共查询到20条相似文献,搜索用时 15 毫秒
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苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况,合成乙苯,苯乙烯所用的催化剂种类,并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。 相似文献
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责任是人应主动承担的角色义务和对其因过失所造成后果应承担的责罚.有两层涵义:一是义务;二是后果.责任心是个体自觉做好分内事务和履行道德义务的心理倾向,是个性心理品质成分中自我特征维度上的重要内容.责任心具有两个方面的涵义:一是角色分内职责;二是角色道德义务.责任心是一种通过责任认知、责任个性和责任适应的动态形式表现出来的静态品质,责任心是责任心过程结构与责任心关系结构相互制约、相互影响的统一体. 相似文献
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《国际聚合物材料杂志》2012,61(1-4):113-122
Abstract Kinetics and mechanisms of oxidation of 6 acetals by molecular oxygen and ozone in liquid phase have been studied. Reaction with molecular oxygen (70°C, 15–16 hr) leads to the formation monoethers of the corresponding glycols with 68–90% selectivity. Salts of metals and complexes with crown-ethers have increased the reaction rate significally. Ozone have reacted with acetals with formation similar products. The mechanisms of intermediate stages have been proposed. 相似文献
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The variation of the Au 4f binding energy of Au clusters with the cluster size has been established by measuring the binding energies of clusters whose size distributions were independently determined by HREM and STM. The binding energy increases significantly when the cluster size is less than 2 nm. Au-Cu bimetallic clusters of the composition Cu3Au have been deposited for the first time on carbon substrates. The shifts in the core level binding energies of the bimetallic clusters show the effect of alloying in the case of large clusters, but show effects of both alloying and cluster size in the case of the small clusters. The interaction of CO with Cu3Au clusters is stronger than with a bulk Cu metal. The interaction of CO with small Cu clusters also seems to be stronger than with bulk Cu or with large Cu clusters. 相似文献
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塑料挤出机螺杆,机筒耐磨损,耐腐蚀的强化与应用 总被引:4,自引:0,他引:4
对塑料挤出机,注塑机螺杆,机筒的磨损,腐蚀原因及提高螺杆,机筒耐磨损,耐腐蚀的方法、制造与应用作了较详尽的介绍。 相似文献
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Emmanuel Ginsburger Fernand Pla Christian Fonteix Silvère Massebeuf Philippe Swaels 《Chemical engineering science》2003,58(19):4493-4514
This work deals with modelling of emulsion polymerization processes using batch and semi-batch reactors. Specific attention is paid to copolymerization of the system styrene/butyl acrylate.The main key parameters of the model are identified on the basis of batch experimental data in order to describe the complete sketch of emulsion polymerization. The model is then used to simulate, under several operating conditions, the polymerization rate, the global monomers conversion, the number and weight average molecular weights as well as the particle size distribution and the glass transition temperature. Then, the model is generalized to the use of semi-batch processes and validated for this application. 相似文献
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对用甘油锌作光稳定剂的光稳定作用进行了测试,并与光稳定剂NBC,BZ进行了比较。研究了甘油锌,NBC和BZ与双酚A的复配效果。研究结果表明,甘油锌是一种性能优良的光稳定剂。 相似文献
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This study aimed to investigate the structural features, antioxidant activity, tyrosinase inhibitory effect, and mechanism of proanthocyanidins from leaf and fruit of Leucaena leucocephala. MALDI-TOF-MS, thiolysis coupled with HPLC-ESI-MS, and 13C-NMR confirmed that these proanthocyanidins were complex mixtures of propelargonidins, procyanidins, and prodelphinidins. (Epi)catechin, (epi)gallocatechin, (epi)catechin gallate, and (epi)gallocatechin gallate were the main constitutive units. The findings obtained from enzyme analysis revealed that the proanthocyanidins had inhibitory effects on both monophenolase and diphenolase of tyrosinase. The IC50 values of leaf and fruit proanthocyanidins were 73.5?±?2.7 and 52.3?±?3.5 µg/mL for monophenolase activity, and 27.2?±?1.4 and 16.1?±?1.1 µg/mL for diphenolase activity, respectively. The inhibition of diphenolase by proanthocyanidins were proved to be reversible and mixed type. In addition, it was also found from various antioxidant methods that the proanthocyanidins in leaf and fruit possessed potent DPPH radical scavenging activity with IC50 values of 103.4?±?0.8 and 87.8?±?1.1 µg/mL, ABTS radical scavenging activity with IC50 values of 72.9?±?0.4 and 65.7?±?0.9 µg/mL, and ferric reducing antioxidant power with FRAP values of 3.74?±?0.03 and 4.02?±?0.15?mmol AAE/g, respectively. The results obtained suggested that the proanthocyanidins from leaf and fruit of L. leucocephala might have the potential to be exploited as natural tyrosinase inhibitors and antioxidants. 相似文献
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徐兆瑜 《化学推进剂与高分子材料》2003,1(5):40-44
介绍了近期国内外氟化工产品的生产、应用和市场动态 ,尤其对国内目前氟塑料工业的发展前景进行了较详细的阐述。同时提出了一些具有开发前景的氟塑料产品 相似文献
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肥皂和表面活性剂的配方与性质 总被引:1,自引:0,他引:1
将表面活性剂添加到以肥皂为基剂的配方中,可有效降低体系的pH值,如选择合适的中和试剂和表面活性剂还可使溶液呈透明状.同时,专业小组的研究表明:某些表面活性剂的加入可有效提高肥皂配方的许多其他表观特性. 相似文献
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介绍混料和母料的生产和应用情况,生产商,经锁商与消费用户之间的紧密合作,协调关系以及发展趋势。 相似文献
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介绍了国内外合成丁辛醇的工艺技术进展情况,包括戴维合成法、三菱化成合成法、巴斯夫合成法等。在比较不同生产工艺路线的同时,从现有技术成熟角度和应用情况对比,提出了低压羰基法合成丁辛醇的选择原则。同时阐述了未来丁辛醇合成技术的发展趋势。 相似文献
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