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2 天前 · Incandescent light bulb. A 230-volt incandescent light bulb with a medium-sized E27 (Edison 27 mm) male screw base. The filament is visible as the mostly horizontal line between the vertical supply wires. A scanning electron microscope image of the tungsten filament of an incandescent light bulb. Elaborate light in Denver, Colorado.
2 天前 · The Planck constant, or Planck's constant, denoted by , [1] is a fundamental physical constant [1] of foundational importance in quantum mechanics: a photon 's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum.
2 天前 · Renewable energy (or green energy) is energy from renewable natural resources that are replenished on a human timescale. Using renewable energy technologies helps with climate change mitigation, energy security, and also has some economic benefits.[1] Commonly used renewable energy types include solar energy, wind power, hydropower, bioenergy ...
1 天前 · Principal component analysis (PCA) is a linear dimensionality reduction technique with applications in exploratory data analysis, visualization and data preprocessing. The data is linearly transformed onto a new coordinate system such that the directions (principal components) capturing the largest variation in the data can be easily identified.
3 天前 · Marie Curie's birthplace, 16 Freta Street, Warsaw, Poland Maria Salomea Skłodowska-Curie (Polish: [ˈmarja salɔˈmɛa skwɔˈdɔfska kʲiˈri] ; née Skłodowska; 7 November 1867 – 4 July 1934), known simply as Marie Curie (/ ˈ k j ʊər i / KURE-ee, French: [maʁi kyʁi]), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity.
3 天前 · Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, commonly found in nature as quartz.[5][6] In many parts of the world, silica is the major constituent of sand. Silica is abundant as it comprises several minerals and synthetic products. All forms are white or colorless, although impure samples can be ...
2024年5月23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 ...
