首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   218篇
  免费   16篇
  国内免费   11篇
测绘学   9篇
大气科学   15篇
地球物理   86篇
地质学   65篇
海洋学   39篇
天文学   10篇
综合类   6篇
自然地理   15篇
  2022年   4篇
  2021年   4篇
  2020年   11篇
  2019年   8篇
  2018年   12篇
  2017年   7篇
  2016年   3篇
  2015年   5篇
  2014年   19篇
  2013年   15篇
  2012年   12篇
  2011年   10篇
  2010年   11篇
  2009年   15篇
  2008年   17篇
  2007年   7篇
  2006年   12篇
  2005年   9篇
  2004年   13篇
  2003年   7篇
  2002年   5篇
  2001年   10篇
  2000年   4篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1995年   3篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1988年   2篇
  1985年   4篇
  1983年   1篇
  1980年   1篇
  1979年   2篇
  1975年   1篇
  1973年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有245条查询结果,搜索用时 609 毫秒
241.
242.
In this study, laboratory rainfall simulation in an extensive area was used to study the infiltration, and interception and storage from surface runoff in points with different stone cover percentages (0, 10, 20 and 30%) and slopes (5°, 10° and 20°). The experimental results of this study showed that the interrelationships among the slope, stone cover percentage, groundwater level, surface runoff amount, and interception and storage of the ponds were varied and irregular. No systematic patterns were detected for the change in the groundwater level, surface runoff amount, and interception and storage of the ponds with different stone cover percentages at different slopes and no threshold values were apparent. For a 5° slope, if the stone cover percentage was increased, the amount of surface runoff was reduced, the infiltration and the groundwater level experienced no significant change, and the interception and storage of the ponds increased. For a 10° slope, if the stone cover percentage was increased, the amount of surface runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. For a 20° slope, if the stone cover percentage was increased, the amount of runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. With or without stone cover, when the hydraulic conductivity of the top material is close to that of fine sand or laterite, an increase in the slope gradient decreased the amount of surface runoff and increased the storage amount of the ponds. As for the stone distribution, an interlaced style showed better performance in the interception and storage of ponds than that of a regular style. There was no significant change in the groundwater level. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   
243.
Ho  Hung Chak  Wai  Ka Ming  He  Minhao  Chan  Ta-Chien  Deng  Chengbin  Wong  Man Sing 《Natural Hazards》2020,103(1):623-637
Natural Hazards - In this study, we applied the Weather Research and Forecasting model to project 2050 urban and rural temperature. We applied a time-stratified analysis to compare it with...  相似文献   
244.
The feeding habit of Austrolethops wardi (Gobiidae) in the seagrass beds of Barrang Lompo and Bone Batang Island in the Spermonde Archipelago, South West Sulawesi, Indonesia, was investigated through gut content analysis. The feeding preferences of this species are very similar on both islands: A. wardi, a burrow associate of Neaxius acanthus, was found to feed almost exclusively on seagrass (which was found in 100% of the investigated stomachs and made up >94% of food items). However, seagrass epiphytes (<5% of food items) and animal food (<1% of food items) occurred in the guts as well, the latter predominantly in terms of copepods and to a lesser degree in other small invertebrates. These results indicate that animal food is of little importance for A. wardi. Some specimens even contained no parts of animal food.  相似文献   
245.
The significance of the southern Caucasus in understanding Pleistocene hominin expansions is well established. However, the palaeoenvironments in which Palaeolithic occupation of the region took place are presently poorly defined. The Hrazdan river valley, Armenian Highlands, contains a rich Palaeolithic record alongside Middle Pleistocene volcanic, fluvial and lacustrine strata, and thus offer exciting potential for palaeoenvironmental reconstruction. We present the first results of sedimentological, geochemical, tephrostratigraphical and biological (diatoms) study of the sequence of Bird Farm 1, located in the central part of the valley. These data show six phases of landscape development during the interval 440–200 ka. The sequence represents the first quantitative Pleistocene diatom record from the Armenian Highlands and the southern Caucasus, and indicates the persistence of a deep, stratified lacustrine system, with evidence for changing lake productivity that is tentatively linked to climate. Furthermore, major element chemical characterization of visible and crypto-tephra horizons in the sequence enables the first stages of the development of a regional tephrostratigraphy. Together, the evidence from Bird Farm 1 demonstrates the importance of lacustrine archives in the region for palaeoenvironmental reconstruction and highlights the potential for linkages between archives on both a local and regional scale.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号