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Tetraterpenoids
Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. In plants, terpenes and terpenoids are important mediators of ecological interactions, while some insects use some terpenes as a form of defense. Other functions of terpenoids include cell growth modulation and plant elongation, light harvesting and photoprotection, and membrane permeability and fluidity control. Terpenes are classified by the number of carbons: monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), as examples. The terpene alpha-pinene is a major component of the common solvent, turpentine. The one terpene that has major applications is natural rubber (i.e., polyisoprene). The possibility that other terpenes could be used as precursors to produce synthetic polymers has been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
August Kekulé
Friedrich August Kekulé, later Friedrich August Kekule von Stradonitz ( , ; 7 September 1829 – 13 July 1896), was a German organic chemist. From the 1850s until his death, Kekulé was one of the most prominent chemists in Europe, especially in the field of theoretical chemistry. He was the principal founder of the theory of chemical structure and in particular the Kekulé structure of benzene. Name Kekulé never used his first given name; he was known throughout his life as August Kekulé. He did however say it once in his work. After he was ennobled by the Kaiser in 1895, he adopted the name August Kekule von Stradonitz, without the French acute accent over the second "e". The French accent had apparently been added to the name by Kekulé's father during the Napoleonic occupation of Hesse by France, to ensure that French-speakers pronounced the third syllable. Early years The son of a civil servant, Kekulé was born in Darmstadt, the capital of the Grand Duchy of Hesse. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steroids
A steroid is an organic compound with four fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and as signaling molecules. Examples include the lipid cholesterol, sex hormones estradiol and testosterone, anabolic steroids, and the anti-inflammatory corticosteroid drug dexamethasone. Hundreds of steroids are found in fungi, plants, and animals. All steroids are manufactured in cells from a sterol: cholesterol (animals), lanosterol ( opisthokonts), or cycloartenol (plants). All three of these molecules are produced via cyclization of the triterpene squalene. Structure The steroid nucleus ( core structure) is called gonane (cyclopentanoperhydrophenanthrene). It is typically composed of seventeen carbon atoms, bonded in four fused rings: three six-member cyclohexane rings (rings A, B and C in the first illus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Male Sex Hormones
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both males and females during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT ''in utero'' causes differentiation of the penis, scrotum and prostate. In adulthood, DHT contributes to balding, prostate growth, and sebaceous gland activity. Although androgens are commonly thought of only as male sex hormones, females also have them, but at lower levels: they function in libido and sexual arousal. Androgens are t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Synthesis
Chemical synthesis (chemical combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In modern laboratory uses, the process is reproducible and reliable. A chemical synthesis involves one or more compounds (known as '' reagents'' or ''reactants'') that will experience a transformation under certain conditions. Various reaction types can be applied to formulate a desired product. This requires mixing the compounds in a reaction vessel, such as a chemical reactor or a simple round-bottom flask. Many reactions require some form of processing (" work-up") or purification procedure to isolate the final product. The amount produced by chemical synthesis is known as the '' reaction yield''. Typically, yields are expressed as a mass in grams (in a laboratory setting) or as a percentage of the total theoretical quantity that could be produced based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nobel Foundation
The Nobel Foundation () is a private institution founded on 29 June 1900 to manage the finances and administration of the Nobel Prizes. The foundation is based on the last will of Alfred Nobel, the inventor of dynamite. It also holds Nobel Symposia on important breakthroughs in science and topics of cultural or social significance. History Alfred Nobel (; born 21 October 1833, in Stockholm, Sweden) was a chemist, engineer, innovator, armaments manufacturer and the inventor of dynamite. He owned Bofors, a major armaments manufacturer, which he had redirected from its original business as an iron and steel mill. Nobel held 355 different patents, dynamite being the most famous. Nobel amassed a sizeable personal fortune during his lifetime, thanks mostly to this invention. In 1896 Nobel died of a stroke in his villa in Sanremo, San Remo, Italy where he had lived his final years.AFP"Alfred Nobel's last will and testament", ''The Local''(5 October 2009): accessed 14 January 2009. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nobelprize
The Nobel Prizes ( ; ; ) are awards administered by the Nobel Foundation and granted in accordance with the principle of "for the greatest benefit to humankind". The prizes were first awarded in 1901, marking the fifth anniversary of Alfred Nobel's death. The original Nobel Prizes covered five fields: physics, chemistry, physiology or medicine, literature, and peace, specified in Nobel's will. A sixth prize, the Prize in Economic Sciences, was established in 1968 by Sveriges Riksbank (Sweden's central bank) in memory of Alfred Nobel. The Nobel Prizes are widely regarded as the most prestigious awards available in their respective fields. Shalev, p. 8. Except in extraordinary circumstances, such as war, all six prizes are given annually. Each recipient, known as a laureate, receives a green gold medal plated with 24 karat gold, a diploma, and a monetary award. As of 2023, the Nobel Prize monetary award is , equivalent to approximately . The medal shows Nobel in profile with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier Publishing Company
Elsevier ( ) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, ''Trends'', the '' Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services include digital tools for data management, instruction, research analytics, and assessment. Elsevier is part of the RELX Group, known until 2015 as Reed Elsevier, a publicly traded company. According to RELX reports, in 2022 Elsevier published more than 600,000 articles annually in over 2,800 journals. As of 2018, its archives contained over 17 million documents and 40,000 e-books, with over one billion annual downloads. Researchers have criticized Elsevier for its high profit margins and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
