Gene dropping analysis of founder contributions in a closed Japanese black cattle population

Gene dropping simulation was applied to Japanese Black cattle population in Hyogo prefecture, to examine the survivals of alleles originated from founder animals. In the analysis, unique alleles were assigned to founders, and the genotypes of all descendants along the actual pedigree were generated through Monte Carlo simulation following Mendelian segregation rules. By replicating this process 10 000 times, the distribution of frequencies of alleles from each founder was estimated. From the distribution, several quantities useful for the management of genetic diversity, such as the probability of allele extinction and the probability of alleles surviving at a critically low frequency were derived. The materials used were 68 781 animals born in 1955–1998 and their pedigree records traced back to the population in 1937 or before. The expected number of alleles retained in the population drastically decreased during the analyzed period, and reached to 57.9 in the population of 1998, which was only 3.3% of the total number of alleles assigned to founders. Detailed analysis of major founders with relatively high genetic contributions to the current population revealed that alleles from most of the major founders are now at high risk of future extinction. These results strongly suggest that for the management of genetic diversity, the genetic contributions of founders are not fully informative, and emphasize the importance of the detection of live animals having founder alleles with high extinction possibilities.     

新疆博尔塔拉河干流段水量入,出关系分析

本研究运用线性系统的理论和单、双序列的频谱分析方法，分析了新疆博尔塔拉河干流段温泉站入流量、博乐站出流量的自谱特征和互谱关系。文中提出的几点结论可供流域水资源计算及评价参考     

场效应对有机物性质的影响

讨论了场效应对有机化合物的酸性，反应活性及单糖构象稳定性等方面的影响，指出场效应的重要性不能被忽视。     

田山一级泵站技术改造浅析

田山电灌工程是黄河下游山东境内最大的电力引黄提灌工程。文章介绍了田山泵站前池跃前底部消能、跃后上方消波和轴流泵清水润滑新装置,以及提高泵站电力功率因数综合性水泵汽蚀防护和技术改造措施,经济效益显著。对泵站建设和技术改造具有一定的实用价值。     

林火火头前方气流温度场和速度场的测量、数据采集和处理系统的研究

该文介绍了一个用于一林业火头前方温度场和速度场的测量及数据采集和处理系统。该系统的主要特点是 :(1)可以同时测量多个点在同时刻的温度和风速 ;(2 )克服温度和风速波动的影响 ,误差小 ;(3)实时数据采集 ,便于监测 ;(4)数据后处理方便。实际使用说明 ,该系统测量准确可靠     

西南成品油管道输送模拟软件

针对西南成品油管道距离长、站场多、工艺技术较复杂、施工难度较大的特点,研制开发了西南成品油管道输送专用模拟软件,介绍了该模拟软件的理论依据和算法、软件的功能及结构,并在西南成品油管道一期水联运中进行了实际模拟.应用分析表明,模拟结果与实际数据之间的误差在许可范围内,可以为管道的日常运行提供技术支持.     

多年生杜仲叶林栽培模式及其更新复壮

通过对叶林模式的田间生物量进行调查,同时又对叶林模式更新复壮与不复壮两种处理模式的田间生物量进行了对比分析,发现两种处理模式的年变化规律有着明显的差异。     

41%农达防除休闲耕地杂草试验研究

采用农达防除休闲耕地杂草,结果表明:41%农达对苣荬菜的适用剂量(有效量)以3000mlhm-2为宜;野胡萝卜为1125mlhm-2,西伯利亚蓼为2250mlhm-2;旱雀麦等一年生杂草为1500mlhm-2,在杂草株高5~10cm时茎叶喷雾,防效可达80%~90%以上。     

菱形新概念车转向性能分析

采用线性三轮模型分析了菱形新概念车的转向性能,并推导出转向稳定性因子和横摆角速度增益传递函数.通过8自由度非线性模型的仿真,分析了菱形车的阶跃转向响应特性.仿真结果表明,菱形车在高、低速时具有快速、稳定的转向响应特性.与相关统计数据对比分析表明,采用菱形方式布置车轮除了在低速时具有灵活的转向特性外,高速时具有与传统车轮布置方式相当的动态转向响应特性.     

Research on the modeling method of soybean leaf＇s structure simulation

Leaf is one of the most important organs of soybean. The modeling of soybean leaf structure is useful to research of leaf function. The paper discussed it from two aspects that were distilling method of leaf profile and establishing method of leaf simulation model. It put forward basic method of soybean leaf digital process, and successfully established simulation model of soybean leaf structure based on L-system. It also solved a critical problem in the process of establishing soybean growth simulation model. And the research had guiding significance to establishment of soybean plant model.