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991.
ZnO压敏电阻器的性能及发展 总被引:3,自引:0,他引:3
简要回顾了ZnO压敏电阻器的历史,阐述了ZnO压敏电阻器的性能以及当前基础性研究的现状,并对其发展进行了展望。研究了Bi2O3和TiO2的掺杂对低压ZnO压敏电阻性能和微观结构的影响规律,从理论上分析了Bi2O3和TiO2添加剂的作用机理。为ZnO压敏电阻的低压化提供了理论依据和方法。 相似文献
992.
993.
Ralf Dümpelmann Noel W. Cant David L. Trimm 《Applied catalysis. B, Environmental》1995,6(4):L291-L296
On-line infrared spectroscopy has been used to show that isocyanic acid, HNCO, is a substantial primary product of the reaction between NO, CO and H2 over a Pt/SiO2 catalyst. At 230°C it accounts for more than 40% of the CO converted. No isocyanic acid is seen when Al2O3 is placed downstream of Pt/SiO2, or when using a Pt/Al2O3 catalyst under the same conditions, due to rapid hydrolysis of HNCO on the alumina. Isocyanic acid may exist as a trace intermediate in automobile catalytic converters during their warm-up phase but it is unlikely to emerge from the pore system of aluminabased catalysts. 相似文献
994.
Zan-guo?Peng Kus?Hidajat Mohammad?ShahabuddinEmail author 《Korean Journal of Chemical Engineering》2003,20(5):896-901
A colloidal suspension of magnetic particles coated with double layer surfactant molecules was prepared, characterized and
used for separation of some chemicals. The aqueous magnetic fluid was prepared by chemical precipitation method and characterized
by total organic carbon analyzer (TOC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The TOC
and TGA measurements indicate that the prepared magnetic particles are coated with surfactant molecules in double layers.
The outer surfactant layer has free polar heads. TEM measurement results show that magnetic particles are nanosized. A mixture
of 2-hydroxyphenol (strong polar) and 2-nitrophenol (weak polar) was chosen as the target system. Results show that the magnetic
fluid can selectively adsorb 2-hydroxyphenol from the mixture, whereas the adsorption of 2-nitrophenol is insignificant. For
2-hydroxyphenol, the adsorption equilibrium can be described well by Langmuir isotherm, and the adsorption kinetic can be
fitted well by a linear driving force mass transfer model. 相似文献
995.
Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC‐PU) and poly(2‐ethoxyethyl methacrylate) poly(2‐EOEMA) were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate (EGDM) as crosslinker. GC‐PU/poly (2‐EOEMA) interpenetrating polymer networks were obtained by transfer molding. The novel GC‐PU/poly (2‐EOEMA) IPNs are found to be tough films. These IPNs are characterized in terms of their resistance to chemical reagents thermal behavior (DSC, TGA) and mechanical behavior, including tensile strength, Young's modulus, shore A hardness, and elongation. The morphological behavior was studied by scanning electron microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1029–1034, 2004 相似文献
996.
997.
The effect of the reaction conditions on the grafting parameters during grafting of 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid onto sodium carboxymethylcellulose using H2O2/Fe+2 redox pair are studied at 30°C. The grafting ratio, add on, and conversion initially increase with the H2O2 concentration in the range of (10.0–15.0) × 10?2 mol dm?3. Thereafter, these parameters decrease with the H2O2 concentration. The grafting ratio, add on, and conversion increase when increasing the ferrous ion concentration from (0.5 to 4.0) × 10?2 mol dm?3 and decrease with a further increase in the concentration. It is observed that the grafting ratio and add on increase with the monomer concentration, whereas the conversion decrease. The hydrogen ions seem to be facilitating the grafting reaction up to a certain concentration and after this concentration seem to be retarding the process. The grafting ratio, add on, and conversion decrease with the sodium carboxymethylcellulose concentration. When increasing the time period from 60 to 90 min, the grafting parameters increase but decrease thereafter. Similarly, when increasing the temperature from 25 to 30°C, the grafting parameters increase and decrease thereafter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4819–4825, 2006 相似文献
998.
《Fuel》2003,82(2):147-151
The aim of this paper is to show how a cheap carbonaceous material such as low rank coal-based carbon (or char) can be used in the combined SO2/NO removal from exhaust gas at the linear gas velocity used in commercial systems (0.12 m s−1). Char is produced from carbonization and optionally activated with steam. This char is used in a first step to abate the SO2 concentration at the following conditions: 100 °C, space velocity of 3600 h−1, 6% O2, 10% H2O, 1000 ppmv SO2, 1000 ppmv NO and N2 as remainder. In a second step, when the SO2 concentration in the flue gas is low, NO is reduced to N2 and steam at the following experimental conditions: 150 °C, space velocity of 900 h−1, 6% O2, 10% H2O, 0-500 ppmv SO2, 1000 ppmv NO, 1000 ppmv NH3 and N2 as remainder.It has been shown that the presence of NO has no effect on SO2 abatement during the first step of combined SO2/NO removal system and that low SO2 inlet concentration has a negligible effect on NO reduction in the second step. Moreover, this char can be thermally regenerated after use for various cycles without loss of activity. On the other hand, this regenerated char shows the highest NO removal activity (compared to parent chars, either carbonized or steam activated) which can be attributed to the activating effect of the sulfuric acid formed during the first step of the combined SO2/NO removal system. 相似文献
999.
本文设计并实现了基于J2EE的高校教师业务管理系统.文章详细讨论了系统实现的业务模型、功能模型等需求分析过程,以及系统架构、通用查询框架、基于角色访问控制策略的“用户一角色.功能模块”的权限管理系统设计与实现等关键技术. 相似文献
1000.