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991.
The preconcentration and voltammetric behavior of BiIII on a sodium humate modified carbon paste electrode was studied by means of cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV). The proposed measurement involves an initial nonelectrolytic preconcentration step in which BiIII is complexed by the surface modifier in a solution of 0.05 M KNO3-0.0106 M HNO3 (pH 2.0) and a subsequent electrochemical scan step in which the preconcentrated BiIII was reduced and then oxidized promptly in supporting electrolyte of 0.5 M HNO3. The resulting DPSV anodic current was proportional to the concentration of BiIII ion over the range of 4.78 × 10−8–1.44 × 10−5 M. The detection limit was 4.78 × 10−8 M. The proposed method was used to determine bismuth in various samples. Various factors affecting the electrode behavior were also investigated at the same time. 相似文献
992.
The C(60)-gamma-cyclodextrin and Nafion chemically modified electrode exhibits two redox waves by cyclic voltammetry. Such an electrode will effect reduction and oxidation of cytochrome c and be capable of mediating the electron transfer to cytochrome c. 相似文献
993.
Jun Zhou Jie Yang Li Qi Xuan Shen Dunru Zhu Yan Xu You Song 《Transition Metal Chemistry》2007,32(6):711-715
A novel dinuclear nickel(II) complex, [Ni2(MOBPT)2Cl2(H2O)2]Cl2 · 7H2O (MOBPT = 4-(p-methoxyphenyl) −3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, IR and single crystal X-ray
diffraction methods. The crystal structure determination shows that the dinuclear Ni2N8 unit is almost planer in which each NiII ion is coordinated by four nitrogen atoms from MOBPT equatorially and a water molecule and a chloride ion axially in a distorted
octahedral geometry. Magnetic measurements reveal a relatively weak antiferromagnetic exchange in the complex. 相似文献
994.
The effect of pH on the dilution enthalpies of D-p-hydroxyphenylglycine in phosphate buffer solutions has been investigated by isothermal titration microcalorimetry at 298.15 K. The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept. The results show that the enthalpies of dilution of D-p-hydroxyphenylglycine in phosphate buffer solutions at different pH are all positive. The overall trend is that enthalpies of dilution become more positive with an increase of pH, but there is a minimum of the enthalpy of dilution at pH = 7.0. The enthalpic pair interaction coefficients, h
2, all have negative values. The results are interpreted from the point of view of solute-solute and solute-solvent interactions involved in the solvent effects. 相似文献
995.
Shiyang Sun Shouye Sun Yuan Ren Xin Tan Pingping Xu 《Surface and interface analysis : SIA》2020,52(4):167-173
The surface structure and properties of aluminum nitride (AlN) play an important role in many applications. Using the first principle calculations method, we analyzed the surface terminal structure of AlN and its evolution under different conditions by determining the surface energy, adsorption energy, and evaporation energy of the Al and N terminals on the AlN(0001) surface. Our results show that the reason why the N terminal is less stable than the Al terminal is not only because of its high surface energy but also because its adsorption performance is extremely sensitive to the adsorption position. The surface N atoms combine to form N2 molecules that escape during the evaporation process at high temperature. After surface N atoms escape, the AlN surface structure reconstitutes to form a hexagonal closest packing (HCP)–like structure, and the energy barrier for the reconstructing process is 3.2 eV. This shows that the structure and form of the AlN(0001) terminals depend on the environmental conditions. 相似文献
996.
997.
A new family of bifunctional catalysts (N-oxides-Ti(OiPr)4 (2:1)) containing a Lewis acid and a Lewis base was developed and applied to the catalytic cyanosilylation of ketones. Utilizing rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex as catalysts, the cyanosilylation products were obtained in 42-97% yield. Based on experimental phenomena and kinetic studies, a catalytic cycle was proposed to explain the remarkable activities of these catalysts. Investigations indicated that rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex should promote the reaction via a dual activation of the ketone by the titanium and TMSCN by the N-oxide. 相似文献
998.
动态单滴法研究乳状液液膜的稳定性 总被引:2,自引:0,他引:2
乳状液液膜作为化学分离的一种手段,自七十年代发现以来已有了许多进展,但是如何将其工业化还有许多课题有待于进一步研究.目前,除了乳状液液膜的水静态渗透性质以外,对乳状液液膜的稳定性和溶胀性质的研究主要采用搅拌法.虽然得到较好的规律性,但是搅拌法具有乳状液滴粒径分布广的弱点,对于不同的搅拌方式及条件,乳状液液膜的有效面积不同,对液膜作用的机械强度不同,因此结果会有很大差别.我们自行设计的动态单滴法实验装置,可定量地研究乳状液液膜的溶胀、稳定性及水渗透性质. 相似文献
999.
5-Hydroxytryptamino-induced calcium sparks in cultured rat stomach fundus smooth muscle cells 总被引:1,自引:0,他引:1
With the imaging fluorescence probe of Ca2+ (fluo-3) and a laser scanning confocal micro-scope, the spontaneous localized calcium release event was first discovered in resting rat cardiac myocytes by Cheng[1] in 1993. A mathematical simulation is developed with computer in order to reveal the effect, which is immediately suggested that these events are likely to reflect the local-ized release of Ca2+ from a small cluster of ryanodine-sensitive Ca2+ release channels in sar-coplasmic reticulum … 相似文献
1000.
Zhan‐Xin Zhang Wei‐Dong Xie Ping‐Lin Li Yan‐Ping Shi Zhong‐Jian Jia 《Helvetica chimica acta》2006,89(12):2927-2933
Six new compounds were isolated from the whole plant of Sonchus uliginosus, including three eudesmane‐type sesquiterpenoids (1β,6α)‐1,6,14‐trihydroxyeudesm‐3‐en‐12‐oic acid γ‐lactone ( 1 ), (1β,6α)‐1,6,14‐trihydroxyeudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone ( 2 ), and (1β,6α)‐1,6‐dihydroxy‐14‐O‐[(4‐hydroxyphenyl)acetyl]eudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone ( 3 ), and three phenylpropane derivatives, 4‐hydroxy‐γ,3,5‐trimethoxybenzenepropanol ( 6 ), γ,3,4,5‐tetramethoxybenzenepropanol ( 7 ), and γ,3,4,5‐tetramethoxybenzenepropanol acetate ( 8 ), together with the two known compounds 4 and 5 . The new structures were elucidated by means of spectroscopic methods, such as IR, EI‐MS, HR‐ESI‐MS, 1D‐ and 2D‐NMR, and by comparison of the spectroscopic data with those reported for structurally related compounds. 相似文献