最近一个周期中，M82的重力增强了M81周围密度波的脉动，导致M81的旋臂更浓密。
Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms.
对不同空间臂长的接枝结果进行了比较，发现空间臂越长，接枝密度越大，血小板黏附以及变形越少。
From the result we found that the longer the spacer is, the bigger the grafting density and the fewer blood platelet adhesion is.
本文从密度波理论出发，讨论三维盘状星系的旋臂结构。
In this paper we discuss the spiral structure of dish galaxies in three-dimension according to the density wave theory.
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