SBS聚合物改性沥青的试验分析

用针入度、软化点、动粘度及脆点等常规试验方法与动态力学分析方法对Styrene- Butadiene-Styrene(苯乙烯-丁二烯-苯乙烯，简称SBS)聚合物改性沥青的物理特性及流变特性进行了研究.结果表明SBS改性沥青在25℃时的针入度降低，软化点升高，温感性降低，动粘度也有所增加；SBS聚合物可有效地提高沥青粘合料在高温状态下的动态力学模量，降低相位角，而在低温状态下，SBS可以降低沥青粘合料的复合模量，增加相位角；此外，由于SBS的改性作用，导致沥青粘合料的脆点降低和低温(5℃)针入度的增加，SBS还可降低沥青的玻璃质过渡温度及温感性.     

布尔山羊精液保存条件的试验研究

本研究对不同条件下，用不同成分的黧液保存布尔山羊精液的效果进行了对比试验。试验证明，选用Ａ液（３０ｇ／Ｌ葡萄糖、１３ｇ／Ｌ柠醋酸钠和１ｇ／Ｌ乙二胺四乙酸钠），按５０ｍＬ／Ｌ加入贸黄，稀释布尔山羊精液，在常温（１５￣２１℃）和低温（４℃）条件下分别保存３０ｈ和９６ｈ，其活力分别为０．５０和０．５２，可完全满足输精要求；选用Ｂ液（５４ｇ／Ｌ葡萄糖和１０ｇ／Ｌ柠檬酸钠），进行细管冷冻保存布尔山羊精液，冻     

波动干燥工艺对桦木干燥应力的影响

进行了桦木波动干燥工艺和常规干燥工艺的对比试验.结果表明:波动干燥过程中,在降温干燥阶段,木材厚度方向上温度梯度和含水率梯度方向保持一致.与常规干燥工艺相比,含水率梯度和干燥应力小,可有效避免干燥过程中开裂现象的产生.     

早期断奶仔猪的饲养管理特点

早期断奶仔猪因自身生理缺陷,易受断奶应激和疾病流行的威胁,造成疾病和死亡。在饲养管理中应从抓好断奶关、减少应激、提早补料、建立免疫耐受力等九个方面入手,减少疾病的发生,提高仔猪成活率和生产性能。     

中蜂新式蜂箱与精细化饲养管理技术初探

中华蜜蜂(简称中蜂)是我国宝贵的蜂种资源,是促进农业增产增收和维护我国生态平衡的重要授粉昆虫。中蜂的野性比西方蜜蜂强,目前人们仍采用圆桶蜂箱、意蜂活框蜂箱和其他各式蜂箱对其进行饲养。研发了一种中蜂新式蜂箱和配套管理技术,旨在为形成一套十分适应中蜂生物学习性的标准蜂箱与饲养管理技术提供借鉴。     

Comparative analysis of antibiotic resistance characteristics of Gram-negative bacteria isolated from laying hens and eggs in conventional and organic keeping systems in Bavaria, Germany

By investigating the prevalence and resistance characteristics of Gram-negative bacteria from organic and conventional kept laying hens against 31 (Campylobacter: 29) different antibiotics using the microdilution method, we determined to what extent different keeping systems influence bacterial resistance patterns. For this purpose, samples from 10 organic and 10 conventional flocks in Bavaria (Germany) were investigated four times between January 2004 and April 2005. Altogether, 799 cloacal swabs and 800 eggs (contents and shells) were examined. The bacterial investigation performed with standardized cultural methods showed prevalence for all bacteria groups in about the same order of magnitude in the two different keeping systems: Salmonella spp. 3.5% (organic ([org])) versus 1.8% (conventional ([con])); Campylobacter spp. 34.8%(org) versus 29.0%(con) and E. coli 64.4%(org) versus 69.0%(con). Coliforms (Citrobacter, Enterobacter, Pantoea) were only isolated in single cases. In eggs, generally less bacteria were detected, predominantly Escherichia; Salmonella and Campylobacter were only scarcely isolated. Salmonella enterica ssp. enterica serovar Typhimurium (n=10) were resistant to up to nine, S. of the serogroup B (n=4) up to six antibiotics. All tested Salmonella (n=23) proved to be resistant to spectinomycin. Escherichia coli (n=257(org) and 276(con)) from organic layers showed significant lower resistance rates and higher rates of susceptible isolates to nine agents, namely amoxicillin/clavulanic acid, ampicillin, cefaclor, cefoxitin, cefuroxime, doxycycline, mezlocillin, neomycin and piperacillin. In contrast, only two antibiotics turned out to be more effective in conventional isolates (gentamicin and tobramycin). In the case of Campylobacter jejuni (n=118(org) and 99(con)), statistically significantly better rates were observed for isolates from organic flocks concerning imipenem and amoxicillin/clavulanic acid, whereas fosfomycin was more potent in strains from conventional flocks. Results of this study indicate that both resistance rates and mean minimum inhibitory concentrations of bacteria isolated from organic keeping systems have lower values than those from conventional ones, particularly recognizable for E. coli. Thus, organic livestock farming with its restrictions and additional requirements contributes to further effectiveness of antibiotics.     

A SYBR Green Ⅰ Based on Real-time Quantitative RT-PCR Assay for Specific Detection of Peste des Petits Ruminants Virus

The study was aimed to establish a rapid and sensitive diagnostic method for the prevention and control of peste des petits ruminants.In this study,a fragment of PPRV N gene was amplified and cloned into pMD19-T cloning vector.Real-time quantitative PCR assay was performed using SYBR premix Ex Taq.The standard curve was plotted and the specificity,sensitivity and reproducibility of the assay were assessed.The generated standard showed linearity over the entire range from 2.82×10⁰ to 2.82×10⁷ copies/μL with a linear correlation（R²）of 0.992.The specificity of the assay showed that other viruses failed to show an amplification signal.The coefficient of variation（CV）values for intra- and inter-assay variability were low,ranging from 0.27%~2.77% and 0.41%~3.39%,respectively.The lower detection limit,based on plasmid copy number,achieved was 2.82 copies/μL and was 1 000 times more sensitive than conventional PCR assay.cDNA of 12 samples were tested using this method,9 were positive,and 3 were negative.The samples were also tested using conventional PCR,7 were positive and 5 were negative,proving that the two-step SYBR Green Ⅰ based Real-time quantitative RT-PCR assay reported here were more sensitive than conventional PCR.The establishment of this detection method is of great significance to rapid and sensitive diagnosis of peste des petits ruminants and preventing the spread of peste des petits ruminants.     

切分西红柿微波短时处理常温贮藏保鲜试验研究

目前由于在果蔬的储运中常发生霉变、腐烂,鲜度下降,甚至完全失去商品价值,造成巨大的经济损失,难以满足市场要求。因此,解决果蔬的贮藏特别是运输过程中的保鲜,不仅能满足市场需要,增加果蔬市场供应品种和调节供应,同时还将获得巨大的经济效益。通过正交试验对切分西红柿进行了微波处理常温保鲜的试验研究,得出了真空包装的切分西红柿在微波短时处理后只达到巴氏杀菌的低温杀菌温度,却得到能长期贮存的品质优良的样品的结果;确定了这种方法的最佳处理参数,其最佳参数为0.12%维生素C处理时间为54s;对样品进行图像处理,得到色彩直方图和色彩均值,用确切的数值说明保鲜方法的保鲜作用;分析包装对西红柿保鲜的影响作用,认为切分西红柿应采用避光包装保存     

A comparison of soil and water properties in organic and conventional farming systems in England

Organic farming and improvements to agricultural sustainability are often seen as synonymous. However, an extensive European review demonstrated that in practice this is not always true. This study aims to compare the status of soil and water properties between separate fields managed in either an organic or a conventional manner. Soil samples were collected from 16 pairs of farms, throughout England, with both arable and grass fields within each pair on similar soil type. Chemical (nutrients, pesticides, herbicides) and physical (aggregate stability, field capacity, shear strength, soil organic matter, infiltration rates) soil properties were measured in four main soil texture classes in organic and conventional fields. The physical soil properties varied significantly between the different classes of texture and land use. The heavier textured soils have significantly higher soil organic carbon (SOC), aggregate stability and shear strength. The coarse‐textured soils have significantly lower field capacity moisture contents. The grassland has a significantly higher level of SOC, field capacity moisture content, aggregate stability and soil shear strength. However, there were no significant differences between organic and conventional treatments for any of the soil physical properties measured. There were fewer traces of agrochemicals in the soil water from the organic fields compared with the conventionally managed fields. The conventional arable fields had higher levels of total inorganic nitrogen than the other land uses and treatments. There was evidence to show that infiltration rates were significantly higher on organically managed grassland soils (7.6 mm/h) than conventionally managed grassland (2.5 mm/h) with lower stocking rates. The results suggest that improved grassland management, whether organic or conventional, could reduce predicted runoff by 28%.     

喷施保铃剂与杀虫剂种子处理技术配套使用对棉花生长发育及产量的影响

本研究表明，叶面喷施保铃剂与常规拌种剂（６０％甲拌磷乳油＋５０％林丹胶悬剂）配套使用，表现出显著的防虫壮苗、促进生长、保铃增产的正联合作用。较单一的种子处理果枝数分别增加１３．５％和１．４％；现蕾数增加５１％和１４％；单株成铃数提高２９．４％和１７．３％，产量提高２９．３％和３１．４％。较空白对照处理保铃增产效果更加显著