论当前电子商务的发展

近年来,电子商务在世界各地得到蓬勃发展,在商贸活动中发挥着越来越重要的作用,电子商务的迅猛发展正在引起商贸环境的深刻变革,这种变革对社会经济生活和企业竞争力的影响正在逐步显现出来,电子商务将成为21世纪重要的商贸方式和推动全球经济增长的一个重要动力,其作用甚至可以与200年前工业革命对经济发展的促进作用相提并论。本文从多个不同的角度对当前电子商务的发展进行了详细的阐述。     

冷板车制冷机组隔振仿真研究

针对冷藏运输车的振动问题,基于二自由度振动分析理论建立了制冷机组的振动力学模型,并通过现状仿真和优化隔振效果仿真得到了冷板车制冷机组最优减振隔振方案.通过现状仿真得到了满载和空载工况下隔振器变形随时间变化的曲线以及机组与车体加速度的对比曲线,并给出了制冷机组取得较好隔振效果隔振器必须满足的频率和刚度范围.结果表明:制冷机组现有的隔振效果很差;通过优化隔振效果仿真得到了不同隔振器固有频率时车体和机组最大加速度的响应曲线以及隔振器最大变形曲线.     

Determination of anthropogenic CO2 in the North Atlantic Ocean using water mass ages and CO2 equilibrium chemistry

A new method to calculate the anthropogenic CO₂ (ΔDIC_ant) within the water column of the North Atlantic Ocean is presented. The method exploits the equilibrium chemistry of the carbonate system with reference to temperature, salinity and the partial pressure of atmospheric CO₂ (pCO_2,atm). ΔDIC_ant is calculated with reference to the ventilation ages of water masses derived from tracer data and to the time history of pCO_2,atm. The method is applied to data recorded during the WOCE program on the WHP A1/E transect in the North Atlantic Ocean, where we characterise six key water masses by their relationships of dissolved inorganic carbon (DIC) and apparent oxygen utilisation (AOU). The error in determining ΔDIC_ant is reduced significantly by minimising the number of values referred to, especially by avoiding any use of remineralisation ratios of particulate organic matter. The distribution of ΔDIC_ant shows highest values of up to 45 μmol kg⁻¹ in the surface waters falling to 28–33 μmol kg⁻¹ in the Irminger Sea west of the Mid-Atlantic Ridge. The eastern basin is imprinted by older water masses revealing decreasing values down to 10 μmol kg⁻¹ ΔDIC_ant in the Antarctic Bottom Water. These findings indicate the penetration of the whole water column of the North Atlantic Ocean by anthropogenic CO₂.     

The study of correlative factors to resistin and its regression equation in type 2 diabetes

Objective To study the changes of resistin and the relationship between resistin and other indexes in patients with type 2 diabetes mellitus. Methods Seventy patients with type 2 diabetics were chosen and divided into three groups according to weight index and 15 healthy persons were chosen as controls. ELISA was adopted to determine resistin concentration. Oxydase method was adopted to measure blood sugar. Radio immunoassay was used to measure insulin level. Results Resistin concentration of patient groups r(23.06±9.34)μg/L ] was significantly higher than that of control group [( 9. 89±4. 47) μg/L, P<0. 01 ]. Resistin was positively related to body mass index (r = 0.4 467) and fat distribution (r= 0. 3 314, P<0.01). Resistin was also positively correlated to the area under the curve of sugar tolerance (r=0. 7 063, P<0. 01), negatively related to the insulin resistance index (r=-0. 4 154, P<0.01), but not related to area under the curve of synchronous insulin release (P>0. 05). And a formula was obtainted : Resistin=- 15. 869 0. 339×GAUC 0.790×BMI. Conclusion The level of reslstin in type 2 diabetics is higher. And reslstin is related to other factors. This formula is of great significance for clinical study of diabetic's disor- ders.     

电磁兼容技术在机车变流器布线中的应用

依据产品开发过程中电磁兼容技术的常用理论,结合国际上先进水平的大功率变流器电磁兼容技术的设计概念和工艺方式,就国产化铁路机车变流器中各种电缆的布线设计及工艺进行分析,总结出布线过程中减少电磁干扰的方法。     

COX-2蛋白表达与口腔鳞癌侵袭转移的关系

从COX-2的生物学特性，可知促进口腔鳞癌侵袭转移的机制为促进肿瘤新生血管的生成、刺激肿瘤细胞的增殖、抑制肿瘤细胞的凋亡、促进肿瘤的浸润和转移、抑制机体的免疫反应、参与前致癌物的活化。（可应用COX-2抑制剂防治肿瘤）     

ATS在CA6121URN2城市客车冷却系的设计

ATS具有结构简单、布置方便、节省能源、保护环境、可提高发动机工作寿命等诸多优点。近年来,在客车发动机冷却系统中得到越来越多的应用。目前ATS的不足之处在于价格昂贵,在大功率发动机的配套上使用受限。本文是ATS在CA6121URN2城市客车冷却系设计中的应用实例。     

汽车传动轴CO_2气体保护焊接工艺研究

在对B480QZR和40Cr两种不同钢材的焊接性能分析的基础上,研究和制定了B480QZR+40Cr异种钢焊接接头的工艺方案,通过采用CO2气体保护焊的焊接实践,或得了较好的焊接接头质量,满足了传动轴产品的设计和使用要求。     

二维矩形块布局的交叉熵方法实现

给定一个小矩形块集和一个固定宽度而高度变化的大矩形的二维布局问题,就是将这矩形集中的所有矩形正交布置于这个大矩形中,并且保证矩形块之间不发生重叠,目的就是使得布局后这个大矩形块的高度最小.本文提出通过DROP或DROPF（DROP FILL）的启发式解码策略与交叉熵算法相结合求解该类问题.试验结果显示,算法稳定有效,较经典元启发式算法在提高空间利用率上有较大提高.     

防城港码头工程前后潮流场的数值模拟

基于双时间层的有限差分方法(ADI),建立了水深平均二维浅水潮流数学模型,采用逆风格式和追赶法求解二维浅水方程,在对模型进行潮位验证和潮流验证的基础上,对防城港码头工程实施前后的潮流场进行了数值模拟研究。研究表明:该工程建设不会减少湾内纳潮量,不会对海域水动力学条件产生较大影响,只会对码头附近产生较小影响。