n.

an investigator who is employed to find missing persons or missing goods

an instrument used to make tracings

(radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes

ammunition whose flight can be observed by a trail of smoke

同義詞：tracer bullet

Tracers in the sea
Tracers in the Sea
The Tracers in the Sea
Biomass burning — a review of organic tracers for smoke from incomplete combustion
Radiolabeled alpha(v)beta3 integrin antagonists: a new class of tracers for tumor targeting.
A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2
Description and evaluation of the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4)
Cutin and suberin biomarkers as tracers for the turnover of shoot and root derived organic matter along a chronosequence of Ecuadori...
MOZART, a global chemical transport model for ozone and related chemical tracers: 2. Model results and evaluation
Lignin pyrolysis products, lignans, and resin acids as specific tracers of plant classes in emissions from biomass combustion