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61.
Xiao-Ling Wu Gui-Hong Liao Lin Luo Xu-Feng Shan Li-Ping Zhang Chen-Ho Tung 《Tetrahedron》2007,63(15):3133-3137
Two novel hydroxyl- and carboxyl-functionalized cubane-like photodimers from methyl 2-naphthoate have been successfully achieved under mild conditions. X-ray crystal structures confirm that the cubane-like structure is well retained in these two derivatives and the intermolecular OH?O hydrogen bonding plays an important role in crystal packing. It is of significance that the isolated racemic mixture can be subsequently resolved into two optically pure enantiomers by high-performance liquid chromatography. 相似文献
62.
Yang Q Zhang XL Ma M Huang KJ Zhang JX Ni WZ Fang CX Zheng CY 《Journal of chromatography. A》2007,1146(1):23-31
Pheomelanin is an important type of melanin distributed in the skin, eye and hair in the mammal, which is of great social, clinical and cosmetic significance. In this study, a new HPLC method with fluorescence detection is described originally for the sensitive determination of pheomelanin in biological materials. The pheomelanin polymer is decomposed into two specific degradation products, 3-amino-4-hydroxyphenylalanine (3-AHP) and 4-amino-3- hydroxyphenylalanine (4-AHP) with hydriodic acid. Then the two AHP isomers are derivatized using a fluorescent probe naphthalene-2,3-dicarboxaldehyde in the presence of cyanide. The resulting highly stable 2-substituted 1-cyanobenz[f] isoindole derivatives were separated on a 5NH(2)-MS aminopropyl packed HPLC column with binary isocratic elution profile and detected fluorimetrically. The assay shows high sensitivity of 0.11nM (2.2fmol per injection, the lowest reported) at signal-to-noise ratio of 3 for each AHPs, good accuracy and precision (RSDs<3.1%), and linearity (range of 0.02-10microM, r>0.995). The results obtained by using fluorescence detection have been compared with other detection systems (electrochemical and UV). The sensitivity can increase from 100 to respect electrochemical detection and 30000 times respect UV detection. The method has been used for the quantitative determination of pheomelanin in various biological samples, including cell cultures from five types of melanoma cell lines of human and rat origin, hair samples of various colors, melanoma tissue and the urines from human melanoma patients and healthy subjects. This original application of HPLC-fluorescence detection represents a powerful tool for investigating pheomelanin synthesis in vitro and in vivo under physiological and pathophysiological conditions. 相似文献
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本文研究了新试剂 2 -羧基 - 5 -硝基苯基重氮氨基 - 4 -苯基 - 2 -噻唑 ( CNPDAPT)在 Triton X- 1 0 0的存在下 ,与铜显色反应的适宜条件。结果表明在 p H1 0 .0的 Na2 B4O7- Na OH缓冲介质中 ,铜与试剂形成 1∶ 1红色配合物 ,其最大吸收波长位于 5 1 5 nm,表观摩尔吸光系数 ε=4.5 9× 1 0 4 L· mol- 1· cm- 1 ,铜量在0 - 2 0 μg/ 2 5 m L范围内遵守比耳定律。方法用于水样中微量铜的测定 ,结果满意。 相似文献
64.
Application of Hadron-Hadron Nuclear Interaction Parametrization Model in the Study of Superhigh Energy Cosmic Rays
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Under the assumption of mixed primary cosmic ray composition and using a hadron-hadron interaction parametrization model to describe hadron-hadron nuclear interaction,the behavior of superhigh energy cosmic ray particles in the atmosphere is simulated,and the simulated results compared with experimental data of Mt.emulsion chamber in details.The influences from the mean transverse momentum value of secondary particles in fragmentation region on simulated results are discussed also in details. 相似文献
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Mono-、 di- and tri-substituted derivatives of FeCo2(CO)9(μ3-S) with P(OR)3 were synthesized. They have the following formular, FeCo2(CO)9-n(μ3-S)[P(OR)3]n [n=1, R=CH2CH2CH3(a); n=1,2,3, R=CH2CH2CH2CH3(b); n=1,2,R=CH(CH3)(CH2)2CH3(c)]. The six new compounds were characterized by elemental analysis, IR, 1H NMR and MS spectra and their molecular structures were deduced. 相似文献
69.
极坐标中应力与应力函数之间的关系 总被引:2,自引:1,他引:1
在极坐标下,通过极坐标的应力平衡方程推导出极坐标应力()与应力函数之间的关系. 相似文献
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