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单词 half life
释义

WordReference Random House Learner's Dictionary of American English © 2024
ˈhalf-ˌlife or ˈhalf ˌlife, n. [countable], pl. -lives. 
  1. Physicsthe time required for one half the atoms of a given amount of a radioactive substance to decay:a half-life of over 50,000 years.

WordReference Random House Unabridged Dictionary of American English © 2024
half-life  (haf′līf′, häf′-),USA pronunciation n., pl. -lives 
    (-līvz′).USA pronunciation 
  1. Physicsthe time required for one half the atoms of a given amount of a radioactive substance to disintegrate.
  2. [Pharm.]the time required for the activity of a substance taken into the body to lose one half its initial effectiveness.
  3. Informal Termsa brief period during which something flourishes before dying out.
Also, half′ life′, half′life′. Also called half′-life pe′riod. 
  • half + life 1905–10

Collins Concise English Dictionary © HarperCollins Publishers::
half-life n
  1. the time taken for half of the atoms in a radioactive material to undergo decay
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更新时间：2025/7/31 4:37:43