We have an ability to smell incredibly small concentrations, down to as little as two parts per trillion.
人类可以闻到微小浓度的物质，哪怕浓度小到一万亿分之二。
The bees can detect the target chemicals in the air in concentrations as low as a few parts per trillion.
而且蜜蜂能觉察到空气中浓度仅万亿分之一单位的特定化学物质。
Still widely used, this electronic nose is able to sniff out a few parts per trillion of chemicals found in the soil, water or air.
这种仪器直至今天仍然广泛使用，它可以从土壤、水或空气中发现的数以万计的化学物中嗅到一部分（需要的）的东西。
The plan was to sample nitryl chloride levels in Marine air, which computer models predicted would not exceed 50 parts per trillion.
他们计划对途经海洋的空气进行抽样调查，计算机模型预测这些海洋空气中硝基氯含量不会超过万亿分之五十。
In the case of valeric acid, for example, that concentration was seven parts per trillion-a level only just detectable by bloodhounds.
比如，缬草酸的汗臭味浓度为万亿分之七，这种浓度只有警犬才能发觉。
Studies have shown that dogs 'noses can detect scents as faint as 500 parts per trillion, making it possible that dogs sense a seizure-indicating pheromone3 prior to an attack.
研究表明，狗鼻子能嗅出微弱到兆分之五百程度的味道，所以它能闻出显示癫痫即将发作的信息素。
To be sure, the concentrations of these pharmaceuticals are tiny, measured in quantities of parts per billion or trillion, far below the levels of a medical dose.
要肯定的是这些药物浓度极少，量是以每10亿或万亿为单位来计算。远远要低于医用水平。
To be sure, the concentrations of these pharmaceuticals are tiny, measured in quantities of parts per billion or trillion, far below the levels of a medical dose.
要肯定的是这些药物浓度极少，量是以每10亿或万亿为单位来计算。远远要低于医用水平。
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