蛋鸡髓细胞瘤型白血病的诊断

贵州省开阳县某蛋鸡场进入育成阶段后,鸡群整体消瘦、贫血和发育不良,59 d后开始出现不正常死亡,至71 d时死亡率达1.3%.经流行病学和血清学调查、病理学观察和分子生物学鉴定,确诊鸡群感染J亚群禽白血病病毒并发生髓细胞瘤型禽白血病.调查发现,感染鸡群死淘率显著增加,生产性能严重下降.     

鸡布氏艾美耳球虫致病性研究

用１８日龄公雏作为试验对象,以增重、病变和死亡为判定指标,用Ｅ．ｂｒｕｎｅｔｉ的０．５万／只、１万、５万、１０万、２０万、５０万和１００万／只为接种梯度,研究了布氏艾美耳球虫的致病性。结果表明：接种０．５万／只至２０万／只剂量的Ｅ．ｂｒｕｎｅｔｉ都明显影响鸡的增重;（与对照组相比,均存在极显著性差异（Ｐ＜０．０１）,各剂量组间增重无差异,）５０万／只和１００万／只剂量组的鸡出现减重。５０万／只剂量组鸡死亡５０％,１００万／只剂量组鸡死亡１００％;Ｅ．ｂｒｕｎｅｔｉ接种５万／只剂量组及以上各组鸡饮食欲消失,鸡失去自洁行为,粪量少,含有粘液和血液;剖检病变主要在小肠至直肠,肠壁变薄,易碎,呈粉红色至暗红色,肠粘膜上有小的出血点,肠内容物以粘液和血液为主。部分鸡的盲肠内容物干、呈暗红色。（病变计分为：对照组０分,０．５万／只为０．５７＋;１万／只０．０３＋;５万／只１．１７＋;１０万／只１．５０＋;２０万／只２．２３＋;５０万／只３．６４＋;１００万／只３．８３＋。）１００万／只剂量组中有两只鸡出现腿麻痹症状,不能站立。     

新城疫活疫苗对控制鸡大肠杆菌病的效果观察

为了研究鸡新城疫活疫苗紧急免疫控制鸡大肠杆菌病的效果,通过大肠杆菌人工感染30日龄蛋鸡,待出现病症后,紧急免疫新城疫La-sota弱毒苗(Ⅳ系)4羽份.免疫后5～17 d,通过血凝抑制试验测定血清新城疫抗体水平,试验组新城疫抗体水平逐步提高,对照组抗体略有下降,免疫后17 d两组抗体水平差异显著(P＜0.05);对照组...     

广州市森林公园游客满意度影响因素分析

在借鉴相关研究的基础上,筛选出影响森林公园满意度的关键指标,设计调查问卷。采用分层抽样法对广州市11个森林公园进行调查,以随机方式对游客进行拦截访问,对所获数据进行描述性统计分析、交叉分析、相关性分析和回归分析。结果表明：广州市森林公园的游客满意度主要受管理服务、内部环境、景点项目、游览路线、指示系统、停车设施、可达度、喜爱度、忠诚度等因素的影响,其中环境安静、温湿舒适、停车方便、公交地铁和（高速）公路便利、距常住地距离合意等为核心因素,管理有序、空气清新、植物丰富、景观怡人、购物餐饮租车和卫生小憩设施便利等为重要因素,景点布局新奇、游览路线合理、指示系统清晰等为边缘因素,但影响程度明显分为不同层次,但多数影响因素与游客属性没有显著差异。因此,广州市森林公园建设与管理应坚持以提高游客满意度为抓手,努力实现游客健康休闲环境与设施的供求匹配。     

华北地区夏玉米田马唐治理的生态经济杀除阈期研究

作者于1992～1994年研究夏玉米田马唐(Digitaria sanguinalis L.)治理的生态经济阈期,借助计算机进行数学模拟,建立夏玉米的相对产量与马唐的相对干扰生长时间、相对出苗时间的函数关系。苗后马唐干扰生长的相对时间即相对天数(Xu)与夏玉米相对产量(Yu)的关系式为: Yu=101.5/{1.0 0.01756EXP[—(—0.0876Xu 0.0004888Xu~2)]}…………(1)苗后马唐出苗的相对时间与玉米相对产量的关系式为: Yd=100.73/{1.0 0.96EXP[—(0.06346Xd-0.00006859Xd~2)]}……………(2) 根据生态经济杀除阈期的定义和(1)、(2)两公式计算可知:夏玉米田马唐防除的生态经济杀除阈期的始期应从夏玉米苗后生育期总天数的11.8％开始,结束于夏玉米苗后生育期总天数的53.9％。例如华北地区夏玉米全生育期总天数一般是95天,夏玉米苗后生育期总天数(T)约为88天,故夏玉米田马唐防除的生态经济杀除阈期约在夏玉米苗后10.6—47.5天之间。     

Influence of Ammoniacal Copper Quaternary treatments on mechanical properties of blue-stained Lodgepole Pine wood

Three concentrations （2.8%, 2.0%, 1.2%） of Ammoniacal Copper Quaternary （ACQ） was selected to treat Lodgepole pine wood for evaluating ACQ treatment on mechanical properties of blue-stained wood. The bending modules of elasticity （MOE）, modules of rupture （MOR）, toughness and shearing strength parallel to grain on tangential surface, are tested according to the criteria GB1927-1943-91. Non-treated sample were also tested according to the same procedure. The results showed that the three groups specimen impregnated by different concentrations of ACQ solution met the AWPA standard 2003 of America （UC4A 6.4g/cm^3）. There were significant difference of toughness between treated wood and non-treated wood （p=0.01）, but there were no statistically significant differences among three concentrations in terms of toughness, and toughness of treated wood was approximately 20% lower than non-treated. MOR, MOE as well as sheafing strength parallel to grain were found to be not significantly different between treated wood and non-treated one, and there were no statistically significant difference among three concentrations of ACQ too. Toughness, MOR, MOE and sheafing strength parallel to grain increased with decrease of concentration of ACQ, but they were hardly affected by ACQ preservatives.     

Integrated rice management simultaneously improves rice yield and nitrogen use efficiency in various paddy fields

The hilly area of Southwest China is a typical rice production area which is limited by seasonal droughts and low temperature in the early rice growth period. A field experiment was conducted on three typical paddy fields (low-lying paddy field, medium-elevation paddy field, and upland paddy field) in this region. Nitrogen (N) treatment (180 kg N ha^-1 year^-1) was compared to a control treatment (0 kg N ha^-1 year^-1) to evaluate the effects of integrated rice management (IRM) on rice growth, grain yield, and N utilization. Integrated rice management integrated raised beds containing plastic mulch, furrow irrigation, and triangular transplanting. In comparison to traditional rice management (TRM), IRM promoted rice tiller development, with 7-13 more tillers per cluster at the maximum tillering stage and 1-6 more tillers per cluster at the end of tillering stage. Integrated rice management significantly increased the rice aboveground biomass by 34.4%-109.0% in different growth periods and the aboveground N uptake by 25.3%-159.0%. Number of productive tillers significantly increased by 33.0%, resulting in a 33.0% increase in grain yield and 8.0% improvement of N use efficiency (NUE). Grain yields were significantly increased in all three paddy fields assessed, with IRM being the most important factor for grain yield and productive tiller development. Effects of paddy field type and N level on N uptake by aboveground plants were reflected in the rice reproductive growth period, with the effects of IRM more striking due to the dry climate conditions. In conclusion, IRM simultaneously improved rice yield and NUE, presenting a valuable rice management technique in the paddy fields assessed.     

棉铃疫病在阿拉尔的发生

棉铃疫病是长绒棉铃期的重要病害,在新疆阿拉尔地区,七月底至八月上旬,若遇低温、阴雨、高湿的环境条件也能严重流行。种植抗病品种和改善生态因素是控制病害发生和流行的重要途径。     

发根农杆菌Ri质粒的研究和利用

本文综述了作为遗传转化高等植物载体的发根农杆菌Ri质粒,在其结构、功能及用作基因导入方面的研究进展,并讨论了被转化植物的利用策略。     

甘草渣中碱木质素的提取工艺研究

采用一般碱法从甘草渣中提取木质素,以水浴温度、恒温时间、碱液用量、碱液浓度为因素,进行正交试验,确定了其最佳提取工艺条件为:水浴温度40℃、恒温时间2.5h、碱液浓度0.8mol/L、碱液用量30 mL/g,木质素的提取率为4.88％.碱木质素的总羟基、酚羟基和醇羟基含量分别为5.43％、3.18％、2.43％.