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

本文新旧标准中表面粗糙度的标注进行析。

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

介绍新型聚封件的研究开发和使用过程,并与进口同类封件进行,有一定的实用价值。