目的探讨基于4因子的纤维化(FIB-4)指数联合肝脏硬度值(LSM)对非酒精性脂肪性肝病(NAFLD)肝纤维化的预测价值。方法我院收治的NAFLD患者118例,根据肝纤维化评分(NFS)将患者分为轻度肝纤维化组(NFS<0.676, n =67)和严重纤维化组(NFS&g...目的探讨基于4因子的纤维化(FIB-4)指数联合肝脏硬度值(LSM)对非酒精性脂肪性肝病(NAFLD)肝纤维化的预测价值。方法我院收治的NAFLD患者118例,根据肝纤维化评分(NFS)将患者分为轻度肝纤维化组(NFS<0.676, n =67)和严重纤维化组(NFS>0.676, n =51)。测量患者的LSM水平,计算FIB-4指数,分析FIB-4指数、LSM与NAFLD肝纤维化严重程度的相关性;评估LSM、FIB-4指数及二者联合对NAFLD肝纤维化的预测价值。结果轻度肝纤维化组LSM和FIB-4指数均小于重度肝纤维化组( P <0.05);LSM、FIB-4指数与肝纤维化分期均呈正相关,且LSM与肝纤维化分期的相关性高于FIB-4指数;ROC曲线分析结果显示,LSM、FIB-4指数及二者联合对NAFLD患者重度肝纤维化均有预测价值,ROC曲线下面积(AUC)分别为0.746、0.713和0.853( P <0.05),二者联合应用可提高诊断的敏感度和特异度。结论LSM、FIB-4指数与NAFLD肝纤维化分期呈正相关,均可对NAFLD患者的肝纤维化发展进行有效预测,可作为诊断NAFLD肝纤维化的参考指标,FIB-4指数联合LSM可提高诊断的敏感度和特异度。展开更多
【目的】对中国土栖性白蚁地理分布进行准确区划将对我国土栖性白蚁危害的精准防治具有重要指导价值。本研究旨在通过利用数学模型,结合影响土栖性白蚁分布的环境因子,探析中国土栖性白蚁地理分布区划。【方法】遴选影响白蚁分布的温度...【目的】对中国土栖性白蚁地理分布进行准确区划将对我国土栖性白蚁危害的精准防治具有重要指导价值。本研究旨在通过利用数学模型,结合影响土栖性白蚁分布的环境因子,探析中国土栖性白蚁地理分布区划。【方法】遴选影响白蚁分布的温度、降水量、湿度、土壤pH值等环境因子,利用迭代局部搜索算法(iterative local search, ILS)创建中国土栖性白蚁区划模型。【结果】ILS区划模型分区结果与实际的土栖性白蚁分布较为符合,将我国土栖性白蚁密度依次从南至北分为高密度区(D3)、中密度区(D2)和低密度区(D1)。D3最北分界线,东起江苏南京,经安徽芜湖、湖北麻城和沙市、贵州凤岗、四川宜宾,西至云南香格里拉。其北界线基本上沿长江中下游。D2最北分界线,东起江苏盐城,经安徽阜阳、河南驻马店、陕西商州、甘肃成县,西至四川廉定。其北界线东部大致沿淮河形成最后端凸起的曲线。D1最北分界线,东起山东东营,经河北邯郸、山西长治、甘肃华亭和合作、青海玉树,西至西藏日喀则,其北界线基本上沿黄河下游北上,形成一条中间凸起的曲线。【结论】我国土栖性白蚁地理分布已跨过黄河,总体密度呈南多北少和东多西少的特点,从南到北大体以长江、淮河、黄河等自然地理分界划分为高、中、低3个密度区。展开更多
A modified CQESTR model, a simple yet useful model frequently used for estimating carbon sequestration in agricultural soils, was developed and applied to evaluate the effects of intensive cropping on soil organic mat...A modified CQESTR model, a simple yet useful model frequently used for estimating carbon sequestration in agricultural soils, was developed and applied to evaluate the effects of intensive cropping on soil organic matter （SOM） dynamics and mineralization as well as to estimate carbon dioxide emission from agricultural soils at seven sites on the Huang-Huai-Hai Plain of China. The model was modified using site-specific parameters from short- and mid-term buried organic material experiments at four stages of biomass decomposition. The predicted SOM results were validated using independent data from seven long-term （10- to 20-year） soil fertility experiments in this region. Regression analysis on 1 151 pairs of predicted and measured SOM data had an r2 of 0.91 （P≤0.01）. Therefore, the modified model was able to predict the mineralization of crop residues, organic amendments, and native SOM. Linear regression also showed that SOM mineralization rate （MR） in the plow layer increased by 0.22% when annual crop yield increased by 1 t ha^-1 （P ≤ 0.01）, suggesting an improvement in SOM quality. Apparently, not only did the annual soil respiration efftux merely reflect the intensity of soil organism and plant metabolism, but also the SOM MR in the plow layer. These results suggested that the modified model was simple yet valuable in predicting SOM trends at a single agricultural field and could be a powerful tool for estimating C-storage potential and reconstructing C storage on the Huang-Huai-Hai Plain of China.展开更多
The behavior of pesticide in soil is influenced by dissolved organic matter(DOM)through competition adsorption,adsorption,solubilization,accelerated degradation,and so on.Thus DOM and its components play an important ...The behavior of pesticide in soil is influenced by dissolved organic matter(DOM)through competition adsorption,adsorption,solubilization,accelerated degradation,and so on.Thus DOM and its components play an important role in the environmental risk in the soil ecosystem and groundwater environment.Currently,most studies focused on the short-term effect of high concentration of DOM on the pesticide residues.However,soil DOM is mainly at low level.Therefore,there is of some practical significance to probe into the environmental behavior of soil pesticides under natural level of DOM.Thus a site investigation was conducted in the farmland with long-term application history of pesticide.By using the three dimensional excitation-emission fluorescence matrix(3D-EEM)technology,together with the fluorescence regional integration(FRI)quantitative method,the long-term effects of pesticide residues under low concentration of natural DOM were analyzed.Results showed that:(1)The long-term effects of the natural DOM components on the environment behavior of most soil organo-chlorine pesticides were not significant except for a few pesticides such asγ-HCH,p,p'-DDE,etc.(2)The influencing effects of DOM components on different type of pesticides were varied.Among which,the content of tyrosine component showed a significantly negative correlation(p〈0.05)with the concentration ofγ-HCH and p,p'-DDE.There were significant positive correlations(p〈0.05)between the by-products of microbial degradation in DOM components and the concentration of heptachlor.There were also a significant positive correlation(p〈0.05)between the content of active humus component of humic acid in the DOM and the concentration of heptachlor epoxide.These results suggested that the distribution of different types of pesticides residue in the soil was influenced by different components at different levels of significance.(3)The humification degree of soil organic matter showed minor effect of DOM on the pesticide residues in the soil.In this study,3D-EEM and FRI technology were firstly coupled in use for studying the influence of different components of DOM in soil on the environmental behavior of pesticides,which provides a new idea for the research on the mechanism of pesticides transportation and transformation in soil and groundwater environment.展开更多
文摘目的探讨基于4因子的纤维化(FIB-4)指数联合肝脏硬度值(LSM)对非酒精性脂肪性肝病(NAFLD)肝纤维化的预测价值。方法我院收治的NAFLD患者118例,根据肝纤维化评分(NFS)将患者分为轻度肝纤维化组(NFS<0.676, n =67)和严重纤维化组(NFS>0.676, n =51)。测量患者的LSM水平,计算FIB-4指数,分析FIB-4指数、LSM与NAFLD肝纤维化严重程度的相关性;评估LSM、FIB-4指数及二者联合对NAFLD肝纤维化的预测价值。结果轻度肝纤维化组LSM和FIB-4指数均小于重度肝纤维化组( P <0.05);LSM、FIB-4指数与肝纤维化分期均呈正相关,且LSM与肝纤维化分期的相关性高于FIB-4指数;ROC曲线分析结果显示,LSM、FIB-4指数及二者联合对NAFLD患者重度肝纤维化均有预测价值,ROC曲线下面积(AUC)分别为0.746、0.713和0.853( P <0.05),二者联合应用可提高诊断的敏感度和特异度。结论LSM、FIB-4指数与NAFLD肝纤维化分期呈正相关,均可对NAFLD患者的肝纤维化发展进行有效预测,可作为诊断NAFLD肝纤维化的参考指标,FIB-4指数联合LSM可提高诊断的敏感度和特异度。
文摘【目的】对中国土栖性白蚁地理分布进行准确区划将对我国土栖性白蚁危害的精准防治具有重要指导价值。本研究旨在通过利用数学模型,结合影响土栖性白蚁分布的环境因子,探析中国土栖性白蚁地理分布区划。【方法】遴选影响白蚁分布的温度、降水量、湿度、土壤pH值等环境因子,利用迭代局部搜索算法(iterative local search, ILS)创建中国土栖性白蚁区划模型。【结果】ILS区划模型分区结果与实际的土栖性白蚁分布较为符合,将我国土栖性白蚁密度依次从南至北分为高密度区(D3)、中密度区(D2)和低密度区(D1)。D3最北分界线,东起江苏南京,经安徽芜湖、湖北麻城和沙市、贵州凤岗、四川宜宾,西至云南香格里拉。其北界线基本上沿长江中下游。D2最北分界线,东起江苏盐城,经安徽阜阳、河南驻马店、陕西商州、甘肃成县,西至四川廉定。其北界线东部大致沿淮河形成最后端凸起的曲线。D1最北分界线,东起山东东营,经河北邯郸、山西长治、甘肃华亭和合作、青海玉树,西至西藏日喀则,其北界线基本上沿黄河下游北上,形成一条中间凸起的曲线。【结论】我国土栖性白蚁地理分布已跨过黄河,总体密度呈南多北少和东多西少的特点,从南到北大体以长江、淮河、黄河等自然地理分界划分为高、中、低3个密度区。
基金Project supported by the National Key Technologies Research and Development Program of China during the 10th Five-Year Plan Period (No. 2004BA520A14C02) and the Program for Changjiang Scholars and Innovative Research Team in University of China (No. IRT0412).
文摘A modified CQESTR model, a simple yet useful model frequently used for estimating carbon sequestration in agricultural soils, was developed and applied to evaluate the effects of intensive cropping on soil organic matter （SOM） dynamics and mineralization as well as to estimate carbon dioxide emission from agricultural soils at seven sites on the Huang-Huai-Hai Plain of China. The model was modified using site-specific parameters from short- and mid-term buried organic material experiments at four stages of biomass decomposition. The predicted SOM results were validated using independent data from seven long-term （10- to 20-year） soil fertility experiments in this region. Regression analysis on 1 151 pairs of predicted and measured SOM data had an r2 of 0.91 （P≤0.01）. Therefore, the modified model was able to predict the mineralization of crop residues, organic amendments, and native SOM. Linear regression also showed that SOM mineralization rate （MR） in the plow layer increased by 0.22% when annual crop yield increased by 1 t ha^-1 （P ≤ 0.01）, suggesting an improvement in SOM quality. Apparently, not only did the annual soil respiration efftux merely reflect the intensity of soil organism and plant metabolism, but also the SOM MR in the plow layer. These results suggested that the modified model was simple yet valuable in predicting SOM trends at a single agricultural field and could be a powerful tool for estimating C-storage potential and reconstructing C storage on the Huang-Huai-Hai Plain of China.
基金National Science&Technology Pillar Program during the 12th Five-year Plan Period(2012BAC19B03)National Natural Science Fund(41271236)+2 种基金Ministry of water resources“948”project(201328)National Public Benefit(Ministry of water resources)Research Foundation(201301039)Science Foundation for Young Scholars North China University of Water Resources and Electric Power(70459)
文摘The behavior of pesticide in soil is influenced by dissolved organic matter(DOM)through competition adsorption,adsorption,solubilization,accelerated degradation,and so on.Thus DOM and its components play an important role in the environmental risk in the soil ecosystem and groundwater environment.Currently,most studies focused on the short-term effect of high concentration of DOM on the pesticide residues.However,soil DOM is mainly at low level.Therefore,there is of some practical significance to probe into the environmental behavior of soil pesticides under natural level of DOM.Thus a site investigation was conducted in the farmland with long-term application history of pesticide.By using the three dimensional excitation-emission fluorescence matrix(3D-EEM)technology,together with the fluorescence regional integration(FRI)quantitative method,the long-term effects of pesticide residues under low concentration of natural DOM were analyzed.Results showed that:(1)The long-term effects of the natural DOM components on the environment behavior of most soil organo-chlorine pesticides were not significant except for a few pesticides such asγ-HCH,p,p'-DDE,etc.(2)The influencing effects of DOM components on different type of pesticides were varied.Among which,the content of tyrosine component showed a significantly negative correlation(p〈0.05)with the concentration ofγ-HCH and p,p'-DDE.There were significant positive correlations(p〈0.05)between the by-products of microbial degradation in DOM components and the concentration of heptachlor.There were also a significant positive correlation(p〈0.05)between the content of active humus component of humic acid in the DOM and the concentration of heptachlor epoxide.These results suggested that the distribution of different types of pesticides residue in the soil was influenced by different components at different levels of significance.(3)The humification degree of soil organic matter showed minor effect of DOM on the pesticide residues in the soil.In this study,3D-EEM and FRI technology were firstly coupled in use for studying the influence of different components of DOM in soil on the environmental behavior of pesticides,which provides a new idea for the research on the mechanism of pesticides transportation and transformation in soil and groundwater environment.
