A coarse - grained granite , sometimes rich in rare elements such as uranium , tungsten , and tantalum 花岗伟晶岩一种有时富含铀、钨和钽等稀有元素的粗纹理花岗岩
3.
Preservative features of rare elements and its prospect of exploitation and application in coal - bearing strata of dagaozhuang mine field 大高庄井田煤系稀有元素赋存特征与开发利用前景
4.
This product is mainly used for softening hard water and preparing pure and high purity water . it also serves as catalyst and dehydrolyzing agent . in addition , it is used in separation and purification of trace elements as well as hydro - metallurgy and pharmaceutical industry 本产品主要用于硬水软化及纯水和高纯水的制作，也用于催化剂和脱水剂，以及湿法冶金，分难提纯稀有元素，制药工业等。
5.
Through quantitative comparison of the salinity , temperature , wind , wave , current , tide , biogenesis elements , and rare elements of coral reef in the coral reef zone of the nansha islands in china with these in the open sea , it is found that the nutrients and primary productivity in the coral reef are several dozen or several hundred times higher than those in the open sea . it is indicated that , given sufficient sunlight , the coral reef eco - environment could provide very intense photosynthesis , thus pointing to the important reason why the coral reef zone is highly productive 根据中国南沙群岛珊瑚礁区的温度、盐度、风、浪、流、潮、生源要素、稀有元素分析并与礁外海域定量比较，得出珊瑚礁区的营养物质和初级生产力比敞海高出几十倍到几百倍，表明只要有充足的阳光，珊瑚礁生态环境就可以提供十分强烈的光合作用，从而证明了珊瑚礁海区高生产力的重要原因。
