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2 天前 · 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 · 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 ...
1 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 ...
3 天前 · A glass of cow milk. Cows in a rotary milking parlor. Milk is a white liquid food produced by the mammary glands of mammals and the caecilian Siphonops annulatus. [1] It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. [2]
1 天前 · Diabetes mellitus, often known simply as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. [10] [11] Diabetes is due to either the pancreas not producing enough insulin, or the cells of the body becoming unresponsive to the hormone's effects. [12] Classic symptoms include thirst, polyuria ...
4 天前 · Phosphorus is a chemical element; it has symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth. It has a concentration in the Earth's crust of about one gram per kilogram (compare copper at about ...
2 天前 · Pyrus dioica Moench. An apple is a round, edible fruit produced by an apple tree ( Malus spp., among them the domestic or orchard apple; Malus domestica ). Apple trees are cultivated worldwide and are the most widely grown species in the genus Malus. The tree originated in Central Asia, where its wild ancestor, Malus sieversii, is still found.
