Now chemists have developed a technique that identifies what kind of degradation process an old book or historical document is going through, based on the odors it gives off.

现在，化学家们研发出一种技术，这种技术基于旧书或是历史文档所散发出来的气味，能够鉴别出它们所经历的不同老化过程。

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The aroma should be clean and fresh, without any of the off-odors mentioned above.

葡萄酒的香气应该是干净和新鲜的，不含以上提到的任何缺陷气味。

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I am even better off than a laboratory attendant, because there are no bad odors here, just the smell of lead burning.

我是绝对免疫的，我甚至比一个实验室工作人员的境况还好些，因为这儿没有不好的气味，只有铅燃烧的味儿。

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Other studies have concluded that people give off different body odors that correspond to certain emotional situations, but what hasn't been shown is whether other people become a little stressed after smelling the body odor from stressed people, Wysocki said.

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The presence or attempted acquisition of large quantities of household chemicals or fertilizers that could be used in bomb-making is another clear tip off, as are unusual odors or chemical burns.

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Pheromones have been popularized as a factor in sexual desire -- namely, that certain odors that people give off attract potential mates -- but their role in humans is still controversial.

CNN: Sweat may give off stress signals, study says