全文获取类型
收费全文 | 2484篇 |
免费 | 637篇 |
国内免费 | 1068篇 |
专业分类
测绘学 | 473篇 |
大气科学 | 288篇 |
地球物理 | 448篇 |
地质学 | 1923篇 |
海洋学 | 525篇 |
天文学 | 32篇 |
综合类 | 142篇 |
自然地理 | 358篇 |
出版年
2024年 | 21篇 |
2023年 | 61篇 |
2022年 | 143篇 |
2021年 | 199篇 |
2020年 | 146篇 |
2019年 | 175篇 |
2018年 | 179篇 |
2017年 | 155篇 |
2016年 | 127篇 |
2015年 | 161篇 |
2014年 | 159篇 |
2013年 | 197篇 |
2012年 | 248篇 |
2011年 | 232篇 |
2010年 | 211篇 |
2009年 | 208篇 |
2008年 | 269篇 |
2007年 | 233篇 |
2006年 | 259篇 |
2005年 | 212篇 |
2004年 | 146篇 |
2003年 | 123篇 |
2002年 | 103篇 |
2001年 | 71篇 |
2000年 | 71篇 |
1999年 | 31篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 7篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1963年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有4189条查询结果,搜索用时 15 毫秒
971.
972.
973.
Southeastern extension of the Red River fault zone (RRFZ) and its tectonic evolution significance in western South China Sea 总被引:3,自引:0,他引:3
LIU Baoming XIA Bin LI Xuxuan ZHANG Minqiang NIU Binhua ZHONG Lifeng JIN Qinghuan JI Shaocheng 《中国科学D辑(英文版)》2006,49(8):839-850
The tectonic evolution features in the western South China Sea (SCS) are directly related to the Tethys tectonic province. The Red River fault zone (RRFZ) comprises a large part of the Tethys tectonic province and is the boundary between the Europe Block and the India-Asia Block[1]. It serves as the contact between the uplift of the Qinghai-Tibet Plateau and the SCSopening. The RRFZ, which is an important dividing line in the geology of the SE Asia, is about 1000 km long in the co… 相似文献
974.
A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin 总被引:20,自引:0,他引:20
The surface water and groundwater are important components of water cycle, and the interaction between surface water and groundwater is the important part in water cycle research. As the effective tracers in water cycle research, environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively. The study area is the Huaisha River basin, which is located in Huairou district, Beijing. The field surveying and sampling for spring, river and well water were finished in 2002 and 2003. The hydrogen and oxygen isotopes and water quality were measured at the laboratory. The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed. The altitude effect of oxygen isotope in springs was revealed, and then using this equation, theory foundation for deducing recharge source of spring was estimated. By applying the mass balance method, the annual mean groundwater recharge rate at the catchment was estimated. Based on the groundwater recharge analysis, combining the hydrogeological condition analysis, and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin, part of the runoff in the Huaisha River basin is recharged outside of this basin, in other words, this basin is an un-enclosed basin. On the basis of synthetically analyses, combining the compositions of hydrogen and oxygen isotopes and hydrochemistry, geomorphology, geology, and watershed systems characteristics, the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated, and the interaction between surface water and groundwater was re- vealed lastly. 相似文献
975.
976.
977.
978.
979.
980.