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气相色谱法测定黄芪中2,2-双(4-氯苯基)-1,1-二氯乙烯

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兰州大学学报（自然科学版） 2024年第4期60卷 536-541页

作者：蒲晓亚郭亮胡莹莹宋高林杨丽娟甘肃省产品质量监督检验东部分中心甘肃天水741000 天水市食品检验检测中心甘肃天水741000

建立一种气相色谱条件下有机氯农药残留2,2-双(4-氯苯基)-1,1-二氯乙烯(p,p′-DDE)的检测分析方法.收集8批黄芪样品,采用分析柱、验证柱和加标试验进行分析,通过质谱方法验证干扰物质,在GC-63Ni-ECD条件下成功实现干扰物质的分离和目标... 详细信息

建立一种气相色谱条件下有机氯农药残留2,2-双(4-氯苯基)-1,1-二氯乙烯(p,p′-DDE)的检测分析方法.收集8批黄芪样品,采用分析柱、验证柱和加标试验进行分析,通过质谱方法验证干扰物质,在GC-63Ni-ECD条件下成功实现干扰物质的分离和目标成分的测定.p,p′-DDE在1.06~106.09 ng/mL范围的线性关系良好(R=0.9996),阴性样品的回收率为81.31%~88.27%,阳性样品的回收率为75.81%~79.94%.阴性样品的加标溶液在24 h内稳定性良好(相对标准偏差≤3.21%).该方法的检出限为0.21μg/kg,定量限为0.71μg/kg.结果表明,黄芪中存在干扰p,p′-DDE测定的物质,检测过程中应予以高度关注.该检测方法准确、可靠、成本低,可用于黄芪中有机氯农药残留p,p′-DDE的测定.

关键词：黄芪气相色谱法 2,2-双(4-氯苯基)-1,1-二氯乙烯有机氯农药残留

湖南省“一村一品”发展现状及空间分布特征分析

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南方农业学报 2024年第3期55卷 889-898页

作者：胡盈盈李玉萍李海亮罗红霞杨歆歆禹萱郑倩中国热带农业科学院科技信息研究所/海南省热带作物信息技术应用研究重点实验室海南海口571101 山东农业大学图书馆山东泰安271018

【目的】探究湖南省“一村一品”发展情况及空间分布格局,为农业特色产业优化布局和提升现代农业发展水平提供理论依据。【方法】基于2011—2022年湖南省获得农业农村部认定的135个全国“一村一品”示范村镇数据,借助地理信息系统(GIS)... 详细信息

【目的】探究湖南省“一村一品”发展情况及空间分布格局,为农业特色产业优化布局和提升现代农业发展水平提供理论依据。【方法】基于2011—2022年湖南省获得农业农村部认定的135个全国“一村一品”示范村镇数据,借助地理信息系统(GIS)技术,综合利用平均最近邻域分析、核密度分析、地理重心迁移等空间分析方法,对湖南省“一村一品”示范村镇空间分布特征及演变规律进行分析。【结果】湖南省“一村一品”示范村镇空间分布特征表现为西北部、东北部和南部示范村镇分布多,中部和中西部分布较少;2011—2022年“一村一品”示范村镇呈极显著聚集分布(P<0.01),主要聚集在区位特色资源明显的湘西,以及交通便利、经济发达的长沙和湘潭。湖南省不同地区“一村一品”产业结构发展不均衡。种植业是最具优势产业,其产业聚集度在全省呈遍地分布的特点,高值区聚集在长株潭都市农业区。“一村一品”产品类别多样化且有明显分布特点,其中果品、蔬菜和茶叶三大类最为突出及具有竞争力。果品类主要聚集在东南西三面环山的主产区,其分布与海拔呈显著正相关(r=0.96,R^(2)=0.93,P<0.05);蔬菜类主要聚集在长株潭都市农业区,茶叶类主要集中在茶叶主产区湘西。“一村一品”获批数量呈波动增长趋势,示范村镇的地理重心整体上分布在中部。【建议】加大特色资源挖掘,提升示范村镇数量和质量;深入发展农产品深加工、涉农服务业、电商和信息化乡村产业融合发展平台,促进一二三产融合发展;依据现有特色产品的区位优势,优化乡村产业布局;重视品牌的差异化定位,多途径培育品牌,多样化推广宣传,提升品牌影响力。

关键词：一村一品空间分布核密度分析主导产业 GIS 湖南省

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

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Chinese Chemical Letters 2009年第12期20卷 1498-1501页

作者： Zhen Zhen hu ying ying Zhong Yun Chang Fan Yan Zhu Department of Chemistry Xixi Campus Zhejiang University Hangzhou 310028 China

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

关键词： Inorganic anions Ethyl acetate In-line hollow fiber membrane extraction Ion chromatography

A Marked Increase in Obstetric Hysterectomy for Placenta Accreta

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Chinese Medical Journal 2015年第16期128卷 2189-2193页

作者： Xiao-Yu Pan Yu-Ping Wang Zheng Zheng Yan Tian ying-ying hu Su-hui Han Department of Obstetrics and Gynecology China-Japan Friendship Hospital Beijing 100029 China Department of Ultrasound Diagnosis China-Japan Friendship Hospital Beijing 100029 China Department of Radiology China-Japan Friendship Hospital Beijing 100029 China

Background：Obstetric hysterectomy （OH） as a lifesaving measure to manage uncontrolled uterine hemorrhage appears to be increasing *** objective of this study was to determine the etiology and changing trends of OH and to identify those at particular risk of OH to enhance the early involvement of multidisciplinary intensive ***：A retrospective study was carried out in patients who had OH in China-Japan Friendship Hospital from 2004 to *** characteristics,preoperative evaluation,operative reports,and prenatal outcomes were studied in ***：There were 19 cases of OH among a total of 18,838 *** the study periods between 2004-2010 and 2011-2014,OH increased from 0.8/1000 （10/12,890） to 1.5/1000 （9/5948）.Indications for OH have changed significantly during this study period with uterine atony decreasing from 50.0% （5/10） to 11.1% （1/9）（P 〈 0.05）,and placenta accreta as the indication for OH has increased significantly from 20.0% （2/10） to 77.8% （7/9）（P 〈 0.05）.Ultrasonography and magnetic resonance imaging （MRI） have been used to make an exact antepartum diagnosis of placenta accreta.A multidisciplinary management led to improved outcomes for patients with placenta ***：As the multiple cesarean delivery rates have risen,there has been a dramatic increase in OH for placenta *** advance antenatal diagnosis of ultrasonography,and MRI,and a multidisciplinary teamwork can maximize patients＇ safety and outcome.

关键词： Cesarean Section Hysterectomy Placenta Accreta

Comparison of machine learning algorithms for mapping mango plantations based on Gaofen-1 imagery

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Journal of Integrative Agriculture 2020年第11期19卷 2815-2828页

作者： LUO Hong-xia DAI Sheng-pei LI Mao-fen LIU En-ping ZHENG Qian hu ying-ying YI Xiao-ping Institute of Scientific and Technical Information Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Practical on Tropical Crops Information Technology in HainanHaikou 571000P.R.China Land Use Key Laboratory of the Ministry of Natural Resources of China Chinese Land Survey and Planning InstituteBeijng 100101P.R.China Key Laboratory of Agricultural Remote Sensing Ministry of Agriculture and Rural AffairsBeijing 100100P.R.China

Mango is a commercial crop on Hainan Island,China,that is cultivated to develop the tropical rural *** development of accurate and up-to-date maps of the spatial distribution of mango plantations is necessary for agricultural monitoring and decision management by the local ***-based and object-oriented image analysis methods for mapping mango plantations were compared using two machine learning algorithms(support vector machine(SVM)and Random Forest(RF))based on Chinese high-resolution Gaofen-1(GF-1)imagery in parts of Hainan *** assess the importance of different features on classification accuracy,a combined layer of four original bands,32 gray-level co-occurrence(GLCM)texture indices,and 10 vegetation indices were used as input *** five different sets of variables(5,10,20,and 30 input variables and all 46 variables)were classified with the two machine learning algorithms at object-based *** of the feature optimization suggested that homogeneity and variance were very important variables for distinguishing mango plantations *** object-based classifiers could significantly improve overall accuracy between 2–7%when compared to pixel-based *** there were 5 and 10 input variables,SVM showed higher classification accuracy than RF,and when the input variables exceeded 20,RF showed better *** the accuracy achieved saturation points,there were only slightly classification accuracy improvements along with the numbers of feature increases for both of SVM and RF *** results indicated that GF-1 imagery can be successfully applied to mango plantation mapping in tropical regions,which would provide a useful framework for accurate tropical agriculture land management.

关键词： mango plantations GLCM texture SVM RF GF-1

Changes in extreme high temperature warning indicators over China under different global warming levels

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Science China Earth Sciences 2024年第6期67卷 1895-1909页

作者： Yuxia ZHANG ying SUN Ting hu Chinese Academy of Meteorological Sciences Beijing 100081China National Climate Center Laboratory for Climate StudiesChina Meteorological AdministrationBeijing 100081China

High temperature warning indicators play a pivotal role in meteorological departments,serving as crucial criteria for issuing warnings that guide both social production and daily *** their importance,limited studies have explored the relationship between different global warming levels and changes in high temperature warning *** this study,we analyze data from 2,419 meteorological stations over China and utilize the Coupled Model Intercomparison Project Phase 6(CMIP6)models to examine historical changes in high temperature warning indicators used by the China Meteorological *** evaluate model performance and estimate future changes in these indicators using an annual cycle bias correction *** results indicate that since 1961,the number of high temperature days(TX35d and TX40d)and length of season(TX40d and TX40l)with daily maximum temperature reaching or exceeding 35℃ and 40℃ have increased over *** intensity of high temperatures(TXx)has strengthened and the geographical extent affected by high temperatures has *** 2022,the occurrence of 40℃ high temperatures surges,with Eastern China experiencing a two-day increase in TX40d and an extended seasonal length in TX40l by over five *** CMIP6 models have underestimated the high temperature indictors associated with 35℃ during historical periods,notable difference is not observed between the models and observations for TX40d and TX40l,given their rare ***,future projections,after bias correction,indicate that the increasing trends for 35℃ and 40℃ high temperature days and length of season become more pronounced than the raw projection,suggesting a more severe increase than that anticipated *** global warming intensifies,the high temperature days and length of season are projected to increase non-linearly,while the intensity of high temperatures is expected to increase *** every 1℃ increase in global temperature,the intensity is

关键词： Extreme high temperatures Meteorological warning CMIP6 Global warming levels Future projection

Association between Vitamin D Insufficiency and the Risk for Gestational Diabetes Mellitus in Pregnant Chinese Women

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Biomedical and Environmental Sciences 2012年第4期25卷 399-406页

作者： WANG Ou NIE Min hu ying ying ZHANG Kui LI Wei PING Fan LIU Jun Tao CHEN Li Meng XING Xiao Ping Department of Endocrinology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Key Laboratory of Endocrinology Ministry of Health Beijing 100730 China Department of Obstetrics& Gynecology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China Department of Nephrology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China

Objective To investigate the association between vitamin D deficiency and risk of gestational diabetes rnellitus （GDM） in pregnant Chinese women. Methods A nested case-control study was conducted. Clinical and biochemical data were analyzed for 200 subjects with GDM and 200 subjects with normal glucose tolerance （NGT）. Results The median （interquartile range） serum 25-hydroxyvitamin D （25OHD） levels were 22.39 （17.67, 29.38） and 25.86 （19.09, 34.88） nmol/L in the GDM and NGT groups, respectively. Rates of 25OHD deficiency or insufficiency were significantly higher in the GDM group than in the NGT group. Subjects with 25OHD levels 〈25 nmol/L had a 1.g-fold higher risk of GDM compared with subjects with higher vitamin D levels. In the GDM group, serum 25OHD was independently associated with HbAlc and insulin resistance after adjusting for confounding factors. In the NGT group, serum 25OHD was independently associated with fasting plasma glucose and systolic blood pressure after adjusting for maternal age and other confounding factors. Conclusion 2SOHD insufficiency is very common in Chinese women. Low 25OHD status may be associated with insulin resistance and act as a risk factor for GDM.

关键词： Gestational diabetes mellitus Vitamin D insufficiency Chinese women

Semi-Varying Coefficient Panel Data Model with Technical Indicators Predicts Stock Returns in Financial Market

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Journal of Systems Science & Complexity 2024年第4期37卷 1638-1652页

作者： hu Xuemei PAN ying LI Xiang School of Mathematics and Statistics Chongqing Technology and Business UniversityChongqing 400067China Chongqing Key Laboratory of Social Economy and Applied Statistics Chongqing 400067China Research Center for Economy of Upper Reaches of the Yangtse River Chongqing Technology and Business UniversityChongqing 400067China

Accurately predicting stock returns is a conundrum in financial *** this conundrum can bring huge economic benefits for investors and also attract the attention of all circles of *** this paper the authors combine semi-varying coefficient model with technical analysis and statistical learning,and propose semi-varying coefficient panel data model with individual effects to explore the dynamic relations between the stock returns from five companies:CVX,DFS,EMN,LYB,and MET and five technical indicators:CCI,EMV,MOM,ln ATR,ln RSI as well as closing price(ln CP),combine semi-parametric fixed effects estimator,semi-parametric random effects estimator with the testing procedure to distinguish fixed effects(FE) from random effects(RE),and finally apply the estimated dynamic relations and the testing set to predict stock returns in December 2020 for the five *** proposed method can accommodate the varying relationship and the interactive relationship between the different technical indicators,and further enhance the prediction accuracy to stock returns.

关键词： Fixed effects random effects semi-varying coefficient panel data model stock returns technical indicators

The important role of Turbidity Maximum Zone in sedimentary dynamic of estuarine mangrove swamp

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Frontiers of Earth Science 2024年第1期18卷 219-226页

作者： Tao LIU ying LIU Baoqing hu Key laboratory of Environment Change and Resources Use in Beibu Gulf(Ministry of Education) Nanning Normal UniversityNanning 530001China School of Civil Engineering and Architecture Guangxi UniversityNanning 530004China

Sedimentation is a key process affecting wetland sustainability and carbon burial *** context of sea level rise,climate change and human activities,further understanding about the sedimentary dynamic in wetland is critical in predicting the landscape evolution or the change in carbon burial *** this study,based on the field hydrological observation in a mangrove system in the Nanliu River estuary,we found the net flux of suspended sediment to mangrove is 39−72 kg/m in tidal cycles with Turbidity Maximum Zone(TMZ)forming in surface layer and only is 9−18 kg/m in tidal cycles without *** higher net flux of suspended sediment to mangrove in tidal cycles with TMZ forming in surface layer is attributed to high SSC in rising tide and intense flocculation in *** significant discrepancy in sedimentation rate in the mangrove patches also can be explained by the probability of TMZ forming in the surface layer of *** future,rapid sea level rising may lead to the change of TMZ pattern in estuary,which will result in non-negligible variation in sedimentation rate in *** to the present data of sedimentation rate in wetlands,the fragility of wetlands in river estuary may be miscalculated.

关键词： mangrove wetland sedimentation Turbidity Maximum Zone Nanliu River