Second Hospital of Jilin University;
Changchun 130021;
P.R.China;
Key Laboratory of Groundwater Resource and Environment;
Ministry of Education;
College of Environment and Resources;
Jilin University;
Changchun 130021;
P.R.China;
Sunflower; stem; SnO2/ZnO; Graded; porous; structure; Gas; sensitivity; n-Butanol;