Search results
Results from the WOW.Com Content Network
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
This is a form of nuclear decay. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to attach and detach from each other is responsible for most of the physical changes observed in nature. Chemistry is the science that studies these changes.
The Visible Human Project is an effort to create a detailed data set of cross-sectional photographs of the human body, in order to facilitate anatomy visualization applications. It is used as a tool for the progression of medical findings, in which these findings link anatomy to its audiences. [ 1 ]
Organotrophs use organic compounds as electron/hydrogen donors. Lithotrophs use inorganic compounds as electron/hydrogen donors.. The electrons or hydrogen atoms from reducing equivalents (electron donors) are needed by both phototrophs and chemotrophs in reduction-oxidation reactions that transfer energy in the anabolic processes of ATP synthesis (in heterotrophs) or biosynthesis (in autotrophs).
For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time . The original term, half-life period , dating to Ernest Rutherford 's discovery of the principle in 1907, was shortened to half-life in the early 1950s. [ 1 ]
Disaccharides are formed when two monosaccharides, or two single simple sugars, form a bond with removal of water. They can be hydrolyzed to yield their saccharin building blocks by boiling with dilute acid or reacting them with appropriate enzymes. [6] Examples of disaccharides include sucrose, maltose, and lactose.
The elongated Cu−S 2 bonding destabilizes the Cu(II) form and increases the redox potential of the protein. The blue color (597 nm peak absorption) is due to the Cu−S 1 bond where S(pπ) to Cu(d x 2 −y 2) charge transfer occurs. [21] In the reduced form of plastocyanin, His-87 will become protonated with a pK a of 4.4.
Many other isotopes have been used in specialized radiopharmacological studies. The most widely used is 67 Ga for gallium scans. 67 Ga is used because, like 99m Tc, it is a gamma-ray emitter and various ligands can be attached to the Ga 3+ ion, forming a coordination complex which may have selective affinity for particular sites in the human body.