什么是光谱学
一种分析技术,用於鉴别化学元素和化合物,测量物质在外部能源的激发下,吸收或发射电磁波谱(包括γ射线、X射线、紫外辐射、可见光、红外辐射、微波以及无线电频率的辐射)中特徵波长的辐射能量,从而阐明其原子和分子结构。所用的仪器是分光镜(用於直接观察)和摄谱仪(用於记录光谱)。实验包括一个光源、一块用来形成光谱的棱镜或光栅、用来观察或记录光谱细节的探测器(视觉的、光电的、测辐射的或者摄影的)、测量波长和强度的装置以及对测得的量作出解释以识别它的化学身分,或给出关於它的原子和分子结构的线索。19世纪中叶用光谱技术分析太阳光谱而发现了氦、铯和铷。专门的光谱技术有拉曼光谱(参阅Raman, Chandrasekhara Venkata)、核磁共振、原子核四极矩共振、动态反射光谱、微波和γ射线光谱,以及电子自旋共振。亦请参阅mass spectrometry、spectrophotometry。
spectroscopy
Branch of analysis devoted to identifying elements and compounds and elucidating atomic and molecular structure by measuring the radiant energy absorbed or emitted by a substance at characteristic wavelengths of the electromagnetic spectrum (including gamma ray, X ray, ultraviolet, visible light, infrared, microwave, and radio-frequency radiation) on excitation by an external energy source. The instruments used are spectroscopes (for direct visual observation) or spectrographs (for recording spectra). Experiments involve a light source, a prism or grating to form the spectrum, detectors (visual, photoelectric, radiometric, or photographic) for observing or recording its details, devices for measuring wavelengths and intensities, and interpretation of the measured quantities to identify chemicals identifications or give clues to the structure of atoms and molecules. Helium, cesium, and rubidium were discovered in the mid-19th century by spectroscopy of the sun's spectrum. Specialized techniques include Raman spectroscopy (see Chandrasekhara Venkata Raman), nuclear magnetic resonance (NMR), nuclear quadrupole resonance, dynamic reflectance spectroscopy, microwave and gamma ray spectroscopy, and electron spin resonance (ESR). See also mass spectrometry, spectrophotometry.
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什么是库兴氏综合征
又译柯兴氏综合征。因肾上腺皮质分泌过量的皮质醇引起的症候群。又称皮质醇增多症。典型表现有:脸如满月,红润多脂;躯干肥胖,四肢瘦小;皮肤菲薄,多有紫纹;高血压,低血钾等。本病由美国著名神经外科医生H.库兴于1912年首先描述,故得名。常见的病因是垂体分泌过多的促肾...
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什么是皮肤肿瘤
原发于皮肤或其附属器的肿瘤和由其他内脏器官、组织的恶性肿瘤(如乳腺癌、胃癌等)转移到皮肤的转移瘤。有些皮肤表现可以是系统性肿瘤,特别是淋巴系统肿瘤的一个组成部分,如淋巴瘤、淋巴细胞性白血病等。皮肤肿瘤也可以转移到体内器官。皮肤肿瘤有良性与恶性之分。...
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什么是扁鹊
战国时期医学家。中医早期脉诊的倡导者。名秦越人。渤海郡鄚;(今河北任丘)人。相传扁鹊为远古时的名医之号,因秦越人精于医术,故人亦称其为扁鹊。年轻时从长桑君学医,尽得其传。他善于诊断,尤精于望诊和脉诊。史载他以望诊判断齐桓侯的病症,由浅入深,并预言其预后不...
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什么是激素
由内分泌细胞合成和分泌的、能将一定的化学信息传递到靶细胞并产生生物效应的微量化学物质。过去人们认为,激素是由体内无导管的内分泌腺体产生并直接分泌进入血液循环,转运到远处的靶器官发挥一定的生理作用。现已知激素的产生不限于传统的内分泌腺体,激素的转运...