2BLZ-2型垄上镇压精密播种机的研制与试验

２ＢＬＺ－２型垄上镇压精密播种机是为ＳＺＬ－２型深施肥整地联合作业机研制的配套机具。对该机的结构设计与技术参数做一介绍,并对田间试验进行了统计分析。     

野生樱桃李对北方根结线虫和花生根结线虫的抗性

为探明野生樱桃李抗根结线虫种质资源的价值,以实生钵苗为试材,采用人工接种等方法,研究其对北方根结线虫和花生根结线虫的抗性.结果表明:接种后30 d,野生樱桃李根系中北方根结线虫、花生根结线虫的雌成虫数量分别占2龄线虫接种量的0.16％和0.03％,依据抗性评价标准判定其高抗北方根结线虫和花生根结线虫;接种北方根结线虫的群体中包含免疫、高抗和中抗3种类型,分别占群体总数的46％、48％和6％;接种花生根结线虫的包含免疫和高抗2种类型,分别占群体总数的56％和44％;接种北方根结线虫和花生根结线虫的植株未被侵染率分别为46％和52％,所有供试植株根系表面均未发现线虫卵块.野生樱桃李高抗北方根结线虫和花生根结线虫,其对北方根结线虫、花生根结线虫的抗性均存在显著的株间分离现象;抗侵入、抗发育和抗繁殖是其对北方根结线虫和花生根结线虫的主要抗性机制;野生樱桃李是抗根结线虫核果类果树砧木种质资源树种.     

不同绣球切花品种采后水分变化及其影响因子分析

[目的]探索影响绣球切花采后水分平衡及品质的因子,以期为绣球切花采后保鲜提供理论依据.[方法]以目前市场流行的10个绣球切花品种为试验材料,于盛花期(50%小花开放)采收绣球切花,对其采后瓶插寿命及瓶插过程中鲜重变化、水分平衡变化、气孔密度、气孔开放率、萼片角质层厚度及木质化程度进行测定分析.[结果]不同绣球切花品种瓶插寿命差异显著(P<0.05),寿命最长达24.00 d(绿焰),最短为16.33 d(珠儿);鲜重变化率负值最早于瓶插后第3 d出现(瑞丽和钻石),最晚于第15 d出现(绿焰),鲜重变化率负值出现越晚的品种瓶插寿命越长;绣球切花瓶插期间的吸水量和失水量变化趋势一致,表明失水产生的蒸腾拉力是吸水的主要动力;不同绣球切花品种的气孔密度、气孔开放率和角质层厚度差异明显,气孔开放率总体呈先升高后下降的变化趋势(瑞丽和阿利阁除外),其差异与瓶插寿命无相关性,气孔密度和角质层是影响其水分蒸腾的两个主要方面;角质层发达的绣球切花品种寿命较长,品种热恋、绿焰和珊瑚的角质层厚度最大,分别为1.65、1.50和1.56μm,也是瓶插寿命长的品种,角质层厚度最小的珠儿(0.86μm)瓶插寿命最短;角质层不发达的绣球切花品种的瓶插寿命则受气孔的影响较大,即角质层不发达的品种中,狂想曲气孔密度较大,为24.06个/mm2,其瓶插寿命(17.67 d)短;小夜曲的气孔密度最小,为11.22个/mm2,其瓶插寿命(23.00 d)却较长;供试的10个品种萼片已具有一定程度的木质化,但品种间无明显差异.[结论]水分亏缺是影响绣球切花采后寿命的主要因子,蒸腾是影响水分平衡的关键因子,角质层厚度和气孔密度的差异是不同绣球切花品种盛花期采收时采后寿命差异的主要原因.     

基于改进占空比扰动法的光伏系统的研究

针对车辆轮荷的显著差异会降低车辆的平顺性和驱动能力这一问题,提出了一种油气耦连悬架系统.首先介绍了该系统的结构和原理,并在Matlab/Simulink下搭建了其动力学模型,最后将该模型与车辆动力学仿真软件Carsim进行联合仿真,在不平路面下对是否装有该耦连悬架系统车辆的侧倾角、不足转向度、发动机输出功率等指标进行仿真对比,研究该耦连悬架系统对车辆平顺性和操纵稳定性的影响.仿真结果表明,油气耦连悬架系统可以增加车辆的通过性和驱动能力,提高车辆的平顺性.     

The potential of informal institutions for marine fisheries management—A case study of a coastal commune in Vietnam

The potential of informal institutions for sustainable management of marine fisheries was examined. The study is based on both primary data collected through two group discussions and interviews and secondary information, including material related to fishing gear operation and whale worship. It shows that informal institutions, including fisher groups, fishing community norms, fisher's knowledge and whale worship have potential to strengthen institutional, ecological, social and community aspects of sustainable fisheries development. Although these informal institutions are not able to fix completely all the problems faced by formal institutions, they are able to complement and consolidate formal institutions to manage marine fisheries effectively. The findings of this study suggest it is imperative that formal institutions should be improved simultaneously with informal institutions to enhance current management for sustainable marine fisheries development.     

含水量对非饱和黄土强度的影响

试验和分析表明，在较大的含水量变化范围内，非饱和黄土的粘聚力和含水量之间呈幂函数关系。依据库伦－摩尔强度准则，非饱和黄土的抗剪强度随外部压力和含水量的变化规律可用强度曲面描述，提出了非饱和黄土强度的临界含水量计算式。     

Expression of interleukin-10 activity by Epstein-Barr virus protein BCRF1

Cytokine synthesis inhibitory factor (CSIF; interleukin-10), a product of mouse TH2 T cell clones that inhibits synthesis of cytokines by mouse TH1 T cell clones, exhibits extensive sequence similarity to an uncharacterized open reading frame in the Epstein-Barr virus BCRF1. Recombinant BCRF1 protein mimics the activity of interleukin-10, suggesting that BCRF1 may have a role in the interaction of the virus with the host's immune system.     

新型玉米秸秆切碎机设计及动刀片磨损试验研究

为减少玉米秸秆加工过程中水分流失,以及满足鹅类等畜禽所需饲料粒度小的要求,设计了一种采用三维切割方式的玉米秸秆切碎机。介绍了切碎机主要结构和设计参数,对切割前、后的青玉米秸秆进行了水分测试、饲料粒度分析,并对动刀片进行了磨损性能测试。结果表明:切割后秸秆水分损失率约为31.9%,饲料颗粒的三维尺寸为8~10 mm的颗粒约占78%,切碎机的实际生产率与理论生产率基本接近;动刀片磨损过程大致分为线磨损率分别呈高速磨损、减速磨损和稳定磨损3个阶段。在每一磨损阶段,第一组、第二组、第三组刀片的线磨损量和线磨损率均呈递减趋势。     

玉米丸粒化种子配套排种器的研究

对玉米丸粒化种子在单粒排种装置窝眼充种过程进行分析 ,并采用正交试验设计 ,优选出适合于丸粒化玉米种子的型孔轮式排种器 ,即型孔中间位置、直径 15mm、偏心角度 +14°的型孔轮式排种器。通过试验各项试验指标均满足机械精量播种的要求 ,为玉米丸粒化种子在现有播种机上实现机械精量播种开辟了一条新途径。     

Comment on "HST2 mediates SIR2-independent life-span extension by calorie restriction"

Calorie restriction (CR) increases life span in yeast independently of Sir2. Lamming et al. (Reports, 16 September 2005, p. 1861) recently proposed that Sir2-independent life-span extension by CR is mediated by the Sir2 paralogs Hst1 and Hst2. Contradictory to this, we find that CR greatly increases life span in cells lacking Sir2, Hst1, and Hst2, which suggests that CR is not mediated by Sir2, Hst2, or Hst1.