This dense disc may be the origin ofthe hourglass structure of the nebula.
这个浓密的尘埃盘可能是沙漏状星云的起源所在。
The structure and the working principle of a new kind of hourglass worm gearing, which is called non-backlash hourglass worm gearing, are introduced.
阐述了一种新型环面蜗杆传动——无侧隙双滚子包络环面蜗杆传动的结构和传动原理。
The structure and the working principle of a new kind of hourglass worm gearing, which is called non-backlash hourglass worm gearing, are introduced.
阐述了一种新型环面蜗杆传动——无侧隙双滚子包络环面蜗杆传动的结构和传动原理。
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