全文获取类型
收费全文 | 2547篇 |
免费 | 465篇 |
国内免费 | 689篇 |
专业分类
测绘学 | 109篇 |
大气科学 | 529篇 |
地球物理 | 622篇 |
地质学 | 1333篇 |
海洋学 | 272篇 |
天文学 | 278篇 |
综合类 | 248篇 |
自然地理 | 310篇 |
出版年
2024年 | 5篇 |
2023年 | 47篇 |
2022年 | 125篇 |
2021年 | 142篇 |
2020年 | 90篇 |
2019年 | 117篇 |
2018年 | 159篇 |
2017年 | 136篇 |
2016年 | 149篇 |
2015年 | 124篇 |
2014年 | 147篇 |
2013年 | 138篇 |
2012年 | 115篇 |
2011年 | 182篇 |
2010年 | 179篇 |
2009年 | 134篇 |
2008年 | 109篇 |
2007年 | 107篇 |
2006年 | 87篇 |
2005年 | 100篇 |
2004年 | 96篇 |
2003年 | 96篇 |
2002年 | 72篇 |
2001年 | 63篇 |
2000年 | 99篇 |
1999年 | 119篇 |
1998年 | 96篇 |
1997年 | 95篇 |
1996年 | 93篇 |
1995年 | 96篇 |
1994年 | 69篇 |
1993年 | 67篇 |
1992年 | 48篇 |
1991年 | 33篇 |
1990年 | 20篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1937年 | 4篇 |
1934年 | 2篇 |
1933年 | 9篇 |
1927年 | 2篇 |
1924年 | 6篇 |
1923年 | 2篇 |
排序方式: 共有3701条查询结果,搜索用时 15 毫秒
51.
In the context of tower measured radiation datasets.following the correction principle meetinga diagnostic equation in data quality control and in terms of a technique for model construction ondata and ANN(artificial neural network)retrieval for BP correction of radiation measurementswith rough errors available,a BP model is presented.Evidence suggests that the developed modelworks well and is superior to a convenient multivariate linear regression model,indicating its wideapplications. 相似文献
52.
53.
54.
2001年昆仑山口8.1级巨震后中国大陆、云南地震趋势研究 总被引:2,自引:1,他引:2
分析研究了2001年11月14日昆仑山口8.1级巨震对中国大陆云南未来几年地震趋势的影响,指出巨震后6年大陆可能仍然处于地震活跃期,其间大陆西部发生7.0级以上大震可能性较大;受2000-2001年欧亚带东南段大震活动过程及巨震调整影响,未来1-3年云南省可能进入新的活跃期,6.5级以上强震危险性增加。 相似文献
55.
SIMULATION OF HEAVY RAINFALL IN THE SUMMER OF 1998 OVER CHINA WITH REGIONAL CLIMATE MODEL 总被引:11,自引:0,他引:11
The heavy rainfall in the summer of 1998 over China has been simulated with the NCCRegional Climate Model(RegCM_NCC).It was successful for RegCM_NCC to reproduce thelocation and seasonal shift of the seasonal rain belt in the summer of 1998 over China.The rainyseason in the summer of 1998 over China can be divided into 7 episodes,including the pre-summerrainy season in South China.the Meiyu onset over the Yangtze-Huaihe River Basin,shortappearance of North China rain season and the retreat of seasonal rain belt,the second Meiyuseason over the Yangtze River Valley,the rainy period over the Yellow and Huaihe River Valleyand the seasonal retreat of rain belt over North China.The shortcoming of the RegCM_NCC isover-estimation of precipitation amounts.The regions with large latent heat flux,upper soilmoisture and total runoff are located in the rainy area and move with the simulated rain belt duringthe different episodes.On the contrary,the regions with small sensible heat flux are located in thesimulated rainy area and move with the simulated rain belt during the different episodes. 相似文献
56.
Re-Os Age of Cu-Ni Ores from the Huangshandong Cu-Ni Sulfide Deposit in the East Tianshan Mountains and Its Implication for Geodynamic Processes 总被引:4,自引:0,他引:4
MAO Jingwen YANG Jianmin QU Wenjun DU Andao WANG Zhiliang HAN Chunming Faculty of Geosciences Resources China University of Geosciences Beijing E-mail: jingwenmao@.netInstitute of Mineral Resources Chinese Academy of Geological Sciences Beijing National Research Center of Geoanalysis Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》2003,77(2):220-226
An isochron age of 282±20 (95% conf. limit) Ma of the sulfide ores in the Huangshandong Cu-Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re-Os isotopic measurement. The age implies that the Cu-Ni sulfide deposit and other related deposits in the same area occurred in a Permian extensional environment of post-collision instead of Devonian-Early Carboniferous ophiolite-related oceanic or island arc environments inferred before. It shares the same ages with the orogenic and epithermal gold deposit systems in the same area. An initial 187Os/188Os ratio of 0.25±0.04 (1σ) and a γos value of 99 on average display the participation of large quantities of crustal components into the rock-forming and ore-forming system during mineralization and magmatic emplacement. 相似文献
57.
58.
Introduction Greeting the coming of the 21st century, Professor HU Yu-xian and other Chinese scholars briefed the trend of earthquake engineering in China and aboard (HU, 1999; HU, ZHOU, 1999). The experiences and lessons learning from the destructive earthquakes in China and abroad in re-cent years, the damage action of the large velocity impulse in ground motion in near field in seis-mic design, numerous earthquake examples show that there are many weaknesses in aspects of earthquake p… 相似文献
59.
In this paper, we briefly describe the general destruction caused by historic earthquakes in major cities of China, preliminarily analyze the heaviness and widespread occurrence of earthquakes in cities of China, and suggest that research on scenario earthquakes in cities should be developed as a part urban disaster reduction research. 相似文献
60.