Science / Chemistry / Atomic Nucleus: A tiny, incredibly dense positively charged mass at the heart of the atom. The nucleus is composed of protons and neutrons (and other particles). It contains almost all of the mass of the atom but occupies only a tiny fraction of the atom's volume.
Science / Chemistry / Atomic Number (Z): The number of protons in an atomic nucleus. The atomic number and the element symbol are two alternate ways to label an element. In nuclide symbols, the atomic number is a leading subscript; for examp MORE
Science / Biology / Nucleus (Cell): The largest, most prominent organelle in eukaryotic cells; a round or oval body that is surrounded by the nuclear envelope and contains the genetic information necessary for control of cell structure MORE
Science / Biology / Nucleus (Atom): An atoms core; contains protons and one or more neutrons (except hydrogen, which has no neutrons). MORE
Health / First Aid / Anatomical Position: A basic position that all anatomical references assume. The subject is standing, looking straight ahead with arms hanging down at both sides and palms facing forward. In most cases, the toes are point MORE
Science / Biology / Micronucleus: In the protistan group known as the ciliates, the small nucleus containing a single copy of the genome that is used for sexual reproduction. MORE