全文获取类型
收费全文 | 2210篇 |
免费 | 677篇 |
国内免费 | 1440篇 |
专业分类
测绘学 | 70篇 |
大气科学 | 309篇 |
地球物理 | 751篇 |
地质学 | 2464篇 |
海洋学 | 257篇 |
天文学 | 38篇 |
综合类 | 316篇 |
自然地理 | 122篇 |
出版年
2020年 | 2篇 |
2016年 | 9篇 |
2015年 | 17篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 218篇 |
2010年 | 129篇 |
2009年 | 196篇 |
2008年 | 51篇 |
2007年 | 132篇 |
2006年 | 266篇 |
2005年 | 341篇 |
2004年 | 614篇 |
2003年 | 389篇 |
2002年 | 301篇 |
2001年 | 243篇 |
2000年 | 147篇 |
1999年 | 115篇 |
1998年 | 122篇 |
1997年 | 170篇 |
1996年 | 88篇 |
1995年 | 64篇 |
1994年 | 50篇 |
1993年 | 155篇 |
1992年 | 181篇 |
1991年 | 95篇 |
1990年 | 18篇 |
1989年 | 47篇 |
1988年 | 10篇 |
1987年 | 41篇 |
1986年 | 22篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1970年 | 1篇 |
1962年 | 1篇 |
1952年 | 1篇 |
1950年 | 2篇 |
1943年 | 1篇 |
1940年 | 2篇 |
1937年 | 6篇 |
1934年 | 5篇 |
1933年 | 2篇 |
1931年 | 1篇 |
1927年 | 1篇 |
排序方式: 共有4327条查询结果,搜索用时 31 毫秒
111.
112.
113.
喀喇沁玻基橄辉岩中的磷酸盐质熔体及磷灰石 总被引:2,自引:0,他引:2
磷酸盐在本文讨论的坡基橄辉岩中以多种形式产生,有早期结晶的磷灰石斑晶;有熔离的磷酸盐质熔浆液滴;也有晚期穿入橄榄石斑晶的磷酸盐质细脉,表明元素磷活跃在岩浆演化的每一个阶段。磷酸盐质熔浆液滴的存在,说明磷酸盐质熔体可能是由于岩浆的熔离作用而形成的。沿着橄榄石晶格生长石出现的磷酸盐质玻璃细脉则进一步证实地幔中含磷流体不但存在,而且具有很强的活动性。 相似文献
114.
David COOKE 《《地质学报》英文版》2000,74(4):807-826
Three major types of Ordovician intrusive-related gold-copper deposits are recognized in central-west New South Wales, Australia: porphyry, skarn and high sulphidation epithermal deposits. These deposits are mainly distributed within two Ordovician volcano-intrusive belts of the Lachlan Fold Belt: the Orange-Wellington Belt and the Parkes-Narromine Belt. Available isotopic age data suggest that mineralization of the three types of deposits is essentially coeval with the Ordovician intrusive rocks (480-430 Ma).Porphyry gold-copper deposits can be further divided into two groups. The first group is associated with monzonite showing shoshonitic features, represented by Cadia and Goonumbla. The second group is associated with diorite and dacite, including the Copper Hill and Cargo gold-copper deposits. Gold skarn is associated with Late Ordovician (430-439 Ma) monzonitic intrusive complexes in the Junction Reefs area (Sheahan-Grants, Frenchmans, and Cor-nishmens), Endeavour 6, 7 and 44, Big and Little Cadia 相似文献
115.
High quality marine source rock (HQMSR) is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in dif-ferent spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The ... 相似文献
116.
QIAO Xiufu GAO Linzhi PENG Yang 《《地质学报》英文版》2007,81(3):385-397
In the Mesoproterozoic time, the northern part of the Sino-Korean Plate experienced a period of intensive tectonic extension and breakup. 1. An abundance of sedimentary earthquake records is preserved in the Chuanlinggou, Tuanshanzi and Gaoyuzhuang formations in the Mesoproterozoic Changcheng System (1800-1400 Ma) and in the Mesoproterozoic Wumishan Formation of the Jixian System (1400-1000 Ma). These earthquake records are characterized by various liquefied sand-veins, carbonate microspar and coarser spar veins, limestone dikes, liquefied breccia and various forms of liquefied contorted bedding. This deformation is always associated with synsedimentary faults and igneous activity. 2. Three liquefaction models for soft carbonate sediments are recognized, including liquefaction in laminated carbonate rocks, liquefaction in thin-bedded carbonates and large-scale liquefaction along huge carbonate dikes. 3. Based on the record of earthquake and volcanic activities, the Sino-Korean Plate experienced at least twice intraplate breakups. One occurred between 1800-1400 Ma, and the other occurred at about 1200 Ma. The last breakup resulted in formation of the Yan-Liao aulacogen, a tectonic zone characterized by deeper material vibrancy, active faults, major igneous activity and frequent earthquakes. 相似文献
117.
Provenance of Precambrian Fe- and Al-rich Metapelites in the Yenisey Ridge and Kuznetsk Alatau, Siberia: Geochemical Signatures 总被引:2,自引:0,他引:2
Major, trace and rare earth element contents of Fe- and Al-rich metapelites from the Korda (Yenisey Ridge) and Amar (Kuznetsk Alatau) formations were determined to examine the nature, origin and evolution of their protoliths. Results indicate that these rocks are the redeposited and metamorphosed products of Precambrian kaolinitic weathering crusts, while the geochemical distinctions between the studied metapelites are determined by different weathering conditions in the source area and tectonic settings. The protolith of the Korda Formation metapelites was produced by erosion products of the post-Archean granitoid rocks, which accumulated under humid climate conditions in shallow-water basins along the continental margin. The geochemical characteristics of the deeper primary deposits of the Amar Formation suggest that volcanogenic material of mafic composition derived from an island-arc environment had a major role in supplying the erosion zone. These results agree with lithofacies data and with the geodynamic reconstruction of the evolution of the Yenisey Ridge and Kuznetsk Alatau during the Mesoproterozoic and Neoproterozoic, respectively. It was shown that REEs had limited mobility during contact metamorphism. The coherent mobility of REEs during collisional metamorphism may be attributed both to mineral reactions responsible for modal changes and to local chemical heterogeneity inherited from the initial protolith. 相似文献
118.
PANG Xiongqi LI Sumei JIN Zhijun BAI Guoping Key Laboratory of Hydrocarbon Accumulation Ministry of Education Beijing E-mail: pangxq@bjpeu.edu.cnBasin & Reservoir Research Center University of Petroleum Beijing Sinopec Petroleum Exploration Exploitation Institute Beijing 《《地质学报》英文版》2004,78(3):615-625
Based on a detailed survey of the distribution and organic geochemical characteristics of potential source rocks in the South Slope of the Niuzhuang Sag, Bohai Bay Basin, eastern China, a new approach to assess the amount of hydrocarbons generated and expelled has been developed. The approach is applicable to evaluate hydrocarbons with different genetic mechanisms. The results show that the models for hydrocarbon generation and expulsion vary with potential source rocks, depending on thermal maturity, types of organic matter and paleoenvironment. Hydrocarbons are mostly generated and expelled from source rocks within the normal oil window. It was calculated that the special interval (algal-rich shales of the ES4 member formed in brackish environments) in 相似文献
119.
The Classification and Model of Coalbed Methane Reservoirs 总被引:8,自引:0,他引:8
SU Xianbo LIN Xiaoying SONG Yan ZHAO Mengjun Henan University of the Sciences Jiaozuo Henan Research Institute of Petroleum Exploration Development PetroChin Beijing 《《地质学报》英文版》2004,78(3):662-666
Coalbed methane has been explored in many basins worldwide for 30 years, and has been developed commercially in some of the basins. Many researchers have described the characteristics of coalbed methane geology and technology systematically. According to these investigations, a coalbed methane reservoir can be defined: "a coal seam that contains some coalbed methane and is isolated from other fluid units is called a coalbed methane reservoir". On the basis of anatomization, analysis, and comparison of the typical coalbed methane reservoirs, coalbed methane reservoirs can be divided into two classes: the hydrodynamic sealing coalbed methane reservoirs and the self-sealing coalbed methane reservoirs. The former can be further divided into two sub-classes: the hydrodynamic capping coalbed methane reservoirs, which can be divided into five types and the hydrodynamic driving coalbed methane reservoirs, which can be divided into three types. The latter can be divided into three types. Currently, hydrodynamic s 相似文献
120.
Intracontinental Collisional Orogeny During Late Permian-Middle Triassic in South China: Sedimentary Records of the Shiwandashan Basin 总被引:2,自引:0,他引:2
LIANG Xinquan LI Xianhua QIU Yuanxi Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou Guangdong Geoscience Department Zhongshan University Guangzhou Guangdong 《《地质学报》英文版》2004,78(3):756-762
Sedimentary response to an orogenic process is important for determining whether South China had compressional or extensional orogeny during the period from the Late Permian to the Middle Triassic besides the tectonic and magmatologic evidence. An intracontinental collision event took place between the Yangtze and Cathaysia blocks in the Late Permian. Beginning at the Late Triassic, the tectonic movement was completely changed in nature and entered a post-collisional extensional orogenic and basin-making process. This paper presents sedimentological evidence from the Late Permian to the Middle Triassic in the Shiwandashan basin at the southwestern end of the junction zone between the Yangtze and Cathaysia blocks. 相似文献