|Terpenes are series of isomeric, unsaturated hydrocarbons of the general formula C10H16 found in the steam volatile essential (ethereal) oils of plant origin, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeteria. They are often strong-smelling. They may protect the plants that produce them by deterring herbivores and by attracting predators and parasites of herbivores. Many terpenes are aromatic hydrocarbons and thus may have had a protective function. The difference between terpenes and terpenoids is that terpenes are hydrocarbons, whereas terpenoids contain additional functional groups. The name "terpene" is derived from the word "turpentine". Terpenes and terpenoids are the primary constituents of the essential oils of many types of plants and flowers. Essential oils are used widely as natural flavor additives for food, as fragrances in perfumery, and in medicine and alternative medicines such as aromatherapy. Synthetic variations and derivatives of natural terpenes and terpenoids also greatly expand the variety of aromas used in perfumery and flavors used in food additives. Vitamin A is a terpene.
Scientific journal is a periodical publication intended to further progress of science, usually by reporting novel research. There are thousands of scientific journals in publication, and many more have been published at various points in the past. Most journals are highly specialized, although some of the oldest journals publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that are peer reviewed, to ensure that articles meet the journal's standards of quality, and scientific validity. The publication of the results of research is an essential part of the scientific method. If they are describing experiments or calculations, they must supply enough details that an independent researcher could repeat the experiment or calculation to verify the results. Each such journal article becomes part of the permanent scientific record.