以已知浓度的柠檬酸作为定量外标,琥珀酸和烟酰胺分别作为定量内标,建立了食品中水苏糖的核磁共振定量分析检测方法。该方法在0.025~6.40 g/L质量浓度范围内线性良好,相关系数 R 2>0.999;以柠檬酸作为外标方法加标回收率为97.91%,日...以已知浓度的柠檬酸作为定量外标,琥珀酸和烟酰胺分别作为定量内标,建立了食品中水苏糖的核磁共振定量分析检测方法。该方法在0.025~6.40 g/L质量浓度范围内线性良好,相关系数 R 2>0.999;以柠檬酸作为外标方法加标回收率为97.91%,日内精密度与日间精密度分别为1.65%和5.27%;琥珀酸和烟酰胺作为内标方法加标回收率分别为101.39%和106.35%,日内精密度分别为1.34%和0.83%,日间精密度分别为0.65%和2.46%;对市售不同食品基质(固态、液态)中水苏糖含量进行检测,测定结果准确。与现行行业标准(QB/T 4260—2011)高效液相色谱法相比,该方法简化了样品的前处理操作,节约了时间,定量准确,对食品中水苏糖的定量检测具有更广泛的适用性。展开更多
以宁波天然甜槠阔叶混交林为研究对象,选择30个常用的树高—胸径经验模型,利用调整决定系数(R a 2)、均方根误差(RMSE)、平均绝对误差(MAE)、相对平均绝对误差(RMAE)和Akaike信息准则(AIC)等5个模型评价指标,比较分析模型之间差异。结...以宁波天然甜槠阔叶混交林为研究对象,选择30个常用的树高—胸径经验模型,利用调整决定系数(R a 2)、均方根误差(RMSE)、平均绝对误差(MAE)、相对平均绝对误差(RMAE)和Akaike信息准则(AIC)等5个模型评价指标,比较分析模型之间差异。结果表明,除M23无法求解,其余29个模型均可求解。29个模型中,M11和M24在5个模型评价指标中表现优异,M11优于M24,说明M11为适宜的天然甜槠阔叶混交林树高—胸径模型,其R a 2=0.9101。展开更多
We took Co_(0.2)Ni_(0.8)-MOF-74 with bimetallic synergistic effect as the basic material,and selected rare earth ions Ho,Gd,and Er with ion radii close to Co and Ni as the research objects for doping.The influence of ...We took Co_(0.2)Ni_(0.8)-MOF-74 with bimetallic synergistic effect as the basic material,and selected rare earth ions Ho,Gd,and Er with ion radii close to Co and Ni as the research objects for doping.The influence of rare earth ion doping amount and doping type on the eNRR performance of the catalyst was explored.The experimental results show that the ammonia yield rate and Faraday efficiency doped with Co_(0.2)Ni_(0.8)-MOF-0.5Ho are the highest,reaching 1.28×10^(-10)mol·s^(-1)·cm^(-2)/39.8%,which is higher than the1.12×10^(-10)mol·s^(-1)·cm^(-2)/32.2%of Co_(0.2)Ni_(0.8)-MOF-74,and is about 14.3%/23.7%higher than that without doping,respectively.And the stability of Co_(0.2)Ni_(0.8)-MOF-0.5 Ho is good(after 80 hours of continuous testing,the current density did not significantly decrease).This is mainly due to doping,which gives Co_(0.2)Ni_(0.8)-MOF-74 a larger specific surface area and catalytic active sites.The catalyst doped at the same time has more metal cation centers,which increases the electron density of the metal centers and enhances the corresponding eNRR performance.展开更多
The biomass and productivity of Schima superba-Castanopsis carlesii forests in Tiantong,Zhejiang Province,were determined using overlapping quadrants and stem analyses.The total community biomass was(225.3±30.1) ...The biomass and productivity of Schima superba-Castanopsis carlesii forests in Tiantong,Zhejiang Province,were determined using overlapping quadrants and stem analyses.The total community biomass was(225.3±30.1) t hm-2,of which the aboveground parts accounted for 72.0% and the underground parts accounted for 28.0%.About 87.2% of biomass existed in the tree layer.The resprouting biomass was small,of which over 95.0% occurred in the shrub layer.The productivity of the aboveground parts of the community was(386.8±98.9) g m-2a-1,in which more than 96.0% was present at the tree level.The trunk's contribution to productivity was the greatest,while that of leaves was the smallest.In China,the community biomass of subtropical evergreen broadleaved forests differs significantly with the age of the forest.The community biomass of the 52-year-old S.superba-C.carlesii forests in this study was lower than the average biomass of subtropical evergreen broadleaved forests in China,and was lower than the biomass of other subtropical evergreen broadleaved forests elsewhere in the world.Moreover,its productivity was lower than the model estimate,indicating that without disturbance,this community has great developmental potential in terms of community biomass and productivity.展开更多
文摘以已知浓度的柠檬酸作为定量外标,琥珀酸和烟酰胺分别作为定量内标,建立了食品中水苏糖的核磁共振定量分析检测方法。该方法在0.025~6.40 g/L质量浓度范围内线性良好,相关系数 R 2>0.999;以柠檬酸作为外标方法加标回收率为97.91%,日内精密度与日间精密度分别为1.65%和5.27%;琥珀酸和烟酰胺作为内标方法加标回收率分别为101.39%和106.35%,日内精密度分别为1.34%和0.83%,日间精密度分别为0.65%和2.46%;对市售不同食品基质(固态、液态)中水苏糖含量进行检测,测定结果准确。与现行行业标准(QB/T 4260—2011)高效液相色谱法相比,该方法简化了样品的前处理操作,节约了时间,定量准确,对食品中水苏糖的定量检测具有更广泛的适用性。
文摘以宁波天然甜槠阔叶混交林为研究对象,选择30个常用的树高—胸径经验模型,利用调整决定系数(R a 2)、均方根误差(RMSE)、平均绝对误差(MAE)、相对平均绝对误差(RMAE)和Akaike信息准则(AIC)等5个模型评价指标,比较分析模型之间差异。结果表明,除M23无法求解,其余29个模型均可求解。29个模型中,M11和M24在5个模型评价指标中表现优异,M11优于M24,说明M11为适宜的天然甜槠阔叶混交林树高—胸径模型,其R a 2=0.9101。
基金Funded by the Central Government Guides Local Funds for Scientific and Technological Development(No.2023ZYQ004)the Hunan Provincial Natural Science Foundation of China(No.2021JJ50036)the Hunan Provincial Key Research and Development Plan(No.2023GK2083)。
文摘We took Co_(0.2)Ni_(0.8)-MOF-74 with bimetallic synergistic effect as the basic material,and selected rare earth ions Ho,Gd,and Er with ion radii close to Co and Ni as the research objects for doping.The influence of rare earth ion doping amount and doping type on the eNRR performance of the catalyst was explored.The experimental results show that the ammonia yield rate and Faraday efficiency doped with Co_(0.2)Ni_(0.8)-MOF-0.5Ho are the highest,reaching 1.28×10^(-10)mol·s^(-1)·cm^(-2)/39.8%,which is higher than the1.12×10^(-10)mol·s^(-1)·cm^(-2)/32.2%of Co_(0.2)Ni_(0.8)-MOF-74,and is about 14.3%/23.7%higher than that without doping,respectively.And the stability of Co_(0.2)Ni_(0.8)-MOF-0.5 Ho is good(after 80 hours of continuous testing,the current density did not significantly decrease).This is mainly due to doping,which gives Co_(0.2)Ni_(0.8)-MOF-74 a larger specific surface area and catalytic active sites.The catalyst doped at the same time has more metal cation centers,which increases the electron density of the metal centers and enhances the corresponding eNRR performance.
基金supported by the National Key Basic Research and Development Program of China (Grant No. G2000046801)the National Natural Science Foundation of China (Grant No. 30130060 )the A3 Foresight Program Project (NSFC)
文摘The biomass and productivity of Schima superba-Castanopsis carlesii forests in Tiantong,Zhejiang Province,were determined using overlapping quadrants and stem analyses.The total community biomass was(225.3±30.1) t hm-2,of which the aboveground parts accounted for 72.0% and the underground parts accounted for 28.0%.About 87.2% of biomass existed in the tree layer.The resprouting biomass was small,of which over 95.0% occurred in the shrub layer.The productivity of the aboveground parts of the community was(386.8±98.9) g m-2a-1,in which more than 96.0% was present at the tree level.The trunk's contribution to productivity was the greatest,while that of leaves was the smallest.In China,the community biomass of subtropical evergreen broadleaved forests differs significantly with the age of the forest.The community biomass of the 52-year-old S.superba-C.carlesii forests in this study was lower than the average biomass of subtropical evergreen broadleaved forests in China,and was lower than the biomass of other subtropical evergreen broadleaved forests elsewhere in the world.Moreover,its productivity was lower than the model estimate,indicating that without disturbance,this community has great developmental potential in terms of community biomass and productivity.
