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1. In a study of the metabolism of l-[(35)S]methionine in vivo, the labelled sulphur compounds of rat liver and brain were separated first by ion-exchange chromatography into two fractions containing (i) free sulphur amino acids such as methionine, cystathionine, cyst(e)ine and homocyst(e)ine and (ii) glutathione. 2. Two-dimensional paper chromatography with butan-1-ol-acetic acid or propionic acid-water in the first direction and 80% acetone or acetone-ethyl methyl ketone-water in the second direction was found superior to other solvent systems for separating the sulphur amino acids. 3. At 10min. after injection of [(35)S]methionine only a small part of the (35)S was found combined in free methionine or other free sulphur amino acids. 4. Evidence was obtained of the presence of adenosyl[(35)S]methionine and adenosyl[(35)S]homocysteine in perchloric acid extracts of rat liver and brain. 5. The trans-sulphuration pathway was active in brain as well as in liver. 相似文献
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C. D. Cook F. Geller G. B. Hutchison P. Gerald F. H. Allen 《American journal of human genetics》1962,14(3):290-294
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Gerald Houghton 《Bulletin of mathematical biology》1966,28(4):487-500
A two-dimensional nonlinear integro-differential equation with time-varying coefficients describing the behavior of the fluttering
wing-body systems typical of natural flight mechanisms has been deduced from the Navier-Stokes equation which generalizes
local pressure and velocity distributions in the externally oscillating air field. The resulting equation for the wing forces
is combined with an analogous expression for the forces of gravitation and acceleration associated with the body. The air
acceleration force, not previously considered in bio-physical models of insect and bird flight, is shown to arise from a formal
analysis of unsteady or time-varying contributions to the velocity field, while the square form of the conventional steady
state aerodynamic forces is derived from the intertial terms in the Navier-Stokes equation with the aid of the approximations
of Newtonian impact theory. Previous calculations (Houghton, 1964) have indicated that the contribution to gravitational stability
of air acceleration and aerodynamic life are roughly in the ratio of 3:1. 相似文献
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