Trace Nb微量铌tracen.痕迹；微量；踪迹v.追踪；描绘；找出根源trace carbon and sulfur纯银trace elements analysis微量元素分析trace metal segregation微量金属熔析trace material evidence微量物证trace amounts of iodine微量碘trace organic compounds痕量有机物traceability management可追溯管理trace palladium in alloy合金中微量钯trace conditioned reflex痕迹条件反射trace mineral supplement微量元素添加剂,微量矿物质添加剂,微量添加剂