喷灌设施的小气候效应在苗木培育中的影响

喷灌设施对苗圃小气候影响的试验表明：在夏季高温季节,可为苗木生长提供温凉湿润的气候条件,与常规相比,白天平均温度降低3．1℃,最高气温降低3．4℃,可有效减轻苗木受高温干旱的影响。喷灌设施应用可使苗木成活率提高23．1％,促进成形苗出圃速度;1hm^2年增加产值近8万元,经济效益明显。     

基于多目标全息反馈的UPFC非线性控制策略

文章选取UPFC两侧逆变器的SPWM脉宽调制比和调制相角作为控制量,进行UPFC装置数学建模。基于非线性多目标全息反馈控制原理,构建含有8个控制目标的跟踪方程组,得到非线性多目标控制律,并利用包含发电机组的单机无穷大系统进行暂态仿真。仿真结果证明,该控制方法在简化传统非线性控制方法的同时,能充分发挥UPFC的潮流控制性能,增强输电线路供电可靠性,提升电力系统的动、静态稳定性。     

动探与承载力关系的研究

通过对动力触探试验与载荷试验的对比,绘制P-S曲线,保留曲线变化均匀,拐点相对明显的数据保留;剔除不理想的试验数据,进行动力触探试验和载荷试验对比分析,总结动力触探与地层承载力关系的规律。     

Identification of AFLP fragments linked to seedlessness in Ponkan mandarin (Citrus reticulata Blanco) and conversion to SCAR markers

Seedlessness is a desirable trait in citrus and has been an important breeding objective. In this study, we employed the amplified fragment length polymorphism (AFLP) technique to find molecular markers linked to the seedless trait in the Ponkan mandarin (Citrus reticulata Blanco). After screening with 72 primer pairs, 5 AFLP markers were identified that putatively correlated with the target trait. Their association was also tested by analyzing the AFLP profile from pooled individual accessions. The five fragments were cloned and sequenced, and BLAST searches showed that four of the markers had high homology to functional genes, providing some promising information that may aid in understanding the molecular mechanism of seedlessness in citrus. Based on the sequence information, eight specific primers were designed and eventually fragments AFLP-2 and AFLP-5 were successfully converted into sequence characterized amplified region (SCAR) markers. Thus, the markers detected could be useful for accelerating citrus breeding programmes by enabling early screening for seedlessness mutations using marker-assisted selection.     

Characterization of Botryosphaeriaceae from plantation‐grown Eucalyptus species in South China

The Botryosphaeriaceae is a species‐rich family that includes pathogens of a wide variety of trees, including Eucalyptus species. Symptoms typical of infection by the Botryosphaeriaceae have recently been observed in Eucalyptus plantations in South China. The aim of this study was to identify the Botryosphaeriaceae associated with these symptoms. Isolates were collected from branch cankers and senescent twigs of different Eucalyptus spp. All isolates resembling Botryosphaeriaceae were separated into groups based on conidial morphology. Initial identifications were made using PCR‐RFLP fingerprinting, by digesting the ITS region of the rDNA operon with the restriction enzymes CfoI and KspI. Furthermore, to distinguish isolates in the Neofusicoccum parvum/N. ribis complex, a locus (BotF15) previously shown to define these species, was amplified and restricted with CfoI. Selected isolates were then identified using comparisons of DNA sequence data for the ITS rDNA and translation elongation factor 1‐alpha (TEF‐1α) gene regions. Based on anamorph morphology and DNA sequence comparisons, five species were identified: Lasiodiplodia pseudotheobromae, L. theobromae, Neofusicoccum parvum, N. ribis sensu lato and one undescribed taxon, for which the name Fusicoccum fabicercianum sp. nov. is provided. Isolates of all species gave rise to lesions on the stems of an E. grandis clone in a glasshouse inoculation trial and on the stems of five Eucalyptus genotypes inoculated in the field, where L. pseudotheobromae and L. theobromae were most pathogenic. The five Eucalyptus genotypes differed in their susceptibility to the Botryosphaeriaceae species suggesting that breeding and selection offers opportunity for disease avoidance in the future.     

LPG 发动机微机控制点火与数据采集系统的研究

国内 LPG 发动机多由汽油机改装而成,第二代电控 LPG 系统的开发和应用水平不高。介绍了一种小功率单缸汽油机的普通电子点火改装成 LPG 发动机微机控制点火与数据采集系统的实验研究。