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981.
982.
Qian Wu Chunhui Deng Shun Shen Guoxin Song Yaoming Hu Daxi Fu Jiakuan Chen Xiangmin Zhang 《Chromatographia》2004,59(11-12):763-767
Headspace solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) has been applied to the determination of the volatile compounds of a common traditional Chinese medicine , Flos Chrysanthemi indici. Twenty-six compounds were identified by the present method, which are similar to the results from steam distillation. Difference in analysis from ten growing areas was found to be in their relative content and total concentrations. Four active compounds (cineole, 3-thujanone, borneol and bornyl acetate) were applied to the evaluation of the quality of Flos Chrysanthemi indici from different areas. By comparing their peak areas, it was found that Flos Chrysanthemi indici with the best quality was from Hangzhou in China. These results show that HS-SPME-GC-MS is a simple, rapid and solvent-free method for the analysis of the volatile compounds in this material and a potential tool for its quality assurance. 相似文献
983.
In this paper, we consider a predator-prey system with stage structure and harvesting (where the predator population has two stages, an immature stage and a mature stage with harvesting, and the growth of the prey population is of Lotka-Volterra nature). We obtain the conditions of the globally asymptotic stability for three nonne-gative equilibria of this system. 相似文献
984.
985.
Domenico Gioffré Francesco Ghetti Francesco Lenci Cristina Paradiso Renke Dai Pill-Soon Song 《Photochemistry and photobiology》1993,58(2):275-279
Abstract— Photosensory responses in the ciliated protozoan Blepharisma japonicum are mediated by a hypericin-like chromophore, blepharismin, localized in granules distributed under the cell membrane. A blepharismin-binding protein, with an apparcnt molecular weight ranging between 35 and 38 kDa, has been isolated by means of column separations and preparative isoelectric focusing and characterized by means of gel electrophoresis, analytic isoelectric focusing as well as absorption and fluorescence spectroscopy. 相似文献
986.
TBP萃淋树脂吸附钪的性能研究及应用 总被引:6,自引:0,他引:6
本文采用静动态两种方法较系统地研究了TBP草淋树脂在高氟酸介质中吸附钪的性能,并用自己设计的减压微色谱柱考察了共存离子的萃取色谱行为,选择了分离微量钪的最佳条件,获得了良好的分离效果,用于标准矿样中微量机的测定,分析结果与标准值相近。 相似文献
987.
988.
本文利用液体的绝对速度理论得到液体的粘滞系数随温度变化的关系式,在不同的温度下测得液体的粘滞系数,找出液体的粘滞系数随温度变化的数学表达式。 相似文献
989.
The nature of the lowest triplet configuration of flavins 总被引:1,自引:0,他引:1
Abstract— The phosphorescence spectrum of riboflavin has been reexamined at 77°K in an ethylene glycol: water matrix. The phosphorescence occurs at approximately the 605 nm (ca. 2-·05 eV) region, in reasonable agreement with the theoretical calculations of 1·6–1·8 eV [21]. The emission was found to be negatively polarized, and to have a relatively long lifetime (0·56 sec). On the basis of this data and additional theoretical results, it is concluded that the lowest triplet of riboflavin is of 3(τ,τ*) type. Upon addition of potassium iodide, the phosphorescence emission is enhanced through spin-orbit perturbation. The presence of oxygen (atmospheric pressure) in the frozen glass apparently has no effect on the emission. The phosphorescence spectra of alloxazine are also presented. Results of the present work have been applied to the photodephosphorylation of menadiol diphosphate in elucidating its mechan ism involving the riboflavin triplet and singlet oxygen. 相似文献
990.
L.T. Yang J.K. Liang G.B. Song J. Luo F.S. Liu H.F. Yang G.H. Rao 《Applied Physics A: Materials Science & Processing》2005,80(4):865-870
The compound FeSr2NdCu2O7+ (Fe1212) was successfully synthesized by solid-state reaction. X-ray diffraction data indicate that the sample is of single phase. Rietveld whole-pattern-fitting method was used to refine the crystal structure of samples prepared under different annealing conditions using the tetragonal system with space group P4/mmm. Magnetization measurements indicate that magnetic susceptibility changes with temperature in a Curie-type manner. Resistance measurements indicate that these samples have a semiconductor-like behavior. PACS 61.10.Nz; 74.72.Jt 相似文献