| 释义 |
WordReference Random House Learner's Dictionary of American English © 2024nu•cle•us /ˈnukliəs, ˈnyu-/USA pronunciation n. [countable], pl. -cle•i /-kliˌaɪ/USA pronunciation -cle•us•es. - a central part about which other parts are grouped or gathered;
core:The police managed to arrest some members of the gang, but none that make up its nucleus. - Biology, Cell Biologya special, usually round mass of material in a cell that directs its growth and reproduction and contains most of the genetic material.
- Physicsthe central, positively charged mass within an atom, made up of neutrons and protons and making up most of the atom's mass.
WordReference Random House Unabridged Dictionary of American English © 2024nu•cle•us (no̅o̅′klē əs, nyo̅o̅′-),USA pronunciation n., pl. -cle•i (-klē ī′),USA pronunciation -cle•us•es. - a central part about which other parts are grouped or gathered;
core:A few faithful friends formed the nucleus of the club. - Biology, Cell Biologya specialized, usually spherical mass of protoplasm encased in a double membrane, and found in most living eukaryotic cells, directing their growth, metabolism, and reproduction, and functioning in the transmission of genic characters. See illus. under ameba.
- Physicsthe positively charged mass within an atom, composed of neutrons and protons, and possessing most of the mass but occupying only a small fraction of the volume of the atom.
- Anatomya mass of nerve cells in the brain or spinal cord in which nerve fibers form connections.
- MeteorologyAlso called condensation nucleus. a particle upon which condensation of water vapor occurs to form water drops or ice crystals.
- Chemistrya fundamental arrangement of atoms, as the benzene ring, that may occur in many compounds by substitution of atoms without a change in structure.
- Astronomythe condensed portion of the head of a comet.
- Phonetics
- the central, most prominent segment in a syllable, consisting of a vowel, diphthong, or vowellike consonant, as the a- sound in cat or the l- sound in bottled;
peak. - the most prominent syllable in an utterance or stress group;
tonic syllable.
- Latin: kernel, syncopated variant of nuculeus, equivalent. to nucu(la) little nut (nuc-, stem of nux nut + -ula -ule) + -leus noun, nominal suffix
- 1695–1705
- 1.See corresponding entry in Unabridged center, kernel, heart.
Collins Concise English Dictionary © HarperCollins Publishers:: nucleus /ˈnjuːklɪəs/ n ( pl -clei / -klɪˌaɪ/, -cleuses)- a central or fundamental part or thing around which others are grouped; core
- a centre of growth or development; basis; kernel: the nucleus of an idea
- (in the cells of eukaryotes) a large compartment, bounded by a double membrane, that contains the chromosomes and associated molecules and controls the characteristics and growth of the cell
- the central portion in the head of a comet, consisting of small solid particles of ice and frozen gases, which vaporize on approaching the sun to form the coma and tail
- the positively charged dense region at the centre of an atom, composed of protons and neutrons, about which electrons orbit
- a fundamental group of atoms in a molecule serving as the base structure for related compounds and remaining unchanged during most chemical reactions
Etymology: 18th Century: from Latin: kernel, from nux nut |