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The protected ceramide: N‐((2S,3S,4R)‐3,4‐bis(benzyloxy)‐1‐hydroxyoctadecan‐2‐yl)tetracosanamide, was attempted to introduce a triflate as a leaving group followed by a nucleophilic substitution with azido group in one‐pot manner. Unexpectedly, the oxazole ring formed via a thermodynamically favored intramolecular cyclization was opened to generate the original ceramide by triflic acid. In addition, the residual acid promoted a formylation of the primary hydroxy group in DMF. 相似文献
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The three parts of Radix Angelicae Sinensis (Danggui) were reported to have different therapeutic effects. In order to investigate their chemical compositions of different parts of Danggui, gas chromatography-mass spectrometry (GC-MS) combined with chemometrics data analysis was applied to provide a more detailed study. Subwindow factor analysis (SFA) and a modified augmented evolving window orthogonal projection (AEWOP) method were used to resolve the batch GC-MS data sets from the Danggui samples. Then, t-test, Wilcoxon rank sum test, and principal component analysis (PCA) were applied to carry out the comparison job. The results indicate which components are found to have significant differences among the three parts. These findings may be helpful for further research of the pharmacological activities of Danggui. 相似文献
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The quantum field theory of stimulated Raman scattering is formulated. It is shown to give the correct classical limit. Ilowever, the quantum growth rate is bigger. An additional physical process of creation of two plasmons from two photons is intrinsically predicted by the theory. 相似文献
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In this report,the stable corona discharge region of multi-wire proportional cham-ber(MWPC)has been measured.In this region we observed double peak pheno- menon in Fe55 pulse amplitude distribution,and establish the fact that,once cornadischarge region is present in MWPC,the spatial resolution power for light partic-les will be lost. 相似文献
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ZHAO ZHEN-LAN XU YUAN-BIAO GUO YING-HUAN LO SHI-HUA HUANG ZHONG-WIANG YANG RUI-YING 《中国物理C(英文版)》1982,6(1):111-112
In present paper, a non-classical method of obtaining the decay constant andhalf-life of 99mTc was introduced. The results were compared with that obtained bythe classical method of the least square analysis. The half-life by non-classioal me-thod is 6.006±0.004 hours, that by classical method is 6.009±0.005 hours. 相似文献
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无损残余应力测量及其新技术 总被引:1,自引:0,他引:1
简述及比较了主要的残余应力无损测量技术,重点为磁力法,并介绍一台新的磁力仪MAPS,且对MAPS及传统磁力仪作了比较,同时以X射线及中子衍射得到的结果验证了MAPS的可靠性,也介绍了文献上较少见的火车钢轨残余应力分布图。 相似文献
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