全文获取类型
收费全文 | 771篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 63篇 |
地球物理 | 158篇 |
地质学 | 269篇 |
海洋学 | 87篇 |
天文学 | 91篇 |
综合类 | 2篇 |
自然地理 | 115篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 33篇 |
2015年 | 17篇 |
2014年 | 24篇 |
2013年 | 58篇 |
2012年 | 30篇 |
2011年 | 51篇 |
2010年 | 40篇 |
2009年 | 35篇 |
2008年 | 42篇 |
2007年 | 35篇 |
2006年 | 21篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 32篇 |
2002年 | 23篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有798条查询结果,搜索用时 78 毫秒
91.
92.
93.
94.
VOCs in Ground Water Influenced by Large Scale Withdrawals 总被引:1,自引:0,他引:1
95.
96.
Robert A. Watson Pedro Carreira Kieran Cleary Rod D. Davies Richard J. Davis Clive Dickinson Keith Grainge † Carlos M. Gutiérrez Michael P. Hobson Michael E. Jones Rüdiger Kneissl Anthony Lasenby Klaus Maisinger Guy G. Pooley Rafael Rebolo José Alberto Rubiño-Martin ‡ Ben Rusholme § Richard D. E. Saunders Richard Savage Paul F. Scott Ane Slosar Pedro J. Sosa Molina Angela C. Taylor David Titterington Elizabeth Waldram Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065
97.
Measurements of phytoplankton distribution and production, and zooplankton abundance and biomass were made during the summer of 1979 along several shelf-slope transects in the Mid-Atlantic Bight. At the shelf-break, macrozooplankton (>200 μm) grazing was estimated to be sufficient to remove a substantial proportion of daily phytoplankton production. In contrast, on the shelf and in slope waters, where ciliates were abundant, estimates of macrozooplankton grazing indicated a consumption rate less than 15% of the daily primary production. Ciliate grazing, even at non-maximum rates, potentially could have consumed the entire daily primary production in all areas sampled. The findings indicate that the nature of the heterotrophic community is spatially variable in offshore waters even during summer conditions and could influence not only trophodynamic pathways but perhaps nutrient regeneration and recycling. This would be an important consideration in evaluating the fate of particle-bound chemcial species in the water column since fecal pellet producing zooplankton would affect rates of removal and sedimentation in a different manner than ciliates which produce non-compacted digestive debris. 相似文献
98.
99.
The Hydrogeology of an Induced Streambed Infiltration Area 总被引:1,自引:0,他引:1
Perry H. Rahn 《Ground water》1968,6(3):21-32
100.
Francis Joseph Turk Byung-Ju Sohn Hyun-Jong Oh Elizabeth E. Ebert Vincenzo Levizzani Eric A. Smith 《Meteorology and Atmospheric Physics》2009,105(1-2):99-108
In order to properly utilize remotely sensed precipitation estimates in hydrometeorological applications, knowledge of the accuracy of the estimates are needed. However, relatively few ground validation networks operate with the necessary spatial density and time-resolution required for validation of high-resolution precipitation products (HRPP) generated at fine space and time scales (e.g., hourly accumulations produced on a 0.25° spatial scale). In this article, we examine over-land validation statistics for an operationally designed, meteorological satellite-based global rainfall analysis that blends intermittent passive microwave-derived rainfall estimates aboard a variety of low Earth-orbiting satellite platforms with sub-hourly time sampling capabilities of visible and infrared imagers aboard operational geostationary platforms. The validation dataset is comprised of raingauge data collected from the dense, nearly homogeneous, 1-min reporting Automated Weather Station (network of the Korean Meteorological Administration during the June to August 2000 summer monsoon season. The space-time RMS error, mean bias, and correlation matrices were computed using various time windows for the gauge averaging, centered about the satellite observation time. For ±10 min time window, a correlation of 0.6 was achieved at 0.1° spatial scale by averaging more than 3 days; coarsening the spatial scale to 1.8° produced the same correlation by averaging over 1 h. Finer than approximately 24-h and 1° time and space scales, respectively, a rapid decay of the error statistics was obtained by trading-off either spatial or time resolution. Beyond a daily time scale, the blended estimates were nearly unbiased and with an RMS error of no worse than 1 mm day?1. 相似文献