基于委托代理模型的乳品供应链质量控制策略研究

综合运用最优化原理、博弈论和委托代理理论,研究了信息对称、单边信息不对称和双边信息不对称情况下,乳品供应链中乳品加工与销售环节的最优质量控制策略,分析了乳品加工企业和超市实施质量协同控制的条件,并通过数值模拟验证了所建模型的科学性和研究结论的正确性。研究结果表明:当质量预防水平隐匿时,乳品加工企业将采取“质量预防不足”策略;当质量检验水平隐匿时,超市将实施“质量检验过度”策略;当质量预防水平和质量检验水平均隐匿时,乳品加工企业的“质量预防不足”与超市的“质量检验过度”同时存在;合理的合同设计,可促使乳品加工企业与超市实施质量协同控制,采取“预防为主、检验为辅”的基本策略。     

肉毒毒素重组抗原表达系统研究进展

肉毒中毒是肉毒杆菌引起的一种致死性的神经麻痹性疾病,应对内毒中毒的最有效方法是预防或疫苗接种,肉毒毒素Hc段是研制亚单位疫苗的首选.通过基因重组技术能够将肉毒毒素Hc片段在大肠杆菌或酵母表达系统中进行大规模表达.阐述了这2种表达载体在肉毒毒素亚单位疫苗的研制及发酵生产情况.     

Effect of cultivation time on soil heavy metal accumulation and bioavailability in Phyllostachys praecox stands

Phyllostachys praecox is a bamboo species cultivated for edible shoots under intensive management. However, the potential pollution risk of heavy metals in bamboo soils is not clear under the intensive management for a long term. The objective of this study was to evaluate the effect of cultivation time on soil heavy metal accumulation and bioavailability in bamboo stands subjected to intensive management. Soil samples were collected from a chronosequence of bamboo stands which had been cultivated for 0, 1, 2, 4, 8, and 10 years in Lin''an, Zhejiang Province of China. Eight heavy metals (Cu, Zn, Pb, Ni, Cr, Cd, As, and Hg) present in the soil were selected, and their potential pollution risk was evaluated by chemical speciation analysis. Possible heavy metal sources were explored using multivariate and cluster analysis. Our results showed that Zn, Cu, Hg, and Cd contents in the soil increased with the cultivation time, while Ni, Cr, Pb, and As levels were similar among all stands. Furthermore, the bioavailabilities of all analyzed heavy metals increased with the cultivation time. Multivariate and cluster analysis showed that sources of Ni, Cr, Pb, and As were likely lithogenic in origin, whereas input of Zn, Cu, Hg, and Cd was mainly due to cultivation practices. Current bamboo management strategies raised the potential risks of heavy metal pollution in bamboo shoots in the long term. Soil acidification in P. praecox stands induced by intensive cultivation should be controlled since it stimulated and improved the bioavailability of heavy metals. Appropriate management strategies should thus be adopted to ensure safe and sustainable production of bamboo shoots.     

Response of organic carbon fractions and microbial community composition of soil aggregates to long-term fertilizations in an intensive greenhouse system

Journal of Soils and Sediments - Soil organic carbon (SOC) content and stability, which are regulated by microbial communities, vary depending on aggregate size. The objectives of this study were...     

Validation of dual-crop coefficient method for calculation of rice evapotranspiration under drying–wetting cycle condition

Based on data collected from rice fields under drying–wetting cycle condition, the procedure of dual-crop coefficient (K _cd) approaches was calibrated and validated to reveal its feasibility and improve its performance in rice evapotranspiration (ET _c) estimation. It was found that K _cd based on FAO-recommended basal crop coefficients (K _cb) underestimated dual-crop coefficients in monsoon climate region in East China. The recommended coefficient (K _cp) value of 1.2 was not high enough to reflect the pulse increase of rice ET _c after soil wetting. The K _cb values were calibrated as 1.52 and 0.63 in midseason and late season, and the K _cp value was adjusted as 1.29 after soil wetting in rice field under drying–wetting cycle condition. The dual-crop coefficient curves based on locally calibrated K _cbCal and K _cpCor matched well with the measured crop coefficients and performed well in calculating rice evapotranspiration from paddy fields under drying–wetting cycle condition. So it can be concluded that the procedure of dual-crop coefficient method is feasible in rice ET _c estimation, and locally calibrated K _cb and K _cp can improve its performance remarkably.     

45%丙环唑悬浮剂对不同小麦品种室内安全性测定

为了探索45%丙环唑悬浮剂对青海省春小麦的安全性,设置45%丙环唑悬0.2、0.4、0.8 mg·g-1的不同处理。结果表明以株高和鲜重抑制率为指标,各品种对药剂的敏感性差异显著;在0.2 mg·g-1剂量下青春38、青春39、通麦1号、阿勃4个品种安全;在丙环唑0.4 mg·g-1剂量下对青春38、青春39、阿勃安全,对通麦1号安全性差;在丙环唑0.8 mg·g-1剂量下对4个品种的安全性都较差。     

西藏查吾拉地区不同性别牦牛产肉性能和肉营养成分的比较

为了研究性别对查吾拉地区牦牛的产肉性能及肉营养成分的影响,随机选取8岁健康的查吾拉牦牛10头,公母各半,对不同组别间牦牛进行屠宰试验比较肉营养品质的差异。结果表明,母牦牛屠宰率、净肉率、胴体率、骨肉比均高于公牦牛,但无统计学差异。肉营养成分分析结果显示,母牦牛肉中维生素A、E、B₁₂、半胱氨酸、组氨酸、精氨酸、钙、硒、脂肪酸含量高于公牦牛(P<0.05)。研究结果表明,查吾拉牦牛富含较高的营养成分,可为人类提供优质健康的动物蛋白,具备作为优质牦牛肉源生产的潜力。相比较,母牦牛肉优于公牦牛。     

新疆兵团主要植棉区机采棉田杂草调查

采用倒置“W”九点取样法对新疆兵团北疆、东疆主要植棉师蕾期、铃期棉田杂草进行调查。结果表明：北疆第六师、东疆第十三师机采棉田杂草主要有16科31种，其中禾本科杂草占16.1%，阔叶杂草占80.7%，莎草科杂草占3.2%；1年生杂草占64.5%，多年生杂草占35.5%。北疆第六师蕾期棉田优势杂草为龙葵、野西瓜苗、田旋花、灰藜，铃期优势杂草为龙葵、田旋花、灰藜。东疆第十三师蕾期棉田优势杂草为灰藜、反枝苋、狗尾草，铃期优势杂草为龙葵、灰藜、反枝苋、田旋花。不同地区、不同生育时期棉田优势杂草有所差异。研究结果将为新疆兵团机采棉田杂草的科学可持续防控提供重要依据。     

苗期甘蔗氮高效基因型评价指标的筛选

本研究通过低氮压力选择,筛选出甘蔗氮高效种质,分析影响甘蔗氮高效的重要指标,为甘蔗氮高效育种及栽培提供理论依据。以58份甘蔗种质资源为材料,在苗期采用正常供氮（2 mmol/L N）和低氮（0.2 mmol/L N）处理,分析甘蔗植株形态、干重及氮素在各器官中累积分配的特征。通过主成分分析方法筛选影响甘蔗氮高效利用的重要指标,通过聚类分析对58份种质进行聚类。结果表明,低氮（0.2 mmol/L N）处理可以明显从植物形态区分不同种质的氮利用差异,58份种质低氮条件下的干重范围为0.64~14.75 g/株,氮累积量为5.53~63.00 mg/株,氮利用率范围为115.40~279.30 g/g。对低氮压力下甘蔗干重及氮累积等25个指标进行主成分分析后,提取出4个主要成分,总贡献率为92.35%。通过高、低氮条件下与氮利用效率有关的氮转移系数及基因潜力等19个指标分析后提取出5个主成分,总贡献率为82.21%。影响甘蔗氮高效的重要指标有甘蔗的干重（全株、叶、根）、氮累积量（全株、叶、茎）、氮利用率（全株、叶）、叶的相对氮利用率、茎的基因潜力、茎的相对干物质量和茎的相对氮累积量。经聚类分析后初步将58份甘蔗种质分为氮高效基因型、偏氮高效基因型、偏氮低效基因型和氮低效基因型。