氮抑制剂对蔬菜产量和硝态氮含量的影响

在单施化肥的基础上,分别添加5种氮抑制剂,研究其对蔬菜硝酸盐、亚硝酸盐含量及产量的影响。结果表明吡啶、咪唑和双氰胺3种氮抑制剂的施用对降低蔬菜硝酸盐含量效果明显,降低幅度为9.6%～31.1%,而对蔬菜产量的影响不大;各处理的亚硝酸盐含量均很低;氢醌、儿茶酚两种氮抑制剂的施用效果不明显。     

均匀设计在无籽西瓜快繁研究中的应用

采用均匀设计U9(96)方案研究农友新 1号无籽西瓜组培增殖培养基配方的植物激素用量 ,在 6-BA、IBA、IAA等 3因素 9水平试验方案中 ,只用 9个处理的较少试验次数便获得成功。分析结果认为 ,获得≥ 0 5cm正常芽的增殖培养基优化配方为改良MS + 6-BA1 80 2 8(mg·L- 1,下同 ) +IAA1 6。     

乙烯处理对番茄离体小花柄脱落的影响

 以番茄‘辽园多丽’品种为材料, 比较花蕾期、开花期及幼果期的小花(果) 柄对乙烯诱导脱落的敏感性。结果表明, 开花期小花柄最易接受乙烯的诱导而脱落, 20μL·L ^-1乙烯是最佳诱导浓度。该浓度处理的小花柄在脱落后期, 各部位POD、CMC-Na 酶及E_xo-PG活性升高, 但不同部位的POD、CMC-Na酶、E_xo-PG活性及可溶性蛋白含量变化不一致。     

粉锈宁缓释剂防治玉米丝黑穗病

玉米丝黑穗病是贵州省玉米的主要病害之一,每年都造成严重损失。按常规使用0.08％粉锈宁农药直接拌干玉米种防治此病,防效差,易产生药害。将粉锈宁与聚乙烯醇等复配成缓释剂后拌萌动的玉米种,解决了药害问题,还提高了防效。     

Evaluation of a multiplex real-time RT-PCR for quantitative and differential detection of wild-type viruses and C-strain vaccine of Classical swine fever virus

Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), one of OIE listed diseases. Most of the currently available detection methods do not allow discrimination between wild-type CSF viruses and the vaccine strains. This study was designed to develop a multiplex real-time RT-PCR for the quantitative and differential detection of wild-type viruses and C-strain vaccine widely used in China. CSFV specific primers and two differently labeled TaqMan probes for the differentiation of wild-type viruses from C-strain vaccine were designed in the 5'-untranslated region of the viral genome of CSFV. The two TaqMan probes specifically hybridize wild-type viruses of different subgroups and C-strain vaccine, respectively, in the multiplex real-time RT-PCR, with no cross-reaction to a number of non-CSFV porcine viruses. The sensitivity of the assay for detecting wild-type and C-strain-type vaccine viruses was determined to be 41.8 and 81.5copies/microL viral RNA, respectively. Completely correct differentiation of wild-type viruses from C-strain vaccine was achieved when testing reference strains and characterized field isolates of CSFV in China. The multiplex real-time RT-PCR was able to detect the viral RNA in the whole blood samples of experimentally infected pigs as early as 2 days post-infection, 3 to 4 days prior to the onset of clinical signs in co-housed pigs. The agreements between the multiplex real-time RT-PCR and a multiplex RT-nested PCR for detection of wild-type and C-strain-type viruses were 96.9% and 100%, respectively, when detecting 106 different field samples. There is a positive correlation between the titers of C-strain vaccines titrated in rabbits and RNA copies quantitated by the multiplex real-time RT-PCR. The novel assay described here is rapid and sensitive, and is useful for differentiating field strains and C-strain of CSFV in China.     

Expression and significance of PTEN in canine mammary gland tumours

To explore the expression and clinical importance of the anti-oncogene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in canine mammary gland tumours, PTEN expression was compared in 50 cases of canine mammary tumour and four examples of normal mammary tissue using real-time quantitative PCR. PTEN expression was similar in benign mammary tumours and normal mammary tissues (P>0.05), but was lower in malignant tumours than in normal mammary tissues or benign mammary tumours (P<0.001). PTEN expression was also low in the lymph node metastases of malignant mammary tumours. The expression profile of PTEN in malignant mammary tumours compared to those without lymph node metastasis varied significantly. Low-level PETN expression might play an important role in carcinogenesis and the progression of canine mammary tumours, and PTEN protein detection might be useful in evaluating tumour development and prognosis.     

纸浆模塑餐具热压干燥过程的研究

该文对纸浆模塑餐具热压干燥工艺过程进行了分析,在此基础上建立了模具热传导方程,采用分离变量法推导出模具热传导方程的解析解,同时应用Matlab软件进行数值求解。根据热传导方程的解析解、数值解计算的模具表面温度值与与实测值较为吻合。对模具的传热分析为模具结构设计及加热管布置提供了理论依据。根据热传导方程并结合生产实际经验,推导出相应的湿坯热压时间,为热压过程的控制提供了基础。     

资源边际效益与种植业结构调整目标规划

根据北京市统计资料和已有研究数据,运用数学规划模型,对北京市种植业结构调整的目标与资源的边际效益间的关系作了分析,把模型的最优解建立在较为合理的资源边际效益和目标边际成本的基础上。结果表明：要提高水的效益和种植业产值,必须控制粮食作物和饲料作物的种植面积,在可灌溉耕地上的露地作物均应实行喷灌,应大力发展设施农业并实行微灌。     

基于改进型FCM算法的牛肉大理石花纹提取方法

提出了一种基于改进型模糊C均值聚类算法的牛肉大理石花纹提取方法。该方法结合了快速模糊C均值（FCM）聚类算法,对传统FCM算法中的隶属函数、聚类数C和初始聚类中心点选取方法进行了优化。试验表明,该方法使牛肉大理石花纹提取的准确度由     

连续可变量喷雾系统响应特性试验

构建了以电动调节阀为变流器件的变量喷雾系统,并采用试验方法得出了系统的阶跃响应特性,试验结果表明:在阶跃幅值△Q分别为0.4、1.4、3.4、3.9、4.4 L/min条件下,系统上升时间的最大值为1 s,表明系统响应速度与现有的调压变量喷雾系统相当;系统上升时间、峰值时间和超调量都有幅值相关性,说明系统是非线性系统.因此对此类调流变量喷雾系统,其控制设计必须考虑非线性问题.