全文获取类型
收费全文 | 31篇 |
免费 | 1篇 |
国内免费 | 34篇 |
专业分类
大气科学 | 2篇 |
地球物理 | 6篇 |
地质学 | 35篇 |
海洋学 | 15篇 |
天文学 | 1篇 |
综合类 | 6篇 |
自然地理 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有66条查询结果,搜索用时 10 毫秒
61.
Xiu HU Peng LU Youli LI Duowen MO Wanfa GU Qingri LIU Ailun GUO Panpan CHEN Hui WANG Yan TIAN Xu WANG Yayi HU Jiqin ZHANG Zhen WANG Quanxing LUO Junjie XU 《中国科学:地球科学(英文版)》2023,(5):1120-1132
The emergence of the "Ancient State" is considered an important stage in the discourse on human civilizations.Based on its complex and hierarchical social structure,the Shuanghuaishu site of Henan Province is regarded as an "Ancient state",specifically the "Heluo Ancient State".The site is situated in the middle reaches of the Yellow River region and played a key role in prehistoric China.However,the reasons behind its decline are unclear.Here,we conducted an integrated investigation of the arch... 相似文献
62.
Gang Zhao Yu-Qin Chen Jian-RongShi Yan-Chun Liang Jin-Liang Hou Li Chen Hua-Wei Zhang Ai-Gen Li National Astronomical Observatories Chinese Academy of Sciences Beijing Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Department of Astronomy School of Physics Peking University Beijing Department of Physics Astronomy University of Missouri Columbia MO USA 《中国天文和天体物理学报》2006,6(3):265-280
A project of a spectroscopic survey of Galactic structure and evolution with a Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) is presented. The spectroscopic survey consists of two observational modes for various targets in our Galaxy. One is a major survey of the Milky Way aimed at a systematic study of the stellar abundance and Galactic chemical evolution through low resolution (R=1000-2000) spectroscopy. Another is a follow-up observation with medium resolution (R = 10000) spectrographs aimed at detailed studies of the selected stars with different chemical composition, kinematics and dynamics. 相似文献
63.
64.
Numerous refinements have been proposed to traditional pumping test analyses, yet many hydrogeologists continue to use the Jacob method due to its simplicity. Recent research favors hydraulic tomography and inverse numerical modeling of pumping test data. However, at sites with few wells, or relatively short screens, the data requirements of these methods may be impractical within physical and fiscal constraints. Alternatively, an improved understanding of the assumptions and limitations of Theis and, due to their widespread usage, Jacob analyses, leads to improved interpretations in data-poor environments. A fundamental requirement of Jacob is a "small" value of u = f(r(2)/t), with radial distance, r, and pumping time, t. However, selection of a too stringent (i.e., too low) maximum permissible u-value, u(max), results in rejection of usable data from wells beyond a maximum radius, r(max). Conversely, data from small radii, less than r(min), where turbulent- and vertical-flow components arise, can result in acceptance of inappropriate data. Usage of drawdown data from wells too close to the pumping well, and exclusion of data from wells deemed too far, can cause unrealistic aquifer transmissivity, permeability, and storativity determinations. Here, data from an extensive well field in a glacial-outwash aquifer in north-central Minnesota, USA, are used to develop a new estimate for u(max). Traditionally quoted values for u(max) range from 0.01 to 0.05. Our proposed value for Jacob distance-drawdown analyses is significantly higher with u(max) up to 0.2, resulting in larger allowable r(max)-values and a higher likelihood of inclusion of additional wells in such pumping test analyses. 相似文献
65.
66.
MO Jinyou ZHAO Zhongru WANG Wei XU Xing 《《地质学报》英文版》2007,81(4):550-554
A new hadrosaurid dinosaur,Nanningosaurus dashiensis gen.et sp.nov.,is described based on an incomplete skeleton from the Late Cretaceous red beds of the Nalong Basin,Guangxi,southern China.Diagnostic features for the new taxon include the presence of a tall and sharply peaked dorsal process of the maxilla with reduced process of the jugai and a distinct lacrimal facet,gracile humerus with low,rounded deltopectoral crest,mandibular condyle of the quadrate transversly broad with reduced paraquadrate notch,dentary tooth with sinuous median carina and subsidiary ridge,relatively few tooth positions,ischial shaft straight along most of its distance,but to curve dorsally and expand at the distal end before the ischial foot begins.Phylogenetic analysis suggests that Nanningosaurus dashiensis is a basal member of Lambeosanrinae. 相似文献