trace tov.上溯；追溯到tracen.痕迹；微量；踪迹v.追踪；描绘；找出根源traceability logistics地理信息系统（GIS）Trace element in serum血清微量元素trace chemical element微量化学元素trace-back algorithm回溯算法traces of heavy metals重金属痕量Trace Analysis Methods痕量分析方法trace heavy metal ions痕量重金属trace following device径迹跟踪装置trace of electron beam电子扫迹trace haloacetic acids痕量卤代乙酸