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湘黔下寒武统矿化黑色岩系中元素的表生迁移和环境效应 被引量:5
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作者 肖启云 李胜荣 《北京城市学院学报》 2002年第3期44-52,共9页
湘黔下寒武统矿化黑色岩系含大量的有用元素,包括有利于农作物生长的微量元素,但其中也广泛地、呈不同浓度地富集对人体有害的元素,其中的矿床被开发利用时,矿物质和有机质的分解,微量元素、毒重元素、放射性元素、酸性离子及其物质活... 湘黔下寒武统矿化黑色岩系含大量的有用元素,包括有利于农作物生长的微量元素,但其中也广泛地、呈不同浓度地富集对人体有害的元素,其中的矿床被开发利用时,矿物质和有机质的分解,微量元素、毒重元素、放射性元素、酸性离子及其物质活化后很有可能造成环境污染,影响人和牲畜的健康,甚至破坏生态环境。本文重点探讨元素的表生迁移及原生矿化黑色岩系的环境效应。 展开更多
关键词 下寒武统 矿化黑色岩系 微量元素 表生迁移 环境效应
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θ-improved limited tolerance relation model of incomplete information system for evaluation of water conservancy project management modernization 被引量:4
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作者 Yu-qin GAO Guo-hua FANG Ya-qin LIU 《Water Science and Engineering》 EI CAS CSCD 2013年第4期469-477,共9页
The modernization of water conservancy project management is a complicated engineering system involving a management system, a management method, management personnel, the exertion of social, economic, and ecological ... The modernization of water conservancy project management is a complicated engineering system involving a management system, a management method, management personnel, the exertion of social, economic, and ecological effects, and so on. However, indices for evaluating the modernization of water conservancy project management are usually unobtainable in practical applications. Conducting appropriate extension of the classical rough set theory and then applying it to an incomplete information system are the key to the application of the rough set theory Based on analysis of some extended rough set models in incomplete information systems, a rough set model based on the θ-improved limited tolerance relation is put forward. At the same time, upper approximation and lower approximation are defined under this improved relation. According to the evaluation index system and management practices, the threshold for θ is defined. An example study indicates the practicability and maneuverability of the model. 展开更多
关键词 key words modernization of water conservancy project management O-improved limitedtolerance relation model upper and lower approximations threshold
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