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81.
Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives 总被引:1,自引:0,他引:1
Mou Cheng Li Li Li Jiang Wen Qi Zhang Yu Hai Qian Su Zhen Luo Jia Nian Shen 《Journal of Solid State Electrochemistry》2007,11(4):549-553
Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone
additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone
concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated.
Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals.
The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with
a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm2 only increases the grain size from 60 to 62 nm. 相似文献
82.
The structure of an unusual covalent adduct formed by thiol-activated neocarzinostatin chromophore (NCS-chrom) and a RNA-DNA hybrid having an overhang of four unpaired residues at the 3'-end of the RNA strand has been elucidated by MS and NMR spectroscopic analyses. Unlike previously characterized adducts formed by NCS-chrom on the sugar residue of the DNA target, this adduct has been found to be on one of the uracil bases in the RNA overhang. Covalent linkage is between C-6 of the post-activated NCS-chrom and C-5 of the uracil. A novel mechanism involving adduction of the NCS-chrom C-6 radical, generated by 2-mercaptoethanol activation, to C-5 of the uracil at the U9 position of the RNA 11-mer, oxidation by dioxygen, reduction by the thiol, and subsequent dehydration is proposed for adduct formation. 相似文献
83.
Shi Zhen CHEN Yun Peng BAI Zhao Long LI 《中国化学快报》2006,17(2):258-260
Fluorous-phase chemistry is currently a topic of considerable interest1-6. Since fluoroustriphasic reactions were first described by the Curran and co-workers7, this triphasicsystem has been widely used for detagging7,8 and phase-vanishing reactions9-11. … 相似文献
84.
Two title compounds, 4,4'-diformyl-diphenoxyethane (compound 1, C16H14O4)and 4,4',4'-triformyl-triphenoxytriethylamine (compound 2, C27H27NO6), were synthesized by condensation of 4-hydroxybenzaldehyde with 1,2-dichloroethane and tris2-chloroethylamine, respectively in dimethyl formamide in the presence of anhydrous potassium carbonate. The crystal data are: monoclinic, P21/c, a = 7.571(2), b = 12.608(3), c = 7.357(2) ', = 105.823(6)o, V = 675.7(2)'3, Mr = 270.3, Z = 2, Dc = 1.328 g/cm3, F(000) = 284, (MoK = 0.096 mm-1, R = 0.0537 and wR = 0.2189 for compound 1; and monoclinic, P21/n, a = 11.7162(6), b = 9.0042(6), c = 22.908(2) ', = 99.505(1)°, V = 2383.5(3) '3, Mr = 461.50, Z = 4, Dc = 1.286 g/cm3, F(000)= 976, (MoK = 0.091 mm-1, R = 0.0464 and wR = 0.1462 for compound 2. The molecule of compound 1 dialdehyde is located at the crystallographic inversion center nearby the midpoint of C8-C8A single bond. The three chains in the molecule of compound 2 trialdehyde are of non-crystallographic pseudo-C3 symmetry, and each of them is quite planar. 相似文献
85.
RongZhongYUAN ZuoLongYU MeiZhenQU 《中国化学快报》2003,14(7):755-758
A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders,using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%. 相似文献
86.
Yun‐Yu Liu Guang‐Shan Zhu Guo‐Zhen Fan Shi‐Lun Qiu 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):m159-m160
In the title compound, poly[μ5‐pyrazine‐2,3‐dicarboxylato‐cadmium(II)], [Cd(C6H2N2O4)]n or [Cd(pdc)]n, where pdc is the pyrazine‐2,3‐dicarboxylate anion, the CdII atom is six‐coordinated by five carboxylate O atoms and one N atom from five different pdc ligands in a distorted octahedral CdO5N coordination geometry. Two CdII atoms are bridged by carboxylate groups of the pdc ligands to create a dimeric unit. The dimeric units are further connected by the pdc ligands to generate an interesting two‐dimensional structure. 相似文献
87.
Quan HAN Hong Tao YAN* Zhen Jie QIAN Department of Chemistry Northwest University Xi抋n 《中国化学快报》2002,13(12)
Thermal lens spectrometry (TLS) is an excellent tool for trace analysis1. TLS allows the detection of absorbances of 10-7~10-8, concentration of ≈ 10-11 mol稬-1 and the analysis of 10-15 L volumes with ≈10-2 absorbing molecules2. Kinetic analysis is playing an increasingly important part in modern analytical chemistry. Therefore, TLS shows much promise in combination with kinetic analysis. However, there are few data on TLS applications in kinetic analysis method so far3~4. A ne… 相似文献
88.
Jianyang Dong Xiaochen Wang Zhen Wang Hongjian Song Yuxiu Liu Qingmin Wang 《Chemical science》2020,11(4):1026
Formyl-selective deuteration of aldehydes is of high interest for labeling purposes and for optimizing properties of drug candidates. Herein, we report a mild general method for formyl-selective deuterium labeling of aldehydes with D2O, an inexpensive deuterium source, via a synergistic combination of light-driven, polyoxometalate-facilitated hydrogen atom transfer and thiol catalysis. This highly efficient, scalable reaction showed excellent deuterium incorporation, a broad substrate scope, and excellent functional group tolerance and selectivity and is therefore a practical method for late-stage modification of synthetic intermediates in medicinal chemistry and for generating libraries of deuterated compounds.Formyl-selective deuteration of aldehydes with D2O mediated by the synergistic combination of light-driven, polyoxometalate-facilitated HAT and thiol catalysis is reported. 相似文献
89.
丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)在烟草生长生理、抗病抗逆等方面具有积极作用.为探明烟株患黑胫病后对根内AMF多样性和群落结构的影响,分别以烟草K326和云烟87健康、感染黑胫病烟株的根部及根际土壤作为研究对象,应用Illumina Miseq高通量测序技术探明烟草根部AMF多样性,采用显微形态观察烟草根内AMF侵染水平和根际土壤孢子密度,并分析土壤理化性质和AMF侵染特征的相关性.高通量测序结果表明在烟草根部共检测出1 655个AMF-OTUs,隶属于1纲4目5科6属,其中,Glomus为云烟87健康烟株根内AMF的优势属,其余样品优势属均为Paraglomus.聚类分析表明两个品种健康烟株根内AMF群落相似性较高,患病植株间根内AMF群落比较类似.侵染结果显示,患病烟株AMF侵染状况与土壤孢子密度均低于健康烟株根际土壤. RDA分析结果表明,全钾是影响AMF孢子密度和侵染状况的主要驱动因子,其次为速效磷和全磷;土壤p H值为烟株根内AMF多样性的主要影响因素,且两者呈负相关;此外,土壤中钾含量对烟草根内AMF群落组成的影响最为明显.研究... 相似文献
90.
本文提出以虚拟杆为主要特点的几何形体法用于求解并联机械手的位置正解。与“六维搜索算法”相比,具有初值选取简单,适用性强的特点。为并联机械手的工作空间分析与综合、误差分析与综合等提供了一个有力的工具。 相似文献