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成型是钇铝石榴石(YAG)透明陶瓷研制的关键环节,对透明陶瓷的致密化过程及其力学、热学和光学性能有重要影响。本工作围绕YAG透明陶瓷的基于数字光处理(DLP)技术的光固化3D打印成型,系统地开展了YAG陶瓷浆料的研制、陶瓷生坯的构筑及坯体脱脂和烧结工艺研究。采用流变仪分析了固含量对陶瓷浆料流变特性的影响,借助分析曝光参数对单层陶瓷膜特性的影响,确立了最佳的光固化工艺参数。结合TG–DTA分析,对陶瓷坯体脱脂制度进行了精准控制。采用真空高温烧结工艺制备得到高致密YAG透明陶瓷,讨论了固含量、烧结温度等工艺参数对YAG透明陶瓷微结构演变及光学质量的影响,基于DLP光固化成型技术成功制备出可见光透过率高达82.9%的高性能YAG透明陶瓷。 相似文献
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分析了火炸药与武器信息化的关联性;论述了火炸药在武器装备发展中的综合地位与作用;提出作为武器信息化条件下火炸药发展策略和基本点的六项技术,即火炸药相关信息量的整合与准确表达、高能量与高安全性的统一、能量释放的可控制性、洁净燃烧与爆炸技术、燃烧爆炸的物理与化学作用延伸、非致命武器与化学战剂等. 相似文献
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以山核桃、油茶和板栗3类果蓬为原料,研究了此类原料与杉木、松木屑在不同配比条件下对果蓬类致密成型特征及其机制炭质量的影响。证实了果蓬类原料因纤维素含量、木质素含量与杉木、松木存在差异,且因较高的灰分含量限制,需与杉木或松木屑等原料在一定配比条件下才可实现良好的致密成型。而配比选择试验结果则表明,果蓬原料与杉木、松木屑混合原料以3:7比例配料为宜;在此条件下,制备的机制炭外形平直无裂缝,得率为 33.85%~36.73%,固定碳含量 79.80%~86.20%,热值28.96~31.92 MJ/kg。 相似文献
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On Porosity of Carbon Aerogels from Sol-Gel Polymerization of Phenolic Novolak and Furfural 总被引:1,自引:0,他引:1
Rui Zhang Yonggen Lü Qinghan Meng Liang Zhan Gangping Wu Kaixi Li Licheng Ling 《Journal of Porous Materials》2003,10(1):57-68
Carbon aerogels were prepared by sol-gel polymerization of phenolic novolak and furfural followed by supercritical drying and pyrolysis. The porosity and morphologies of carbon aerogels were characterized by nitrogen adsorption, apparent density, He- pycnometer method, and transmission electronic microscopy (TEM). Effect of ratios of phenolic novolak to furfural (Ra) and total concentration of reactants (C) in sol-gel step on porosity and morphologies of carbon aerogels was investigated. The carbon aerogels synthesized are rich in meso- and macropores. The Ra determines the cross-linking density of polymers, thereby the compatibility of the polymers, and ultimately the shrinkage of gels in the drying and pyrolysis. The network sizes and the porosity of organic and carbon aerogels are mainly determined by Ra. The C has no effect on volume shrinkage of gels in drying and pyrolysis and has only dilute effect in determining bulk density of organic and carbon aerogels, and ultimately the porosity of carbon aerogels. Conversion of mesopores to micro- and macropores is observed, which is related to combination of C and Ra, and determines the partition of micro-, meso- and macropores. 相似文献
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从化学组成上区分宋代汝瓷与民窑钧瓷 总被引:7,自引:0,他引:7
应用质子激发X荧光分析技术测定了一组宋代汝瓷和一组宋代民窑钧瓷瓷片的化学组成及浓度,对汝瓷与民窑钧瓷的主量,次量化学组成和痕量化学组成进行了比较,应用模式识别方法加以研究,得到了区分宋代汝瓷和民窑钧瓷的可视分类图和数学判据。 相似文献
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Fifty years with bile acids and steroids in health and disease 总被引:3,自引:0,他引:3
Cholesterol and its metabolites, e.g., steroid hormones and bile acids, constitute a class of compounds of great biological importance. Their chemistry, biochemistry, and regulation in the body have been intensely studied for more than two centuries. The author has studied aspects of the biochemistry and clinical chemistry of steroids and bile acids for more than 50 years, and this paper, which is an extended version of the Schroepfer Medal Award lecture, reviews and discusses part of this work. Development and application of analytical methods based on chromatography and mass spectrometry (MS) have been a central part of many projects, aiming at detailed characterization and quantification of metabolic profiles of steroids and bile acids under different conditions. In present terminology, much of the work may be termed steroidomics and cholanoidomics. Topics discussed are bile acids in human bile and feces, bile acid production, bacterial dehydroxylation of bile acids and steroids during the enterohepatic circulation, profiles of steroid sulfates in plasma of humans and other primates, development of neutral and ion-exchanging lipophilic derivatives of Sephadex for sample preparation and group separation of steroid and bile acid conjugates, profiles of steroids and bile acids in human urine under different conditions, hydroxylation of bile acids in liver disease, effects of alcohol-induced redox changes on steroid synthesis and metabolism, alcohol-induced changes of bile acid biosynthesis, compartmentation of bile acid synthesis studied with 3H-labeled ethanol, formation and metabolism of sulfated metabolites of progesterone in human pregnancy, abnormal patterns of these in patients with intrahepatic cholestasis of pregnancy corrected by ursodeoxycholic acid, inherited and acquired defects of bile acid biosynthesis and their treatment, conjugation of bile acids and steroids with N-acetylglucosamine, sulfate-glucuronide double conjugates of hydroxycholesterols, extrahepatic 7alpha-hydroxylation and 3-dehydrogenation of hydroxycholesterols, and extrahepatic formation of C27 bile acids. The final part discusses analysis of free and sulfated steroids in brain tissue by capillary liquid chromatography-electrospray MS and suggests a need for reevaluation of the function of steroid sulfates in rat brain. 相似文献
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PVC是一种应用广泛的高分子材料,但因其具有热稳定性差、易燃烧、发烟量大的缺点而限制了发展,因此PVC的阻燃与抑烟成为阻燃科学研究领域的关键问题之一。纳米型阻燃抑烟剂克服了传统型阻燃抑烟剂添加量大、阻燃抑烟效果不明显的缺点,为研究和解决PVC阻燃抑烟提供了一个新途径。本文介绍了PVC纳米阻燃抑烟剂的制备方法、表征手段及其在PVC中的应用以及PVC降解、阻燃与抑烟的表征,最后简要论述PVC阻燃抑烟的发展趋势。 相似文献
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油气是重要的战略资源,关系国计民生。随着工业化和城镇化的加速推进以及汽车进入普及期,我国油气供需形势日趋严峻。解决我国油气供应不足的问题。应首先立足于开发利用国内的油气资源,不断提高自给水平,然而却存在管理体制和政策的掣肘。世界油气主产国都不断改善其油气资源开发利用的管理体制与政策,促进更加有效与合理地开发利用和保护油气资源。本文总结了该领域的国际经验,从加强油气资源法律法规体系建设、促进油气资源管理体制改革、完善油气资源矿业管理等方面提出了对我国的启示和改革建议。 相似文献
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B. Serdarevich 《Journal of the American Oil Chemists' Society》1967,44(7):381-393
Isomerization of isopropylidene glycerol ketals and benzylidene glycerol acetals was studied, and isoraerization equilibria
were established. Reaction of benzaldehyde with glycerol gave four benzylidene glycerol isomers, which were separated by column
chromatography and characterized by NMR spectroscopy and other methods.
Isomerization of 1- and 2-monoglycerides and of 1,2- and 1,3-diglycerides, and their separation by column chromatography,
are described. Mechanisms of isomerization in mono- and diglycerides and factors which affect them are discussed.
Isomerization of 1- and 2-glycerophosphates and of cyclic glycerophosphates by acid and base was also studied. Hydrolysis
products of L-3-glycerylphosphorylcholine and 2-glycerylphosphorylcholine were separated by column chromatography and characterized
by periodic acid oxidation, optical rotation, and NMR spectroscopy. No isomerization of unhydrolyzed L-3-glycerylphosphorylcholine
and 2-glycerylphosphorylcholine was observed. Evidence indicated that acid-catalyzed hydrolyses of phosphoglycerides are under
thermodynamic control whereas most base-catalyzed hydrolyses are under kinetic control. 相似文献
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The results of an analysis of the current state of the Moscow Coal Basin and the development of science and technology for the multiple use and conversion of coal into refined energy carriers, products, and materials with new consumer properties are presented. It is demonstrated that a number of processes and facilities based on the coals and overburden rocks of the basin have been prepared for technical implementation, namely: the generation of heat and power at plants with in-cycle coal gasification; the fluidized-bed combustion of coal in low-power boiler units (50?C60 MW); the manufacture of ballast-free humic plant growth stimulators and coagulants for the purification of wastewater and drinking water; and the use of coals and coal mining and benefication wastes as catalytic additives in the process of hydrogenation. 相似文献