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不知您注意过没有，我们胳膊上、腿上的血管看起来都不是红色的，而是呈现出近似于青色、蓝色的颜色。这又是什么原因呢？原来，都是波长惹的祸。Surprisingly, the reason why the blood in our veins looks blueonlyemerged in 1996 following research done by the physicist Dr.LothorLilge and his colleagues at the Ontario Laser and LightWaveResearch Centre of Canada. They showed that when lightstrikeswhite skin, the longer, redder wavelengths penetrate deeper,andare absorbed by the blood vessels. As a result the lightreflectedback from the skin covering a blood vessel has arelatively higherproportion of the shorter wave lengths which givesit isblue-purple tinge. The veins of people with dark skin dontshowthis effect so strongly because the skins melanin absorbsalmostall wavelengths of light on the skins surface.
The reason we go red rather than blue when we blush is becauseofthe relative depths of the blood vessels affected. According toDrLilge, a vein has to be at least 0.5 mm below the skins surfacetolook blue .The small capillaries that fill up with blood whenweblush are much closer to the skins surface and so look red.
capillary: 毛细管
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