n.

(chemistry) two or more atoms bound together as a single unit and forming part of a molecule

同義詞：groupchemical group

an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule than has lost an electron and will stabilize itself by stealing an electron from a nearby molecule

"in the body free radicals are high-energy particles that ricochet wildly and damage cells"

同義詞：free radical

a person who has radical ideas or opinions

a character conveying the lexical meaning of a logogram

a sign placed in front of an expression to denote that a root is to be extracted

同義詞：radical sign

(linguistics) the form of a word after all affixes are removed

同義詞：rootroot wordbasestemtheme

Free radicals in biology and medicine
The biology of oxygen radicals
The biology of oxygen radicals
Free Radicals in the Physiological Control of Cell Function
Oxygen-derived free radicals in postischemic tissue injury.
Free radicals, metals and antioxidants in oxidative stress-induced cancer.
Oxygen toxicity, oxygen radicals, transition metals and disease.
Antioxidant determination by use of stable free radicals
Dietary carcinogens and anticarcinogens. Oxygen radicals and degenerative diseases.
2006 Mar 10;160(1):1-40. Epub 2006 Jan 23. Free radicals, metals and antioxidants in oxidative stress-induced cancer.