论文部分内容阅读
人类的头发主要由一种叫角朊的蛋白质组成,并含有水分及在身体其他部分也可找到的微量金属和矿物质。头发唯一有生命的部分是在头皮下面,当它长出头皮时便成为无生命组织。头发的自然光泽来自它自身的护发素:油脂,它含有蜡和脂肪,还含有抗感染的自然抗菌剂。油脂含量过多会导致油性发质,相反,油脂含量过少则会导致干性发质。头发每个月可长12毫米,如果一个人从不剪发,头发会长至107厘米才开始脱落。在夏天和睡觉的时候头发生长得较快。一根头发的寿命可长达7年。健康的头发非常富有弹性,可拉长20%或30%而不断。一根头发比同等粗细的铜丝还要结实。满头头发合在一起的力量可经得起99个人的重量。
Human hair consists mainly of a protein called keratin and contains moisture and trace metals and minerals found in other parts of the body. The only part of the hair that has life is under the scalp. When it grows, it becomes a non-living tissue. The natural shine of hair comes from its own hair conditioner: oils, which contain waxes and fats, and anti-infective natural antibacterial agents. Too much oil and fat will cause oily hair. Conversely, too little oil or fat will result in dry hair. The hair can be 12 mm long each month. If a person never cuts hair, the hair will grow to 107 cm before it begins to fall off. Hair grows faster in summer and sleep. A hair can last up to 7 years. Healthy hair is very elastic and can be stretched by 20% or 30% continuously. A hair is stronger than copper wire of the same thickness. The strength of the head-to-toe together can withstand the weight of 99 people.