我们的头脑似乎天然地反对浪费，但在这方面，我们人类是自然界中比较独特的物种。

Our brains seem wired to resist waste, but we are relatively unique in nature for this.

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壳聚糖是自然界中产量仅次于纤维素的第二大天然高分子化合物，是一种高效的天然抗菌剂。

Chitosan is the second polymer and its amount is only inferior to cellulose in nature, it is a good antimicrobial.

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塔格糖是一种在自然界中较为稀有的天然己酮糖，属于稀少糖的一种，稀少糖是指在自然界存在但含量极少的一类单糖。

D-tagatose, a rare natural hexoketose, is one of the rare sugars, which are defined as monosaccharides and their derivatives that rarely exist in nature.

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So, a natural product is something that is made by nature, and often natural products, whether it comes from a plant or a marine organism have some really good, useful properties. And so, one particular compound has anti-tumor properties. So, again, along this line of cancer research.

天然产物是在自然界中生成的,通常一个天然产物，不管是来自植物或者海洋生物,都有些非常好非常实用的性质，其中的一个特殊的化合物,可以治疗癌症,再一次我们又来到癌症研究上。

麻省理工公开课 - 化学原理课程节选