retractio相关论文
针对国内外煤矿的综采工作面搬家工艺回撤巷道顶板支护方式费时费力、劳动强度大、浪费木材且支护高度、支护速度、自动化程度、可......
We will introduce a new connection between some transformations and some aspects of differential geometry of some curves......