illustration of cross-section through leaf, showing upper epidermis, palisade mesophyll, xylem vesse - 植物細胞 幅插畫檔、美工圖案、卡通及圖標
medical resarch icon set - biomedical, clinical trials, epidemiology, genomic, drug development, immunology - 植物細胞 幅插畫檔、美工圖案、卡通及圖標圖示, 科學研究, 研究