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2024年5月12日 · Structure of a typical L-alpha-amino acid in the "neutral" form Amino acids are organic compounds that contain both amino and carboxylic acid functional groups.[1] Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins.[2] Only these 22 appear in the genetic code of life.[3 ...
2024年5月13日 · A protein is a polyamide. Secondary structure: regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the α-helix, β-sheet and turns. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
4 天前 · Veganism is the practice of abstaining from the use of animal products—particularly in diet—and an associated philosophy that rejects the commodity status of animals.[c] A person who follows the diet or philosophy is known as a vegan. Distinctions may be made between several categories of veganism. Dietary vegans, also known as "strict ...
5 天前 · George Washington (February 22, 1732 – December 14, 1799) was an American Founding Father, military officer, and politician who served as the first president of the United States from 1789 to 1797. Appointed by the Second Continental Congress as commander of the Continental Army in 1775, Washington led Patriot forces to victory in the American Revolutionary War and then served as president ...
6 天前 · Copper is a chemical element; it has symbol Cu (from Latin cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a ...
4 天前 · Eurovision Dance Contest. American Song Contest. The Eurovision Song Contest ( French: Concours Eurovision de la chanson ), often known simply as Eurovision, is an international song competition organised annually by the European Broadcasting Union. Each participating country submits an original song to be performed live and transmitted to ...
6 天前 · 7-Eleven, Inc.[2] is an American convenience store chain, headquartered in Irving, Texas and owned by Japanese company Seven & I Holdings through Seven-Eleven Japan Co., Ltd.[3] The chain was founded in 1927 as an ice house storefront in Dallas. It was named Tote'm Stores between 1928 and 1946. After Ito-Yokado, a Japanese supermarket chain ...
