density step灰度等级densityn.密度；浓度；比重Density functional t heory密度泛函理论density of arterial street干路网密度density-based algorithms基于密度的算法density-analyzing method密实度计量分析法density current in estuary河口密度流density of interface state界面态密度density reproduction ratio密度复制比density independent factor非密度制约因素, 密度无关因素Density of use of language好；说明语言的应用密度density of dectronic state局域态密度