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

本文对新旧标准中表面粗糙度标对比分析。

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究开发和使用过程,并与口同类密封件对比,有一定实用价值。