Topically, 1 pound of steam can be used to generate a little less than 1 pound of vapor through evaporation. 总体来说一磅的水通过蒸发可以产生不到一磅的蒸汽。
They manipulate the water in the xylem under negative pressure -- what's called a metastable liquid state -- right on the verge of becoming a vapor. 但木质部通道的两端都结合有带微孔的膜,这些孔能够阻碍通道中的水超越其表面张力,发生蒸发。