇 |
2009年 | 122篇 |
2008年 | 100篇 |
2007年 | 71篇 |
2006年 | 67篇 |
2005年 | 45篇 |
2004年 | 42篇 |
2003年 | 51篇 |
2002年 | 31篇 |
2001年 | 50篇 |
2000年 | 31篇 |
1999年 | 36篇 |
1998年 | 30篇 |
1997年 | 29篇 |
1996年 | 23篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1990年 | 18篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1987年 | 12篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 26篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 13篇 |
1975年 | 17篇 |
1973年 | 14篇 |
1972年 | 10篇 |
1969年 | 9篇 |
排序方式: 共有2060条查询结果,搜索用时 15 毫秒
991.
Summary Indirect phase reflection height measurements have been performed at the Panská Ves Observatory, Czechoslovakia, on two frequencies of 162 (earlier 164) and 153 kHz (earlier 155) for 30 years. However, they were used only for solar flare effect (SFA) monitoring. After introducing new measuring equipment in 1985, the quality of the 162 kHz records became sufficient to apply the indirect phase height analysis (IPHA) method in full. The method itself, the measuring equipment, and the method of evaluation are described in [1]. The purpose of this paper is to describe the first results and to verify the reliability of the 162 kHz IPHA data. The IPHA method as applied to the 162 kHz measurements made at Panská Ves, allows ionospheric and neutral atmospheric parameters to be studied simultaneously and appears to provide reliable and good quality data. The expected seasonal variation and response to sudden stratospheric warmings are observed. The use of the 162 kHz IPHA data in the international MAC/SINE and DYANA campaigns and for monitoring pressure variability at 80 km are briefly described. 相似文献
992.
Karel Diviš Jiří Trešl Jan Kostelecký Reviewer M. Pick 《Studia Geophysica et Geodaetica》1981,25(4):321-331
Summary With the aid of a simplified model, the gravitational effect of the anomalous part of the atmosphere was analysed theoretically and formulae were derived for numerical computation. It was found that under extreme meteorological conditions this effect is of the same order as the present accuracy of absolute gravity observations, i.e. ±100–150 nm s–2. It is, therefore, recommended to reduce these observations to some model of the normal atmosphere by introducing computational corrections. 相似文献
993.
994.
995.
996.
Jörn Thiede Torleiv Agdestein Jan Erik Strand 《Earth and Planetary Science Letters》1980,47(3):416-422
The upper Mesozoic and Cenozoic distribution of calcareous, biogenic particles which are produced by planktonic foraminifers and nannoplankton and which are the most important components of pelagic sediments since mid-Mesozoic times, has been reconstructed using data from North Atlantic deep-sea drill sites. Two phases of sedimentation of carbonate-rich sediments are separated by an interval from 100 to 80 m.y. B.P. when CaCO3 particles were diluted by chiefly terrigenous material. Prior to 100 m.y. B.P. the highest concentrations of calcareous matter were confined to the deepest part of the then 4–4.5 km deep North Atlantic. After 80 m.y. B.P. sediments with high concentrations of calcareous matter have been deposited above 3 km paleodepth, but during the last 25 m.y. also between 4 and 5.5 km paleo-water depth. The latter occurrence is associated with indications of downslope displacement of calcareous material into the abyssal plains of the deepest parts of the North Atlantic. 相似文献
997.
998.
Summary The results of the twelve-year (1962–1973)SEA (27 kHz) andSDA (5 kHz) measurements at the Panská Ves Observatory are presented with an emphasis on peculiar events. About half of allSIDs are observed asSEA events and about 10% asSDAs. NoSID has been observed only as anSDA. A fewSIDs have been observed asSEA only, most of them being probably of non-solar origin. A few events observed asSEA andSDA only, or as anSID withSDA, but withoutSEA, are briefly discussed, too. 相似文献
999.
Jan Laštovička Z. Ts Rapoport Reviewer L. Křivský 《Studia Geophysica et Geodaetica》1979,23(3):263-274
Summary The post-storm effect (PSE) of the December 16–18, 1971 geomagnetic storm is studied with the use of the ionospheric radio wave absorption measurements and f
min
data from a network of the GDR, USSR and Czechoslovak observatories. Only a high latitude effect of the storm was found. We found more significant absorption effects associated with later weaker enhancements of geomagnetic activity. The part played by the interplanetary magnetic field is demonstrated. A magnetospheric explanation of the observed variability of PSE based on the time-development of filling up the slot region is suggested. 相似文献
1000.