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pressure

(Encyclopedia)pressure, in mechanics, ratio of the force acting on a surface to the area of the surface; it is thus distinct from the total force acting on a surface. A force can be applied to and sustained by a si...

respiration

(Encyclopedia)CE5 Respiratory system respiration, process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is tran...

protein

(Encyclopedia)protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellu...

Lebanon, country, Asia

(Encyclopedia)CE5 Lebanon lĕbˈənən, –nŏnˌ [key], officially Lebanese Republic, republic (2015 est. pop. 5,851,000), 4,015 sq mi (10,400 sq km), SW Asia. The country is bordered on the west by the Mediter...

Pakistan

(Encyclopedia)CE5 Pakistan păkˈĭstănˌ, päkĭstänˈ [key], officially Islamic Republic of Pakistan, republic (2015 est. pop. 189,381,000), 310,403 sq mi (803,944 sq km), S Asia. Pakistan is bordered by Ind...

isomer

(Encyclopedia)isomer īˈsəmər [key], in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of ...

iron

(Encyclopedia)iron, metallic chemical element; symbol Fe [Lat. ferrum]; at. no. 26; at. wt. 55.845; m.p. about 1,535℃; b.p. about 2,750℃; sp. gr. 7.87 at 20℃; valence +2, +3, +4, or +6. Iron is biologically s...

sun, in astronomy

(Encyclopedia)CE5 Structure of the sun sun, intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the sola...

elementary particles

(Encyclopedia)CE5 elementary particles, the most basic physical constituents of the universe. The first subatomic particle to be discovered was the electron, identified in 1897 by J. J. Thomson. After the...

nucleic acid

(Encyclopedia)CE5 Replication of strands of DNA CE5 nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replica...