The Application of GIS in Small Watershed Classification in Loess Plateau

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拮抗细菌Enterobacter cloaeae B8的一株抗菌素抗性突变体(英文)

为了研究拮抗细菌Enterobacter cloacae B8在野外水稻叶面上的定殖情况及拮抗作用,由自然选择和Tn5诱变从B8产生了一株抗菌素抗性突变体BX8.BX8能在含利福平达400μg/ml或卡那霉素达300μg/ml的LB培养基中生长.实验表明该抗菌素抗性的产生没有降低BX8的拮抗活性.该抗性比较稳定,在无抗菌素培养基中培养.BX8至少分裂生长60代内抗性不变.     

陕北枣树主要害虫防治对策

对陕北黄河沿岸枣树害虫的调查发现,原来的常灾性害虫枣尺蠖、枣镰翅小卷蛾、桃小食心虫、枣飞象等继续蔓延成灾,以往被认为次要的虫种如蚱蝉、大球胸象、黑绒金龟及日本蜡蚧等已上升为主要虫种。本文根据上述8种主要害虫的发生危害特点、已有的技术成果及群众的防治经验,结合陕北当前枣树生产的实际提出了相应的防治对策。     

从洋马、三仓两个乡的实践看农业结构调整中支柱产业的培植

江苏省盐城市所辖的射阳县洋马乡和东台市三仓镇,近几年来,在农业结构调整中,因地制宜确立主导产业,千方百计培育主导产业,分别成为远近闻名的中药材之乡和西瓜之乡,1999年洋马乡中药材种植面积达3333.3公顷,实现产值1.6亿元,分别占全乡耕地面积和种植业产值的70%和75%;三仓镇种植大棚西瓜2020公顷,实现产值1.2亿元,分别占全镇耕地面积和种植业产值的40%和64.6%.     

图书馆工作人员应该转变的六个观念

文章认为，要使图书馆工作适应新的技术革命和社会主义市场经济的需要，就必须转变观念。当前需要转变的观念有以下六个方面:图书馆由藏书中心变成文献资料中心、信息中心、智力开发中心;从关门办馆到开门办馆:从无偿服务到有偿服务:从独自办馆到馆际协作:从手工操作到运用现代技术手段:从与世无争到积极竞争。     

北京黑猪和长白猪脂肪代谢的比较

猪在断奶后的生长期内,体内脂肪逐渐增加,和其它家畜相比,猪更倾向沉积体脂。但猪体脂的沉积还要受遗传、年龄、日粮营养水平等因素的影响。在饲粮消化能量(DE)水平保持在3000—3200Kcal/kg,蛋白质含量为14％—15％的饲养条件下,我们分别测定了纯系北京黑猪(肉脂兼用型,平均瘦肉率为51％)和纯系长白猪(瘦肉型猪、平均瘦肉率为62％)的某些脂肪合成酶活性和脂肪代谢的一些生化指标。北京黑猪(公母各半)脂肪组织(背膘)中苹果酸酶(ME),葡萄糖—6—磷酸脱氢酶(G—6—PDH),异柠檬酸脱氢酶(ICDH)三种NADPH—生成酶活性随体重增加而升高,差异极其显著(P<0.001)。体重90kg的酶活性比56kg约高三倍。脂纺组织中上述NADPH生成酶活性北京黑猪比长白猪(体重均为90kg,公母各半)高一倍(P<0.001)。给北京黑猪(30头,公母各半,起始体重为60kg)注谢重组猪生长激素(rPGH,每天每头2mg,连续注谢28天),除表现生长加快,脂肪率下降约21％—23％外,其脂肪组织中NADPH生成酶活性降低十分明显(P<0.001)。苹果酸酶,葡萄糖—6—磷酶脱氢酶,异柠檬酸脱氢酶,三种酶总活性比对照组降低20％。血精中三酰甘油,游离脂肪酸,总胆固醇,高密度脂蛋白(HDL)胆固醇、乳糜微粒,极低密度脂蛋白(VLDL)胆固醇含量,6月龄时,北京黑猪明显高于长白猪(P<0.001—0.0005);而4月龄时,北京黑猪血清中三酰甘油,高密度脂蛋白胆固酶含量则均明显低于长白猪。北京黑猪血清中三酰甘油,高密度脂蛋白胆固醇含量,随月龄(4月龄—6月龄)增长而增加(P<0.0005)。而长白猪则相反,随月龄而呈下降趋势(P<0.05—0.0005)。两种猪的脂蛋白电泳和含量测定未见有年龄和品种间的差异。     

近冰点温度贮藏草莓的研究

草莓呼吸旺盛,果皮薄易受伤,难以贮藏。利用近冰点温度贮藏可以明显地抑制草莓的呼吸作用,结合小袋包装的气密性,改善了包装内部的气体组成,提高草莓果实周围的相对湿度并减少空气对流,从而抑制了草莓在贮藏过程中糖分、水分的损耗,减少了糖酸比值的下降。保持了一定的感观指标,可使草莓的贮藏时间延长。     

靠接换砧矫治枳砧甜橙缺铁黄化研究

靠接红桔、酸桔和枸头橙砧,矫治枳砧甜橙缺铁黄化有明显效果。其中,以枸头橙效果最好,以下依次为酸桔和红桔,靠接砧苗后树势逐年恢复,产量成倍增加,靠接红桔、酸桔和枸头橙分别比对照增产3.3、1.4和1.5倍;对提高果实含糖量、果汁率和降低含酸量亦有良好效果。     

Porcine reproductive and respiratory syndrome virus: morphological, biochemical and serological characteristics of Quebec isolates associated with acute and chronic outbreaks of porcine reproductive and respiratory syndrome.

Cytolytic and noncytolytic strains of the porcine reproductive and respiratory syndrome virus (PRRSV) were isolated in primary cultures of porcine alveolar macrophages (PAM) from lung homogenates of stillborn fetuses or blood samples of dyspneic piglets collected from Quebec pig farms having experienced acute or chronic outbreaks of PRRS. Serological identification of the virus was confirmed by indirect immunofluorescence and indirect protein A-gold immunoelectron microscopy using reference antiserum prepared from experimentally-infected specific pathogen free (SPF) piglets and monoclonal antibodies (MoAbs) directed against the p15 nucleocapsid (N) protein of the reference ATCC-VR2332 isolate. Intracytoplasmic enveloped viral particles that tended to accumulate into cytoplasmic vesicles were observed in the infected PAM; no budding was demonstrated at the level of the cytoplasmic membrane. The extracellular virions appeared as pleomorphic but mostly spherical enveloped particles, 50-72 nm in diameter (averaged diameter of 50 particles was 58.3 nm), with an isometric core about 25-30 nm. Buoyant density of the virus in CsCL density gradients was estimated to 1.18-1.20 g/mL. No hemagglutinating activity was demonstrated. Analysis of semipurified virions of isolate IAF-exp91 by radioimmunoprecipitation (RIPA) and Western immunoblotting experiments, using reference rabbit and porcine hyperimmune sera, revealed four major viral proteins, a predominant 15 kD N protein and three other proteins with predicted M(r_ of 19, 26 and 42 kD. Progeny viral particles produced in PRRSV-infected PAM in the presence of tunicamycin lacked the 42 kD protein, thus confirming its N-glycosylated nature. Immunoprecipitation experiments using the anti-ATCC-VR2332 MoAbs confirmed the close antigenic relationships between Quebec and American reference isolates of PRRSV.     

广东山区开发的理论与实践：—广东山区开发理论与实践研讨会综述

本文述了“广东山区开发理论与实践研讨会”所达成共识的观点：广东山区开发具有重要的战略意义，广东山区开发必须走可持续肆展，农业产业化经营、工业化道路，同时必须搞好基础设施建设，组织好商品流通工作，优化资源配置。