参考椭球的定义常数和导出常数
defining constants and derived constants for the r
磁性微球的研究进展
A progress in research on magnetic micro-sphere
地面控制的球型安全阀
ball type surface controlled safety valve
地球的赤道半径
equatorial radius of earth
地球的维持生命的质量
life-sustaining qualities of the Earth