基于DEA模型的长沙市城市用地经济效益评价

文章采用数据包络分析(DEA)方法的C2R模型,借助MatLab软件的数学计算,对长沙市2000～2010年城市用地经济效益进行时间上的纵向评价,并对长沙市2010年的土地利用经济效益与其他10个国内城市进行横向比较。结果表明,近年来长沙市土地利用经济效益总体水平比较高,但是与国内发达城市相比尚有较大差距。     

Improved GC‐MS/MS Method for Determination of Atrazine and Its Chlorinated Metabolites in Forage Plants—Laboratory and Field Experiments

Abstract

Analytical procedures using gas chromatography–ion trap tandem mass spectrometry (GC‐MS/MS) were developed to analyze atrazine (ATR) and its dealkylated metabolites in four forage species (switchgrass, tall fescue, smooth bromegrass, and orchardgrass). Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were extracted with methanol (CH₃OH) followed by liquid–liquid extraction and partitioning into chloroform, with additional cleanup by C₁₈ solid‐phase extraction (SPE). Through the optimization of ionization conditions and ion storage voltages, the background noise of product ion spectra (MS/MS) was reduced dramatically, providing sub‐µg/kg detection limits. Mean recoveries of ATR, DEA, and DIA were 94.3, 105.6, and 113.1%, respectively. The estimated limit of detection (LOD) was 0.6 µg/kg for ATR, 1.3 µg/kg for DEA, and 0.3 µg/kg for DIA. These LODs were one to two orders of magnitude lower than those reported for other GC‐MS, GC‐MS/MS, high pressure liquid chromatography (HPLC)‐UV, or HPLC‐MS/MS procedures designed for food‐safety monitoring purposes. To validate the developed method, a field experiment was carried out utilizing three replications of four forage treatments (orchardgrass, tall fescue, smooth bromegrass, and switchgrass). Forage plants were sampled for analyses 25 days after atrazine application. DEA concentrations in C3 grasses ranged from 47 to 96 µg/kg, about 10‐fold higher than in switchgrass, a C4 species. The ATR and DIA concentrations were similar, ranging from 1.5 to 13.2 µg/kg. The developed method provided sufficient sensitivity to determine the fate of ATR and its chlorinated metabolites via plant uptake from soil or dealkylation within living forage grasses. It also represented significant improvements in sensitivity compared to previous GC methods.     

基于DEA的农业循环经济相对有效性评价——以四川省为例

选取农业能耗指数、化肥施用量、农作物播种面积、农林牧渔业从业人员作为区域农业循环经济发展投入指标,农林牧渔业总产值、农村居民人均纯收入、粮食单产作为产出指标,构建了DEA模型对四川省21个地市农业循环经济相对有效性进行评价。评价结果表明:13个地市农业循环经济发展相对有效,8个地市相对无效;劳动力资源过剩和土地资源利用不足是各地区农业循环经济非DEA有效的主要原因;各地根据各自的问题调整投入,同时以"3R"原则为指导,采取各种措施,农业循环经济发展程度将会有所提高;21个地市州中,眉山市和广安市规模经济递减,两地农业经济增长方式亟待转变。     

综合变量DEA与传统DEA的实证比较研究

综合变量DEA是传统DEA方法的修正,它能克服原有DEA的缺陷,得到更加科学的评价结果。本文分别用传统DEA与综合变量DEA方法对我国商业银行绩效进行了评价,结果表明基于综合变量DEA的绩效评价结果更加科学,区分能力更强。     

资源禀赋与闽台茶产业合作

文章通过分析台湾茶业现状和台湾茶业生产收益情况,并结合DEA模型定量分析台湾茶业的技术进步率和资源冗余情况,就今后闽台茶业的合作提出相关政策建议。     

基于DEA的农业科研团队绩效评价研究

文章建立了一套基于DEA分析的投入产出评价指标体系,并采用DEA的评价方法对农业科研团队的投入和产出进行有效性分析。     

基于数据包络分析的新疆农用地利用效益评价

本文应用数据包络分析(DEA)的理论与模型对新疆农用地利用效率进行了评价。根据DEA有效性值,从土地投入与产出两个方面分析了各地区的DEA有效性,呈现南疆最高、北疆次之、东疆最低的格局,以及非DEA的区域性差异;农业发展水平越高,DEA有效值越高,反之,DEA有效值越低,总体而言新疆农用地利用效益还有较大的增长空间。根据计算结果提出了提高农用地利用效率的建议。     

Production Efficiency of Two-Oriented Agriculture Based on Three-Stage DEA Model

Two-oriented agriculture was a complex organism coupling production,economics,society and ecology.Its development process was affected by various factors such as producers,nature,society,etc.In order to overcome measurement error of traditional data envelopment analysis caused by ignoring random,three-stage DEA model was studied to remove environmental factors and random effects.On the foundation of this model was two-oriented agriculture comprehensive production efficiency of 14 cities were estimated in Hunan Province in 2008,and brown forth corresponding policy proposals to promote agricultural development.     

玉米主产省生产效率测度及影响因素分析——基于DEA-Tobit模型的实证研究

本文通过利用2004—2018年中国20省（直辖市、自治区）玉米投入产出面板数据,运用DEA-Malmquist方法,分析研究阶段内中国玉米生产效率的变化、空间差异及玉米生产过程中投入产出冗余情况,同时使用Tobit模型分析影响中国玉米生产效率的主要因素。研究结果表明:技术进步是促进中国玉米全要素生产率增长的主要关键因素,综合技术效率提升较小,其主要依赖于规模效率的增加;中国玉米生产综合技术效率总体呈现北方春播玉米区>西北灌溉玉米区>黄淮海夏播玉米区>西南山地玉米区;其中山西省、辽宁省、山东省、湖北省、云南省、陕西省、甘肃省均存在产出不足或投入冗余现象;农业机械总动力、受灾面积及地区差异对玉米生产技术效率影响显著。基于研究结论,提出3点建议,第一培育新型技术人才,加强玉米发展动力;第二改善基础设施建设,减缓自然灾害冲击;第三落实结构调整政策,开展规模适度经营。     

“租补分离”模式下中国公共租赁住房的定价模型设计

从资源环境系统的内部结构出发，将资源环境评价体系分为生产系统和环境治理系统，针对该结构建立了扩展强自由处置性下的网络DEA模型——E-NSBM模型，将其与窗口分析法相结合，对2005-2012年中国各省资源环境效率进行了评价。结果表明：我国经济发达地区的生产系统效率普遍较高而环境治理系统效率较低；中、西部地区环境治理系统效率较高，但东部地区环境治理系统效率改进幅度最大；综合效率表现差的省份普遍表现为高的能耗强度、碳排放强度和硫强度。因此，各省应根据各自发展需要来确定资源环境效率的改进途径。