That polyacetylenes are present in flames has been demonstrated many times.

已多次证实火焰中存在聚乙炔.

辞典例句

Aryl substituted polyacetylenes and their derivatives exhibit a lot of novel optical , electric, magnetic properties.

芳基取代聚炔及其衍生物呈现出光电磁等许多新颖的性能.

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