"SDN:P07::CF12N4" . . "2009-07-06 15:41:29.0" . "1" . . . . "1" . "SDN:P07::CF12N4" . . . "atmosphere_mass_content_of_alkenes"@en . . . "SDN:P07::CF12N4" . "2009-07-06 15:41:29.0" . "" . "false" . "accepted"@en . "\"Content\" indicates a quantity per unit area. The \"atmosphere content\" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. Alkenes are unsaturated hydrocarbons as they contain chemical double bonds between adjacent carbon atoms. Alkenes contain only hydrogen and carbon combined in the general proportions C(n)H(2n); \"alkenes\" is the term used in standard names to describe the group of chemical species having this common structure that are represented within a given model. The list of individual species that are included in a quantity having a group chemical standard name can vary between models. Where possible, the data variable should be accompanied by a complete description of the species represented, for example, by using a comment attribute. Standard names exist for some individual alkene species, e.g., ethene and propene."@en .