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941.
A carbon paste electrode modified with multi-walled carbon nanotubes (MWCNT) was prepared and the determination of ultra trace amount of zirconium based on the anodic adsorptive voltammetry of the zirconium-calcium-alizarin red S mix-polynuclear complex is described in this paper for the first time. The results showed that the sensitivity and the selectivity of the method are excellent. The second derivative linear scan voltammograms of the complex were recorded by polarographic analyzer from 200 to 1200 mV (vs. SCE) and it was found that the complex can be adsorbed on the surface of the electrode, yielding a peak at about 840 mV, corresponding to the oxidation of ARS in the complex. The peak current increases linearly with Zr (IV) concentration in the range of 6.0×10^-12--6.0×10^-11 mol. L^-1 (accumulation time 120 s), 6.0×10^-11--2.0×10^-9 mol. L-1 (accumulation time 90 s) and 2.0×10^-9--1.0×10^-7 mol. L^-1 (accumulation time 60 s) and the detection limit (S/N = 3) is 2.0×10^-12 mol. L^-1 (accumulation time 180 s). The procedure has been successfully applied to the determination of zirconium in the ore samples. 相似文献
942.
It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. ^40Ar/^39gAr incremental heating results on groundmass selected from the samples show that the age spectra are meaningless geologically. However, singe crystal total fusions of CO2 lasing on the sanidine separates could yield rational 4^40Ar/^39Ar results and distinguish their sources in this study. Timing on three formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this paper. The lowermost portion of the Chawan Formation gives an age of 113.7±0.3 Ma; the lower part of the Xishantou Formation was formed 116.4±0.4 Ma ago and the bottom of the Gaowu Formation took its shape at 118.4±0.4 Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations. 相似文献
943.
宋飞 《贵州师范大学学报(社会科学版)》2008,(4)
1997年爆发的东亚金融危机给整个地区造成了巨大的经济损失,这使东亚各国和地区认识到建立区域货币合作的重要性和紧迫性。文章通过从国际政治经济学的角度对东亚货币合作中各国的权力与利益进行分析,进而在此基础上提出东亚货币合作的实现必须处理好全球霸权国、地区大国及东盟各国间的权力与利益的关系。 相似文献
944.
Carbon dioxide reacts with porous media while flowing through them enhancing their permeability. Its flow behavior as well as the permeability enhancement effects were studied in synthetic cores, natural cores and microtubes with an inner diameter of 5 μm. The results show that the permeability of H2O-saturated cores (containing carbonate ingredients) was enhanced by increasing the injection volume of a CO2-H2O solution. This enhancement is attributable to carbon dioxide's corrosion, which is justified by SEM scanning. The same phenomenon occurs with a CO2-H2O solution in microtubes, but for a different reason. The gas flow velocity of carbon dioxide in microtubes was approximately 100% faster than that of nitrogen because of the scale and the squeezing effects. Carbon dioxide molecules dissolved in water accelerate the diffusion rate of water molecules within the boundary layer, which in turn diminishes the thickness of the water film and enlarges the effective pore size. This flow behavior facilitates the injection of carbon dioxide into low-permeability reservoirs for oil-displacement and formation energy buildup purposes. This behavior also increases the potential for carbon dioxide channeling or release from the formation. 相似文献
945.
Salinity is one of the most severe environmental factors that may impair crop productivity. A proteomic study based on two-dimensional gel electrophoresis is performed in order to analyze the long-term salinity stress response of Thellungiella halophila, an Arabidopsis-related halophyte. Four-week-old seedlings are exposed to long-term salinity treatment. The total crude proteins are extracted from leaf blades, separated by 2-DE, stained with Coomassie Brilliant Blue, and differentially displayed spots are identified by MALDI-TOF MS or QTOF MS/MS. Among 900 protein spots reproducibly detected on each gel, 30 spots exhibit significant change and some of them are identified. The identified proteins include not only some previously characterized stress-responsive proteins such as TIR-NBS-LRR class disease resistance protein, ferritin-1, and pathogenesis-related protein 5, but also some proteins related to energy pathway, metabolism, RNA processing and protein degradation, as well as proteins with unknown functions. The possible functions of these proteins in salinity tolerance of T. halophila are discussed and it is suggested that the long-term salinity tolerance of T. halophila is achieved, at least partly, by enhancing defense system, adjusting energy and metabolic pathway and maintaining RNA structure. 相似文献
946.
947.
以钛酸丁酯为先驱物,经过溶胶凝胶过程在漂珠转换(FB)表面负载成膜,得到具有光催化特性的样品(TiO2/FB).经扫描电镜(SEM)、X射线粉末衍射(XRD)以及傅立叶转换红外光谱分析(FTIR)等多方表征,TiO2在漂珠表面的成膜厚度约为2μm,由粒径尺寸约为100 nm的TiO2颗粒组成;经650℃处理,无定形的TiO2转变为金红石型;TiO2薄膜与漂珠表面之间通过Ti-O-Si键连接.研究了溶胶凝胶条件以及漂珠表面的羟基化处理,对TiO2成膜形貌的影响以及TiO2/FB对亚甲基蓝的光催化降解特性.结果表明,以紫外灯为光源,经180 min照射,TiO2/FB对亚甲基蓝的光降解率达到92%. 相似文献
948.
为了建立在衣藻中快速简便研究外源基因功能的方法,采用玻璃珠转化法将pBI221质粒(35S,Amp,GUS)高效转化至细胞壁缺陷型衣藻品系CW-15(Arg-),通过对转化条件及GUS表达检测条件摸索,发现35S启动子在CW-15中能有效启动GUS表达,且GUS最佳检测时间约为转化后24h,重组细胞先染色后制片更有利于GUS检测. 相似文献
949.
在范畴C中以推出为对象,推出态射为态射构成推出范畴C^□.本文了给出了范畴C^□中的三角可换定理,并得到了C^□中上积存在的条件,进一步还证明了加法范畴的推出范畴仍为加法范畴. 相似文献
950.
基于聚类矩阵的CM—Apriori算法研究 总被引:1,自引:0,他引:1
针对关联规则中Apriori算法的不足,提出了一种基于聚类矩阵的CM-Apriori新算法.该算法只需扫描事务数据库一次,就直接按事务项数生成聚类矩阵,每次只需对部分聚类矩阵进行运算,就可以生成频繁项集.这大大减少了扫描数据库的次数和计算成本,从而有效提高了算法的运算效率,并通过实例说明了它是一种有效的关联规则挖掘方法. 相似文献