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Giorgio Montaudo Emilio Scamporrino Daniele Vitalini Roberto Rapisardi 《Journal of polymer science. Part A, Polymer chemistry》1992,30(4):525-532
The low molecular weight compounds formed by partial ozonolysis of poly(isoprene) and poly(chloroprene) were analyzed by fast atom bombardment mass spectrometry (FABMS). In the poly(chloroprene) case, the ozonized mixtures were treated with piperidine before the MS analysis to transform in amide end groups the reactive acyl chlorides formed by the cleavage of double bonds along the main chain. Only one family of compounds having carboxyl and ketone or carboxyl and amide end groups were obtained from the ozonolysis of poly(isoprene) and poly(chloroprene), respectively. The assigned structures were confirmed by FAB-MS analysis of the GPC separation fractions [poly(chloroprene)] or by FAB-MS of the KOH-doped ozonolysis mixtures [poly(isoprene)]. It has been also ascertained, by GPC experiments, that poly(chloroprene) decomposes more rapidly than poly(isoprene) and poly(butadiene). 相似文献
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用IR和负离子FAB-MS测定不同pH值下EDTA,DTPA,及其碱金属盐类,能直接给出它们的结构及其分子量,对于其碱金属盐类的混合物,不经分离,可以直接测定,能同时得到混合物中各组分的相对分子质量。 相似文献
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综述了芳香环状低聚体结构表征的发展过程及最新进展,以高效液相色谱、快原子(离子)轰击质谱、激光质谱、电喷雾质谱为主结合其他辅助方法分别做以介绍并比较了各种表征方法的特点及应用范围。 相似文献
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Joanna Kurek Wadysaw Boczo Piotr Przybylski Bogumi Brzezinski 《Journal of Molecular Structure》2007,846(1-3):13-22
The colchicine complexes with Li+, Na+ and K+ cations have been synthesized and studied by ESI MS, 1H and 13C NMR, FT-IR and PM5 semiempirical methods. It has been shown that colchicine forms stable complexes of 1:1 stoichiometry with monovalent metal cations. For Li+ cations also formation of the 2:1 stoichiometry complexes has been detected. The most stable structures of the complexes are those in which the acetamide groups are involved in the coordination process. The structures of the colchicine complexes with Li+, Na+ and K+ cations are visualized and discussed in details. 相似文献
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《Journal of Coordination Chemistry》2012,65(13):2292-2301
Mixed ligand complexes of iron(III), [Fe(sb)2(py)Cl]?·?2H2O (1–9) [where sbH?=?Schiff bases (derived from condensation of 2-aminopyridine (sapH), 2-aminophenol (saphH), o-toluidine (o-smabH), aminobenzene (sabH), p-toluidine (p-smabH), 3-nitroaniline (snabH), and anthranilic acid (saaH) with salicylaldehyde and substituted (mercapto-)benzimidazole (mbzH), {2-(o-hydroxyphenyl)}benzoxazole, (pboxH)], have been synthesized by the interactions of iron(III) chloride with corresponding ligands in 1?:?2 molar ratio in refluxing pyridine. These complexes have been characterized by elemental analyses, melting points, spectral, and magnetic studies. Powder X-ray diffraction studies of some representative complexes are also reported herein. The antibacterial and antifungal activities of the free ligands and their iron(III) complexes were found in vitro. The complexes showed good antibacterial and antifungal effect to some bacteria and fungi. Two standard antibiotics (chloromphenicol and terbinafine) were used for comparison with these complexes. 相似文献
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The salting-out effect has been characterized on the basis of the relative peak intensity of silica species, observed by FAB-MS
(fast atom-bombardment mass spectrometry) in solutions of sodium chloride, sodium nitrate, sodium sulfate, calcium chloride,
lithium chloride and magnesium chloride. A critical change in the peak intensity ratios of the linear and cyclic tetramers
of silica against the sodium ion (Na+) concentrations was observed at Na+ concentration between 0.1 and 1 mol⋅dm−3. The degrees of the changes of these peak intensity ratios increased in the order NaNO3 < Na2SO4 < NaCl. In CaCl2 solutions, these peak intensity ratios changed significantly at Ca2+ concentrations between 0.05 and 0.5 mol⋅dm−3. The salting-out effect observed is the total change in the concentration of silica brought about by complex factors, such
as the changing solubility of silicate complexes, the increases in the concentrations of different kinds of soluble silicate
complexes induced by changes in the hydrophobicity and hydrophilicity of the solution, and the contribution of hydrolysis. 相似文献
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When the sodium ion (Na+) concentration is increased above 0.5 mol-dm−3 (M), the concentrations of dissolved silica in aqueous sodium chloride (NaCl) and sodium nitrate (NaNO3) solutions decrease because of the salting out effect. On the other hand, the concentration of the dissolved silica in aqueous sodium sulfate (Na2SO4) solutions increases monotonously as the concentration of Na+ is increased above 0.5 M. The purpose of this study is to determine the reasons why the salting-out effect is not observed in Na2SO4 solutions. FAB-MS (Fast Atom Bombardment Mass Spectrometry) was used to sample directly the silica species dissolved in aqueous Na2SO4, NaCl, and NaNO3 solutions. In the FAB-MS spectra of these solutions, the peak intensity ratios of the linear tetramer to the cyclic tetramer largely increased for Na+ concentrations between (0.1 and 1) M. This shows that some characteristics of the Na2SO4 solutions are similar to those of the NaCl and NaNO3 solutions. In Na2SO4 solutions, however, when the concentration of Na+ is higher than 1 M, the peak intensity of the dimer is much higher than those of the other silicate complexes. In Na2SO4 solutions, the SO42− ion undergoes partial hydrolysis to form HSO−4 and OH− is produced. In particular, in the range where the concentration of SO42− is high, the pH of the solution increases slightly. This higher pH yields more dimers from the hydrolysis of silicate complexes. This increase in dimer production agrees with the observation that silica dissolves in sodium hydroxide (NaOH) solutions mainly as a dimer when the concentration of NaOH is less than 0.1 M. In Na2SO4 solutions at high concentrations, a salting-out effect is not observed for silica. This is due to the increase in the concentration of OH−, which accelerates the hydrolysis of silica and results in dimer formation. 相似文献
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碳苷研究(Ⅵ)——1-芳基-D-吡喃葡萄糖碳苷的快原子轰击质谱 总被引:1,自引:0,他引:1
快原子轰击质谱(FAB-MS)是近几年发展起来的一种质谱新技术[1],特别适于极性大、不易挥发和对热不稳定的化合物,已用于多肽[2]、核酸[3]及苷[4]的结构测定。 相似文献