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921.
The reduction of cupric ion in ammonia solution by aqueous sulfur dioxide was studied. Each run was carried out at constant initial cupric concentration, stirred rate and total mixed gas flow rate. The effect of temperature, partial pressure of sulfur dioxide in gas phase and cupric ion concentration of the solution was investigated. The reaction of Cu3++SO2(aq.)→Cu++SO42? was carried out by bubbling mixed gas (SO2/N2) through the aqueous ammonia complex of copper (II). The color change for the system was from deep blue, green, yellow to white. The pH values in the system changed from 10 to 4. The product of the reaction was identified by the analyses of IR spectrum and X-ray diffraction, having the formula of 7Cu2SO3· 2CuSO3·3(NH4)2SO3·24H2O. The kinetic model of the reduction was proposed as: –d[Cu2+]/dt = k exp(–E/RT)[Cu2+]α[SO2%] According to the experiments, the parameters were determined as: α=1.64±0.03, þ=1.20, E=13.7 Kcal/mol and k = (1.77±0.20)×1010 (g-equ./?)?0.64min?2. 相似文献
922.
Guo‐Fang Lai Yi‐Fen Wang Chun‐Hua Lu Jian‐Xin Cao Yun‐Long Xu Shi‐De Luo 《Helvetica chimica acta》2003,86(6):2136-2141
Three novel triterpenoids named chinenols A – C ( 1 – 3 ), together with two known compounds, glutin‐5‐en‐3β‐ol ( 4 ) and daucosterol ( 5 ), were isolated from the aerial part of Helwingia chinensis Batal . The structures of 1 – 3 were determined on the basis of their HR‐EI‐MS, IR, 1H‐ and 13C‐NMR (DEPT), and 2D (HMQC, HMBC, NOESY) data. Compounds 1 – 3 and 5 showed inhibition activity in an antibacterial assay. 相似文献
923.
924.
Green DR Fenker HC Lai KW LeBritton J Lin YC Pifer AE Davenport TF Goldman JH Hagopian SL Lannutti JE Canough G Chang CC Davis TC Joyner RW Poirier JA Georgiopoulos CH Napier A Schneps J Marraffino JM Waters JW Webster MS Williams EG Woosley J Ficenec JR Torres S Trower WP 《Physical review letters》1986,56(16):1639-1642
925.
The synthesis and mesomorphic properties of a homologous series of N-(3-hydroxypropyl)-4-alkoxylsalicylaldimine, N-(3-hydroxypropyl)-4-(4′-alkoxybenzoxy)salicylaldimine, and their dicopper(II) and di-oxovanadium(VI) complexes are reported. Copper complexes exhibited monotropic smectic A phases; however, vanadyl complexes showed no mesomorphism. A systematic comparison revealed that the meso-genie behaviors of these bimetallic complexes are induced by the weak intermolecular force and determined mainly by the central metal. The effects on the structural variations near the metal central cores and side chain density are also discussed. 相似文献
926.
偶氮胂酸型荧光试剂测定铝的研究 总被引:10,自引:1,他引:10
比较了5种新试剂及偶氮胂-I的铝铬合物的荧光性能,讨论了试剂结构与性能之间的关系。试验出7-〔(4-甲基-2-胂酸基苯)偶氮〕-8-羟基喹啉-5-磺酸为铝的优良荧光试剂,并用其测定茶叶、含茶叶饲料,以及大白鼠排泄物中的铝和水样中的铝,结果满意。 相似文献
927.
以内型3,3-二甲基-2-降冰片基乙醛(1)与叔丁胺反应制得醛亚胺(2),依次和溴化乙基镁,碘乙烷反应制得内型2-(3,3-二甲基-2-降冰片基)丁醛的亚胺(4),再经水解得内型2-(3,3-二甲基-2-降冰片基)丁醛(5)。后者经与乙二醇缩醛化及氧化分别制得该醛的缩醛(6)及羧酸(7)。这些化合物均为新化合物,经纯化后进行了结构分析,并对其质谱进行了讨论。 相似文献
928.
We study the early stage coagulation kinetics for a charged colloidal dispersion which is here modeled by an effective two-body colloid-colloid potential. The colloidal system was physically prepared by choosing sets of colloidal parameters varying in particular the Hamaker constant and the particle's size. The kinetics of coagulation process was driven by the addition of an indifferent electrolyte and assumed to proceed in two quasi-steady steps. In the first step, colloidal particles are destabilized by the presence of a second potential minimum to diffuse from a bulk-stabilized liquid phase to a flocculated phase. In the second step, we assume that different entities are found in the second potential minimum. The entities comprise secondary dimers, secondary dimers undergoing redispersion, and monomers still in singlet states. If, under favorable condition, this kind of interaction-driven diffusive motion continues, a fraction of the secondary dimers will be induced to undergo primary dimers formation in the first deep minimum. Whether or not the latter process occurs is determined either energetically by the potential barrier falling below a prescribed value, say of 15k(B)T, or/and the second potential minimum becoming negligibly small (with a magnitude coagulation transition and would throw a fresh light on the use of both the energy and the kinetic criteria for understanding the colloidal stability such as those observed in the liquid-liquid coexistence. 相似文献
929.
930.
降香黄檀和印度紫檀中微量元素的研究 总被引:1,自引:0,他引:1
运用ICP-AES法测定了呀约降香的基源植物降香黄檀和印度檀心材中14种无机元素含量,发现它们之间含量相近的元素为Cr,Mn,Ti,Fe,含量差别较大的元素有Sr,Co,Ca等。 相似文献