from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A central or essential part around which other parts are gathered or grouped; a core.
- noun Something regarded as a basis for future development and growth; a kernel.
- noun Biology A membrane-bound organelle within a eukaryotic cell that contains most of the cell's genetic material. DNA transcription takes place in the nucleus.
- noun Anatomy A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.
- noun Physics The positively charged central region of an atom, composed of protons and neutrons, about which negatively charged electrons orbit. Extremely small and dense, the nucleus contains almost all of the mass of an atom.
- noun Chemistry A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.
- noun The central, often brightest part of the head of a comet.
- noun The solid part of a comet, composed of ice and smaller amounts of dust and rock.
- noun The central, often brightest part of a galaxy.
- noun Meteorology A particle on which water vapor molecules accumulate in free air to form a droplet or ice crystal.
- noun Linguistics The part of a syllable having the greatest sonority. In the word middlemost (mĭd′l-mōst″) the nuclei of the three syllables are (ĭ), (l), and (ō); in the Czech word krk (“neck”), the nucleus is (r).
from The Century Dictionary.
- noun A very small colony of honey-bees started for the purpose of rearing queens to exchange with the queens of full colonies, thus assisting in the prevention of swarming.
- noun no points at all;
- noun a perfect set. This result (set) is the nucleus EΩ.
- noun A kernel; hence, a central mass about which matter is collected, or to which accretion is made; any body or thing that serves as a center of aggregation or assemblage; figuratively, something existing as an initial or focal point or aggregate: as, a nucleus of truth; a nucleus of civilization.
- noun In biology, the kernel of a cell, in general; a central or interior differentiated mass of protoplasm, found in nearly all cells, vegetable or animal, and consisting of an oval or rounded body composed of
- noun a nuclear membrane
- noun nuclear network, and
- noun nucleoplasm, and containing nucleoli. The nuclear network is made up of threads or fibrils which are composed of a deeply staining part, “chromatin,” and a feebly staining intermediate substance, “linin” or parachromatin (nucleohyaloplasm). In the meshes of the network is found the more fluid part of the nucleus, the nucleoplasm (achromatin, karyochylema, paralinin). Nucleoplasm, according to Carnoy, consists of a plastin network and a granular fluid, “enchylema.” The nuclear membrane is considered by some observers to be an inner limiting layer of cell-protoplasm surrounding the nucleus, by others to be a condensation of the peripheral portion of the nuclear network. There may be but one nucleus or several nuclei in one cell; and a nucleus may be nucleolate or not. Nuclei are generally proportionate in size to the cell containing them: in some instances, however, they form almost the entire cell mass. A structural difference between the nucleus and the rest of the cell-protoplasm is indicated by its greater resistance to powerful reagents, and by its varied reaction with stains. Functionally, the nucleus is the most important portion of the cell, as it is here that the complex series of changes known as karyokinesis take place, resulting in the division of the nucleus and followed by the division of the cell. This process of mitosic or indirect cell-division is found in all varieties of cells, whether vegetable or animal, fetal or adult, normal or pathological. Instances of cell-division not mitosic have, however, been noted. The nucleus of the human ovum was discovered by Purkinje in 1825, and hence is often called the corpuscle of Purkinje. Its usual name in text-books of anatomy is germinal vesicle. See cut under
- noun In zoology:
- noun In ascidians, the alimentary and reproductive viscera collectively, when these are aggregated into a mass, as in the salps.
- noun In protozoans, a solid rod-like or strap-shaped body, having in many cases the functions of an ovary in connection with a nucleolus (see
- noun In echinoderms, the madreporiform body
- noun In anatomy, a collection of ganglion-cells in the brain or other portion of the cerebrospinal axis.
- noun In conchology, the embryonic shell which remains at the apex of the mature shell, as of a gastropod; also, the initial point from which the operculum of a gastropod grows. See
- noun A body having a stronger or weaker attraction for the gas, vapor, or salt of a solution than for the liquid part of it, and therefore modifying by its presence the freezing-and boiling-points.
- noun In astronomy, the bright central point usually present in the head of a comet and often in a nebula.
- noun A genus of gastropods: same as
- noun Same as
from the GNU version of the Collaborative International Dictionary of English.
- noun A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; -- used both literally and figuratively.
- noun (Astron.) The body or the head of a comet.
- noun An incipient ovule of soft cellular tissue.
- noun A whole seed, as contained within the seed coats.
- noun (Biol.) A body, usually spheroidal, in a eukaryotic cell, distinguished from the surrounding protoplasm by a difference in refrangibility and in behavior towards chemical reagents, which contains the chromosomal genetic material, including the chromosomal DNA. It is more or less protoplasmic, and consists of a clear fluid (achromatin) through which extends a network of fibers (chromatin) in which may be suspended a second rounded body, the nucleolus (see
Nucleoplasm). See Cell division, under Division.
- noun The tip, or earliest part, of a univalve or bivalve shell.
- noun The central part around which additional growths are added, as of an operculum.
- noun A visceral mass, containing the stomach and other organs, in Tunicata and some mollusks.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun The
core, central part (of something), round which others are assembled.
- noun An
initialpart or version that will receive additions.
- noun chemistry, physics The massive, positively
chargedcentral part of an atom, made up of protonsand neutrons.
- noun cytology A large
organellefound in cellswhich contains geneticmaterial.
- noun neuroanatomy A
ganglion, cluster of many neuronal bodies where synapsing occurs.
- noun linguistics The central part of a
syllable, most commonly a vowel.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun the positively charged dense center of an atom
- noun any histologically identifiable mass of neural cell bodies in the brain or spinal cord
- noun (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
The remains of the egg nucleus, after having discharged the polar cells, form the _female nucleus_ (Fig. 40, _fn_).
In my scenario, translation outside the nucleus is an added feature and normal translation and transcription in the nucleus can stillgo on during the gradual evolution of the transport system. hrun: The mainstay of darwinian evolution is a gradualistic concept and I have not observed that is replaced by goal-oritented approaches.
In my scenario, translation outside the nucleus is an added feature and normal translation and transcription in the nucleus can stillgo on during the gradual evolution of the transport system.
"It is going to be what they call a nucleus," said Olive, showing a little piece of fancy work.
We had to get what we called our nucleus registration database into a bullet-proof position so we knew we could manage intelligence and entitlements without leaving the consumer sort of left holding the bag where we make mistakes.
Four starters and most of the key reserves will be back next season (barring any transfers), and the nucleus is freshmen and sophomores.
With Pro Bowl tackle Joe Thomas and guard Eric Steinbach holding down the left side and center Alex Mack arriving via the draft in the first round, a solid nucleus is in place.
Although all atoms possess this latent energy, radioactive substances such as uraniumpossess heavy and unstable nucleimaking them easier to manipulate into a chain reaction whereby a heavy nucleus is split into two lighter particles which in turn go off and strike other uranium atoms splitting those.
I think our nucleus is starting to feel comfortable around them as well. ''
"Our results," as they both argued, "seem so far to indicate that the hydrogen nucleus is a more common constituent of the lighter atoms than one has hitherto been inclined to believe."