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991.
Three highly sensitive spectrophotometric methods for the determination of platinum(IV) have been developed, based on its colour reactions with molybdate and basic dyes (BD) in aqueous solution in the presence of poly(vinyl alcohol). Platinum(IV) reacts with molybdate and BD to form ion — association complexes of composition (BD)2[Pt (MoO4)3]. The molar absorptivities are between 6.83 × 105 and 9.51 × 105 dm3mol–1cm–1, the highest value being found with nile blue. Suitable conditions for the reactions and the effects of foreign ions were investigated. The methods can be applied to the spectrophotometric determination of trace amounts of platinum(IV) in some catalysts and ores. 相似文献
992.
应用灰色系统理论和最小二乘原理,推导出连续GM(1,N)模型,并将该模型用于高效液相色谱中溶质保留行为的预测.研究了烷烃、烷基苯及对羟基苯甲酸酯等化合物的容量因子与流动相组成、容量因子与碳数、保留时间与温度、保留时间与碳数的关系,并建立了相应的数学模型,经验证,预测结果良好. 相似文献
993.
Jiunn-Der?LiaoEmail author Chonyu?Chen Yi-Te?Wu Chih-Chiang?Weng 《Plasma Chemistry and Plasma Processing》2005,25(3):255-273
High density and well surface-distributed oxygen microwave plasma with an extensible antenna-coupling design was utilized to modify a densely weaved and large-surface-area Nylon-6 fabric within a short treatment time. Plasma pretreatment and subsequent acrylic acid (AAc) or 2-hydroxyethyl methacrylate (HEMA) grafting process were studied and optimized at the stage after dyed and finished procedure. The monomer-grafted dyed Nylon-6 fabrics evolved lasting hydrophilic properties and thereafter created or improved surface properties such as water diffusion, drainage, moisture regain and water absorbency, in different degrees. The pHEMA-grafted sample exhibited minor effect in color perception, which was also much hydrophilic than the pAAc-grafted one. Based upon surface analyses and wetting assessment, the penetration of HEMA monomer into the plasma-treated fabric matrix contributed to the facilitation of wetting properties. This work accordingly ensures such plasma-induced system to incorporate with the pattern of hydrophilic properties on the analogous textiles without interrupting their finishing process. 相似文献
994.
We show that two simple semiclassical strategies, one based on the Wilson–Sommerfeld rule and the other on the uncertainty principle, yield the exact modified form of the virial theorem for confined systems. An alternative, easier quantum mechanical route to arrive at this result is also sketched. Pilot calculations on confined oscillators reveal decisive trends. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
995.
A nickel-catalysed chemically modified electrode is described which seems to represent a convenient compromise between ease of preparation, reproducibility, precision and detection limits for the determination of carbohydrates in biological matrices. 相似文献
996.
Zhang De-Qing Wang Shao-Jun Sun Hong-Shan Wang Xiu-Li Cao Mao-Sheng 《Journal of Sol-Gel Science and Technology》2007,41(2):157-161
Lead zirconate titanate nanopowders Pb(Zr0.52Ti0.48)O3 (PZT) were prepared by modified sol-gel process in ethylene glycol system with zirconium nitrate as the zirconium source.
The research showed that it was critical to add lead acetate after the reaction of zirconium nitrate and tetrabutyl titanate
in ethylene glycol system for preparing PZT of exact titanium content. The reaction mechanisms of the sol synthesis, preparation
of xerogel and agglutinating process were characterized through using FT-IR, NMR, TG-FTIR, and GC-MS. The experiment proved
that ethylene glycol system did not rely on hydrolysis and condensation reactions in the process of the sol formation, but
on the formation of chain or network large molecules from complexation of ethylene glycol and all Ti and minor Pd, Zr. In
the preparation of xerogel, the complexation reaction was so completed that it formed large molecules network composed of
metal and dioxyethyl. Bulk weight loss happened before 350°C in the process of sintering xerogel to prepare PZT nanopowders.
Volatile matters and vapor phase decomposition resultants were primarily oxy-compounds including ethylene glycol, aldehyde-ketone
compounds, carbon dioxide and nitrate radical conversion matters. After 350°C, primary vapor phase decomposition resultants
were carbon dioxide and minor carbonyl compound. 相似文献
997.
V.L. Auslender I.V. Gornakov V.M. Radchenko E. Shtarklev V.O. Tkachenko L.A. Voronin 《Radiation Physics and Chemistry》2007,76(11-12):1792-1794
The report describes electron beam electromagnetic forming system, which is destined for irradiation of cylindrical long goods, specifically for PE tubes 160 mm diameter. System consists of electromagnet, power supply units, beam distributions control units, etc. for use at an electron accelerator at 5 MeV and 50 kW. The particular geometry of the magnet poles and their mutual arrangement are creating an irradiation field that allows the electrons to irradiate the surface of the product close to 90°. 相似文献
998.
999.
Two types of directional couplers for transverse electric (TE) modes are described: short and multihole couplers, respectively. They selectively pick one mode out of a mode mixture in an overmoded circular waveguide system. Unwanted modes are either statistically kept at low level or are suppressed by destructive interference in the coupling waveguide. Mode selectivity and directivity in multihole couplers oscillate up and down with an increasing number of holes, finally reaching a minimum of approximately 20 dB, unless there are competing modes with rational fractions of the beat wavelength. A multihole coupler for the TE02 mode (28 GHz, 63.4 mm waveguide diameter, 41 holes) and a length of 1.6 m shows a calculated directivity of 68 dB and suppresses the unwanted modes TE01 with 34 dB (24 dB), TE22 with 37 dB (45 dB), and further modes TEm (<5, m<6) with 17 dB to 34 dB in forward direction (figures in parentheses are for unwanted modes propagating in backward direction).A short directional coupler for the TE01 mode (28 GHz, 63.4 mm waveguide diameter) with 16 holes and a length of 230 mm shows a directivity of 55 to 100 dB between 27.9 and 28.1 GHz, suppressing the TE02 mode with 35 to 80 dB, the TE03 mode with 30 to 65 dB, and the TE22 mode with 30 to 70 dB. 相似文献
1000.
提出了一种动力学李代数方法来研究取代苯体系的非线性光学性质. 对于给定的PPP模型(Pariser-Parr-Pople)哈密顿量, 生成了一个动力学李代数. 依据这些代数元构造出演化算子作为群参数的函数, 通过求解一组非线性微分方程能够得到这些群参数. 再按照统计力学中的密度算子公式给出取代苯分子体系偶极矩的统计平均值. 于是导出二阶极化率的表达式. 与其他量子力学计算结果比较, 表明这种动力学李代数方法在预言有机共轭分子的非线性光学性质上同样有用. 相似文献