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The A4 version uses 30 closely spaced rings, while the B5 one uses 26. Less common variants such as a 20 ring A5 version also exist. [6] Personal organizer with metallic ring binder. Many personal organizers and memorandum books use a six- or seven-hole system, including Filofax and FranklinCovey. Most systems have the rings on the left side of ...
A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism , cell communication , cell cycle ...
Among the many-celled groups are animals and plants. The number of cells in these groups vary with species; it has been estimated that the human body contains around 37 trillion (3.72×10 13) cells, [7] and more recent studies put this number at around 30 trillion (~36 trillion cells in the male, ~28 trillion in the female). [8]
To bind a document, the user first punches holes in the paper with a specialized hole punch. Pages must be punched a few at a time with most of these machines. If hard covers are desired, they must be punched as well. In bulk applications, a paper drilling machine may be used. Then the user chooses a spine size that will match the document.
2-Azetidinone, the simplest β-lactam. A β-lactam (beta-lactam) ring is a four-membered lactam. [1] A lactam is a cyclic amide, and beta-lactams are named so because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl.
A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring.
With a total of 26 π-electrons, of which 18 π-electrons form a planar, continuous cycle, the porphyrin ring structure is often described as aromatic. [ 2 ] [ 3 ] One result of the large conjugated system is that porphyrins typically absorb strongly in the visible region of the electromagnetic spectrum, i.e. they are deeply colored.
The trophoblast (from Greek trephein: to feed; and blastos: germinator) is the outer layer of cells of the blastocyst.Trophoblasts are present four days after fertilization in humans. [1]