煤层气的保存则取决于顶底板的封盖能力、构造活动、水动力环境等条件。
The preservation of CBM pool is mainly controlled by the sealing capacity of roof and floor plate, tectonic activity and hydrodynamic environment.
万能蜂窝底板，活动顶针活动支撑块，灵活定位P CB，方便印刷双面pcb。
Beehive bottom board, thimbles move support board, agile orientate PCB, easy to print dual sides PCB.
改进的装置由J2135型碰撞实验器、绘图板和底板组成，并增加了活动托板和“L”型定位器等装置。
The improved device consists of J2135 collision experiment device, drawing table and soleplate, and also adds a mobile board and a L-type positioning device.
应用推荐