sampling observation

基本解释

DESIGH:Cluster sampling 1∶2 paired observation, case-control study.
设计：整群抽样，1∶2配比观察，病例对照研究。
It has specifically described 22 kinds of import broad-leaved timber structure and identification characteristic through sampling and cut-section observation of import broad-leaved timber .
通过对进口阔叶木材取样与切片观测，对22种进口阔叶材的木材构造与识别特征进行了具体描述。
Wholesome supervisory orgnaization is opposite Xiamen city this eat of type of 27 concentration of whole town (drink) provide disinfection to serve orgnaization meal (drink) had sampling observation.
厦门市卫生监督机构此次对全市27家集中式餐（饮）具消毒服务机构餐（饮）具进行了抽检。