原始互助，基本互助：①指两群体(或个体)生物共同生活在一起时，对双方都有利，但彼此分开以后，各自也能生活的共生现象；②动物的群集趋向，因而有助于单个生物个体的存活- isomeride
- isomerism
- isomerization
- isometheptene hydrochloride
- isometric
- isometropia
- isometry
- isomorphic
- isomorphism
- isomorphous
- isomuscarine
- isomylamine hydrochloride
- isonaphthol
- isonephrotoxin
- isoniazid
- isonicotinoylhydrazine
- isonicotinylhydrazine
- isonipecaine
- isonitril
- iso-oncotic
- iso-osmotic
- Isopaque
- Isoparorchis trisimilitubis
- isopathy
- isophagy