农村体育公共产品供给不足的宏观调控法规制

因市场失灵与政府失灵而引发的农村体育公共产品供给不足，不仅契合了宏观调控法产生的社会根源，而且还符合宏观调控法的价值取向和实施机制。为缩小城乡体育公共产品供给上的差距以及克服农村体育公共产品供给上的区域性失衡与结构不合理等困境，实现体育领域中社会分配正义的价值诉求以及保障国民的体育基本权，应当通过健全完善发展规划法、财政法、税法及金融法等宏观调控法加以克服。     

Soil property differences among high‐ and average‐yielding soya bean areas in Arkansas,USA

Soya bean [Glycine max (L.) Merr] yields >6719 kg/ha (100 bu/ac) have only recently and infrequently been achieved. Quantifying soil property differences between high‐ and average‐yielding areas can help to further identify non‐plant‐related properties contributing to soya bean yield potential. The objective of this study was to evaluate the effects of region and soil depth on soil property differences between high‐ and average‐yielding areas. In each of the seven regions of the ‘Grow for the Green’ yield contest in Arkansas, prior to or just after harvest in 2014 and 2015, soil samples were collected from the top 20 cm of one contest high‐yield (HY ) area that was in close proximity to an average‐yield (AY ) area. Across all regions and both years, soya bean yields differed (P  <  0.05) between yield areas, averaging 4701 and 5498 kg/ha in AY and HY areas, respectively. Averaged across soil depth and years, numerous soil properties differed (P  <  0.05) between HY and AY areas within at least one of seven regions. Total soil C content was at least 20.2% greater in the HY than in the AY area in three of seven regions. Extractable soil P content was, on average, 19.4 kg/ha greater in HY than in AY areas in three of the seven regions. Results from this study have the potential to help producers better understand soil properties that contribute to or hinder achieving ultra‐high (>6719 kg/ha) soya bean yields.     

水产类上市公司经营绩效评价及影响因素分析——基于DEA-Tobit模型

2012年以来水产类上市公司经营面临困局.该研究根据11家水产类上市公司2012～2014年的面板数据,首先运用DEA模型进行生产效率的评价,研究发现水产类上市公司的技术效率、纯技术效率和规模效率3年平均值都较高,但2014年整体绩效有走低的趋势;然后运用Tobit模型,分析经营绩效的影响因素,发现公司总资产周转率和高等教育人员比例与技术效率正相关,而研发人员比例与技术效率不相关.最后,从资产整合、加强营销、重视人才和发展休闲渔业等方面提出了提高水产类上市公司经营绩效的对策建议.     

Drought Tolerance and Water Use of Cereal Crops: A Focus on Sorghum as a Food Security Crop in Sub‐Saharan Africa

Sub‐Saharan Africa (SSA) faces twin challenges of water stress and food insecurity – challenges that are already pressing and are projected to grow. Sub‐Saharan Africa comprises 43 % arid and semi‐arid area, which is projected to increase due to climate change. Small‐scale, rainfed agriculture is the main livelihood source in arid and semi‐arid areas of SSA. Because rainfed agriculture constitutes more than 95 % of agricultural land use, water scarcity is a major limitation to production. Crop production, specifically staple cereal crop production, will have to adapt to water scarcity and improved water productivity (output per water input) to meet food requirements. We propose inclusion and promotion of drought‐tolerant cereal crops in arid and semi‐arid agro‐ecological zones of SSA where water scarcity is a major limitation to cereal production. Sorghum uniquely fits production in such regions, due to high and stable water‐use efficiency, drought and heat tolerance, high germplasm variability, comparative nutritional value and existing food value chain in SSA. However, sorghum is socio‐economically and geographically underutilized in parts of SSA. Sorghum inclusion and/or promotion in arid and semi‐arid areas of SSA, especially among subsistence farmers, will improve water productivity and food security.     

浅议通过标签内容查找农药隐性成分

本文针对农药隐性成分危害大和监管难等问题,剖析了企业主要动机,以农药标签为对象,研究建立了一种查找"问题"农药、锁定农药隐性成分的方法。该方法具有成本低、易于普及、克服检测仪器谱库不足、发挥基层各方力量进行监管等优点。与检测技术结合使用,可以弥补各方不足,更好地发挥监管作用。     

美国农产品分布对我国农产品区域发展的影响研究

美国农业一直处于领先地位,不仅得益于其丰富的自然资源和高科技的农业技术,其合理的农产品分布也不可少的影响因素。中国是一个农业大国,农业的发展离不开农产品,农产品的种植种类、农产品的区域分布、农产品的质量发展都直接影响农产品的发展。美国虽然面积和我国差不多,但因为有合理的布局,农产品贸易一直发展良好。要借鉴美国农产品的发展,研究和分析其农产品分布现状很有必要。     

Movement rules for juvenile steelhead: dynamic linking of movement behaviour to habitat and density

We incorporated explanatory factors including stream habitat type and fish density into individual‐based models with dynamic connections among adjacent habitat units to infer dispersal behaviour of juvenile steelhead Oncorhynchus mykiss in a Great Lakes watershed. We used mark–recapture data and an inverse modelling approach to estimate daily probability of steelhead moving out of a habitat unit, P(move), according to four competing models. The models used included (i) a null model where all fish had equal movement probability; (ii) a habitat‐dependent model where P(move) depended on the habitat type; (iii) a density‐dependent model of P(move); and (iv) a model where P(move) depended on both density and habitat type. The habitat‐dependent model provided the most parsimonious fit to the observed data according to Akaike's information criteria (AICc). In the null model, P(move) averaged 0.70, whereas P(move) averaged 0.75 in pools, 0.68 in riffles and 0.73 in runs in the habitat‐dependent model.     

Time‐lapse monitoring of soil water content using electromagnetic conductivity imaging

The volumetric soil water content (θ) is fundamental to agriculture because its spatiotemporal variation in soil affects the growth of plants. Unfortunately, the universally accepted thermogravimetric method for estimating volumetric soil water content is very labour intensive and time‐consuming for use in field‐scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatiotemporal variation of θ. However, depth‐specific variation in θ, which is important for irrigation management, has been little explored. The objective of this study was to develop a relationship between θ and estimates of true electrical conductivity (σ) and to use this relationship to develop time‐lapse images of soil θ beneath a centre‐pivot irrigated alfalfa (Medicago sativa L.) crop in San Jacinto, California, USA. We first measured the bulk apparent electrical conductivity (EC_a – mS/m) using a DUALEM‐421 over a period of 12 days after an irrigation event (i.e. days 1, 2, 3, 4, 6, 8 and 12). We used EM4Soil to generate EM conductivity images (EMCIs). We used a physical model to estimate θ from σ, accounting for soil tortuosity and pore water salinity, with a cross‐validation RMSE of 0.04 cm³/cm³. Testing the scenario where no soil information is available, we used a three‐parameter exponential model to relate θ to σ and then to map θ along the transect on different days. The results allowed us to monitor the spatiotemporal variations of θ across the surveyed area, over the 12‐day period. In this regard, we were able to map the soil close to field capacity (0.27 cm³/cm³) and approaching permanent wilting point (0.03 cm³/cm³). The time‐lapse θ monitoring approach, developed using EMCI, has implications for soil and water use and management and will potentially allow farmers and consultants to identify inefficiencies in water application rates and use. It can also be used as a research tool to potentially assist precision irrigation practices and to test the efficacy of different methods of irrigation in terms of water delivery and efficiency in water use in near real time.     

广西主要动物源性产品中磺胺二甲嘧啶残留调查与分析

为了解广西动物源性产品中磺胺二甲嘧啶（SM₂）残留情况，本研究采用磺胺二甲嘧啶化学发光酶免疫分析法（SM₂-CLEIA）对2013-2017年采集的4 637份动物源性产品进行检测，共检出超标样品122份，涉及鲜乳、猪肉、水产品和猪尿，其中超标猪尿92份，SM₂含量100.51~860.44 μg/kg，猪尿中抗生素残留会污染水体、土壤，再通过动植物的富集作用进入食物链，危害人类健康，应引起重视；而本次受检的水牛奶、鸡肝脏、鸭肝脏、鸭肉均合格。所有受检样品超标率逐年下降，同时规模化养殖场样品合格率高于农村散养户、超市高于农贸市场。不同年份超标样品含量以2014年最高。采用食品安全指数（IFS）对广西动物源性食品中SM₂残留风险进行评估，结果均远小于1，说明在广西地区，现有的SM₂残留对人体的潜在危害较低。     

Acquired Thermo‐Tolerance and Trans‐Generational Heat Stress Response at Flowering in Rice

In rice, pre‐exposure to sublethal treatment followed by harsh lethal treatment is known to improve tolerance of different abiotic stresses at the vegetative stage within and across generations. Our major aim was to test the phenomenon of thermo‐tolerance at flowering across (trans)‐generations and within generation using rice cultivars contrasting for heat stress tolerance at flowering. To test trans‐generational response, plants were exposed to higher temperature at flowering stage and seeds obtained from previous generations were exposed to heat stress during flowering, which recorded significantly lower fertility when exposed to the same degree of stress in their subsequent generations. A pre‐acclimation to moderately high acclimating temperatures imposed over three different durations during the vegetative and initial reproductive stage showed positive response in the tolerant N22, particularly under severe heat stress (40 °C). This finding indicates the possibility of acquiring ameliorative thermo‐tolerant mechanisms at anthesis, restricted to tolerant genetic backgrounds to combat subsequent harsh conditions within the same generation. However, trans‐generational memory was ineffective in mitigating spikelet sterility losses in both tolerant and susceptible backgrounds. Rice is extremely sensitive to heat stress during flowering; hence, similar exercise across other crops of interest needs to be carried out before generalizing conclusions.