The paper contrastes and analysies the marking for the coarse degree ...

本文对新旧标准中糙度的标注进行对比分析。

This paper introduces studying and using process of new type polyurethane sealing element,contrastes with similar import sealing element.

介绍新型聚胺脂密封件的研究开发和程,并与进口同类密封件进行对比,有一定的实价值。