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431.
PCR-SSP检测人胰腺癌细胞株PC-2K-ras基因点突变及其方式 总被引:1,自引:0,他引:1
目的 检测人胰腺癌细胞株PC 2K ras基因点突变及其突变方式 ,明确基因治疗靶点的碱基序列。方法 针对K ras基因第 1 2位密码子点突变方式 (CGT、CAT、GTT)设计顺序特异性引物 (SSP) ,对人胰腺癌细胞株PC 2进行聚合酶链反应 (PCR) ,扩增产物借助聚丙烯酰胺凝胶电泳判定该细胞株有无K ras基因点突变及其突变方式。结果 人胰腺癌细胞株PC 2存在K ras基因点突变 ,突变方式为CGT。结论 PCR SSP法简便快速 ,特异性高 ,本研究结果为胰腺癌的下一步基因治疗奠定了基础 相似文献
432.
MUHAMMAD F. IBRAHIM 《运输评论》2013,33(2):221-243
A review of the retailing and transportation literature shows that there is an apparently large research gap in the understanding of shoppers’ attitudes towards transport modes for shopping purposes. In particular, not many studies have been done to examine shoppers’ detailed and disaggregated attitudinal image structures of the various transport modes for shopping purposes. Using Singapore as a study area, this paper has attempted to investigate shoppers’ image structure of transport modes and their comparative perception ratings for the various modes of transportation for shopping purposes. Using principal component analysis, the research has unveiled the perceptions of five transport modes for shopping purposes. While some of the factors are unique to certain transport modes, other factors, namely ‘suitability’, ‘practicality’, ‘ease of travel’ and ‘cost’, are common to all modes of transportation. By way of the weighted‐factor rating, the study found that the car recorded the highest overall perception rating while the bus rated the lowest. In addition, the shoppers have reasonably good perception of public transport modes in Singapore. 相似文献
433.
China’s Dalian International Airport is taken to compare the aircraft noise pollution and the cost-risk effects of the expanded an existing inland and a proposed offshore airport. The findings show that the aircraft noise pollution of the offshore airport is much less than that of the expanded inland airport; the land-use cost, noise reduction charges and other risks of the offshore airport are also much less; the creation of the offshore airport may be more favorable to the city’s development. 相似文献
434.
SBS改性沥青软化点试验特性 总被引:1,自引:0,他引:1
软化点是评价改性沥青高温性能的重要指标,为了研究SBS改性沥青软化点特性及其影响因素,采用软化点试验方法,对经过高温储存和常温储存以及短期老化和长期老化后SBS改性沥青的软化点进行了测试。结果表明:改性沥青的软化点表现出复杂的变化规律,其变化与改性沥青的配伍性有关;基质沥青对改性剂的溶胀以及改性剂对沥青的吸附是改性沥青初期性能和储存稳定性的关键,而改性剂在存储和老化条件下的变化是软化点发生变化的根源。 相似文献
435.
传统意义上的测绘已经不能满足信息化智能化测绘时代的需求,无人机倾斜摄影测量技术给测绘行业带来了新的技术手段。研究倾斜摄影测量技术在实际测绘生产项目中的应用流程,通过对航测相机进行检校、航测参数调整、像控点布设方案优化、数据严格检核处理等,最终获取满足规范和项目要求的测绘成果。最后将该方法应用在高速公路改扩建工程中,并对实地标志点、地面标高、雨污水井位、高速路面桥缝等特征点数据进行了残差统计和误差分析。结果表明,该方法测量成果精度可靠,解决了传统测量方式无法直接进行高速测量的问题,提高了工作效率,效果良好。 相似文献
436.
近几年世界范围内的油污事故不仅后果严重,而且带来前所未有的各种问题,引起各国法律界和航运界的高度关注,并在油污损害赔偿的范围上有诸多争议。针对目前油污损害赔偿范围中的几个难点问题加以详细研究,包括:油污事故适用的法律、损害赔偿范围和项目的确定、纯经济损失可否列入损害赔偿的范围、环境污染后引起的海洋资源的中长期损失。 相似文献
437.
车载自动过分相系统地感器的埋点方式 总被引:6,自引:2,他引:6
针对广深线和湘黔线车载自动过分相系统地感器的现状,分析了它们的设置特点,对电气线路上采用何种地感器埋点方式提出了改进建议。改进后的地感器可适用低于300km/h速度范围内的客货列车的自动过分相控制需要。 相似文献
438.
439.
Ports currently face increasing demands to address a variety of environmental issues and achieve sustainability objectives. Using insights from the resource-based view of firms, this study examines the link between economic performance (EP) and environmental performance (ENP) of the top 10 U.S. seaports. Geospatial modeling is used to capture pollution incidents that can be geographically dispersed; in addition, both a bootstrap data envelopment analysis (DEA) approach and an undesirable DEA model are used to measure port ENP and EP. Our findings are in general consistent with assertions that positive EP can be attained in conjunction with good environmental practices. Ports’ capabilities of strategic capital investment in physical assets, collaborative interorganizational processes, and performance monitoring are essential, while they pursue both economic and environmental goals simultaneously. 相似文献
440.
A novel joint source channel distortion model was proposed, which can essentially estimate the average distortion in progressive image transmission. To improve the precision of the model, the redundancy generated by a forbidden symbol in the arithmetic codes is used to distinguish the quantization distortion and the channel distortion, all the coefficients from the first error one to the end of the sequence are set to be a value within the variance range of the coefficients instead of zero, then the error propagation coming from the entropy coding can be essentially estimated, which is disregarded in the most conventional joint source channel coding (JSCC) systems. The precision of the model in terms of average peak-signal-to-noise has been improved about 0.5 dB compared to classical works. An efficient unequal error protection system based on the model is developed, and can be used in the wireless communication systems. 相似文献