| 释义 |
Definition of sigma in English: sigmanoun ˈsɪɡməˈsɪɡmə 1The eighteenth letter of the Greek alphabet (Σ, σ), transliterated as ‘s’. 希腊字母表中第十八个字母（译写为s） The form ς is used instead of σ at the end of a word. The uncial form, resembling the letter c, is also sometimes used Example sentencesExamples - Finally, even if epsilon is the correct reading, in the letter space to its right, where Meritt read part of an iota, are traces of what appears to be a sigma.
- You know you have seen them - those people who walk around wearing paraphernalia emblazoned with odd symbols like phi, sigma, and pi.
- Alpha, rho, tau, sigma, omega, Ash went over the letters he saw in his mind while Lari just stared, apparently in her own little world.
- He coined this latter term and employed the Greek letter lower case sigma to denote its population parameter.
- 1.1Astronomy followed by Latin genitive The eighteenth star in a constellation.
〔天文〕σ星（星座中第十八颗星） 南极座σ星。 Example sentencesExamples - Finally, the final green beam of light was shot straight up at the constellation Sigma.
- 1.2Chemistry Physics Relating to or denoting an electron or orbital with zero angular momentum about an internuclear axis.
〔化，物理〕σ键 the σ orbital is localized symmetrically Example sentencesExamples - These conical intersections are fundamentally different from the ‘H-vinyl’ structures found in simple alkenes because they involve the interaction of four sigma electrons, as opposed to two pi electrons and two sigma electrons.
- The sigma particles can be positive, negative, or neutral.
- The sigma bond occupies the internuclear space, and the two pi bonds are at 90° angles to each other surrounding the carbon-carbon internuclear space.
- The triple bond is composed of one sigma bond from overlap of sp hybrid orbitals, and two pi bonds, from overlap of two sets of p orbitals.
Definition of sigma in US English: sigmanounˈsiɡməˈsɪɡmə 1The eighteenth letter of the Greek alphabet (Σ, σ), transliterated as ‘s.’. 希腊字母表中第十八个字母（译写为s） The form ς is used instead of σ at the end of a word. The uncial form, called lunate sigma and resembling the letter C, is also sometimes used Example sentencesExamples - You know you have seen them - those people who walk around wearing paraphernalia emblazoned with odd symbols like phi, sigma, and pi.
- Alpha, rho, tau, sigma, omega, Ash went over the letters he saw in his mind while Lari just stared, apparently in her own little world.
- He coined this latter term and employed the Greek letter lower case sigma to denote its population parameter.
- Finally, even if epsilon is the correct reading, in the letter space to its right, where Meritt read part of an iota, are traces of what appears to be a sigma.
2SigmaAstronomy
followed by Latin genitive The eighteenth star in a constellation. 〔天文〕σ星（星座中第十八颗星） 南极座σ星。 Example sentencesExamples - Finally, the final green beam of light was shot straight up at the constellation Sigma.
3Chemistry Physics
Relating to or denoting an electron or orbital with zero angular momentum around an internuclear axis. 〔化，物理〕σ键 Example sentencesExamples - The sigma bond occupies the internuclear space, and the two pi bonds are at 90° angles to each other surrounding the carbon-carbon internuclear space.
- The sigma particles can be positive, negative, or neutral.
- These conical intersections are fundamentally different from the ‘H-vinyl’ structures found in simple alkenes because they involve the interaction of four sigma electrons, as opposed to two pi electrons and two sigma electrons.
- The triple bond is composed of one sigma bond from overlap of sp hybrid orbitals, and two pi bonds, from overlap of two sets of p orbitals.
|