N - hydroxyethylpyrrolidone ( NHP ) was synthesized from � � - butyrolactone and ethanolamine on Y molecular sieve catalyst by two steps.以改性Y分子筛为催化剂,γ-丁内酯和乙醇胺为原料,采用γ - 丁内酯法两步合成N - 羟乙基吡咯烷酮 ( NHP )....
By night, the perimeter wire was illumined by lights.到了夜里，周遭的铁丝网都被灯光照亮。The plane veered off the runway and careered through the perimeter fence.飞机突然偏离跑道，高速冲过了周围的护栏。Some 300 trees have been ranged along the perimeter hedg...