The value of the critical density is very small: it corresponds to roughly 6 hydrogen atoms per cubic meter, an astonishingly good vacuum by terrestrial standards!
临界密度的值非常小：它相当于每立方米约6个氢原子，从地球上的标准来看这简直是真空！
2
This paper presents the characteristics of silicon micromachining resonance vacuum sensor and a vacuummeter utilizing this sensor.
文中介绍硅微机械谐振真空传感器的特点及配套研制的真空计。
3
On the working spot of centrifugal water pump, the detection can be carried out only by fixing the negative pressure translator in the original position of vacuummeter.