水肥高效利用灌排系统调控面临的问题研究

通过调查我国水肥利用的现状,指出我国农业水利中干旱缺水、非点源污染、水资源利用率低下和灌排系统不配套等问题,提出灌区水肥高效利用需深入研究的热点问题,对探讨水肥高效利用和灌排系统管理理论,指导我国灌排系统精量调控,以最少的水肥投入量获取最佳的灌区产量和经济及生态环境效益,具有重要意义.     

MPTP慢性帕金森病小鼠海马内氧化应激与细胞凋亡蛋白的表达

目的 观察 MPTP慢性帕金森病小鼠海马氧化应激指标及细胞凋亡相关蛋白的表达.方法 应用MPTP制备慢性帕金森病模型,观察行为学改变,Morris水迷宫实验,检测模型组和对照组小鼠海马内超氧化物歧化酶（SOD）、还原型谷胱甘肽（GSH）及丙二醛（MDA）舍量变化,以及免疫组织化学方法、RT-PCR方法、Western blot方法检测海马Bax和Bel-2蛋白表达.结果 慢性帕金森病模型小鼠行为学特点为震颤、活动减少;水迷宫实验结果提示认知功能降低;与对照组海马比较：模型组海马SOD、GSH含量均下降,而MDA含量升高（P〈0.05）;模型组海马Bax蛋白表达增高,而Bel-2蛋白表达下降（P〈0.05）.结论 氧化应激在慢性帕全森病认知功能障碍发病机制中起重要作用,而Bax和Bcl-2蛋白参与了氧化应激诱导海马神经元凋亡的调控过程.     

敦煌莫高窟蒸散量的估算与非线性分析

通过应用野外称重法测定的折算系数对莫高窟林地的蒸散量进行估算与分析。结果表明,莫高窟林地的年蒸散量为6091mm,符合耗散结构的非线性原理,是较高水平蒸散耗散结构存在的表现。莫高窟林地75%的水分是通过植物根系将深层土壤水分转运出地面后以蒸腾的形式耗散掉的。蒸散量作为各参与因子时空异质性的综合反映,随着土壤水分状况、气候环境、植被种类和植物体量的变化呈现广泛非线性表现。而非线性系统不满足线性叠加原理。因此,本文通过使用折算系数,避免了用蒸发量和蒸腾量的简单的相互叠加,充分考虑了土壤蒸发、植被蒸腾和气候环境之间的相互影响。研究发现,莫高窟林地蒸散量是极干旱气候条件下高水分耗散结构的典型代表。     

基于复杂网络理论的水网节点重要性评价研究

复杂水网节点的重要性排序在工程应用中有重要实践意义,对于水网调度、安全管理有重要借鉴意义.为此,本文在复杂网络理论基础上,以山西大水网节点重要性排序问题为背景,对水网节点重要性评价进行研究.首先从整体角度出发,不考虑水网方向和干支斗毛级别差异,基于水网全局网络拓扑结构,从局部属性、全局属性、传播属性和网络位置四个方面定义了节点重要性评价指标.其次,分别根据这四个指标,对水网节点重要性进行排序分析,结合分析结果对网络位置指标进行了改进.然后,由于单指标评价结果不够全面且适用范围具有很大的局限性,给出了基于TOPSIS的多属性决策方法来综合评价节点的重要性.最后,考虑水网方向和级别差异,提出对水网进行干支斗毛级别划分,基于Page Rank算法对同一级别的有向赋权水网节点重要性评价进行研究.     

磁盘表面形貌对润滑剂分布及磁头／磁盘之间润滑剂转移的影响

磁盘表层润滑剂在磁头与磁盘之间转移会影响磁头飞行的稳定性．本文采用改进后的粗粒珠簧模型,运用分子动力学方法,研究了磁盘上类金刚石薄膜（diamondlikecarbon,DLC）层粗糙度和磁盘表面凸起对润滑剂在磁盘表面分布及磁头／磁盘之间润滑剂转移的影响．研究结果表明,DLC层粗糙度对润滑膜平均厚度及磁盘表层粗糙度的影响很小;磁盘表面凸起对磁盘表层润滑剂分布的影响明显．类金刚石薄膜层的粗糙度和磁盘表层凸起均可增加转移到磁头上的润滑剂的体积．但磁盘表层粗糙度对磁头／磁盘之间润滑剂转移量的影响明显低于由磁盘表层凸起导致的磁头／磁盘之间润滑剂的转移量．     

Microhabitat use and feeding habits of Crossodactylus bokermanni Caramaschi and Sazima, 1985 (Anura,Hylodidae) at a site in south‐eastern Brazil

We studied a population of Crossodactylus bokermanni in a stream at the Reserva Particular do Patrimônio Natural, Santuário do Caraça, south‐eastern Brazil, with respect to microhabitat use and diet. We characterized microhabitats based on substrate, distance to water and exposure level of the occupying individual (exposed or sheltered), and adjacent aquatic microhabitats (evaluated as potential nesting sites based on observed nests), according to water current (absent, slow or fast), substrate and depth. Calling males, silent males, ovigerous females, non‐ovigerous females and juveniles showed spatial niche overlap higher than that expected by chance, with calling males showing the strongest preference for microhabitats close to potential nesting sites (with intermediate depths, fast current and sandy bottom). Only 14 males out of 48 individuals examined for stomach contents had prey in their stomachs. The food items with the highest electivity values were Coleoptera and Diptera, but preys with both high and low mobility were exploited.     

SOFA技术对减轻锅炉水冷壁结渣的可行性分析及数值模拟

研究了水冷壁结渣的两个主要原因即还原性气氛和风粉气流,并提出了解决措施:适当的减弱还原性气氛,防止灰熔点降低.在深刻探讨水冷壁结渣成因的基础上,分析了采用SOFA技术解决这一问题的可行性,并利用CFD数值模拟得出了氧量、温度和氮氧化物生成的特点,模拟的结果为减轻水冷壁结渣和工程应用提供了一定的指导意义.     

一种基于聚类分析的数值积分新算法

通过聚类分析找出一般数值求积公式的被积函数出现数值信息波动较大的区域,自适应地采用相应的高精度公式,构造出高精度的自适应数值求积公式.数值试验结果表明,这种新数值求积算法较一般数值求积公式,能显著地减少数据存储量和计算量,提高数值求积公式的稳定性和数值积分的精度.     

Water mites of the genus Hygrobates Koch, 1837 (Acari: Parasitengona: Hygrobatidae) from Hokkaido,northern Japan

Nine species of Hygrobates (Acari: Parasitengona: Hygrobatidae) from Hokkaido, Japan are described or redescribed from newly collected material and historical specimens. Treated herein are eight species in the subgenus Hygrobates, including one new species, H. bibi sp. nov., as well as H. calliger Piersig, ; H. foreli (Lebert, ); H. japonicus Uchida, ; H. longipalpis (Hermann, ); H. longiporus Thor, ; H. nigromaculatus Lebert, ; and H. sokolowi Thor, . Also treated is H. ezoensis Uchida, in the subgenus Rivobates. A lectotype and paralectotype are designated for H. japonicus Uchida, . Hygrobates (s. str.) heteropalpis Imamura, is synonymized with H. calliger Piersig, . The name H. ezoensis Uchida, is resurrected from synonymy with H. diversiporus Sokolow, . Six species previously known from Hokkaido were collected in the study: H. foreli, H. japonicus, H. longipalpis, H. longiporus, H. diversiporus, and H. ezoensis. New records for both Hokkaido and Japan include H. nigromaculatus and H. sokolowi. A species previously recorded from Hokkaido, H. taniguchii Imamura, , was not found in this study. Three new characters are proposed as useful for the taxonomy of the genus Hygrobates: the ratio of the distance between the P‐4 ventral setae to P‐4 length, the ratio of the length of the longest terminal seta on IV‐L‐5 to the length of IV‐L‐5, and the nature of the outer border of the genital plates.