Knowledge

First pull the headband loose every 2-4 cm, pass the mask headband with your hand, and the metal nose is forward.

Medical surgical masks must comply with YY 0469-2004 "Technical Requirements for Medical Surgical Masks". Important technical indicators include filtration efficiency

The size and shape of the spectacle lenses that conform to the shape of the spectacle frame after the processing of the wool lenses naturally depend on the curve of the inner edge of the spectacle fra

During the manufacture of this lens, a part of metal oxides such as iron, diamond, chromium, strontium, nickel, manganese and some rare earth metal oxides .

The inflection point of new coronaviruses in China has ushered in the most tense period abroad. Such a signal will undoubtedly give everyone a trace of panic and worry.

The so-called low fever refers to a low degree of fever, and fever refers to the body temperature is higher than normal body temperature.

People often judge how hot or cold things are based on their feelings, but such judgments are usually inaccurate due to the existence of many factors

In China's meteorology, instruments that can directly read values without automatic recording devices are collectively called thermometers.

Because the number of each thermal resistance is not large, and because the drift value is not constant for a long time, the bits in Table 6 are not very accurate.

General thermometer users expect the probe to respond quickly, have a solid structure, and have high accuracy.