大型拖拉机发动机异响的判断与分析

发动机异响标志发动机某一机构的技术状态已发生变化.通过分析了发动机发生异响的现象和原因,正确使用发动机发生异响的判断方法,从而及时排除发动机各种异响,减少事故发生,具有非常重要的现实意义.     

2010年春夏季异常气候对酿酒葡萄的影响

以松原职业技术学院实习实训基地酿酒葡萄生产园区酿酒葡萄品种双优、双红为试材,采用多点跟踪调查方法,研究2010年春夏季异常气候对酿酒葡萄的影响。结果表明:2010年气候表现异常,3~4月持续低温,雨雪天气较多,尤其4月12日的大雪危害较重。6月份则持续高温,对没有采取措施预防的酿酒葡萄园,在葡萄产量和浆果品质方面均产生了严重影响。说明,适时采取有效预防措施是应对异常气候对酿酒葡萄的不良影响,保证酿酒葡萄稳产、优质的正确途径。     

荆州市郊红皮洋葱异常生长的原因调查与分析

对荆州市郊2009年秋播的洋葱发生的未熟抽薹、分蘖等情况进行了实地访问与调查,并结合荆州市的气象资料对洋葱异常生长的原因进行了综合分析。结果表明:洋葱生长期间的异常天气是导致2010年荆州市洋葱发生未熟抽薹、分蘖、鳞茎大小不一、鳞茎形成与成熟期偏迟等异常生长的主要原因。     

电力系统短期负荷预计(DFY)

电力系统调度部门,为了经济、可靠和安全供电,一般要进行短期负荷预计.本文介绍一个次日24小时的负荷预计模型和其程序在计算机上的操作过程.负荷模型分为两部分—正常情况和非正常情况下的预计.对湖南电网给出了预计的实际结果.     

鲁棒回归在水工建筑物安全监控模型建立中的应用

建立水工建筑物安全监控模型是预测和控制大坝的运行、避免重大事故发生的不可或缺的重要手段,而大坝安全监测数据中经常出现的异常值对监测模型的稳定性和精度产生较大影响,针对这个异常值问题,采用鲁棒回归方法,有效地剔除或削弱了监测数据中的异常值的影响,实例分析表明:在监测数据中含有异常数据的情况下,基于鲁棒回归的大坝安全监测模型的稳定性和预测效果能够得到保证。     

冬小麦1A缺体单倍体的细胞学研究

对1B/1R易位系冬小麦73(36)9-1的1A缺体单倍体小孢子母细胞和小孢子进行了细胞学观察,结果表明:①减数分裂有双线期,76.7％细胞的全部染色体都有不同形态的双线结构,而中期Ⅰ染色体配对的细胞只有41％;②末端联会较多,并靠联会较少,其分布随每个细胞二价体数目的增加而逐渐减少;③四分体时期有大量的二分体,一分体和三分体,它们进一步发育成大量的败育小孢子和少量异常小孢子;④中期Ⅰ和小孢子中有不同频率的融合细胞。     

Elucidation of the infection process of Ustilaginoidea virens (teleomorph: Villosiclava virens) in rice spikelets

This study reports an efficient inoculation protocol that allowed cytological analysis of the infection process of the rice false smut pathogen Ustilaginoidea virens. Examination of serial semithin and ultrathin sections of infected spikelets showed that the primary infection sites for the pathogen were the upper parts of the three stamen filaments located between the ovary and the lodicules. The stigma and lodicules were also occasionally infected to a limited extent. The pathogen infected the filaments intercellularly and extended intercellularly along the filament base. The host cells were degraded gradually. The pathogen did not penetrate host cell walls directly and did not form haustoria. In the balls the ovary remained alive and was never infected. This suggests that the pathogen is a biotrophic parasite that grows intercellularly in vivo.     

Effects of irrigation on precipitation in the arid regions of Xinjiang,China

Soil moisture is an important parameter for the interaction between soil and atmosphere.It is the second important factor that influences climate change,next to sea surface temperature(SST).Most previous studies focused on the monsoon regions in East China,and only a few laid emphases on arid environments.In Xinjiang, which is located in Northwest China,the climate is typically arid and semi-arid.During the past 20 years,the precipitation in Xinjiang has shown a significant increasing trend,and it is closely related to oasis irrigation.This paper aims at discussing whether abnormal soil moisture in spring can be the signal to forecast summer precipitation.The effects of abnormal soil moisture due to farm irrigation in spring in arid environments on regional climate are investigated by using a regional climate model(RegCM3).The results indicate that positive soil moisture anomaly in irrigated cropland surface in May led to an increase in precipitation in spring as well as across the whole summer. The impact could last for about four months.The effects of soil moisture on the surface air temperature showed a time-lagging trend.The summer air temperature declined by a maximum amplitude of 0.8oC.The increased soil moisture could enhance evaporation and ascending motion in the low troposphere,which brought in more precipitation.The soil moisture affected regional weather and climate mainly by altering the surface sensible and latent heat fluxes.     

Cu2+急性毒性下银鲳幼鱼红细胞核异常和抗氧化酶活性的变化

为探究Cu2+对银鲳幼鱼的致毒效应,采用静态毒性实验方法,开展了Cu2+对银鲳幼鱼的急性暴露实验,研究了不同浓度的Cu2+对银鲳幼鱼外周血细胞微核率、核异常率和肝脏抗氧化酶(SOD、CAT、GPX)活性变化的影响。结果表明:Cu2+对银鲳幼鱼48和96 h的LC50分别为0.860和0.770 mg/L,安全质量浓度为0.077 mg/L;Cu2+的浓度与银鲳幼鱼红细胞微核率及核异常率具有明显的剂量效应关系,在相同浓度Cu2+胁迫下,核异常率又普遍高于微核率;不同浓度Cu2+胁迫下银鲳幼鱼肝组织中的SOD、CAT、GPX活性均表现为低浓度被诱导而高浓度受抑制的规律,与Cu2+浓度呈抛物线型剂量效应关系。研究认为红细胞微核率、核异常率与SOD、CAT和GPX活性的变化均可以反映银鲳幼鱼受伤害的程度,并可用作银鲳安全性风险评价的参考依据,其中SOD还可以灵敏地指示低浓度的早期Cu2+污染。     

一种基于隐马尔可夫链的网络入侵检测研究

提出了一种基于HMM的网络异常入侵建模方法,使用隐马尔可夫模型中的Baum-welch算法识别攻击者攻击意图,给出了计算P(O|λ)和阈值的算法。仿真实验数据基于林肯实验室提供的入侵检测数据集,对系统进行了测试与性能分析,并与Snort系统比较,具有一定的应用价值。