The diurnal vertical migration of planktonic Ostracoda is studied based on the analysis of stratifiedsamples of zooplanktons in the IONESS system.
根据IONESS系统对浮游动物的分层采样结果，研究浮游介形动物的昼夜垂直移动。
2
The survey was completed on the basis of combining stratified sampling and random sampling, collecting 1005 valid samples in total.
调查在分层逐级抽样法与随机抽样法相结合的抽样基础完成，共收集有效样本1005个。
3
Methods: According to the fifth national demographic investigations, the norm samples aged 10 to 15 years were collected in a stratified and random way.