density step灰度等级densityn.密度；浓度；比重density-dependent viscosity粘性依赖于密度Density of glandular trichome腺毛密度density distribution gradient密度分布梯度density-specific adaptation密度特殊适应,密度相关适应density-proportional factor密度比例因子；密度相关因子density gradient fractionator密度梯度分布器density-dependent inhibition密度依赖性抑制density gradient sedimentation密度梯度沉降density of average energy flow平均能流密度density functional calculation密度泛函