liquid nitrogen cooling crystal
液氮致冷晶体

• universal angel block
• universal apparatus
• universal bevel protractor
• universal dividing head
• universal finder
• universal focus lens
• universal gear tester
• universal gravitation
• universal horizontal metroscope
• universal joint mechanism
• universal joint spider
• universal laser
• universal length measuring machine
• universal lens interferometer
• universal level
• universal machine tools
• universal measuring head
• universal measuring microscope
• universal meter
• universal microscope
• universal motor
• universal photomicroscope
• universal refractometer
• universal scale holder
• universal sine-rule