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存放在法国巴黎西南方小镇塞弗尔(Sevres)国际计量局(International Bureau of Weights and Measures,简称BIPM)本部的千克国际标准是一铂-铱合金圆柱体,从1889年至今120年矣.专家们将其与分布在全世界一些国家的计量实验室之“复制品”比对后发现其质量有高达50μg的变化.
The kilogram international standard stored in the headquarters of the International Bureau of Weights and Measures (Sevres) in the southwestern town of Paris, France, is a platinum-iridium cylinder that has been in operation for 120 years from 1889 to the present. Experts compare it with the “replicas” of metrology labs in some countries around the world and find that there is up to a 50 μg change in their mass.