十年前，北美的大多数乙烯是石油脑(一种石油衍生物)所制：其生产过程所产生的副产物正是丙烯。
A decade ago most ethylene in North America was made using naphtha, an oil derivative: it is this process that has propylene as its by-product.
其最终被现代石油化工衍生物所超越，并在20世纪70年代全面停产。
It was eventually superseded by the modern, petrochemical variety, and manufacture stopped altogether by the 1970s.
提出用衍生物- NMR表征石油中的有机硫结构的方法。
A derivatization NMR method for characterization of organic sulfur compounds in petroleum and its residuum was described.
提出用衍生物- NMR表征石油中的有机硫结构的方法。
A derivatization NMR method for characterization of organic sulfur compounds in petroleum and its residuum was described.
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