substratum

n.

底层，下层；

复数：substrata

1. The story has a substratum of truth.
   这故事有事实的基础。
2. There is a substratum of truth in her story.
   她叙述中有事实根据.
3. The soil has a substratum of rock.
   这土壤下面有层石头。

Aquatic insect-substratum relationships
Cell-to-substratum adhesion and guidance of axonal elongation
The occurrence of benthos deep in the substratum of a stream
Possible roles for cell-to-substratum adhesion in neuronal morphogenesis.
Correlation between substratum roughness and wettability, cell adhesion, and cell migration.
The Role of Substratum in Benthic Macroinvertebrate Microdistribution and Litter Decomposition in a Woodland Stream
Pore size of porous hydroxyapatite as the cell-substratum controls BMP-induced osteogenesis.
Exopolysaccharide production in biofilms: substratum activation of alginate gene expression by Pseudomonas aeruginosa.
Afferents of the ventral tegmental area in the rat-anatomical substratum for integrative functions.
Neurite extension by peripheral and central nervous system neurons in response to substratum-bound fibronectin and laminin.