upper laser level
激光高能极，激光上能级

• hydrogen chloride chemical laser
• hydrogen cyanide
• hydrogen deuteride
• hydrogen discharge lamp
• hydrogen fluoride chemical laser
• hydrogen halide
• hydrogen lamp
• hydrogenlike atom
• hydrogenlike electron state
• hydrogen maser
• hydrogen peroxide
• hydrogen-phthalate-crystal
• hydrogeu spectrum
• hydrologic surveying
• hydrolysis
• hydroman
• hydrometer
• hydrophone
• hydroquinone
• hydrosol
• hydrostatic
• hydrostatic oil-pad bearing
• hydrostatic pressure
• hydroxyl group
• hydroxyl ion