全文获取类型
收费全文 | 1536篇 |
免费 | 206篇 |
国内免费 | 433篇 |
专业分类
测绘学 | 47篇 |
大气科学 | 22篇 |
地球物理 | 87篇 |
地质学 | 1409篇 |
海洋学 | 299篇 |
天文学 | 45篇 |
综合类 | 186篇 |
自然地理 | 80篇 |
出版年
2024年 | 15篇 |
2023年 | 49篇 |
2022年 | 52篇 |
2021年 | 53篇 |
2020年 | 35篇 |
2019年 | 70篇 |
2018年 | 34篇 |
2017年 | 32篇 |
2016年 | 38篇 |
2015年 | 42篇 |
2014年 | 122篇 |
2013年 | 84篇 |
2012年 | 118篇 |
2011年 | 144篇 |
2010年 | 84篇 |
2009年 | 101篇 |
2008年 | 103篇 |
2007年 | 70篇 |
2006年 | 108篇 |
2005年 | 62篇 |
2004年 | 58篇 |
2003年 | 61篇 |
2002年 | 58篇 |
2001年 | 75篇 |
2000年 | 46篇 |
1999年 | 65篇 |
1998年 | 51篇 |
1997年 | 59篇 |
1996年 | 42篇 |
1995年 | 35篇 |
1994年 | 39篇 |
1993年 | 26篇 |
1992年 | 42篇 |
1991年 | 36篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1960年 | 1篇 |
1951年 | 1篇 |
1948年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有2175条查询结果,搜索用时 912 毫秒
591.
灵宝市金源矿业有限责任公司第三分公司大湖矿区蕴藏着丰富的多金属资源,潜在价值巨大。然而,发生于1987年11月11日的山体滑坡(造成3人死亡,职工宿舍、空压机房被摧毁,矿山停产一年之久)却一直是高悬在人们头上的一把利剑,给人的心理造成巨大阴影,给企业的资源开发和安全生产带来了的巨大威胁。20多年来,企业在滑坡治理上采取了局部卸载、地裂缝回填、危岩体排险等措施, 相似文献
592.
Dongguan (东莞) City, located in the Pearl River Delta, South China, is famous for its rapid industrialization in the past 30 years. A total of 90 topsoil samples have been collected from agricultural fields, including vegetable and orchard soils in the city, and eight heavy metals (As, Cu, Cd,Cr, Hg, Ni, Pb, and Zn) and other items (pH values and organic matter) have been analyzed, to evaluate the influence of anthropie activities on the environmental quality of agricultural soils and to identify the spatial distribution of trace elements and possible sources of trace elements. The elements Hg, Pb, and Cd have accumulated remarkably here, incomparison with the soil background content of elements in Guangdong (广东) Province. Pollution is more serious in the western plain and the central region, which are heavily distributed with industries and rivers. Multivariate and geostatistical methods have been applied to differentiate the influences of natural processes and human activities on the pollution of heavy metals in topsoils in the study area. The results of cluster analysis (CA) and factor analysis (FA) show that Ni, Cr, Cu, Zn, and As are grouped in factor F1,Pb in F2, and Cd and Hg in F3, respectively. The spatial pattern of the three factors may be well demonstrated by geostatistical analysis. It is shown that the first factor could be considered as a natural source controlled by parent rocks. The second factor could be referred to as "industrial and traffic pollution sources". The source of the third factor is mainly controlled by long-term anthropic activities ,ad a consequence of agricultural fossil fuel consumption and atmospheric deposition. 相似文献
593.
The Gejiu (个旧) deposit is a superlarge tin-copper polymetallic ore-forming concentration area characterized by excellent metallogenic geological settings and advantageous ore-controlling factors. The deposit displays diverse mineralization properties due to different minerals and mineral deposit types. Based on the principal metallogenic factors, metallogenic mechanisms, mineralized components, and occurrence of mineral deposits or ore bodies, the Gejiu mineral district can be divided into 2 combinations of metallogenic series, 4 metallogenic series, 8 subseries, and 27 mineral deposit types. Spatial zonality is evident. The distribution regularity of the elements in both plane and section is Be-W, Sn (Cu, Mo, Bi, Be)-Sn, Pb, Ag-Pb, Zn around a granitic intrusion. The metallogenic epoch is mainly concentrated in the late Yanshanian. During this period, large-scale metallogenic processes related to movement caused by tectonics and magmatism occurred, and a series of magmatic hydrothermal deposits formed. The ore-forming processes can be divided into 4 stages: the silicate stage, the oxide stage, the sulphide stage, and the carbonate stage. Based on the orderliness and diversity (in terms of time, space, and genesis) of the mineralization, the authors have developed a comprehensive spectrum of ore deposits in the Gejiu area. This newly proposed diversity of mineralization and the spectrum developed in this work are useful not only for interpreting the genesis of the Gejiu deposit but also for improving mineral exploration in the area, and in particular, for finding large deposits. 相似文献
594.
为准确评价敦化团北地区激电异常,研究其产生机制,采用提取激电二次信息的视金属因素(Js)方法,突出与电子导体相关的低阻极化体异常,压制与电子导体不相关的激电异常。结果表明:测区西北角视金属因素异常与强激电异常相吻合,与电子导体(金属矿化或矿化)相关,而大范围低缓激电异常区没有视金属因素异常显示,说明与电子导体不相关。在敦化团北地区利用视金属因素压制干扰因素所引起的异常,突出与电子导电体相关的低阻极化体异常效果明显,结合地质揭露工程得出低缓激电异常是由受轻微矿染的花岗斑岩所引起的结论。 相似文献
595.
596.
非线性成矿预测理论:多重分形奇异性-广义自相似性-分形谱系模型与方法 总被引:24,自引:0,他引:24
介绍了“奇异性-广义自相似性-分形谱系”(“3S”: Singularity-generalized self-Similarity-fractal Spectrum)为核心的多重分形现代成矿预测理论与模型(Multifractal Mineralization Prediction Theory and Models)的基本内容和前沿研究方向.讨论了作为非线性、复杂性理论的重要领域之一, 多重分形理论所提供的“奇异性-广义自相似性-分形谱系”等概念和相关的模型.这些新概念和模型不仅能够合理地描述成矿系统、成矿过程、成矿富集规律、矿产资源时空分布, 还提供了定量模拟和识别成矿异常(地质、地球物理、地球化学、遥感异常)的有效模型和实用方法.将多重分形原理与成矿过程、矿产资源分布规律、矿产资源信息获取研究相结合, 可形成具有良好应用前景的现代成矿预测理论与模型.采用该多重分形矿产资源预测理论和在此基础上所开发的专用地学非线性空间信息GeoDASGIS技术, 对国内外多个金属成矿区带进行了矿产资源勘查与评价, 均取得了较理想的预测效果, 表明对开展矿产资源勘查和评价是有效和可行的. 相似文献
597.
随着陆地金属矿产资源的日渐枯竭,深海多金属硫化物逐渐成为海洋矿产资源勘探的新趋势。文章介绍了全球主要海底多金属硫化物矿床的成因及分布特点,阐述了多个国际矿业公司和国际海洋组织对西南太平洋、大西洋和印度洋海底块状多金属硫化物勘探活动的最新进展。从海底多金属硫化物的金属品质、深海采矿的法律政策和环境保护等方面对海底多金属硫化物的开发前景进行探讨,并提出积极投身国际海底资源开发规章制定,进一步细化国内法律制度,为深海采矿提供良好的法律制度环境;提升深海治理能力,增强我国在深海领域的话语权;完善深海技术装备体系,提高深海开发创新能力等建议。 相似文献
598.
599.
截至2019年4月,我国在公海和国际海底区域已进行到第54个航次的调查,航迹遍布太平洋、印度洋和大西洋,调查内容涉及多金属结核、多金属硫化物、富钴结壳、深海环境等多个领域,在国际海底区域获得4块具有专属勘探权和优先开发权的多金属硫化物、多金属结核、富钴结売矿区,海上作业时间超过9000天,调查面积约300万平方千米。我国“多种资源、多海域、多船作业”的深海资源勘查的战略布局初步形成。 相似文献
600.
Polymetalic sulfide is the main product of sea-floor hydrothermal venting, and has become an important sea-floor mineral resources for its rich in many kinds of precious metal elements. Since 2007, a number of investigations have been carried out by the China Ocean Mineral Resources Research and Development Association(COMRA)cruises(CCCs) along the Southwest Indian Ridge(SWIR). In 2011, the COMRA signed an exploration contract of sea-floor polymetallic sulfides of 10 000 km2 on the SWIR with the International Seabed Authority. Based on the multibeam data and shipborne gravity data obtained in 2010 by the R/V Dayang Yihao during the leg 6 of CCCs21, together with the global satellite surveys, the characteristics of gravity anomalies are analyzed in the Duanqiao hydrothermal field(37°39′S, 50°24′E). The "subarea calibration" terrain-correcting method is employed to calculate the Bouguer gravity anomaly, and the ocean bottom seismometer(OBS) profile is used to constrain the two-dimensional gravity anomaly simulation. The absent Moho in a previous seismic model is also calculated.The results show that the crustal thickness varies between 3 and 10 km along the profile, and the maximum crustal thickness reaches up to 10 km in the Duanqiao hydrothermal field with an average of 7.5 km. It is by far the most thicker crust discovered along the SWIR. The calculated crust thickness at the Longqi hydrothermal field is approximately 3 km, 1 km less than that indicated by seismic models, possibly due to the outcome of an oceanic core complex(OCC). 相似文献