Sample selection model

selection bias

addition coefficient selection in equipment selection

~(32)P sample bottle

226Ra-222Rn sample

3-D sample block

3-sample

4-channel-sample

8-form test sample

a stool sample

Abnormal sample plot

absorption spectrum of powder sample

AC sample

accounting sample teaching

Acid dissolved sample

Adaptive Sample

adaptive sample of surfels

adding standard sample

adequate sample

aged sample