The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,al...The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,alkylize and the related position in the sterol nucleus and the side chains were confirmed by the characteristic ions.Total lipids were extracted using Bligh-Dyer method.Sterols were isolated by solvent partition with chloroform-hexane(1 ∶4,by volume),derivated by BSTFA,and analyzed by GC-MS.The regular pattern was used for identifying the sterols in a dinoflagellate from the Symbodinium sp.展开更多
目的:研究在保证图像质量的前提下,自适应迭代降剂量算法(AIDR 3D)降低CT扫描剂量的潜能。方法:采用320层CT容积扫描模式,用不同管电流(50、80、150、250、350、450、550 m A)扫描体模Catphan500的低对比度模块CTP515和高分辨率模块CTP5...目的:研究在保证图像质量的前提下,自适应迭代降剂量算法(AIDR 3D)降低CT扫描剂量的潜能。方法:采用320层CT容积扫描模式,用不同管电流(50、80、150、250、350、450、550 m A)扫描体模Catphan500的低对比度模块CTP515和高分辨率模块CTP528,并用滤过反投影重建算法(FBP)与AIDR 3D的三个迭代等级(mild/standard/strong)分别重建图像,对比分析图像的噪声、对比噪声比、信噪比以及空间分辨率等图像质量参数。结果:采用AIDR 3D重建可以显著降低图像噪声,提高对比噪声比和信噪比,同时不改变空间分辨率。最高降低辐射比例达78.41%。结论:AIDR 3D迭代算法具有良好的降低CT扫描剂量的能力。不同的迭代等级降低剂量的潜能不同。展开更多
文摘The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,alkylize and the related position in the sterol nucleus and the side chains were confirmed by the characteristic ions.Total lipids were extracted using Bligh-Dyer method.Sterols were isolated by solvent partition with chloroform-hexane(1 ∶4,by volume),derivated by BSTFA,and analyzed by GC-MS.The regular pattern was used for identifying the sterols in a dinoflagellate from the Symbodinium sp.
