非线性市场需求下考虑利益关系约束的农产品供应链参与主体决策研究

基于二级农产品供应链,在非线性市场需求环境中,研究强、弱两种利益关系约束下农产品供应链参与主体的最优决策。通过建立利润函数对比最优决策,并利用算例验证结论和探讨利润变化趋势,以提出合理的政策建议。研究表明:在收益共享契约下,强利益约束能使各参与主体获取超额利润,且参与主体的最优决策更贴近保障农产品供需稳定方向;收益共享系数在可行取值域内的增大,对农产品生产商更有利。     

制动工况下液力偶合器涡轮轴向漩涡流场试验分析

轴向漩涡流动是研究液力偶合器能量损耗的重要基础。该文基于粒子图像测速技术采集制动工况下液力偶合器轴向漩涡流场图像,通过图像处理技术识别并提取液力偶合器外壁面上特殊几何结构所呈现的光学特征,完成流动图像动态标定。利用霍夫变化直线检测算法识别泵轮轴向流场流速方向,通过图像互相关算法并采用查询窗口偏移技术提取涡轮轴向漩涡流场结构,应用误矢量识别算法检测错误流速矢量并予以剔除,获得优化的流动图谱。研究结果表明:泵轮轴向流场中液流是一种复合加速运动;涡轮轴向流场中液流是一种多尺度漩涡流动,主流区域上流速值为0.2~0.4 m/s,叶片与壁面组成的角隅区域上形成小尺度涡旋,角隅区域上流速值为0.6~1.1 m/s。上侧叶片与泵轮、涡轮交界面处的角隅区域上存在与主流循环流动方向相同的小尺度涡旋,涡量数值为?8 s?1,此处涡旋将促进液力能量的传递与转换,其他3个角隅区域上的涡旋方向与此相反,涡量数值分别为13、15和20 s?1,由于该局部区域小尺度涡与主循环涡的相互混合作用,引起流动迟缓,造成能量损耗。试验研究结果将为液力偶合器轴向漩涡流动现象提供有价值的参考依据。     

Simulation of the effects of genotype and N availability on rice growth and yield response to an elevated atmospheric CO2 concentration

The objective of this study was to identify physiological processes that result in genotypic and N fertilization effects on rice yield response to elevated atmospheric CO₂ concentrations ([CO₂]). This study conducted growth and yield simulations for 9 rice genotypes grown at 4 climatically different sites in Asia, assuming the current atmospheric [CO₂] (360 ppm) and elevated [CO₂] (700 ppm) using 5 levels of N fertilizer (4, 8, 12, 16, 20 g m⁻² N fertilizer). A rice growth model that was developed and already validated for 9 different genotypes grown under 7 sites in Asia was used for the simulation, integrating additional components into the model to explain the direct effect of [CO₂] on several physiological processes. The model predicted that the relative yield response to elevated [CO₂] (RY, the ratio of yield under 700 ppm [CO₂] to that under 360 ppm [CO₂]) increased with increasing N fertilizer, ranging from 1.12 at 4 g m⁻² N fertilizer to 1.22 at 20 g m⁻² N fertilizer, averaged overall genotypes and locations. The model also predicted a large genotypic variation in RY at the 20 g N treatment, ranging from 1.08 for ‘WAB450-I-B-P-38-HB’ to 1.41 for ‘Takanari’ averaged overall locations. Combining all genotypes grown at the 5N fertilization conditions, a close 1:1 relationship was predicted between RY and the relative [CO₂] response in spikelet number for crops with a small number of spikelets (less than 30,000 m⁻²) under the current atmospheric [CO₂] (n = 18, r = 0.89^***). In contrast, crops with a large number of spikelets under the current atmospheric [CO₂] showed a significantly larger RY than the relative [CO₂] response for spikelet number per unit area. The model predicted that crops with a larger number of spikelets under the current atmospheric [CO₂] derived great benefit from elevated [CO₂] by directly allocating increased carbohydrate to their large, vacant sink, whereas crops with a smaller number of spikelets primarily required an increased spikelet number to use the increased carbohydrate to fill grains. The simulation analyses suggested that rice with a larger sink capacity relative to source availability under the current atmospheric [CO₂] showed a larger yield response to elevated [CO₂], irrespective of whether genotype or N availability was the major factor for the large sink capacity under the current [CO₂]. The model predicted that the RY response to nitrogen was brought about through the N effects on spikelet number and non-structural carbohydrate accumulation. The genotypic variation in RY was related to differences in spikelet differentiation efficiency per unit plant N content. Further model validation about the effects of [CO₂] on growth processes is required to confirm these findings considering data from experimental studies.     

Splenic lipidosis in intensively cultured perch,Perca fluviatilis L.

Macroscopically visible lipid deposition varying in size from pinpoint to 8‐mm diameter was found in spleens of a population of intensively farmed perch, Perca fluviatilis L. over a 24‐month rearing period. Large agglomerates of adipocytes distinguishable from surrounding normal tissue occurred in all individuals with spleen lipidosis. Several affected fish presented total dystrophy of large clusters of hepatocytes. Prevalence of lipidosis was 5.0% at 12 months and 16.6% at 24 months. There was no significant difference between fatty acid profiles of liver or perivisceral fat of perch with and without lipidosis except for linoleic, myristic, γ‐linoleic, cis‐eicosatrienic, palmitooleic acid. Body weight and hepatosomatic, perivisceral fat and splenosomatic indices were not associated with lipidosis. There was no significant effect of lipidosis on mortality or growth.     

持续亚低温对甜瓜幼苗生理生化指标的影响

以厚皮型甜瓜(久红瑞、2-64)、薄皮型甜瓜(久青蜜、002)和厚薄皮中间型甜瓜(久脆蜜、久仙)3种类型的6个甜瓜(Cucumismelon L.)品种为材料,研究了夜间持续亚低温(8～15℃)、白天正常温度条件对不同生态型甜瓜品种苗期生理生化指标的影响.结果表明,在持续亚低温处理期间,可溶性蛋白含量的变化率呈先增大后减小的变化规律;各品种可溶性蛋白含量只有久青蜜先减少后增加,其余品种均一直减小.电导率的变化是久青蜜和2-64电导率的值减小,其余均增加.久青蜜、久红瑞和久仙脯氨酸的含量先减小后增加,其余均一直减小.久青蜜、002和久仙脯氨酸含量的变化率先减小再增加,久红瑞和2-64一直减小,久脆蜜先增加再减小.综合研究来看,对持续亚温有较好抗性的品种为薄皮型的久青蜜和厚皮型的久红瑞.它们可以作为生产上的耐低温品种.     

科尔沁沙地西部地区防护林体系营造技术的研究

本项研究针对科尔沁沙地西部风沙危害严重的玉田皋、那么罕地区生态现状,依据本地区坨－甸－土召镶嵌分布的地貌景观及不同立地条件,以农田、草场为重点保护对象,设计并建成由人工固沙植被、防风阻沙林带、公路防护林带、农田－草牧场防护林网、果园防护林等５种类型组成的沙地综合防护林体系。根据不同立地类型分别采取开沟地、穿透碱层和挖沟排水整地造林技术,造林成活率达８５－９４％。７年生农田防护林带背风面１０－１５Ｈ范围内,平均可以减弱风速４３－４７％;８年生草牧场防护林带２０Ｈ范围内平均降低风速３１－４３％,林网内蒸发量减少１５－２２％。     

兔成纤维细胞的分离与体外培养

用Ⅰ型、Ⅳ型胶原酶消化分离兔皮肤细胞,Ⅰ型胶原酶消化皮肤块获得的细胞数显著高于Ⅳ型胶原酶。用组织块直接培养法,也可以得到皮肤的原代培养细胞。２．５ｇ／Ｌ胰酶消化胎儿组织,可获得足够原代培养的细胞量。结合使用酶消化法和反复贴壁法,经２～３代后,可获得纯化的成纤维细胞。分离纯化的胎儿和皮肤成纤维细胞的生长曲线都正常且相似。胎儿和皮肤成纤维细胞可分别传至第１３代与第１１代,传代后染色体数目不变。     

青脆李新品种—‘巫山脆李’的选育

‘巫山脆李’是由巫山县果品产业发展中心、西南大学和重庆市农业技术推广总站等单位从地方青脆李‘江安大白李’自然芽变植株中选育出的果型端庄、肉质脆嫩、离核味甜青脆李新品种,先后获全国优质李杏评选金奖第一名和“三峡杯”优质脆李评选“果王”等称号,在西南地区推广50万亩。该品种树势强健,生长快,在重庆三峡库区沿江区域7月上中旬成熟,果实卵球形,果顶略凹,中等大小,平均纵径3.3cm、横径4.0cm,平均单果重37.2g,果柄长1.5cm、粗0.1cm。果皮底色绿色至绿黄色,皮中等厚,果点明显,果粉厚,白色。果肉浅黄色,肉质致密,纤维短,汁多味香,脆嫩,纯甜适口。可溶性固形物含量12%～15%,可滴定酸0.43％～0.72％,Ｖｃ含量6.12 mg/100g～8.99mg/100g,果核小,离核,呈扁圆形,果实可食率达94.8%～96.88％。无明显采前裂果和果内流胶,中熟,丰产,果实硬熟时肉质松脆,但软熟后出现肉变粉质、硬度下降现象,常温下不耐贮运。耐高温高湿和寡日照气候,适应性好、适宜在长江上游海拔180m～1000m区域发展。     

单层砖柱厂房的抗震设计

根据国家标准《建筑抗震设计规范》GBJ 50011-2001编制的原则,通过对单层砖柱厂房震害分析,提出了相应的抗震设计方法.     

苹果两向异性力学特性和跌落试验研究

压缩和冲击力学特性是与农业物料的损伤密切相关的物理特性。为了确定苹果的力学特性,利用万能试验机对苹果果肉和果皮进行了力学试验,并分析了苹果果肉的压缩特性和果皮的拉伸特性。针对苹果的冲击力学特性,选择冲击材料、冲击材料的水平速度和苹果跌落方向3个因素设计跌落试验。压缩试验表明:苹果果肉径向和轴向的弹性模量分别为(2.81±0.37)、(3.96±0.69)MPa,两向的弹性模量和屈服强度都具有显著性差异,而果皮的横向和纵向在弹性模量上有显著性差异(p<0.05)。跌落试验表明:果实的轴向抗损伤能力强于径向,果实损伤量随着冲击材料的水平速度增大而减小,且冲击材料的表面粗糙度会影响果实损伤量。本研究可为深入理解果实压缩特性和冲击损伤机理提供帮助,并为建立更准确的果实模型提供基础依据。