空气阀在有压输水管路中的水锤防护作用

以输水管径为2.2 m的某长距离泵站输水系统作为研究对象,运用水锤理论及特征线方法,对泵站输水系统进行泵机组事故断电工况下的过渡过程计算,发现管路节点上存在较大负压,其中最大负压水头为-5.9 m.在管线上布置空气阀对负压进行控制,根据工程上空气阀的布置原则,在管线上安装18个空气阀,分别计算在空气阀流入流量系数依次为0.95,0.75和0.62,流出流量系数依次为0.65,0.45和0.62,以及孔口面积分别为0.018,0.071和0.196 m2下的水力过渡过程,得出在管线上安装空气阀的情况下,最大负压水头已控制在-1 m以内,比较分析空气阀的流入流出流量系数、孔口面积对水锤防护的差异,得出在3种空气阀流量系数下最大负压水头依次为-0.69,-0.70和0.71 m;3种孔口面积下最大负压水头依次为-0.88,-0.69和-0.67 m.对于输水管径为2.2 m的泵站输水系统,采用空气阀流入流量系数为0.95、流出流量系数为0.65,空气阀孔口面积为0.196 m2时,可对管路中的负压进行很好的控制.     

Effects of ferric chloride on structure, surface morphology and combustion property of electrospun polyacrylonitrile composite nanofibers

In this work, the pure polyacrylonitrile (PAN) nanofibers and PAN/FeCl₃ composite nanofibers were prepared by an electrospinning process. Electrospinning solution properties including viscosity, surface tension and conductivity, had been measured and combined with the results of Scanning electron microscopy (SEM), Atomic force microscope (AFM) and Micro Combustion Calorimeter (MCC) to investigate the effects of FeCl₃ on the structure, surface morphology and combustion property of electrospun PAN nanofibers, respectively. It was found from SEM images that the diameters of composite nanofibers were decreased with the addition of FeCl₃, which was attributed predominantly to the increased conductivity of the polymer solutions compared to viscosity and surface tension. The AFM analyses revealed that the surface morphology of electrospun nanofibers changed from smooth and wrinkle-like structure (without FeCl₃) to rough and ridge-like structure (with FeCl₃). The results characterized by MCC showed that the loading of FeCl₃ decreased the heat release rate (HRR) and improved the combustion property of composite nanofibers.     

小麦单倍体无性系抗镰刀菌毒素细胞系的筛选

１９８９～１９９２年以禾谷镰刀菌Ｆ＿４号菌种的粗毒素为选择剂，采用多步正筛选法，从来源于同一个花粉胚的单倍体细胞无性系Ｈ＿（１６）中筛选出三个抗性细胞系──Ｈ，Ｈ和Ｈ。与亲本系相比，这些变异系具有较强的抗毒素毒害能力，在继代培养６次后，其抗性性状表现稳定。     

云南松纵坑切梢小蠹寄生真菌种类调查及其应用技术研究

在云南主要蠹害林区，采集松纵坑切梢小蠹异常虫体７６号，在室内进行分离培养、纯化鉴定，致病测定后，到林间接种试验。筛选出对松纵坑切梢小蠹致病性强的本色镰刀菌ＦｕｓａｒｉｕｍｃｏｎｃｏｌｒＲｅｉｎｒ，球孢白僵菌Ｂｅａｕｖｅｒｉａｂａｓｉａｎａ（Ｂａｓｌｓ）Ｖｕｉｌ．粘孢白僵菌ＢｅａｕｖｅｒｉａｖｅｌａｔａＳａｍｓｏｎｅｔＥｖａｎｓ，青霉菌Ｐｅｎｉｃｉｌｉｕｍｓｐ．拟青霉菌Ｐａｅｃｉｌｏｍｙｃｅｓｓｐ．等５种寄生真菌。经林间蛀干实验，小蠹带菌在干内死亡率分别为８５．６％，８２．１％，８０．５％，８１．５％，８２．１％，９０．１％。     

林分密度和种植点配置对杨树各器官非结构性碳水化合物的影响

【目的】探究林分密度和种植点空间配置对树木各器官非结构性碳水化合物(NSC)的影响,了解杨树Populus在生长季的碳代谢特征。【方法】试验林分以密度为一级因素,种植点配置为二级因素,采用嵌套设计。于‘南林95’杨P.×euramericana ‘Nanlin 95’生长季(7月)选取叶、枝、树干和粗根4个器官,测定各个器官中NSC (可溶性糖和淀粉)的质量分数。【结果】在生长季,杨树各器官中可溶性糖质量分数从大到小依次为叶、根、枝、干,淀粉质量分数从大到小依次为干、根、枝、叶。不同林分密度和种植点配置的杨树叶中可溶性糖质量分数差异极显著(P<0.01),根中可溶性糖和淀粉质量分数受种植点配置影响极显著(P<0.01),总体上枝和树干受林分密度和种植点配置影响差异不显著。尽管林分NSC总储量在2种密度间(278和400株·hm-2)差异不显著,但林分NSC总储量在种植点配置间差异显著(P<0.05)。【结论】在生长季,苏北地区杨树优先将碳资源供给地上部分,其中首要的储存器官是树干。一定密度范围内(278～400株·hm-2),杨树叶中可溶性糖随林分密度增大而升高。林分...     

种植密度对油用牡丹‘凤丹’形态性状和产量的影响

以油用牡丹‘凤丹’(Paeonia ostii T.Hong et J.X.Zhang)为试材,设置4种株距和行距种植密度40cm×60cm、50cm×70cm、60cm×80cm、70cm×90cm。分别于盛花期和收获期,测定并比较分析了株高、冠幅、新枝条数、新枝长度、花横径、花高、叶片数、叶长和叶宽9个关键形态指标以及单株果荚长度、果荚厚度、果荚质量、籽粒质量、籽粒数和千粒质量6个关键产量指标,以期筛选出兼顾优良性状和高产的最适种植密度,为‘凤丹’进一步规范化种植和高产高效提供参考。结果表明:随着种植密度的减小,冠幅、叶片数、叶长、叶宽、单株果荚质量、单株籽粒质量、千粒质量、果荚长度、果荚厚度呈逐渐增大趋势,而株高和新枝长度变化趋势则相反;花横径、花高、新枝条数和单株籽粒数先升高后降低,呈明显的抛物线变化趋势,在60cm×80cm密度下达到最大值,且此密度下群体产量显著高于其它3个密度(P0.05),其籽粒667m~2产量为153.0kg。综上,在60cm×80cm密度下油用牡丹‘凤丹’的形态性状和产量指标均达到较优水平,可被建议为高产高效合理化种植的最佳密度。     

宁夏生态移民家庭碳足迹调查与影响因素研究

基于生命周期评估方法,以农户调研数据为基础,从能源消耗、房屋建设、家庭洗涤剂使用、交通运输、畜禽肉类饮食消费、衣着服饰6方面对宁夏不同安置方式下生态移民家庭碳足迹进行了测算,采用方差分析和相关分析对移民家庭碳足迹特点及影响因素进行了研究。结果表明:(1)移民迁移前碳足迹总量为190 657.46kg CO_2,迁移后碳足迹总量为153 132.47kg CO_2,不同安置方式下移民搬迁后的碳足迹总量均明显小于移民之前。(2)适度集中就近安置移民人均碳足迹为1.46×103 kg CO_2,此类安置方式下的人均碳足迹最大。(3)移民家庭消费碳足迹的主要来源是能源消耗,其次为房屋建设和交通运输,家庭洗涤剂、畜禽肉类饮食消费、衣着服饰类的碳足迹所占比例较小。(4)人口数量、收入水平、消费水平、非农化程度是其重要影响因子。     

生物质炭配施木灰对石灰性土壤固碳和微生物群落的影响

为探讨生物质炭配施木灰对土壤碳固存和微生物群落的影响,通过118 d的室内培养试验,研究了单施生物质炭(B)、生物质炭配施木灰(B+W)处理下土壤碳固存、化学性质、酶活性、微生物群落组成的变化.结果表明:B、B+W处理均降低了CO2-C释放速率和累积释放量,且B+W处理推迟CO2释放速率峰值的出现;B、B+W处理均能提...     

核黄素缺乏对鸡坐骨神经传导功能的影响

采用人工半合成饲料，单因子诱发雏鸡核黄素缺乏症，成功地对不同处理组、不同时期、不同临表现的活体鸡坐骨神经进行了电生理检测，结果果表明，核黄素缺乏可使雏鸡坐骨神经传导速度明显减慢，减慢的速度与核黄素缺乏程度、临床诊表现、神经损伤呈正相关。缺乏组、治疗组实验难的传导速度在任何时期均明显慢于同龄正常鸡，即使症状消失，也未恢复至正常，仍相差很远。表现卷趾或不卷趾麻痹的鸡，传导速度无明显差异。被检测鸡中，76％的动作电位潜伏期延长，上述结果导致坐骨神经经呈现不同程度麻痹。而髓鞘、轴突变性、ATP供给不足和神经发育受阻是造成传导速度减慢、动作电位潜伏期延长的主要原因，。此外，随着年龄的增长（10－38日龄），正常鸡坐骨神经传导速度逐渐加快，35m/s→66m/s，而核黄素缺乏鸡（1．7mg/kg日粮，缺乏组）则没有明显变化，10m/s→22m/s。     

Improving the fermentation quality of wheat straw silage stored at low temperature by psychrotrophic lactic acid bacteria

This study aimed to explore the feasible approaches to develop a silage production technique in regions with low temperatures. An effective low‐temperature silage technology system was constructed and two frigostable Lactobacillus (L.) strains isolated from alpine pastures were selected and proved to be available for wheat straw silage at 5°C. The strains QZ227 and QZ887 were both identified as L. plantarum according to the phenotype, 16S rRNA, and RecA gene analysis. QZ227, QZ887 and a commercial inoculant FG1 consisting of L. plantarum were effective for improving the fermentation quality of wheat straws silage at 5°C for 30 days as indicated by the higher content of lactic acid and for 60 days by lower pH values, while the control with sterile water instead conferred reduced benefits. Additionally, silages fermented at low temperature proved to be acceptable for feeding livestock after being placed in a simulated environmental temperature of 20°C for 14 days to detect its edibility during the early spring when the temperature begins to rise. Both QZ227 and QZ887 showed potential applications of silage making in frigid areas and were effective inoculants in a low‐temperature silage technology system.