覆麦草和遮光对夏季章丘大葱营养生长的影响

以章丘大葱大梧桐品种为试材,研究了夏季栽培中覆麦草和遮光对大葱株高和单株鲜重的影响。结果表明:7～9月各处理的株高和单株鲜重差异显著,覆麦草不利于大葱的长高和增重,而遮光可明显促进大葱生长,不覆麦草、遮光50%的处理株高平均值与对照差异不显著,但平均单株鲜重比对照高63.82%,增产潜力较大。多因素方差分析表明:覆麦草、遮光及两者交互效应对大葱株高和单株鲜重有极显著影响(P<0.01)。     

合作输出对提高英语写作能力影响的实证研究

基于对两人合作写作与个人独立写作的对比研究,发现英语写作教学中合作输出对提高学生英语写作能力的作用显著大于个人独立写作。合作写作可以激发学习者就写作策略、主题思想、篇章结构、遣词造句等方面进行讨论,达到取长补短的目的,从而有效提高输出效果,提高写作水平,同时又增进了友谊和团队合作精神。     

马克思论个人利益

现实的个人是马克思主义的历史的第一前提,集体的个人利益是一切出发点和归宿, 反对整体主义和个人主义。     

玉米主要数量性状对单株产量的效应

通过相关和通径分析,对宁夏种植和自育的60个杂交种(组合)的9个主要性状与单株产量间的关系进行研究.结果表明,各数量性状的变异范围均较大;穗粗、百粒质量、穗长、穗行数和穗位高与单株产量的相关系数达到显著水平;通过通径分析得出,单株产量与其相关性状的直接效应由大到小依次为百粒质量＞行粒数＞穗行数＞穗粗＞穗长＞穗位高＞株高＞茎粗＞秃尖长,确定百粒质量是影响宁夏玉米单株产量的主要因素,其次是行粒数和穗行数.宁夏高产稳产玉米品种应注重选择百粒质量高、行粒数多和穗行数多的品种,同时要求适宜的株高、穗位高和茎粗.     

不同密度对密闭型育苗设施中番茄幼苗生长的动态影响

以番茄中杂9号为试材,利用不同规格穴盘研究不同密度对密闭型育苗设施中番茄幼苗个体及群体生长的动态影响。结果表明：出苗后第13天时,各处理番茄幼苗生长发育正常,而出苗16 d后200孔和288孔处理的番茄幼苗遮光严重,不适于培育更长苗龄的番茄幼苗,此时番茄幼苗2片真叶,株高5.5 cm左右,茎粗2 mm左右|128孔处理的番茄幼苗在第23天时出现较严重的遮挡现象,72孔处理仍存在空隙,若培育更长苗龄的番茄幼苗可选用72孔或穴孔面积更大的穴盘,此时番茄幼苗4片真叶,株高14 cm左右,茎粗3.5 mm左右。     

Evaluation of surveillance strategies for bovine tuberculosis (Mycobacterium bovis) using an individual based epidemiological model

The Netherlands holds the bovine tuberculosis-free (BTB-free) status according to European Union standards, but in recent years small outbreaks of the infection have occurred. After the last outbreak in 1999 with 10 infected herds the question raised if the current surveillance system, visual inspection of carcasses at the slaughterhouse, is efficient enough to detect infected cattle in time and to maintain the official BTB-free status.

Through epidemiological modelling, the risk of a major outbreak is quantified, using one of six surveillance strategies. These are the currently used visual inspection of carcasses at the slaughterhouse (SL), the ELISA test on blood samples of carcasses at the slaughterhouse (ELISA-B), the γ-interferon test on blood samples of carcasses at the slaughterhouse (GAMMA-B), comparative tuberculination of the herd (CT), the combined method of single and comparative tuberculination of the herd (ST + CT) and the ELISA test on samples of bulk milk (ELISA-M). Test frequency of the last three methods was varied as well.

A stochastic individual based model (IBM) was developed to simulate a chain of infected herds, where each individual animal is followed in time. The model mimics the nation-wide situation after the introduction of one infected animal into one herd. BTB-transmission is simulated with an S-E₁-E₂-I state transition model. Output is time until detection of the infection, prevalence in the detected herd and the number of infected herds at the time of detection. For the assessment 500 simulations were used, representing 500 BTB-introductions. Model robustness to parameter values was analysed with Monte Carlo elasticity analysis, for which 1000 simulations were used.

Results of median time until detection and median number of infected farms at detection for SL (302 weeks and seven farms) were in agreement with estimates from an outbreak in the Netherlands in 1999. ELISA-B and GAMMA-B performed better than SL with a much lower median time until detection (189 and 97 weeks, respectively). The results for the tuberculination methods (ST + CT and CT) and ELISA-M depended heavily on the frequency in which the tests were performed. The tuberculination methods ST + CT and CT yield comparable results and detect the infection sooner than SL, also at the lowest tested frequency of once in 5 years. ELISA-M is comparable with SL at frequencies of once in 4 or 5 years, and this test works well at frequencies of once a year or higher. Our study results are used for an economical optimisation analysis of the six surveillance strategies.     

STR在野生东北马鹿个体识别中的应用

为了建立有效的东北马鹿个体识别体系,从12对加拿大马鹿的微卫星引物和6对黑尾鹿的微卫星引物中,筛选出8个具有多态性的微卫星位点。各位点的观察杂合度为0．3314～0．8174,平均杂合度为0．6243;各位点的匹配率为0．0656～0．5130,累计匹配率为1．446×10^-6;各位点的识别率为0．4870～0．9344,累计个体识别能力为0．9999。这8个微卫星位点可以准确地进行东北马鹿的个体识别分析。     

中系马里努阿犬兴奋性选育模式研究

统计中系马里努阿犬3个世代系谱资料和兴奋性状测试记录,对中系马里努阿犬兴奋性状不同的选育方法进行模拟研究。利用系谱资料,F3和F4世代兴奋性状数据,估算个体育种值,依据表型和育种值数据,对F4犬群按照个体表型、家系表型、个体育种值、家系育种值进行排序,各选择35%个体,筛选其在F5代中的个体,统计分析各种选择方法后代表型和遗传进展,评测不同选择方法对中系马里努阿犬兴奋性状选育最优方法。研究结果:选择中系马里努阿犬个体育种值好于选择家系育种值好于选择家系好于选择个体表型,选择中系马里努阿犬公犬效果好于选择母犬的效果。     

文冠果地理分布和生物生态学特性

通过野外踏查和室内分析相结合的方法对文冠果(Xanthoceras sorbifolia)的种群地理分布、个体生长规律以及有性和无性生殖规律进行了研究。结果显示,文冠果分布较为广泛,其中黄土高原是文冠果分布最为集中的地区;在适宜的环境条件下,文冠果1~3 a生幼苗随年龄的增长其根的生物量占总生物量的比例逐渐下降;不同生境类型下有性生殖特性有差别;不同直径级别的伐桩和断根萌发幼苗的能力随着级别的增加而增强。     

核桃楸种实性状变异规律及优良单株选择

对12个地点天然林中核桃楸果实超过100个的单株种实形态性状(包括种子质量、种仁质量、种壳厚、出仁率、三径均值等)进行测定与分析,结果表明:种子质量和种仁质量变异系数(分别为19.9%和20.4%)较大,种壳厚和出仁率变异系数(分别为13.58%和14.42%)中等,三径均值变异系数(8.42%)稍小。对各种源内的种仁质量与种子形态性状拟合,多数种源结果较理想。同时对种仁质量和出仁率分别与环境因子拟合,结果较理想(R2分别为90.71%和76.61%)。通过聚类分析和综合坐标法选出优良种源为三岔子、铁力、金山屯、亚布力,并通过综合坐标法选出各种源优良单株为BX1、BX3、BX13、BX30、BX25,DFH2、DFH9、DFH13、DFH26,DJC2、DJC5、DJC8、DJC13,JY7、JY9、JY14、JY21,LJ2、LJ7、LJ30、LJ8,WC2、WC3、WC4、WC7,HC1、HC7、HC16,HL1、HL10、HL15、HL26、HL14,JST1、JST4、JST24、JST27,YBL1、YBL5、YBL14、YBL16、YBL9,TL5、TL7、TL20、TL30、TL10,SC16、SC17、SC23、SC3、SC18。选择主要提高了出仁率、种仁质量和种壳厚这三个直接影响核桃楸品质的指标,各种源入选率在15%~25%,出仁率增益在5.81%~24.28%,种仁质量增益在5.19%~25.77%,种壳厚除东京城、临江、金山屯和亚布力外,其他种源增益不明显。