In natural environment, tarnish was observed on the surface of a commemoration silver coin of China.
银纪念币在大气环境中表面发生变色,失去原有的金属光泽.
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On his way home he found a silver coin with a man's head on its face.
在回家的路上,他发现了一枚银币,银币上有一个男人头像。
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与此同时,大英帝国的生命血液&银币,便开始被吸取到英属东印度了。
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In this dissertation, the silver coin tarnishing mechanism during storage time was firstly studied.
本文首先研究了银币在存放过程中腐蚀变色机制。
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It is true, foreign trade had always insisted upon a certain amount of gold and silver coin.
国外的贸易总是基于金币和银币是一个事实。
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结果表明,在银币缺陷部位的腐蚀坑内存在以铁元素为主的物质,基材中的铁元素与外界的氯引起银币的腐蚀,造成了表面缺陷。
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