大学生淘宝店创业SWOT分析及对策探讨

在大学生就业难及网购市场快速发展下，淘宝由于品牌度高、低投入、风险小、门槛低等被作为大学生网上创业的首选。文章对于大学生淘宝店创业进行了SWOT分析，并提出完善对策，以期为大学生淘宝创业提供一定的指导。     

基于GPU的原油液体仿真效率优化研究

采用我国省际细分的出口产品数据，结合熵指数、出口复杂度指数度量我国31个省份的出口多样化和出口技术复杂度；建立出口多样化、技术复杂度影响经济增长的计量模型，采用省际面板数据进行实证研究。结果发现，总体上我国出口多样化在波动中有所上升，但在不同地区之间存在明显差异；出口技术复杂度呈现明显上升趋势；出口多样化、技术复杂度的提高均能促进地区经济增长。     

Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems

Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.     

中国食用菌出口发展方向及产业结构优化

面对食用菌产业快速发展中盲从性问题出现,使得食用菌产业缺乏系统的战略规划,出口能力较弱的问题,从价值链、组织链、物流链和信息链等4个视角为其提供产业结构优化对策,助力食用菌产业发展。     

基于遥感的干旱监测方法研究

在全球变暖的气候背景下,近年来干旱频发且不断加剧,对人类的生产生活造成了严重的影响。目前,干旱监测已成为全球气候变化研究的一个热点课题。遥感技术以其客观、及时、经济、覆盖范围广、数据连续等优点,已被证明是干旱监测中最具前景的技术手段。本文基于遥感原理,介绍了归一化植被指数、温度状态指数、标准化降雨指数和标准化降雨蒸散指数等几种常见的干旱指数,综述了运用不同指数干旱监测的主要应用。最后针对目前研究中存在的问题,对今后研究的主要方向作出了展望。     

土地规模化经营对农业生态效率影响及城乡市场分割调节作用探析

土地规模化经营是农业生态效率改善的重要动力,但土地规模化经营作用农业生态效率受到城乡市场分割的门槛调节。该研究借助2001—2017年全国30个地区(因数据缺失,西藏及港澳台地区未涵盖,下同)面板数据,运用面板门槛模型,就城乡市场分割调节土地规模化经营作用农业生态效率过程展开研究。结果表明:(1)我国农业生态效率总体向好,但地区间差异悬殊;(2)土地规模化经营驱动农业生态效率改善,但存在城乡市场分割门槛调节,弱市场分割地区土地规模化经营促进农业生态效率,强市场分割地区作用相反;(3)城乡市场分割调节土地规模化经营作用农业生态效率主要通过限制农产品、劳动力、资本城乡合理流动,削弱农业新型经营主体绿色农业发展意愿和能力途径展开;(4)我国多数地区城乡市场分割水平偏高,区域发展中城市资源偏向和工业优先发展突出,需进行及时改革。该研究可为政府制定绿色农业发展策略提供参考依据。     

Effects of Glyphosate on Soil Salinization and Alkalization in Cotton Fields

We analyzed the effects of glyphosate to the index of salinization and alkalization by simulation in soils collected from cotton fields in Anyang, Henan and Anqing, Anhui, China, in 2014. The results showed that application of glyphosate changed electrical conductivity (EC), total alkalinity (TAL), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR) and pH of soil in both regions，compared with the blank control. With increased frequency of glyphosate application and increased concentration applied, all indices increased in the Anqing cotton fields soil which were treated with concentrations of 2.5-20 g·L^－1 . However, EC, TAL and ESP increased dynamically in Anyang soil to which high concentrations of 20 g·L^－1 were applied only four consecutive times. After different glyphosate treatments, the soil pH value showed an upward trend but smaller changes. Therefore, after repeated use of glyphosate to soils of two different region soils, although the changes of all indices were within the range of non-saline and non-sodic soils, the soils affected by salt in the glyphosate aqueous solution tended towards saline-sodic soils.     

黄芪中药种衣剂对黄芪部分生理指标的影响

黄芪为豆科植物膜荚黄芪(Astragalus membranaceus(Fisch.)Bunge)或蒙古黄芪(A.membranaceus(Fisch.)Bunge var.mongholicus(Bunge)Hsiao)的干燥根。针对药用植物黄芪的农艺性状和栽培中遇到的主要问题,开发制备了黄芪专用型种衣剂,对黄芪种子进行包衣,通过田间试验,定期采样,对黄芪的根系活力、叶绿素质量分数、硝态氮、蛋白质、可溶性糖的质量分数进行测定,检验种衣剂对黄芪的这5种生理指标的影响。     

中国菠萝产业市场定位及拓展策略研究

菠萝是中国重要的热带农业经济作物，但近几年来受国际市场冲击严重。整个产业链资源配置并不合理，致使中国菠萝市场定位仍存在严重局限性。销售终端多集中在国内市场的鲜食部分，菠萝初加工处于萌芽发展阶段，精深加工更有待市场验证。从差异化、动态和目标营销角度对中国菠萝产业市场定位进行分析，并提出市场拓展战略。     

西北旱区喷灌条件下紫花苜蓿生长特征与品质指标的关系

西北旱区由于独特的气候条件,生产的苜蓿干草品质好,产量高。如何根据苜蓿的田间指标估测干草品质参数,对于苜蓿草产品生产销售具有重要意义。研究在喷灌条件下不同灌溉量对紫花苜蓿的生长品质的影响,并利用生长指标对紫花苜蓿的品质进行预测。试验于2014至2015年于中国农业大学石羊河流域生态节水试验站进行为期2年的田间试验。试验共设3个灌溉处理:A₁灌溉量为100%紫花苜蓿蒸腾蒸散量(ETc),A₂,A₃的灌溉量分别为A₁处理的66%,33%,以及一个不灌溉处理A₄。结果表明,苜蓿生长指标如株高(H)和茎叶比(SLR)随生育期的推进呈上升趋势,而鲜干比(FDR)呈下降趋势;所有生长指标随着灌溉量的减少均呈下降趋势。在品质方面,随着生育期的推进,所有处理的粗蛋白(CP)呈下降趋势,而中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)则呈现上升趋势;随着灌溉量的降低,NDF与ADF呈下降趋势,而CP则呈上升趋势。各生长指标与品质指标的拟合结果表明,H和SLR均与各品质指标显著线性相关(P<0.001),且H与品质拟合结果相关系数最高(R²>0.900),而FDR则与各品质指标不显著。这些结果表明,在田间管理较好,长势良好,杂草与病虫害发生较少的情况下,可以用株高对苜蓿干草品质做出预测。