幻日现象经常在北极和南极出现.Sundogs are fairly common occurrences in the Arctic and Antarctic.包含冰晶的高空云所形成黯淡的幻日隐约可见.The high clouds containing the ice crystals are faintly visible as are some sundogs....
螃蟹的螯the claws of a crab植物由于具有螯合机制可能影响土壤的化学特性.Plants may possibly influence soil chemistry by the possession of chelating mechanisms.确定螯合 -- 溶剂萃取法所得到的检测限颇为困难.It is difficult to define the detection limits obtained by chel...