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春节前后,吉安市遭遇到罕见的冰冻雨雪灾害天气,连续出现了低温、阴雨和雨夹雪,成为全省灾情最严重地区之一.特别是1月25日以后,出现了持续大范围的雨雪冰冻天气.冰冻损坏了市区的电网,压垮了树枝,封锁了道路和桥梁. 相似文献
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收集了2010年7月~2011年6月世界塑料工业的相关资料,介绍了2010~2011年世界塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚氯乙烯、聚苯乙烯、ABS树脂),工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚),特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮),通用热固性树脂(酚醛、不饱和聚酯树脂、环氧树脂、聚氨酯)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。 相似文献
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萜类化合物具有可观的经济价值,但是目前的生产过程复杂、产量低。酿酒酵母甲羟戊酸途径为萜类化合物的合成提供直接前体,因此酿酒酵母细胞具有合成异源萜类化合物的天然优势。对酿酒酵母甲羟戊酸途径的清晰认识是对其进行有效利用的基础,本文从代谢途径、关键酶的特点和全局调控机制3个方面对该途径进行了介绍。从代谢途径的构建和优化、模块与底盘细胞的适配、模块构建及组装方式的角度概述了酿酒酵母细胞异源合成单萜、倍半烯萜、二萜、三萜类化合物的研究进展。指出实现酿酒酵母高效合成萜类化合物所需要解决的基础问题是对酿酒酵母甲羟戊酸途径进行更为全面了解和对萜类化合物的天然代谢途径进行明确解析;另外,合成生物学的进一步发展也将为此提供应用基础。 相似文献
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我公司回转窑规格为Φ4.0m×60m.窑内使用的耐火砖为镁铬砖、隔热尖晶石、蓝晶石和黏土砖以及硅莫砖.镁铬砖规格为(81×90×150×200)mm,其它耐火砖规格皆为(81×90×200×200)mm.尽管每个品种的砖品质相同,但由于在镶砌和使用过程中方法不同,寿命有长有短.通过多年实践,现总结如下. 相似文献
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采用动态水热法,以硅酸钠钙为原料合成硬硅钙石晶须,通过搅拌使晶须形成高孔隙率的球形颗粒. 考察了温度、时间和原料CaO/SiO2摩尔比等反应条件对硬硅钙石晶须及其球形颗粒孔隙率的影响. 结果表明,将CaO和SiO2按摩尔比0.90~1.15溶于Na2O浓度为20 g/L的NaOH溶液中,控制液固比为30 mL/g,以300 r/min的转速在220℃下水热反应7 h以上,可制备出直径约200 nm、长径比大于20的硬硅钙石晶须,晶须相互缠绕形成的球形颗粒孔隙率最高可达93%. 相似文献
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以硬硅钙石作阻隔型填料,以金红石型二氧化钛和中空玻璃微珠为反射型功能填料,制备建筑外墙隔热涂料。研究了单掺硬硅钙石、金红石型二氧化钛、中空玻璃微珠以及复合添加3种填料对涂层隔热性能的影响。结果表明:单掺硬硅钙石、金红石型二氧化钛或中空玻璃微珠均可提高涂层隔热性能,硬硅钙石的适宜掺量为9%,金红石型二氧化钛的适宜掺量为30%,空心玻璃微珠的适宜掺量为20%;复合掺入硬硅钙石、金红石型二氧化钛和空心玻璃微珠可进一步提高涂层隔热性能,掺量为9%、30%和15%时,涂层的热反射率可达93.69%。按建筑行业标准JG/T235—2008《建筑反射隔热涂料》进行检测,涂料对波长为250~2 500 nm范围内的太阳反射比为0.85,半球发射率为0.87,隔热温差为13℃,符合标准要求;空心玻璃微珠、二氧化钛和硬硅钙石复合掺入后,发挥协同作用,能更加有效地提高涂层的隔热性能。 相似文献
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Jiafu Chen Yan Li Fengfeng Xue Zhimin Chen Qun Xu 《Polymer Engineering and Science》2011,51(6):1170-1177
Micron‐sized, cross‐linked polystyrene (PS) particles with different morphologies were prepared by the developed dispersion polymerization. By scanning electron microscope (SEM) observation, it was found that these PS particles had interesting shapes such as deformed sphere, hollow hemisphere and spheroid‐like shape when initial monomer concentration, reaction time, and temperature and addition way of the reagent added in the third stage were different. The shape of the PS particles was changed from hollow hemisphere to spheroid‐like shape with prolongation of the reaction time. It was remarkable that the rough surface of hollow‐hemisphere‐like PS particles became smooth and the hollow structure of smooth‐hollow‐hemisphere‐like PS particles grew into solid structure at the same time. The formation mechanism behind these phenomena was discussed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers 相似文献
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Preparation of mono-dispersed mixed metal oxide micro hollow spheres by homogeneous precipitation in a micro precipitator 总被引:1,自引:0,他引:1
For the preparation of mono-dispersed mixed metal oxide micro hollow spheres, homogeneous precipitation was carried out using a mixed metal sulfate precursor solution and an IPA (isopropyl alcohol) solvent in a micro precipitator configured with a micro capillary tip and a millimeter scale glass tube. The prepared micro particles revealed the morphology of hollow spheres with a narrow size distribution. For the preparation of uniform micro hollow particles without agglomeration the micro precipitator had to be operated in a laminar flow region with a low Reynolds number. The size of the particle could be controlled simply by changing the capillary tip diameter and/or the line velocity of the precursor solution and the IPA solvent. Also, the shell thickness of the hollow spheres could be controlled just by the concentration of the precursor solution. The mass production of micro hollow spheres by the micro fluidic device was validated in a micro precipitator inserted with multi-capillary tubes. 相似文献
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本文采用聚(苯乙烯-co-甲基丙烯酸-N,N-二甲氨基乙酯)[P(St-co-DEA)]核壳纳米粒子为模板,在环境条件下以四甲基硅氧烷(TMOS)为前体,原位可控沉积纳米结构SiO2,合成了具有PSt核和PDEA-SiO2杂化的壳层纳米粒子,将杂化粒子进一步煅烧可得到空心的SiO2纳米微球。采用FT IR、TEM以及DLS对所合成的杂化纳米粒子进行了详细的表征。TEM观察证实了纳米结构SiO2在粒子壳层中的沉积,随着矿化反应的进行,体系形成了具有核壳结构的树莓状纳米粒子。研究表明:杂化粒子的表面粗糙程度及大小可以通过简单改变体系试验参数(如TMOS的用量和矿化时间等)而控制。 相似文献
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Guang‐Hui Ma Shinzo Omi Victoria L. Dimonie E. David Sudol Mohamed S. El‐Aasser 《应用聚合物科学杂志》2002,85(7):1530-1543
In a previous study, it was found that monodisperse polystyrene (PSt) hollow particles can be prepared under special conditions by combining a Shirasu Porous Glass (SPG) emulsification technique and subsequent suspension polymerization process. That is, a mixture of styrene (St), N,N‐dimethylamino ethyl methacrylate (DMAEMA), hexadecane (HD), and initiator N, N′‐azobis(2,4‐dimethylvaleronitrile) (ADVN) was used as the dispersed phase in an aqueous phase containing poly(vinyl pyrrolidone) (PVP), sodium lauryl sulfate (SLS), and water‐soluble inhibitor. The dispersed phase was created by pushing the oil phase through the uniform pores of an SPG membrane into the continuous phase to form uniform droplets. Then, the droplets were polymerized at 70°C. It has been puzzling that hollow microspheres were obtained only when sodium nitrite (NaNO2) was used as a water‐soluble inhibitor, while one‐hole particles were formed when hydroquinone (HQ) or diaminophenylene (DAP) was used. In this study, the mechanism of formation of the hollow microspheres was verified by measuring the variation of diameter, molecular weight distribution, and monomer conversion, and by observing morphological changes during the polymerization, as well as by changing the type and amount of hydrophilic monomer, and initiator. It was found that the diameter of the oil droplets decreased, and a large amount of secondary new particles formed immediately after polymerization started in the case of NaNO2. However, there was no such apparent behavior to be observed when HQ or DAP was used. It was determined that the hollow particles formed due to the rapid phase separation between PSt and HD, and as a consequence, a large amount of monomer diffused into the aqueous phase to form the secondary particles. Rapid phase separation confined the HD inside the droplets, a nonequilibrium morphology. On the other hand, one‐hole particles, representing an equilibrium morphology, formed when the phase separation occurred slowly because a lot of monomer existed inside of the droplets to allow mobility of the PSt. The addition of DMAEMA allowed the hollow particles to be formed more easily by decreasing the interfacial tension between the copolymer and aqueous phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1530–1543, 2002 相似文献