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251.
Based on gaseous compound introduction as 1-phenyl-3-methyl-4-benzoylpyrazolone[5](PMBP) chelate of aluminum by electrothermal vaporization in ICP-AES, a method for determination of trace aluminum was developed. Trace aluminum was vaporized at temperature of 1000 degrees C, and the vaporization behavior of aluminum chelate was detailedly investigated. Under the optimum conditions, the detection limit of aluminum was 0.6 ng ml(-1), and the relative standard deviation for 0.1 mug ml(-1) aluminum was 4.7% (n=8). The proposed method was applied to the determination of trace aluminum in rice flour reference materials, and the results well agreed with the reference values. 相似文献
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将酞菁锰(MnPc)掺入阳离子表面活性剂双十二烷基二甲基溴化铵(DDAB)的氯仿溶液,并涂布于热解石墨电极表面,待氯仿挥发后即制得MnPc-DDAB薄膜电极。循环伏安实验表明,在KBr溶液中,该薄膜电极有两对还原氧化峰,第一对峰的Epc1=-0.27V,Epa1=0.01V;第二对峰的Epc2=-0.76V,Epa2=-0.62V(vs.SCE)。本文着重探讨了第二对峰的电化学行为,估计了该体系的电荷传递扩散系数Dct和表观非均相电极反应速率常数K0′等电化学参数,并可将该薄膜电极用于催化三氯乙酸的电化学还原。 相似文献
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Under some conditions, inorganic salts can be as good precursors for sol-gel-type processing as those obtained from expensive metalloorganic precursors such as alkoxides. In this work, the formation of monodispersed hydrous zirconia microsphere particles (particularly nanosized) and gels was achieved in solutions of zirconyl chloride dissolved in alcohol-water mixed solvents. The dielectric property of the mixed alcohol-water solvent directly affects the nucleation and growth of zirconia clusters/particles in homogeneous solutions. A lower dielectric constant of mixed solvent corresponds to a lower solubility of inorganic solute and, thus, a shorter induction period for nucleation as well as higher solid particle growth kinetics. Dynamic light scattering (DLS) was used to monitor the homogeneous nucleation and growth processes, while final particles and gels were studied by scanning electron microscopy (SEM) and high-temperature X-ray diffraction (HTXRD). The sol-gel processes in the mixed solvent system can be adjusted using the processing parameters, including the initial inorganic salt concentration (C), alcohol/aqueous medium volume ratio of the mixed solution (RH), incubation temperature (T), incubation time (t), concentration of hydroxypropyl cellulose (HPC), and ammonia neutralization. Monodispersed submicron and nanoscale (<100 nm) zirconia microspheres/powders were successfully synthesized under conditions of high RH (5) and using HPC (molecular weight of 100,000, 2.0x10(-3) g/cm(3)) and ammonia neutralization. Initial salt concentration affects the particle size significantly. Gel materials were obtained under conditions of low RH (1.0). Microstructure and transparency of gels changed significantly from low (0.05 M) to high (0.2 M) concentration of the metal salt. We have also demonstrated that monodispersed particle production can be achieved not only at low temperatures (<100 degrees C) but also at room temperature using an inorganic salt precursor. Copyright 2000 Academic Press. 相似文献
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本文介绍了以X-射线衍射法测定非品区结构的径向分市函数RDF方法,并将其应用于聚苯乙烯(PS)非晶区的结构研究. 相似文献
259.
Two-dimensional protein database of human pancreas 总被引:7,自引:0,他引:7
We report here the two-dimensional protein database of human pancreas. The proteins were analyzed by two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Totally, 302 proteins were identified, of which about 27% were enzymes with a broad range of catalytic activities. Several of these are specifically expressed in pancreas, such as pancreatic amylase, pancreatic stone protein, pancreatitis-associated protein, pancreatic lipase, pancreatic elastase, etc. Structural and cytoskeletal proteins are also strongly represented on the gels. Thus, the pancreatic proteome reflects the organ's function. This work paves the way for further studies on pancreatic protein expression in health and disease, such as diabetes and pancreatic cancer. 相似文献
260.
We have successfully developed a new one-pot solution-phase route, namely microwave-assisted hydrothermal reduction/carbonization (MAHRC), for a rapid synthesis of coaxial Ag/C nanocables. The nanocables can self-assemble in situ in an end-to-end fashion into interconnected chains. 相似文献