某柴油机油底壳仿真计算分析

本文利用ABAQUS结构仿真软件对某发电用柴油机油底壳进行模态、强度计算。在发动机实际运行工况下,油底壳底部为悬空状态,模态计算结果显示油底壳一阶模态距发动机点火激励频率点较近,低于激励频率的1.2倍,模态不满足设计要求;在发动机装配过程中,油底壳底部压在装配台上,发动机在上下方向三倍的重力加速度冲击载荷工况下,油底壳产生的应力最大值低于对应材料的屈服强度极限,强度满足设计要求。通过对油底壳两种状态下的仿真分析,验证和确保了油底壳结构设计的可行性,有效避免了发动机装配和实际运行过程中故障的发生。     

里坊制解体与北宋东京城市防御体系探析

作为城市防御和管理而形成的里坊制度,其解体是一个综合因素作用的过程,以往的研究偏重于商品经济的影响。从北宋东京城市防御体系的角度出发,主要探讨战争、城市管理、城市治安等军事因素与里坊制解体的关系,指出厢坊制管理模式的出现是里坊制解体的首要标志。     

‘96年春节联欢晚会灯光设计方案的制定与实施

本文简要地阐述了９６年春节联欢会灯光设计方案的制定和实施情况。     

Stumbling upon news on the Internet: Effects of incidental news exposure and relative entertainment use on political engagement

Contemporary concerns that the Internet might lead to political apathy are based on suggestions that people would use the Internet for entertainment purposes rather than news consumption. However, what if someone stumbles upon news when surfing the Internet? Would this incidental news exposure online be helpful in promoting citizens’ political engagement? This study tests whether and how incidental news exposure (INE) and relative entertainment use (REU) on the Internet are associated with political participation. Drawing from US national data, results revealed a significant and positive relationship between INE and offline and online political participation while REU was negatively associated with offline and online political participation. More importantly, the role of INE in facilitating citizens’ online political participation was stronger for those who consume less entertainment online, indicating that incidental news exposure may increase existing gaps in political participation between people who prefer news and people who prefer entertainment online.     

气象因子在海河流域蒸发悖论中的作用机理

蒸发是水文循环的重要环节。利用Mann-Kendall趋势检验方法检测了海河流域1961-2006年蒸发皿蒸发量的演变趋势。结果表明:海河流域蒸发皿蒸发量呈现出显著的下降趋势。利用相关分析、偏相关分析和主成分分析方法,研究了蒸发皿蒸发量与平均气温、相对湿度、平均风速和日照时数4种气象因子之间的关系。基于这4种气象因子,建立了模拟蒸发皿蒸发量的经验公式(E-THWS公式),并利用这一公式的微分形式揭示了这4种气象因子在海河流域"蒸发悖论"中的作用。结果表明:平均气温和相对湿度对海河流域蒸发皿蒸发量的增加作用要小于平均风速和日照时数的减少作用;平均风速的下降是蒸发皿蒸发量下降的主要原因。     

浅谈电脑游戏与娱乐教育

当电脑游戏问世的时候,人们可能意识不到它所带来的社会影响。随着上个实际最后10年互联网迅速的发展,网络游戏也随之风靡全球。这带来了种种问题,广大教育工作者必须正视这些问题。而近几年来,娱乐教育的提出和发展,使教育工作者们的目光又聚焦到电脑游戏之上。电脑游戏的娱乐性如果能和教育应用结合起来,将极大地激发学习者的学习兴趣,提高学习效率和效果。电脑游戏这把双刃剑如果能被我们所掌握,将能改变其"电子海洛英"的恶名,而成为新的教学手段。     

百年欧式俱乐部--汉口西商跑马场调查纪实

通过对汉口西商跑马场的调查,说明它移植武汉的经过和历程,以及它在建筑设计方面的一些特点.     

Chromophore‐Linked Substrate (CLS405): Probing Metallo‐β‐Lactamase Activity and Inhibition

Serine‐ and metallo‐β‐lactamases present a threat to the clinical use of nearly all β‐lactam antibiotics, including penicillins, cephalosporins, and carbapenems. Efforts to develop metallo‐β‐lactamase (MBL) inhibitors require suitable screening platforms to allow the rapid determination of β‐lactamase activity and efficient inhibition. Unfortunately, the platforms currently available are not ideal for this purpose. Further progress in MBL inhibitor identification requires inexpensive and widely applicable assays. Herein the identification of an inexpensive and stable chromogenic substrate suitable for use in assays of clinically relevant MBLs is described. (6R,7R)‐3‐((4‐Nitrophenoxy)methyl)‐8‐oxo‐7‐(2‐phenylacetamido)‐5‐thia‐1‐azabicyclo[4.2.0]oct‐2‐ene‐2‐carboxylic acid 5,5‐dioxide (CLS405) was synthesised in a three‐step protocol. CLS405 was then characterised spectroscopically, and its stability and kinetic properties evaluated. With a Δλ_max value of 100 nm between the parent and hydrolysis product, a higher analytical accuracy is possible with CLS405 than with commonly used chromogenic substrates. The use of CLS405 in assays was validated by MBL activity measurements and inhibitor screening that resulted in the identification of N‐hydroxythiazoles as new inhibitor scaffolds for MBLs. Further evaluation of the identified N‐hydroxythiazoles against a panel of clinically relevant MBLs showed that they possess inhibitory activities in the mid‐ to low‐micromolar range. The findings of this study provide both a useful tool compound for further inhibitor identification, and novel scaffolds for the design of improved MBL inhibitors with potential as antibiotics against resistant strains of bacteria.     

Effect of water content and storage time on white pan bread quality: instrumental evaluation

 The firmness of white pan bread was measured using compression and bending tests to determine the influence of the water content of the dough on bread quality and on the changes taking place with storage time. Three sample breads were prepared using different flours and three different water contents, and firmness was tested at 24, 48 and 72 h. For gluten-enriched flours, higher water contents tended to bring about a decrease in compression force and bending values, improving shelf-life by reducing the increase in firmness over time. Received: 24 March 1997     

Dietary evaluation of Mediterranean fish and molluscs pan‐fried in virgin olive oil

The effect of domestic pan‐frying in virgin olive oil (VOO) on the proximate composition, energy content, cholesterol, squalene and fatty acids in the edible portion of six species of finfish, common squid and mussels just caught from several regions of the Aegean Sea (Mediterranean Sea) was investigated. The species selected are traditionally consumed pan‐fried in VOO by the Greeks. On a fresh weight basis, pan‐frying caused significant water loss and increase of total fat, crude protein and energy content. The amount of VOO absorbed during frying ranged from 4.5 to 14.2% of fresh matter, showing a non‐linear negative correlation with initial fat, fish length and fish weight. Cholesterol content increased from 25 to 106 mg 100 g^?1 fresh weight (fw) to 33–130 mg 100 g^?1 fw after frying. VOO absorbed during frying resulted in a 20–78 times increase of squalene content and in significant alteration of fatty acid composition, the major change being the increase of monounsaturated fatty acids which became predominant in all fried samples. The intakes of fat and major fatty acid classes by consuming the pan‐fried seafood were comparable with the respective average Greek values. Frying in VOO resulted in a two to three times decrease of the atherogenic index and a slightly less decrease of the thrombogenic index. Both indices remained lower than 0.45 in all fried samples. The cholesterol‐saturated fat index and the cholesterol index increased up to twice after frying, ranging between 3.4–9.9 and 2.9–9.3, respectively. From the results obtained it is concluded that fish and shellfish pan‐fried in VOO present a healthy lipid profile in terms of the n‐6/n‐3 ratio, major fatty acid classes and total fat content. Copyright © 2004 Society of Chemical Industry