fraction of life
71Pi — This article is about the number. For the Greek letter, see Pi (letter). For other uses, see Pi (disambiguation). The circumference of a ci …
72Radiocarbon dating — (sometimes simply known as carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon 14 (14C) to estimate the age of carbon bearing materials up to about 58,000 to 62,000 years.[1] Raw, i.e. uncalibrated …
73Mechanical ventilation — In architecture and climate control, mechanical or forced ventilation is the use of powered equipment, e.g. fans and blowers, to move air  see ventilation (architecture). Mechanical ventilation Intervention …
74Breathing gas — is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other artificial gases, either pure gases or mixtures of gases, are used in breathing equipment and enclosed… …
75Chinese mathematics — Mathematics in China emerged independently by the 11th century BC.[1] The Chinese independently developed very large and negative numbers, decimals, a place value decimal system, a binary system, algebra, geometry, and trigonometry. Many[who?]… …
76Communism in Korea — Part of the series on Communism …
77Glossary of environmental science — This is a glossary of environmental science.Environmental science is the study of interactions among physical, chemical, and biological components of the environment. Environmental science provides an integrated, quantitative, and… …
78Colonisation De L'espace —  Pour les autres significations, voir colonisation de l espace en fiction. Dessin d artiste d un habitat spatial …
79Colonisation espace — Colonisation de l espace  Pour les autres significations, voir colonisation de l espace en fiction. Dessin d artiste d un habitat spatial …
80Colonisation spatiale — Colonisation de l espace  Pour les autres significations, voir colonisation de l espace en fiction. Dessin d artiste d un habitat spatial …
