Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to buil...Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to build a theoretical framework of urban activity resilience.Relying on geographic big data,this study identifies the spatial characteristics of activity resilience,reveals the impact of activity environment on activity resilience in Nanjing,and proposes countermeasures.The main conclusions are as follows.1)Activity resilience presents a composite spatial structure of circles and clusters,and most areas are resilient but at a low level.2)There are significantly positive and negative global autocorrelation between activity resilience and activity scale,and activity stability.Simultaneously,there also exists a local spatial autocorrelation with the opposite positive and negative trends.3)Activity environment has a significant effect on activity resilience,and the degree and direction of influence among different dimensions and regions are heterogeneous.4)For activity resilience,it is necessary to increase the matching degree between the scale and stability of activities,and reduce the excessive concentration and flow of activities.For the activity environment,it is necessary to improve the accessibility of the ecological environment,strengthen the high-quality supply of the infrastructure environment,optimize the balance of the location environment,and promote the inclusiveness of the social environment.展开更多
为了优化猪肉中沙门菌定量检测方法,并对成都市部分农贸市场零售的猪肉样品中沙门菌污染浓度进行定量研究。本研究于2020年基于我国沙门菌定性检测方法(GB4789.4-2016)和美国农业部食品安全检验局(Food Safety and Inspection Service,F...为了优化猪肉中沙门菌定量检测方法,并对成都市部分农贸市场零售的猪肉样品中沙门菌污染浓度进行定量研究。本研究于2020年基于我国沙门菌定性检测方法(GB4789.4-2016)和美国农业部食品安全检验局(Food Safety and Inspection Service,FSIS)定量检测方法(MLG 4.08和MLG Appendix 2.05 MPN),使用成都地区市售70份肉猪样品对沙门菌定量检测中选择性增菌液、筛选平板、鉴定方式以及定量稀释比例进行优化,通过t检验分析获得适用的优化方法,使用优化方法对2020年6—10月成都市部分农贸市场采集的40份零售猪肉样品进行沙门菌定量检测。结果显示,对于生鲜猪肉样本,TTB增菌液筛选沙门菌符合度显著高于RV增菌液(0.93±0.32 vs 0.35±0.62,t=8.324,P=0.001),XLT4平板筛选到的可疑菌落符合度显著高于沙门显色培养基(0.77±0.09 vs 1.00±0.00,t=2.971,P=0.017)。使用4个连续梯度稀释的12管MPN法,可获得准确的沙门菌污染浓度数值。经选择性增菌液TTB增菌后划线于XLT4平板,并使用荧光PCR联合MALDI-TOF微生物质谱鉴定,可实现猪肉样品中沙门菌高效分离鉴定。部分农贸市场零售生鲜猪肉中沙门菌的检出率为92.5%(37/40),大部分阳性样品(83.8%,31/37)沙门菌的污染水平在0.1~55 MPN/g范围。本研究优化的沙门菌定量检测方法,可有效对猪肉中沙门菌污染进行定量分析。展开更多
基金Under the auspices of National Social Science Fund of China(No.20AZD040)the Program B for Outstanding PhD Candidate of Nanjing University(No.202002B103)。
文摘Based on the connotation of urban resilience and the main contradictions of China's urbanization,urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to build a theoretical framework of urban activity resilience.Relying on geographic big data,this study identifies the spatial characteristics of activity resilience,reveals the impact of activity environment on activity resilience in Nanjing,and proposes countermeasures.The main conclusions are as follows.1)Activity resilience presents a composite spatial structure of circles and clusters,and most areas are resilient but at a low level.2)There are significantly positive and negative global autocorrelation between activity resilience and activity scale,and activity stability.Simultaneously,there also exists a local spatial autocorrelation with the opposite positive and negative trends.3)Activity environment has a significant effect on activity resilience,and the degree and direction of influence among different dimensions and regions are heterogeneous.4)For activity resilience,it is necessary to increase the matching degree between the scale and stability of activities,and reduce the excessive concentration and flow of activities.For the activity environment,it is necessary to improve the accessibility of the ecological environment,strengthen the high-quality supply of the infrastructure environment,optimize the balance of the location environment,and promote the inclusiveness of the social environment.
文摘为了优化猪肉中沙门菌定量检测方法,并对成都市部分农贸市场零售的猪肉样品中沙门菌污染浓度进行定量研究。本研究于2020年基于我国沙门菌定性检测方法(GB4789.4-2016)和美国农业部食品安全检验局(Food Safety and Inspection Service,FSIS)定量检测方法(MLG 4.08和MLG Appendix 2.05 MPN),使用成都地区市售70份肉猪样品对沙门菌定量检测中选择性增菌液、筛选平板、鉴定方式以及定量稀释比例进行优化,通过t检验分析获得适用的优化方法,使用优化方法对2020年6—10月成都市部分农贸市场采集的40份零售猪肉样品进行沙门菌定量检测。结果显示,对于生鲜猪肉样本,TTB增菌液筛选沙门菌符合度显著高于RV增菌液(0.93±0.32 vs 0.35±0.62,t=8.324,P=0.001),XLT4平板筛选到的可疑菌落符合度显著高于沙门显色培养基(0.77±0.09 vs 1.00±0.00,t=2.971,P=0.017)。使用4个连续梯度稀释的12管MPN法,可获得准确的沙门菌污染浓度数值。经选择性增菌液TTB增菌后划线于XLT4平板,并使用荧光PCR联合MALDI-TOF微生物质谱鉴定,可实现猪肉样品中沙门菌高效分离鉴定。部分农贸市场零售生鲜猪肉中沙门菌的检出率为92.5%(37/40),大部分阳性样品(83.8%,31/37)沙门菌的污染水平在0.1~55 MPN/g范围。本研究优化的沙门菌定量检测方法,可有效对猪肉中沙门菌污染进行定量分析。
