纳米Pd-PEG/C催化剂的制备及其催化加氢二硝基甲苯

本研究采用浸渍-沉淀法制备了理论负载量为5%的Pd/C及Pd-PEG/C催化剂,利用分散度分析、透射电镜(TEM)等表征方法对其结构、形貌进行分析。表征结果表明,PEG的加入有效地提高了Pd纳米颗粒在活性炭上的分散度,且Pd-PEG/C催化剂具有纳米金属钯平均粒径小、分布均匀、高分散度等优点。同时,选取二硝基甲苯(DNT)选择性加氢合成二氨基甲苯(TDA)为探针反应,考察催化剂的催化性能。试验结果表明,在同等反应条件下,Pd-PEG/C催化剂催化性能远优于Pd/C。     

基于EIS的质子交换膜燃料电池输出性能优化

质子交换膜燃料电池(proton exchange membrane fuel cell, PEMFC)输出性能的影响是多方面的，极化曲线仅能反映燃料电池稳态外输出特性，不能充分反映具体影响因素及规律，因此需研究其内部物理参数的动态变化。通过建立电堆内阻和交流阻抗特性模型，利用电化学交流阻抗谱(electrochemical impedance spectroscopy, EIS)分析不同温度和湿度下燃料电池的内阻动态特性。结果表明，在333~353 K温度范围内，随着温度的增加，燃料电池的内阻减小；当温度不变时，相对湿度的增加能减小电堆内阻，燃料电池输出性能增强。最后，基于15kW燃料电池测试平台进行性能试验，验证了燃料电池动态特性分析的正确性，为进一步优化PEMFC输出性能提供理论支持。     

质子交换膜燃料电池平行流场可视化研究

文章设计了一种可视化的质子交换膜燃料电池平行流场,实验研究电池阴极侧的反应气体的流量、电池操作温度对电池性能和流场内排水情况的影响,实验得出:在60℃时,阴极侧的空气流量为600 m L/min,阳极侧氢气流量为800 m L/min时电池的排水效果最好,电池的性能也达到最好。     

粉煤灰制备复合固体酸环境友好催化剂影响因素的探讨

以粉煤灰为主要原料采用沉淀一浸渍法制备FZS型复舍固体酸催化剂，对影响催化剂硫含量、比表面、催化性能等因素进行考察。通过TEM等手段对催化剂结构予以表征。实验结果表明：粉／锆比为3：1、H2SO4浸渍浓度为0．50mol／L、焙烧温度在550℃时制备的催化剂，应用于酯化反应中酯化率可达98.3％。     

MnOx/Al2O3催化臭氧氧化处理含氰废水

本研究采用浸渍法，以Mn(NO₃)₂为前驱体、γ-Al₂O₃为载体，制备负载型金属氧化物催化剂MnO_x/Al₂O₃，用于处理氰化废水中的氰离子。其间考察了臭氧投加量、催化剂制备工艺参数、催化剂投加量、溶液pH等因素对废水中氰化物去除效率的影响。试验表明，从制备催化剂的最佳工艺参数来看，Mn目标负载量为8%，焙烧温度为500℃，焙烧时间为4 h。在优化的试验条件下，氰化物浓度可以从5.4 mg/L降到0.2 mg/L以下。反应机理研究表明，MnO_x/Al₂O₃催化臭氧氧化处理氰化废水遵循羟基自由基机理。反应动力学分析表明，该反应符合一级反应动力学模型，表观反应速率常数为0.031 6 min^-1。     

氧化铝赤泥制备催化剂研究

本文采用柠檬酸溶胶-凝胶法,以氧化铝赤泥为原料,制备出钙钛矿结构赤泥/BaTiO_3催化剂,并利用X射线衍射(XRD)、扫描电镜(SEM)和傅里叶变换红外光谱定量分析方法研究了赤泥/BaTiO_3催化剂的结构及其对性能的影响。讨论了反应温度、氧气浓度、空速对氮氧化物转化率的影响。结果表明:溶胶-凝胶法结合烧结制备出的催化剂结构晶相好,并且在500℃烧结的赤泥/BaTiO_3复合催化剂,在300℃时氮氧化物催化氧化性能最佳(0.054%NO,GHSV=8000h~(-1),15%O~2,N2balance)为50%。这种方法制备的赤泥/BaTiO_3复合催化剂成本较传统贵金属催化剂的低,并且催化性能大幅提升,极大地节约了生产成本,促进了生产效率,具有广泛应用于生产的潜力。     

介孔TUD-1在烯/烷分离的应用研究

三维介孔材料TUD-1通常使用三乙醇胺(TEA)与四乙基氢氧化铵(TEAOH)作为模板剂进行合成。实验采用传统路线与无TEAOH路线合成了介孔硅材料TUD-1,采用等体积浸渍法负载硝酸银以制备乙烯/乙烷分离π络合吸附剂,采用氮气吸附脱附、X射线衍射、透射电镜进行表征,采用自制设备测定了π络合吸附剂的乙烯乙烷等温吸附线,对比了吸附分离性能。结果表明:尽管吸附量减小了约18%,但通过无TEAOH路线合成的π络合吸附剂的分离系数提升了86%,无TEAOH路线合成的TUD-1材料首次被证明是一种优秀的载体材料。     

新一代绿色技术促化工行业清洁生产

甲基丙烯醛、酯和醇系列产品是重要的基础化工产品。甲基丙烯醛（MAL）是生产香料、医药等化学品的重要中间体，可进一步氧化生成酸和酯，可还原生成醇。目前主要以丙醛为原料羟醛缩合、以异丁烯为原料氧化或以异丁烯醇为原料氧化制备，大多限于实验室或小规模制备，没有工业化商品，限制了下游产业链的发展。甲基丙烯酸甲酯是生产有机玻璃、特种光纤、高档涂料等的核心单体，目前 MMA 国际年需求量超过400万吨，我国约70万吨，其中2/3主要依靠国外进口和外企提供，国内企业普遍采用传统丙酮氰醇法生产，规模小、污染重、安全隐患大，且受丙烯腈生产的限制，难以扩大规模。以石油裂解副产碳四为原料的专利技术则由国外公司垄断，对我国严格封锁。甲基丙烯醇是生产第三代高性能混凝土减水剂的聚醚封端剂，目前均采用异丁烯氯化—水解工艺，安全性差、设备要求高、水解过程使用强碱、三废排放大、环境污染严重。因此迫切需要研究开发具有自主知识产权的 MAL、MMA 和MAO 新一代绿色技术。     

On the Major Transformation of the Asia-Pacific Regional Structure北大核心CSSCISSCI

Recent years have witnessedsignificant changes in the Asia-Pacific regionalstructure featuring the shift in power balance among related countries as well as adjust-ments in their respective regional strategies. So what is the prevailing trend in thistransformation and what kind of regional order will likely emerge in the future？ To an-swer these questions, the paper tries to explore the following dimensions： the evolvingregional context, shift in power balance and power conversion, geo-political and geo-e-conomic developments and interactions between them, and evolving regional order. Asthe study shows, the broadening of regional geographical scope, the rise in the numberof actors involved, as well as changesin the relations among them, have combined tocast a pluralistic and complex flavor to the regional structure. While the power balanceamong China, the United States and Japan shifts, and power conversion is also occur-ring. China and Japan are paying increasing attention to their security roles, whereasthe United States under the Obama administration laid more stress on expanding itsgeo-economic clout. In spite of the intensifying geopolitical competition among China,the United States and Japan in recent years, a Sino-US strategic compromise-whichholds the key to regional geopolitics-isother front, some kind of geo-economicmore likely to take place in the future. On thecooperation will probably emerge. In the longerterm, it will be the geo-economic trend thatwill prevail over the geopolitical trend inthe region. Finally, the future evolution of regional order wiI1 mainly follow the eco-nomic logic, accompanied by the dilutionof its hegemonic and hierarchical nature.Hence, a pluralistic and complex regional community will emerge.     

Organization and incentives in the age of sail

The British Navy in the age of sail was the most successful bureaucracy of its time. Its organization and incentive structures differed importantly from contemporaneous private sailing ventures, but closely resembled those of today’s large corporations. To induce efficient effort, the navy used a hierarchical tournament, in which sailors competed for higher pay that came with promotions based on relative performance. Promotion probabilities, the option value of future promotions, and the higher effort required of men in higher ranks and on larger vessels, combined to yield a highly skewed pay structure.     

The German Hanse and Bergen – new perspectives on an old subject

Abstract

The Hanseatic League and her kontors (trading posts) were an integral part of the medieval trade system in Northern Europe. Hanse merchants dominated many markets in this region and managed to maintain a monopoly-like role in towns like Novgorod and Bergen for many centuries. Consequently, one focus of historical research about the Hanseatic League lay on the mechanisms that enabled the Hanse merchants to keep that strong of a position for such a long time.

This article is part of the discussion about this topic. Based on Lübeck merchants with business interest in the Norwegian town of Bergen, the so-called Bergenfahrers (Bergen travellers), it will give new insights into the Hansards' economical and social organization. The three main points are (a) the integration of the Bergen market in the Hanseatic trade network as an intermediary trading place on the vivid East–West route of Hanse trade; (b) the importance of the Bergenfahrers within the Hanse merchants' economical, social and political networks; and (c) the structure of the Bergenfahrers network patterns in the late Middle Ages.

In addition to new insights into the important role of Bergen and the Bergenfahrers within Lübeck's and the other Wendish Hanse towns' trading system, this articles provides further proof for the usefulness of the methods of Social Network Analysis in medieval economic research.     

Financial Reporting and Trade Credit: Evidence from Mandatory IFRS Adoption*

We investigate the effect of mandatory IFRS adoption on trade credit. We document that firms in countries that adopt IFRS receive more trade credit from their suppliers, consistent with improved financial reporting quality and comparability playing a role in facilitating informal financing. This increase is larger for countries with a low level of societal trust, a poor pre‐IFRS‐adoption information environment, and stronger legal enforcement. These cross‐sectional results suggest that the conditions under which higher‐quality information is made publicly available affect suppliers' decisions to provide trade credit. This increase is also larger for firms with greater exposure to foreign markets, a finding that highlights the importance of more comparable international financial reporting standards in facilitating cross‐country trade credit. We also find that IFRS adoption has a stronger positive effect on trade credit for firms with greater liquidity needs. Finally, we find that firms in countries that adopt IFRS also extend more trade credit to their customers. Overall, our results support the notion that financial reporting can have a causal effect on trade credit.     

区域工业产业竞争力指标体系的构建及其评价方法研究

文章通过建立省级区域工业产业竞争力评价指标体系,设计竞争力模型,利用SPSS统计软件,对各省工业产业竞争力进行了评价测定。     

Penetration and Post-infection Development of Meloidogyne Incognita on Tobacco as Treated by Rhizobacteria Pseudomonas Fluorescens Strain P-72-10

The bio-control potential of rhizospere bacteria Pseudomonas fluorescens against plant-parasite nematode had been demonstrated. P. fluorescens had shown the effect to enhance tobacco resistance to root-knot nematode Meloidogyne incognita. Inoculation with P. fluoreseens in tobacco could lead to significant reductions in the number of juveniles that penetrated tobacco root and further life stage development of the juveniles. The number of juveniles penetrated into tobac- co root in treatment with P. fluorescens is significantly different from CK at 2DAI, 6DAI, 8DAI and 10DAI. Significant reduction and delayed development of juveniles that penetrated into tobacco root and treated were observed in treatment at 14DAI, 21DAI, 28DAI and 35DAI. In addition, P. fluoreseens treatment leads to a significant reduction in the number of eggs per egg-mass at 35 DAI. The results show P. fluorescens induced a continuously suppression on root-knot nema- tode M. incognita throughout their entire early infection phase of root penetration, subsequent life stage development and reproduction.     

文化传播中电视暴力对青少年侵犯行为的影响

伴随当代传媒产业的蓬勃发展,暴力也成为影视艺术基本的叙事类型及消费主义文化日趋盛行的现实语境。＂电视暴力＂是作为＂媒介暴力＂的一个子概念存在的;从文化传播看电视暴力,其覆盖面大,且易于接触;电视暴力对受众特别是青少年的影响巨大而深刻。要从制作者、传播者和观众三个方面的自律出发,建立适应我国国情的影视分级制。     

理性与先验的完美整合——论笛卡尔的"上帝"观

笛卡尔是西方近代主体性哲学的先驱,是近代唯理论学说的创始人,他使人们从中世纪宗教势力的禁锢中解放了出来.虽然"上帝"这个被人们视为理性最大敌人的概念在他的哲学中大量存在,但他极力证明上帝存在的最终目的却是为了证明理性的伟大;作为真理化身的上帝,归根到底是为他的理性主义服务的.