Columbia Encyclopedia

Search results

500 results found

catalyst

(Encyclopedia)catalyst, substance that can cause a change in the rate of a chemical reaction without itself being consumed in the reaction; the changing of the reaction rate by use of a catalyst is called catalysis...

physics

(Encyclopedia)physics, branch of science traditionally defined as the study of matter, energy, and the relation between them; it was called natural philosophy until the late 19th cent. and is still known by this na...

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...

Port Radium

(Encyclopedia)Port Radium, mining village, N central Northwest Territories, Canada, on Great Bear Lake. The mines were discovered in 1930 and yielded deposits of pitchblende, from which much radium was produced. Du...

Ritz, Walter

(Encyclopedia)Ritz, Walter, 1878–1909, Swiss physicist. He taught at the universities of Zürich and Göttingen. Ritz's combination principle, confirmed by later research, stated that the frequencies of spectral ...

nuclear physics

(Encyclopedia)nuclear physics, study of the components, structure, and behavior of the nucleus of the atom. It is especially concerned with the nature of matter and with nuclear energy. ...

electrode

(Encyclopedia)electrode, terminal through which electric current passes between metallic and nonmetallic parts of an electric circuit. In most familiar circuits current is carried by metallic conductors, but in som...

Shakti

(Encyclopedia)Shakti shŭkˈtē [key] [Skt.,=power], in Hinduism, name given to the female consorts of male deities. The Shakti personifies the dynamic, manifesting energy that creates the universe, while the male ...

bioluminescence

(Encyclopedia)bioluminescence bīˌōlo͞oˌmĭnĕsˈəns [key], production of light by living organisms. Organisms that are bioluminescent include certain fungi and bacteria that emit light continuously. The dinof...

Julian Day calendar

(Encyclopedia)Julian Day calendar, system of astronomical dating that allows the difference between two dates to be calculated more easily than conventional civil calendars with their uneven months. It was devised ...