NASA said the increased methane was measured to be about 21 parts per billion by volume (ppbv).
美国宇航局表示，测量到的甲烷的体积浓度比增加到21ppbv。
| 单词 | Ppbv |
| 释义 |
Ppbv
原声例句
VOA慢速英语_科技 NASA said the increased methane was measured to be about 21 parts per billion by volume (ppbv). 美国宇航局表示，测量到的甲烷的体积浓度比增加到21ppbv。 VOA慢速英语_科技 One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane. 1ppbv指如果你在火星上吸入1体积的空气，那么其中十亿分之一就是甲烷。
英语百科
Parts-per notation（重定向自Ppbv）
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are ppm (parts-per-million, 10), ppb (parts-per-billion, 10), ppt (parts-per-trillion, 10) and ppq (parts-per-quadrillion, 10). |
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