The action on addition urea is testified, that the urea is not only a nitrogen - containing biological active species, but also can combine phenol to become an easily oxidized content compound.

• 尿素所起的作用,不仅是因为尿素是一种含氮生物活性物,而且还可能因为尿素与酚形成了一种易于氧化的包体化合物。