tracern.追踪者(器)；示踪物；曳光弹；[化]示踪剂tracery parapet镂空女儿墙tracer analysis示踪分析tracer antibody示踪抗体tracer solution示踪溶液tracer activity示踪物的放射性tracer particle示踪粒子tracer chemical示踪化学剂tracer injector示踪注入井；示踪剂注入器tracer material示踪物质,示踪材料tracer facility示踪原子设施