全文获取类型
收费全文 | 45篇 |
免费 | 12篇 |
国内免费 | 18篇 |
专业分类
测绘学 | 1篇 |
地球物理 | 6篇 |
地质学 | 56篇 |
海洋学 | 3篇 |
综合类 | 5篇 |
自然地理 | 4篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 6篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有75条查询结果,搜索用时 15 毫秒
31.
????BDS/GPS CORS????????????α??????????????????λ????????BDS/GPS?????????λ?????о?????????????????BDS/GPS????????????????λ????????1 m??40??????????????λ????0.5 m????????????????α??λ?????????????????????????λ????????0.1??10 m???? 相似文献
32.
中国区域经济发展收敛的空间计量分析 总被引:13,自引:2,他引:11
通过空间计量经济学经济收敛标准分析方法的扩展,就中国240 个地级及以上城市的经济增长收敛性展开讨论。运用Moran's I 探讨中国区域经济空间相关模式与集聚,发现1990-2007 年间人均GDP水平显示出强烈的全局正自相关,且局部空间结构相对稳定,各城市要脱离原来的集群有一定困难。文章指出收敛标准分析存在错误方程设定,空间计量分析方法是合适的。空间计量分析结果表明中国城市间存在绝对β收敛,与非空间模型相比收敛速度显著提高且可信,空间因素在区域经济增长与收敛过程中起到重要作用。但敏感性分析显示,绝对收敛的同一稳态以及在空间上并不稳健。从机制看,中国城市间同时存在新古典增长理论和新增长理论所强调的趋同机制。最后,对促进绝对收敛的区域政策进行了讨论,并提出通过模拟经济收敛过程,是判断区域政策有效性的重要工具。 相似文献
33.
The Zhalaxiageyong lead-zinc-copper polymetallic deposit is a typical porphyry deposit of the Tuotuohe area. Whole-rock geochemical analyses,Zircon U-Pb dating and Hf isotope analysis are undertaken for the ore host trachydacite with the aim of constraining its petrogenesis,magma source and regional tectonic setting.LA-ICP-MS zircon U-Pb dating indicates that the trachydacite was formed in 32. 68 ± 0. 50 Ma( MSWD =1. 6),i. e.,Oligocene. The trachydacite is rich in potassium and poor in Mg#( 5. 10-9. 70),belonging to the peraluminous shoshonite series. The rocks are enriched in LILE( large ion lithophile elements) Rb,Ba,K and LREE,depleted in HFSE( high field strength elements) Nb,Ta,P,Ti,with high Sr and low Y and Yb,having the characteristics of the C type adakite. It is calculated that the initial εHf( t) of the zircons range from-0. 92 to 2. 07 and their two-stage Hf model ages T_(DM2) range from 978 Ma to 1 169 Ma. The magma source should be mainly the partially melt mafic rocks of the thickened Middle Neoproterozoic lower crust of the Northern Qiangtang massif with the addition of ancient aluminosilica material in the melting process. The rocks formed in the tectonic setting of delamination of lithosphere and extension of the thickened crust. During the period of 40-32 Ma,large-scale potassium rich alkaline magmatism occurred in this area. The porphyry metallogenesis is related to the magmatic activities in this period. 相似文献
34.
35.
Comprehensive studies on lithologic association, provenance of metacongelometre, characteristics of metamorphism and deformation, and207Pb/206Pb-dating of single-zircon for metamorphic rocks distributed in Chabu-Chasang areas in Qiangtang block indicate that most of them belong to Middle Proterozoic metamorphic basement except silicilith member ascribed to Triassic. Disintegrated basement strata are called Gemuri group and Guoganjianianri group; they are different in histories of metamorphism and deformation. The single-zircon207Pb/206Pb-ages provide excellent evidence for the existence of an Archean continent nucleus around study areas. Some thermal event ages such as 929–1016 and 509–548 Ma are recorded in Gemuri group. 相似文献
36.
37.
四川盆地MVT型铅锌矿主要产于灯影组白云岩中,它们与古油(气)藏在空间上具有密切关系,显示出铅锌矿成矿与油气成藏紧密的成因联系.本次研究采用地质地球化学分析与扫描电镜观察相结合,对烃源岩和古油气藏中的沥青展开研究,揭示MVT型铅锌矿中成矿金属元素的物质来源.研究表明,与铅锌矿密切共生或伴生的油气藏的烃源岩主要为寒武系筇竹寺组(郭家坝组);部分烃源岩的Pb,Zn,Ba含量异常地高于地壳克拉克值,烃源岩中存在微米级的方铅矿、闪锌矿、黄铁矿和重晶石等,表明部分烃源岩具有为成矿提供金属元素的能力.MVT铅锌矿床中绝大部分沥青均具有异常高的Pb,Zn含量,沥青内也存在微米级的方铅矿、闪锌矿、黄铁矿、重晶石包裹物;沥青中的铅锌含量远高于MVT铅锌矿成矿流体所需要的铅锌含量,表明石油可能不仅起到了金属元素搬运载体的作用,油藏流体可能也是成矿流体.寒武系筇竹寺组(郭家坝组)泥质岩既是烃源岩层也是MVT矿源层,具有双源层特征. 相似文献
38.
The coexistence of Pb‐Zn deposits and oil/gas reservoirs demonstrates that a close genetic connection exists between them. The spatiotemporal relationship between Pb‐Zn mineralization and hydrocarbon accumulation is the key to understanding this genetic connection. The Mayuan large‐scale Pb‐Zn metallogenic belt is composed of a number of Mississippi Valley‐type (MVT) Pb‐Zn deposits that were recently discovered on the northern margin of the Yangtze Block, China. It is hosted in the dolostone of the Sinian (Ediacaran) Dengying Formation (Z2dn). In addition to the abundant bitumen in the Mayuan Pb‐Zn metallogenic belt, the paleo‐oil reservoir and the MVT Pb‐Zn deposit overlap in space. In this study, two precise ages of 468.3 ± 3.8 Ma and 206.0 ± 6.5 Ma were obtained via the Rb‐Sr isotopic dating of galena and sphalerite from the Mayuan Pb‐Zn metallogenic belt, respectively. The early metallogenic age of 468.3 ± 3.8 Ma is similar to the previously published age of 486 ± 12 Ma. The age of 206.0 ± 6.5 Ma is consistent with the age of the metallogenic event that occurred at 200 Ma in the Upper Yangtze Pb–Zn metallogenic province of the Sichuan‐Yunnan‐Guizhou polymetallic zone, which is located on the southwest margin of the Sichuan Basin, suggesting that the metallogenic effects of this period were regional in scale in the peripheral areas of the Sichuan Basin. Previous studies have shown that two periods of hydrocarbon accumulation occurred in the oil/gas reservoir that coexists with the Pb‐Zn deposits in the study area. The Pb‐Zn mineralization at 468.3 ± 3.8 Ma occurred during the first period of hydrocarbon accumulation, while the second mineralization at 206.0 ± 6.5 Ma occurred during the transformation of the paleo‐oil reservoir to a paleogas reservoir. The spatial relationship between the paleo‐oil/‐gas reservoir and the MVT Pb‐Zn deposits and the temporal relationship between mineralization and hydrocarbon accumulation show that a close genetic relationship exists between the MVT Pb‐Zn mineralization and hydrocarbon accumulation. Analysis of metals in the source rocks forming the paleo‐oil/‐gas reservoirs show that source rocks which formed paleo‐oil/‐gas reservoirs may have provided metals for Pb‐Zn mineralization. Both the paleo‐oil/‐gas reservoirs and Pb‐Zn mineralizing fluids had the same origin. 相似文献
39.
滇西高原第四纪以来的隆升和剥蚀 总被引:9,自引:2,他引:7
由滇西高原内古夷平面的抬高、外流水系的河流阶地、高原外营歌海盆地和琼东南盆地的沉积响应,共同揭示滇西高原第四纪以来的快速隆升和剥蚀历史。第四纪以来滇西高原区域性抬升了610~700余米、被剥蚀了1095~1600m,其平均剥蚀速率为0.68~0.94mm/a。根据河流阶地计算出第四纪以来各时段的隆升速率;隆升在0.386~0.296Ma达到峰期,隆升速率为2.24~2.SOmm/a;1.6~0.647Ma隆升速率最缓慢为0.68~0.94mm/a。滇西高原第四纪以来的隆升量和隆升峰期与同期的青藏高原具有相似性,但隆升速率明显低于东喜马拉雅构造结的隆升速率。 相似文献
40.
PALEOCENE—MIDDLE EOCENE DEXTRAL STRIKE-SLIP DEFORMATION AND ITS TECTONIC IMPLICATION IN THE WESTERN YUNNAN, CHINA 相似文献