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41.
在仅以碘化钾为重原子微扰剂、亚硫酸钠为除氧剂及无任何保护性介质存在的水溶液中 ,吲哚_3_丁酸 (IBA)能发射很强的室温光 (RTP) ;详细研究了分析测定条件及有机溶剂对RTP的影响 ;在最大光波长λex/λem =281/447nm处 ,光强度与IBA浓度在2.0×10 -7~1.0×10 -5mol/L范围内呈良好的线性关系 ,检出限4.3×10-8 mol/L ;方法直接用于强化水样和土壤中IBA的测定 ,回收率96 %~104 % ,相对标准偏差2.37 %~3.97 %。 相似文献
42.
氢化物发生—分光光度法测定染发剂中的微量铅 总被引:1,自引:0,他引:1
本文提出了用铁氰化钾将铅氧化至高价,再用氢化物发生-分光光度法测定铅的一种新方法。该法灵敏度高,简便快速,用于分析染发剂中的铅,取得了较好的效果。 相似文献
43.
动力学荧光法分析痕量碘的研究 总被引:11,自引:0,他引:11
基于在磷酸介质中,碘能催化过碘酸钾氧化罗丹明6G的反应,使荧光猝灭,建立了催化荧光法测定痕量碘的新方法。方法的检出限为0.019mg/L,线性范围为0.020mg/L-0.80mg/L,可直接用于加碘食盐、海带、紫菜和盐酸胺碘酮药片中碘的测定。 相似文献
44.
Xing Hai Li Xin Ling Yang Xiao Mei Liang Zhen Peng Kai Yun Ling Fu Heng Chen Dao Quan Wang 《中国化学快报》2007,18(12):1476-1478
α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ. 相似文献
45.
催化光度法测定痕量甲醛 总被引:24,自引:2,他引:24
基于磷酸介质中甲醛催化溴酸钾氧化溴甲酚紫的褪色反应 ,建立了测定痕量甲醛的方法。方法的检出限为 1.0× 10 - 5g·L- 1,线性范围为 0 .0 2 0~ 0 .4 8μg·ml- 1,方法简便 ,用于空气中测定痕量甲醛 ,结果满意。 相似文献
46.
The dehydration of 2-picolinamide to produce 2-cyanopyridine was investigated thoroughly using silica supported potassium oxide as a heterogeneous catalyst. Both large specific surface area and pore size of SiO_2 (B) contributed to the favorable catalytic performance for the synthesis of 2-CP. In addition, the yield of 2-CP showed the linear relationship with the amounts of medium basicity of the catalysts,demonstrating that medium basic sites were the active sites of silica supported potassium oxide catalysts. The catalysts were further characterized by XRD and FT-IR to clarify the active species. The results indicated the Si—O—K group produced by the reaction of K_2CO_3 with Si—OH was the active species, which was further evidenced by the adjustment of the amount of Si—OH by silylation and hydroxylation procedure. 相似文献
47.
Ethylene diamine (EDA)/salt solvent systems can dissolve cellulose without any pretreatment. A comparison of the electrical
conductivity of different salts in EDA was made at 25 °C, and conductivity decreased in the order of KSCN>KI>NaSCN at the
same molar concentration. Among the salts tested, potassium thiocyanate (KSCN) was capable of dissolving both high molecular
weight (DP>1000) and low molecular weight (DP = 210) cellulose, and this was confirmed by polarized light microscopy. 39K and 14N NMR experiments were conducted at 70 °C as a function of cellobiose concentration with EDA/KSCN as the solvent. The results
showed that the K+ ion interacts with cellobiose more than the SCN− ion does. Recovered cellulose was studied by infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). Changes
in the FTIR absorption bands at 1,430 and 1,317 cm−1 were associated with a change in the conformation of the C-6CH2OH group. The changes in positions and/or intensities of absorption bands at 2,900, 1,163, and 8,97cm−1 were related to the breaking of hydrogen bonds in cellulose. X-ray diffraction studies revealed that cellulose, recovered
by precipitating cellulose solutions with water, underwent a polymorphic transformation from cellulose I to cellulose II. 相似文献
48.
Pd(PPh3)4 catalyzed Suzuki-Miyaura cross-coupling reactions of 4-tosyloxycoumarins or 4-tosyloxyquinolin-2(1H)-one with various potassium aryl trifluoroborates afforded the corresponding 4-substituted coumarins or 4-substituted quinolin-2(1H)-ones in good to excellent yield. 相似文献
49.
Ezequiel?P.?M.?LeivaEmail author C.?G.?Sánchez 《Journal of Solid State Electrochemistry》2003,7(9):588-592
In the present work, an important point concerning the NEMCA effect is addressed. We analyse the reasons why the changes in the work function of the gas exposed catalyst-electrode surface are one to one related to the changes in the catalyst working electrode potential E with respect to a reference electrode. It is concluded that this is due to the unique properties of the catalyst/solid electrolyte interface: the structure of the double layer in this region is very different from that in liquid electrolytes, being the potential difference at this interface mainly determined by the specific adsorption of the mobile species in the solid electrolyte.
相似文献
Ezequiel P. M. LeivaEmail: |
50.
Rodion V. Panin Nellie R. Khasanova Evgeny V. Antipov Walter Schnelle 《Journal of solid state chemistry》2007,180(5):1566-1574
NaPd3O4, Na2PdO3 and K3Pd2O4 have been prepared by solid-state reaction of Na2O2 or KO2 and PdO in sealed silica tubes. Crystal structures of the synthesized phases were refined by the Rietveld method from X-ray powder diffraction data. NaPd3O4 (space group Pm3¯n, a=5.64979(6) Å, Z=2) is isostructural to NaPt3O4. It consists of NaO8 cubes and PdO4 squares, corner linked into a three-dimensional framework where the planes of neighboring PdO4 squares are perpendicular to each other. Na2PdO3 (space group C2/c, a=5.3857(1) Å, b=9.3297(1) Å, c=10.8136(2) Å, β=99.437(2)°, Z=8) belongs to the Li2RuO3-structure type, being the layered variant of the NaCl structure, where the layers of octahedral interstices filled with Na+ and Pd4+ cations alternate with Na3 layers along the c-axis. Na2PdO3 exhibits a stacking disorder, detected by electron diffraction and Rietveld refinement. K3Pd2O4, prepared for the first time, crystallizes in the orthorhombic space group Cmcm (a=6.1751(6) Å, b=9.1772(12) Å, c=11.3402(12) Å, Z=4). Its structure is composed of planar PdO4 units connected via common edges to form parallel staggered PdO2 strips, where potassium atoms are located between them. Magnetic susceptibility measurements of K3Pd2O4 reveal a Curie-Weiss behavior in the temperature range above 80 K. 相似文献