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41.
《Petroleum Science and Technology》2007,25(10):1293-1304
Aromatic hydrogenation is one of the important classes of hydrotreating reactions and its thermodynamics play a significant role in achieving the product specifications. This article comprehensively reviews the available experimental thermodynamic data as well as the methods to estimate the data for aromatic hydrogenation. The data indicate that aromatic hydrogenation reactions are thermodynamically more favorable at about 200°C-250°C and moderate pressures (3-5 MPa). Industrially, however, these reactions are carried out at 300°C-375°C to have reasonable kinetics. Hence there is a need for highly active catalysts, which can facilitate significant kinetics of hydrotreating reactions at around 200°C-250°C. 相似文献
42.
Tang Yuanyan 《Frontiers of Computer Science in China》2007,1(2):123-125
This paper gives an introduction and remarks on two review papers for Chinese character recognition. One review is made by
Chinese authors, another is from American scientists. They investigate Chinese character from different language environments;
they do the research from different points of view. Thus, a more comprehensive view on Chinese character recognition, which
is an important branch of pattern recognition, can be provided to the readers. Meantime, one article pays attention to online
process, and other paper deals with offline recognition, which complement each other.
The author is the Associate Editor-in-Chief of Frontiers of Computer Science in China 相似文献
43.
多维气相色谱快速测定汽油中的烯烃、芳烃和苯含量 总被引:10,自引:0,他引:10
针对车用无铅汽油国家标准GB17930-1999中对烯烃,芳烃和苯含量提出的明确限值要求,以及现有标准方法和其它分析技术在分析汽油组成时存在的问题,结合国外汽油分析的发展趋势及我国汽油生产的工艺和汽油组成分布特点,提出了一套新的多维气相色谱技术测定汽油中烯烃。芳烃和苯含量的方法。并研制了新的烯烃捕集阱,可捕集汽油中高达70%的烯烃,且具有良好的可逆性和使用寿命,提出的方法可以在12min内通过一次色谱进样实现汽油中烯烃总量,芳烃总量和苯含量的测定。试验结果与荧光指示剂吸附法(FIA,GB/T11132-1989)相比具有很好的一致性。但分析速度和方法的再现性得到明显改善。试验成本也大大降低。 相似文献
44.
It has been reported that it is harder to switch to a strong, well-practiced task from a weaker, less-practiced task than vice versa. Three experiments replicated this surprising asymmetry and investigated how it is affected by a reduction in interference between tasks. Experiment 1 progressively delayed the onset of the stimulus attribute associated with the stronger task. Experiments 2 and 3 separated the response sets of the tasks. Both manipulations reduced, without eliminating, interference of the stronger with the weaker task but reversed the asymmetry of switch costs, resulting in a larger cost of switching to the weaker task. The results are interpreted in terms of a model of the interactions between control input, task strength, and task priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
46.
Yoon Carolyn; Feinberg Fred; Hu Ping; Gutchess Angela Hall; Hedden Trey; Chen Hiu-Ying Mary; Jing Qicheng; Cui Yao; Park Denise C. 《Canadian Metallurgical Quarterly》2004,19(3):379
Understanding how aging influences cognition across different cultures has been hindered by a lack of standardized, cross-referenced verbal stimuli. This study introduces a database of such item-level stimuli for both younger and older adults, in China and the United States, and makes 3 distinct contributions. First, the authors specify which item categories generalize across age and/or cultural groups, rigorously quantifying differences among them. Second, they introduce novel, powerful methods to measure between-group differences in freely generated ranked data, the rank-ordered logit model and Hellinger Affinity. Finally, a broad archive of tested, cross-linguistic stimuli is now freely available to researchers: data, similarity measures, and all stimulus materials for 105 categories and 4 culture-by-age groups, comprising over 10,000 fully translated unique item responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
47.
Novel star-like wholly aromatic copolyesters having four arms based on a tetraamine star core, p- and m- hydroxybenzoic acids and 6-hydroxy-2-naphthoic acid have been successfully synthesized and spun into fibers for the investigation of the effect of the star-like structure on improving compressive properties of the fiber. The reactivity of the star core was demonstrated using a model compound with FTIR, 1H and 13C NMR spectroscopy. The 13C NMR spectrum of the star-like terpolymer having a molar ratio of 10:1 of the monomers to star core showed a characteristic peak at around δ62 ppm which corresponds to a tetra-substituted carbon and thereby demonstrates that the star core was really incorporated into the polymer. The star-like copolyester exhibited a clear stir opalescence and liquid crystalline morphology in the temperature range of 150-280 °C. However, no transition was observed in the DSC thermogram except a clear Tg at 110 °C. The star-like terpolymer fiber, prepared from a polymer with a molar ratio of 500:1 for the monomers to imide core, was spun in the liquid crystalline state at 180 °C. Fiber structure and properties have been studied. 相似文献
48.
20世纪90年代,后现代主义被嫁接到中国的视觉艺术中。在中国当代艺术发展处于多种可能时,许多画家自觉不自觉地将眼光投向市场,于是趣味取代了艺术家精神创造者的位置,提供给艺术家一个俗人的标准,一个消费与被消费者的角色与机会,但后现代主义的增生原则,真正体现了艺术的多样性和丰富性。 相似文献
49.
山西省横泉水库在原有遗留工程基础上进行重新建设,以往的4次施工,填兢了长400m、高17m左右的左岸坝体,填土约120万m^3,但坝体填筑质量极差,干客重和渗透系数根本无法满足设计要求。此次重新建设,决定对这部分干客重不迭设计要求且具有湿陷性的左岸旧坝体以及左岸黄土台地进行强夯处理,对坝体进行强夯处理在省内还是首次进行,在国内也比较少见,通过处理,坝体质量达到了设计要求,并且节约了投资,效果明显。 相似文献
50.
潘云唐 《术语标准化与信息技术》2003,(4):19-20
对中国人的姓名采用汉语拼音字母拼写的各种方案以及早期用英语字母的“威妥玛式拼音法”进行了较全面的介绍,通过分析比较其中的利弊,提出了建设性的拼写方案建议。 相似文献