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91.
92.
土地利用变化对延安市生态服务价值的影响 总被引:2,自引:0,他引:2
利用延安市2001-2007年土地利用基础数据,计算土地利用动态度,并在Costanza生态系统服务价值理论基础上,结合谢高地等的中国生态系统生态服务价值当量因子表,计算出延安不同生态系统单位面积生态服务价值。并依此尝试计算延安市2001年至2007年延安市生态系统服务价值量。研究发现,2007延安市的生态系统服务价值将达到424.28亿元,比2001年增加28.79亿元,增长率为7.28%;各种土地利用方式的生态系统服务价值的敏感性指数(CS)均小于1,表明其对生态系统的价值变化是缺乏弹性的。 相似文献
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随着GPS技术的飞速前进,利用网络RTK技术建立的连续运行卫星定位系统已成为GPS应用的发展热点之一。通过对胜利油田单基站CORS系统的组成、功能及在胜利油区石油天然气井位测量中的应用方式及精度分析的论述,对单基站CORS系统在石油天然气井位测量中的现实意义和应用前景进行了展望。 相似文献
95.
Contribution of mantle components within juvenile lower-crust to collisional zone porphyry Cu systems in Tibet 总被引:17,自引:0,他引:17
Zengqian Hou Yuanchuan Zheng Zhiming Yang Zongyao Rui Zhidan Zhao Sihong Jiang Xiaoming Qu Qinzhong Sun 《Mineralium Deposita》2013,48(2):173-192
Most porphyry Cu–Mo–Au deposits are found in magmatic arcs worldwide, and are associated with hydrous, high-fO2, calc-alkaline magmas, derived from a mantle wedge that was metasomatized by the fluids from a subducted oceanic slab. Recently, such deposits have been documented as occurring widely in collisional settings, where they are associated with potassic magmas generated during the collisional process, but the genesis of the fertile magmas and the mechanism of metallic enrichment remain controversial. Here we present new geochemical and Sr–Nd–Hf isotopic data from the post-collisional fertile and barren porphyries of the Miocene Gangdese porphyry belt in the Tibetan orogen, an orogen formed by the collision of India and Asia in the early Cenozoic. Both types of porphyry are characterized by high K2O contents, and have geochemical affinities with adakite, but the fertile magmas were most likely derived from the melting of a thickened juvenile mafic lower-crust, formed by the underplating of earlier asthenospheric melts at the base of crust, whereas the derivation of the barren magmas involved variable amounts of old lower-crust in Tibet. The melting of sulfide-bearing phases in the juvenile mantle components of the Tibetan lower-crust probably provided Cu, Au, and S to the fertile magmas. The breakdown of amphibole during melting at the source released the fluids necessary for the formation of the porphyry Cu deposits in Tibet. The thickened crust (up to 70–80 km), due to collision, is thought to be responsible for a decrease in the fO2 of the fertile magmas during their ascent to the upper crust, thus preventing the generation of more porphyry Cu–Au and epithermal Au deposits in this collisional zone. 相似文献
96.
中国现代干旱灾害的时空特征* 总被引:28,自引:0,他引:28
本文提出了一个考虑前期降水短缺影响的干旱指数。利用1951-1991年逐月全国160个站的降水资料划分干旱等级,分析了我国干旱,包括多旱、重旱和持续干旱的区域分布,指出我国主要有四大干旱中心;分析了干旱随时间的变化,发现全国及多数区域的现代干旱存在着线性增长的趋势。最后利用全国干旱受灾和成灾面积讨论了干旱的影响,指出全国近代干旱受灾和成灾面积存在着三个高值期,且总体线性增长趋势也很明显。 相似文献
97.
LiangShu Shu Yan Wang JinGeng Sha ShaoYong Jiang JinHai Yu YanBin Wang 《中国科学D辑(英文版)》2009,52(12):1969-1978
Two types of the Jurassic basins are distinguished in SE China based on their geodynamic features: the Late Triassic-Early
Jurassic post-orogenic basins and the Middle Jurassic intra-continental extensional basins. The Lower Jurassic sequence shows
a change from coarse- to fine-grained accumulation, suggesting a gradually deepening depositional environment from river to
shore-lake and to deep-water lake. In contrast, the Middle Jurassic accumulation was changed from claystone to conglomerate
along the coastal provinces in SE China, indicative of an initial crustal uplift. The Wuyi Mountains have been a paleogeograghic
separating zone since the Middle Jurassic. The Late Jurassic strata are absent in most areas of SE China. A large-scale bimodal
intra-continental rift-type volcanism occurred during the Middle Jurassic along a 40–60 km wide and 200 km long area in western
Fujian and southern Jiangxi provinces, which is most likely the strongest volcanism in SE China since the Cambrian. The SHRIMP
zircon U-Pb analyses on the rhyolite from the Dongkeng basin in the southern Jiangxi area yield a concord U-Pb age of 160±0.5
Ma, providing an upper age limit for the bimodal volcanic eruption. The analyses of the basin features indicate a change of
the depositional environment during the interval from Middle Triassic to Late Triassic from a shallow-sea to an intra-continent
in SE China in response to the strong collision between the Yangtze and North China Blocks. Sedimentary structures record
a southward direction of Early Jurassic paleo-currents, reflecting that their source areas were to the north side. We propose
that the Wuyi region was uplifted as early as Middle Jurassic, followed by a wide E-W-trending extended depression and bimodal
volcanism in the western foot of the Wuyi Mountains. Presumably the uplift of the Wuyi domain changed the Middle Jurassic
paleogeographic outline and formed the transformational tectonic regime from compression to extension as a tectonic response
to the Pacific plate subduction. 相似文献
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曾杉 《地球信息科学学报》1996,(1):57-61
宋莉(节目主持人):听众朋友,欢迎您收听中央人民广播电台的“专家热线”节目,今天为您安排的是“专家热线-院士访谈:酷爱人类居住的星球”。 听众朋友,陈述彭院士是在我国地学界享有很高声誉的科学家。他1950年参加中国科学院地理所的筹建,任地图研究室主任和航空像片综合利用研究室主任。1972年任中国科学院制图自动化系统研制组组长,1978年任中国科学院腾冲航空遥感实验副指挥。1979年陈先生筹建中国科学院遥感应用研究所,任副所长,兼任国家遥感中心研究发展部主任。 相似文献