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physical chemistry

(Encyclopedia)physical chemistry, branch of science that combines the principles and methods of physics and chemistry. It provides a fundamental theoretical and experimental basis for all of chemistry, including or...

salicylic acid

(Encyclopedia)salicylic acid or 2-hydroxybenzoic acid, C6H4(OH)CO2H, a colorless, crystalline organic carboxylic acid that melts at 159℃; it is soluble in ethanol and ether but is only slightly soluble in water. ...

brake, in technology

(Encyclopedia)CE5 Shoe brake CE5 Disk brake brake, in technology, device to slow or stop the motion of a mechanism or vehicle. The vacuum brake system, or vacuum brake, depends upon the use of a vacuum to ...

interstellar matter

(Encyclopedia)interstellar matter, matter in a galaxy between the stars, known also as the interstellar medium. The interstellar gas, which constitutes about 99% of the interstellar matter, consists mostly of hyd...

photosynthesis

(Encyclopedia)photosynthesis fōˌtōsĭnˈthəsĭs [key], process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the pr...

dengue fever

(Encyclopedia)dengue fever dĕngˈgē, –gā [key], acute infectious disease caused by four closely related viruses and transmitted by the bite of the female Aedes mosquito; it is also known as breakbone fever and...

chiropractic

(Encyclopedia)chiropractic kīrəprăkˈtĭk [key] [Gr.,=doing by hand], medical practice based on the theory that all disease results from a disruption of the functions of the nerves. The principal source of inter...

Charles Albert

(Encyclopedia)Charles Albert, 1798–1849, king of Sardinia (1831–49, see Savoy, house of). Because he had not been entirely unsympathetic to the revolutionary movement of 1821 in Sardinia, Charles Albert develop...

Chen Duxiu

(Encyclopedia)Chen Duxiu or Ch'en Tu-hsiu both: chŭn do͞o-shyo͞o [key], 1879–1942, Chinese educator and Communist party leader. He was active in the republican revolution of 1911 and was forced to flee to Japa...

altitude

(Encyclopedia)altitude, vertical distance of an object above some datum plane, such as mean sea level or a reference point on the earth's surface. It is usually measured by the reduction in atmospheric pressure wit...