为研究热处理工艺对HHD(high-Cr hot working die steel)模具钢复合材料耐腐蚀性能的影响,以中频熔炼+VD方法炼制HHD模具钢复合材料,并用不同温度热处理。用金相显微镜与扫描电子显微镜,观测热处理后HHD模具钢复合材料的显微组织及在混...为研究热处理工艺对HHD(high-Cr hot working die steel)模具钢复合材料耐腐蚀性能的影响,以中频熔炼+VD方法炼制HHD模具钢复合材料,并用不同温度热处理。用金相显微镜与扫描电子显微镜,观测热处理后HHD模具钢复合材料的显微组织及在混合酸酒精溶液内浸泡后的腐蚀形貌与点腐坑;对HHD模具钢复合材料进行开路电位与电化学阻抗谱等检测。结果表明:在混合酸酒精溶液浸泡下,开路电位与淬火温度正相关,开路电位与耐腐蚀性能正相关;回火温度升高时,材料的耐腐蚀性能先降后升,回火处理温度为600℃时,材料的耐腐蚀性能最差。展开更多
To construct the suicide vector of hhd B gene marker-free mutant in Haemophilus parasuis( HPS),two pairs of specific primers were designed and synthesized according to the hhd B gene upstream and downstream sequences ...To construct the suicide vector of hhd B gene marker-free mutant in Haemophilus parasuis( HPS),two pairs of specific primers were designed and synthesized according to the hhd B gene upstream and downstream sequences of HPS published in Gen Bank. The hhd B gene upstream and downstream sequences were amplified by PCR,which were further ligated( hhd B-up + down) through overlapping PCR method. NotⅠand SalⅠrestriction enzyme sites were introduced on both ends of the ligated sequence. After the corresponding digestion,the hhd B-up + down sequence was directionally cloned to the suicide plasmid vector p EMOC2. Results showed that the suicide vector of hhd B gene marker-free deleted( p EMOC2Δhhd B) with stable inheritance in E. coli β2155 strain was successfully obtained,thereby laying the foundation for construction of HPS-hhd B gene marker-free mutant strain.展开更多
近期，随着SSD价格的大幅度下调，60GB～128GB SSD的价格已不再高高在上。用SSD来加速系统的成本支出，变得可以让大多数玩家接受。但问题随之而来．面对多种分级存储的混合组建方式，我们是只用SSD装系统和常用软件．还是选择SRT？除...近期，随着SSD价格的大幅度下调，60GB～128GB SSD的价格已不再高高在上。用SSD来加速系统的成本支出，变得可以让大多数玩家接受。但问题随之而来．面对多种分级存储的混合组建方式，我们是只用SSD装系统和常用软件．还是选择SRT？除此之外，直接选择方便省事的HHD（Hybrid Hard Disk．混合硬盘）效果又如何呢？展开更多
Malnutrition remains a significant global challenge,particularly in developing countries.Policymakers have increasingly focused on improving household food security and nutrition through farm production diversity(FPD)...Malnutrition remains a significant global challenge,particularly in developing countries.Policymakers have increasingly focused on improving household food security and nutrition through farm production diversity(FPD).While research indicates that FPD correlates positively with reduced malnutrition,other studies emphasize the importance of market access for improved nutritional outcomes.However,this evidence varies by region and remains inconsistent.To address this knowledge gap,this study analyzed survey data from 450 smallholder farmers in Punjab,Pakistan,using regression models to examine the relationship between FPD and dietary diversity,as well as the underlying impact pathways.The findings demonstrate that FPD significantly correlates with increased household dietary diversity score(HDDS).FPD influences dietary diversification through both own-farm production and market food consumption pathways,with the ownfarm production pathway showing greater impact.The increase in food expenditure through own-farm production yielded a marginal return of 8% in household dietary diversity compared to 5.3% through marketing.Gender differences emerged as significant,with male-headed households showing relatively lower dietary diversity.These findings have substantial implications for countries with smallholder farming systems,providing valuable insights for the formation of agricultural policies,resource optimization,and rural development initiatives.展开更多
文摘为研究热处理工艺对HHD(high-Cr hot working die steel)模具钢复合材料耐腐蚀性能的影响,以中频熔炼+VD方法炼制HHD模具钢复合材料,并用不同温度热处理。用金相显微镜与扫描电子显微镜,观测热处理后HHD模具钢复合材料的显微组织及在混合酸酒精溶液内浸泡后的腐蚀形貌与点腐坑;对HHD模具钢复合材料进行开路电位与电化学阻抗谱等检测。结果表明:在混合酸酒精溶液浸泡下,开路电位与淬火温度正相关,开路电位与耐腐蚀性能正相关;回火温度升高时,材料的耐腐蚀性能先降后升,回火处理温度为600℃时,材料的耐腐蚀性能最差。
基金Supported by Science and Technology Project of Guangdong Province(2013B020307002)
文摘To construct the suicide vector of hhd B gene marker-free mutant in Haemophilus parasuis( HPS),two pairs of specific primers were designed and synthesized according to the hhd B gene upstream and downstream sequences of HPS published in Gen Bank. The hhd B gene upstream and downstream sequences were amplified by PCR,which were further ligated( hhd B-up + down) through overlapping PCR method. NotⅠand SalⅠrestriction enzyme sites were introduced on both ends of the ligated sequence. After the corresponding digestion,the hhd B-up + down sequence was directionally cloned to the suicide plasmid vector p EMOC2. Results showed that the suicide vector of hhd B gene marker-free deleted( p EMOC2Δhhd B) with stable inheritance in E. coli β2155 strain was successfully obtained,thereby laying the foundation for construction of HPS-hhd B gene marker-free mutant strain.
文摘近期，随着SSD价格的大幅度下调，60GB～128GB SSD的价格已不再高高在上。用SSD来加速系统的成本支出，变得可以让大多数玩家接受。但问题随之而来．面对多种分级存储的混合组建方式，我们是只用SSD装系统和常用软件．还是选择SRT？除此之外，直接选择方便省事的HHD（Hybrid Hard Disk．混合硬盘）效果又如何呢？
基金appreciation to the National Natural Science Foundation of China(72071074)Natural Science Foundation of Hunan Province,China(2025JJ30031)for their financial support。
文摘Malnutrition remains a significant global challenge,particularly in developing countries.Policymakers have increasingly focused on improving household food security and nutrition through farm production diversity(FPD).While research indicates that FPD correlates positively with reduced malnutrition,other studies emphasize the importance of market access for improved nutritional outcomes.However,this evidence varies by region and remains inconsistent.To address this knowledge gap,this study analyzed survey data from 450 smallholder farmers in Punjab,Pakistan,using regression models to examine the relationship between FPD and dietary diversity,as well as the underlying impact pathways.The findings demonstrate that FPD significantly correlates with increased household dietary diversity score(HDDS).FPD influences dietary diversification through both own-farm production and market food consumption pathways,with the ownfarm production pathway showing greater impact.The increase in food expenditure through own-farm production yielded a marginal return of 8% in household dietary diversity compared to 5.3% through marketing.Gender differences emerged as significant,with male-headed households showing relatively lower dietary diversity.These findings have substantial implications for countries with smallholder farming systems,providing valuable insights for the formation of agricultural policies,resource optimization,and rural development initiatives.
