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261.
Synthesis of new tetrazene(N-N=N-N)-linked bi(1,2,4-triazole) 总被引:2,自引:0,他引:2
Sheng Hua Li Si Ping Pang Xiao Tong Li Yong Zhong Yu Xin Qi Zhao 《中国化学快报》2007,18(10):1176-1178
The reaction of 4-amino-1,2,4-triazole with sodium dichloroisocyanurate (SDCI) afforded new tetrazene(N-N=N-N)-linked bi(1.2,4-triazole) 2a in excellent yield.Increasing the molar ratio of SDCI to 4-amino-1,2,4-triazole,the chlorinated product 1,5,5′- trichloro-4,4′-azo-1,2,4-triazole (2b) was formed.These new compounds have been characterized by MS,~1H NMR,~(13)C NMR,and elemental analysis. 相似文献
262.
The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol~(-1).cm~(-1) for Nd and 62.5 l.mol~(-1).cm~(-1) for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures. 相似文献
263.
Ping Wang Yi-Zeng Liang Ben-Mei Chen Neng Zhou Lun-Zhao Yi Yan Yu Zhi-Biao Yi 《Chromatographia》2007,65(3-4):209-215
A rapid, simple and specific liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed
and validated for the simultaneous determination of enalapril and its major active metabolite enalaprilat in human plasma.
Benazepril hydrochloride was used as the internal standard. Plasma was deproteinized with acetone and centrifuged. The supernatant
was transferred and evaporated to dryness and the residue dissolved in mobile phase. Samples were separated on a C18 column
with a mobile phase of methanol–20 mM ammonium acetate (53:47, v/v) containing 0.15% trifluoracetic acid (v/v) with a pH of 3.0. Enalapril, enalaprilat and the internal standard were measured by electrospray positive selective ion
monitoring mode. The method was validated over a linear range of 1.56–400 ng mL−1 and the limits of quantification were 1.56 ng mL−1 for both enalapril and enalaprilat using 0.1 mL plasma. Extraction efficiency was more than 84% and recoveries were in range
of 93.65–101.17%. The intra-day relative standard deviations (RSD) were less than 8.16 and 7.05% and inter-day RSDs were within
8.42 and 5.72% for enalapril and enalaprilat, respectively. The storage stability of QC samples was investigated under various
conditions. The method was successfully applied for the evaluation of the pharmacokinetics and bioequivalence of enalapril
and enalaprilat in 20 healthy volunteers after an oral dose of 20 mg enalapril maleate. 相似文献
264.
Chen P Nie S Mi W Wang XC Liang SP 《Rapid communications in mass spectrometry : RCM》2004,18(2):191-198
A simple method of solid-phase derivatization and sequencing of tryptic peptides has been developed for rapid and unambiguous identification of spots on two-dimensional gels using post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The proteolytic digests of proteins are chemically modified by 4-sulfophenyl isothiocyanate. The derivatization reaction introduces a negative sulfonic acid group at the N-terminus of a peptide, which can increase the efficiency of PSD fragmentation and enable the selective detection of only a single series of fragment ions (y-ions). This chemically assisted method avoids the limitation of high background normally observed in MALDI-PSD spectra, and makes the spectra easier to interpret and facilitates de novo sequencing of internal fragment. The modification reaction is conducted in C(18) microZipTips to decrease the background and to enhance the signal/noise. Derivatization procedures were optimized for MALDI-PSD to increase the structural information and to obtain a complete peptide sequence even in critical cases. The MALDI-PSD mass spectra of two model peptides and their sulfonated derivatives are compared. For some proteins unambiguous identification could be achieved by MALDI-PSD sequencing of derivatized peptides obtained from in-gel digests of phosphorylase B and proteins of hepatic satellite cells (HSC). 相似文献
265.
266.
Native water-soluble enzymes were transformed into interface-binding enzymes via conjugation with hydrophobic polymers, thus enabling interesting interfacial biocatalysis between immiscible chemicals at oil/water interfaces. Such interfacial biocatalysis demonstrated a significantly improved catalytic efficiency as compared to traditional biphasic reactions with enzymes contained in the bulk aqueous phase. Particularly, polystyrene-conjugated beta-galactosidase showed a catalytic efficiency that was more than 145 times higher than that of the native enzyme for a transgalactosylation reaction. It is believed that the improved accessibility of the biocatalysts to chemicals held in both phases across the interface is the key driver for the enhancement of enzyme activity. 相似文献
267.
IntroductionItiswellknownthatyttriumcanbeusedinmanyfields ,suchasmetallurgy ,ceramics ,lasersandelectron ics ,especiallyinfluorescentmaterialswhoseneedforhighpurityyttriumoxideisincreasing .InChina ,there sourceofyttriumisrich ,andthehighpureyttriumisbe ingo… 相似文献
268.
Zhen‐Yu Li Ping Chen Hong‐Gui Xu Shu‐Ying Peng Yi‐Ming Yang Zhong‐Zhen Zhao Yue‐Wei Guo 《Helvetica chimica acta》2007,90(7):1353-1359
Five new polycyclic Daphniphyllum alkaloids, macropodumines F ( 1 ) and G ( 2 ), 17‐oxoyuzurimine ( 3 ), and macropodumines H ( 4 ) and I ( 5 ), were isolated from the leaves of D. macropodum Miq ., collected in Sichuan Province, China. The structures and relative configurations of the new compounds – as well as of four known, related alkaloids – were elucidated on the basis of in‐depth spectroscopic and mass‐spectrometric analyses, by chemical derivatization, and by comparison of spectroscopic data with those of known compounds. 相似文献
269.
Wei DENG Wei Ping YANG Zhu Jun ZHANG* Xiao Rong LI College of Chemistry Materials Science Shaanxi Normal University Xi抋n 《中国化学快报》2003,14(3)
Chromiumexistsindifferentoxidationstatesingroundwater,industrialwastewater,seawater,andsoilofourenvironment1,2.Chromium(III)isanessentialtraceelementforhumans,requiredforthemaintenanceofnormalglucose,cholesterol,andfattyacidmetabolism.Ontheotherhand,watersolublechromium(VI),intheformCr2O72-orCrO42-,ishighlyirritatingandtoxictohumansandanimals3.Itsacutetoxiceffectsincludeanimmediatecardiovascularshockandlatereffectsonkidney,liver,andblood-formingorgans.Therefore,itisnecessaryforriskassessme… 相似文献
270.
基于卟啉对癌细胞的特殊亲和作用和哌嗪化合物的抗肿瘤、抗病毒作用,设计并合成了具有哌嗪结构的新型卟啉化合物5,10,15,20-四[4-(4'-乙基哌嗪基)苯基]卟啉(TEPPPH2),其结构经UV-Vis, 元素分析,1H NMR等手段证明。采用UV-Vis光谱和荧光光谱研究了TEPPPH2和小牛胸腺DNA 的相互作用模式和结合机理。实验发现,TEPPPH2能嵌入到DNA的碱基对中,1个小牛胸腺DNA分子对TEPPPH2分子的最大结合数n约为88,结合常数为8.4×106mol•L-1 。TEPPPH2与DNA的结合数和结合常数大于已知的四(4-N-甲基吡啶基)卟啉和Ca/sal-his、Ni/sal–aln型席夫碱抗癌药物。 相似文献