Yahoo奇摩 網頁搜尋

搜尋結果

  1. The elements in the group, like those of groups 7–11, have high melting points, and form volatile compounds in higher oxidation states. All the elements of the group are relatively nonreactive metals with a high melting points (1907 °C, 2477 °C, 3422 °C); that of tungsten is the highest of all metals.

  2. e. The finite element method ( FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential .

  3. en.wikipedia.org › wiki › Alu_elementAlu element - Wikipedia

    Alu element. An Alu element is a short stretch of DNA originally characterized by the action of the Arthrobacter luteus (Alu) restriction endonuclease. [1] Alu elements are the most abundant transposable elements in the human genome, present in excess of one million copies. [2] Alu elements were thought to be selfish or parasitic DNA, because ...

  4. en.wikipedia.org › wiki › CopperCopper - Wikipedia

    Characteristics Physical A copper disc (99.95% pure) made by continuous casting; etched to reveal crystallites Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color. Copper, silver, and gold are in group 11 of the periodic table; these three metals have one s-orbital electron on top of a filled d-electron shell and are ...

  5. en.wikipedia.org › wiki › RoentgeniumRoentgenium - Wikipedia

    Roentgenium (German: [ʁœntˈɡeːni ʊm] ) is a synthetic chemical element; it has symbol Rg and atomic number 111. It is extremely radioactive and can only be created in a laboratory. The most stable known isotope, roentgenium-282, has a half-life of 120 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes.

  6. Rare-earth elements occur in nature in combination with phosphate ( monazite ), carbonate - fluoride ( bastnäsite ), and oxygen anions. In their oxides, most rare-earth elements only have a valence of 3 and form sesquioxides (cerium forms CeO2 ). Five different crystal structures are known, depending on the element and the temperature.

  7. Website. element.com. Element is a global Testing Inspection and Certification (TIC) company headquartered in London. It specialises in materials testing and provision of certification schemes in building material, aerospace, transportation, health sciences, oil and gas, and fire protection. The company was ranked as number 15 in the Sunday ...