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51.
随着我国经济水平不断提高,化工设备检修手段也在不断发展,以改装机械加工设备来解决化工装置检修问题成为了当下提高检修效率的热议话题之一。文章主要分析化工装置检修,阐述了以改装机械加工设备方式解决化工装置检修难题的过程,总结经验以供参考。 相似文献
52.
渗灌是节水农业中最有效的措施之一,有利于作物产量和水分利用率的提高。本研究以甘肃省金昌市杨柳青公司紫花苜蓿‘艾迪娜’(M.sativa L.‘Aidina’)试验地渗灌区土壤为研究对象,通过田间试验与室内分析相结合的方法,研究不同渗灌次数(0次、1次、2次、3次)对苜蓿出苗期不同土层深度及管距位置土壤化学性质的影响。结果表明:在0~10cm和10~20cm土层深度,pH最高值均出现在管上,较CK升高了8.21%和8.68%,最低值都出现在管中,较CK降低了2.70%和3.37%;2水和3水均能显著提高不同土层深度及不同管距位置的pH值(P0.05)。不同渗灌次数,不同土层深度管中的水溶性盐含量均高于管上和管近,且最大值都出现在1水,较CK分别增加了83.26%和96.34%;不同土层深度,2水的水溶性盐含量平均值都低于1水和3水;不同渗灌次数,不同土层深度,钠离子和钾离子含量的最大值均出现在管中。不同渗灌次数,不同土层深度,管中的水解性氮含量均高于管上和管近,最大值都出现在1水管中,较CK分别增加了112.68%和34.48%。随着渗灌次数的增多,0~10cm土层深度不同管距的速效磷含量均呈现下降趋势,速效钾含量均呈现上升趋势。随着灌水次数的增加,不同土层深度及管位的有机质含量均呈现先上升后下降的趋势,2水显著提高了各位置土壤有机质含量(P0.05)。综上所述,渗灌2次比较好,土壤水溶性盐含量较低且有机质含量较高,利于苜蓿幼苗生长。 相似文献
53.
皆伐与不同迹地清理方式对杉木土壤化学性质的影响 总被引:3,自引:0,他引:3
以福建将乐国有林场杉木人工林为研究对象,按照立地条件相一致的原则,利用空间代替时间的方法设置皆伐前、皆伐1个月、皆伐3个月、整地1 a、整地3 a、炼山1 a、炼山3 a等不同条件下总计21块标准样地,旨在研究皆伐与不同迹地清理方式对杉木林地土壤化学性质的影响。经过对标准地土壤化学性质测定,结合显著性差异法对试验数据进行处理分析。结果表明:皆伐后土壤化学性质趋于恶化,不同迹地清理方式土壤化学性质差异显著,带状整地法在短期1 a内对土壤化学性质的改善显著强于炼山法,并且炼山3 a后土壤化学性质基本恢复至炼山前,总体看来皆伐后带状整地的迹地清理方式优于炼山法。 相似文献
54.
Three of the most commonly used veterinary antibiotics—enrofloxacin (ENR), sulfamethoxazole (SMX), and oxytetracycline (OTC)—were chosen as representative antibiotics for UV/H2O2 treatments. The objective was to determine the optimization of UV/H2O2 to remove antibiotics from aquaculture discharge water using response surface methodology. The degradation of the antibiotics was investigated under varying UV/H2O2 conditions in environments with different levels of pH, water matrices, humic acid, and constituent ions. The degradation results demonstrated that increasing the H2O2 dosage facilitated ENR degradation at a neutral pH while facilitating degradation of SMX and OTC at a slightly acidic pH. The optimum removal conditions for ENR, which was used in all influential effect experiments and the contact tank experiments, was obtained at 10 mM H2O2, a pretreated COD of 87.51 mg L−1, and an initial pH of 6.15. Among the tested anions, only the presence of Cl- showed slight positive effects on ENR degradation, due to the generation of secondary active radicals. During the reaction, the hydroxyl radical (OH) was present at a higher pH while singlet oxygen (1O2) was slightly present at a lower pH. The experimental results from H2O2 sequential addition indicated that freshly added H2O2 could quench the recently generated OH and therefore a high H2O2 concentration with frequent adding was not necessary. Our contact system reduced the ENR concentration in both the effluent reservoir and in the UV irradiation zone. The overall results supported the use of the UV/H2O2 system to treat remnant antibiotics in the discharge water. 相似文献
55.
56.
《Communications in Soil Science and Plant Analysis》2012,43(3):123-130
Abstract Corn yields and leaf samples were obtained from experimental plots receiving varying rates of N, P and K. Yields were regressed on leaf levels of N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn as independent variables. Various polynomial regressions were fitted to the yields and “goodness of fit”; of particular mathematical models was used as a basis for evaluating particular biological and statistical concepts. It was found that no regression, where chemical elements were used as ratios, fit the observations as well as a quadratic polynomial or its square root transformation. This suggests that within the set of data used, emphasis on particular cation or anion ratios does not necessarily result in the “best”; explanation of variation in yield. “Classical”; growth equations were fitted to corn yields, but were not as precise in predicting yields as the polynomials. A modified stagewise regression procedure was used for fitting one mathematical model, but results were less satisfactory than those obtained with usual least squares procedures. 相似文献
57.
Rose Luiza Moraes Tavares Zigomar Menezes de Souza Diego Silva Siqueira Newton La Scala Júnior Alan Rodrigo Panosso 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(8):755-762
Sugarcane management systems affect soil attributes such as the carbon cycle. This fact has stimulated the sugar and alcohol industry to refine the sugarcane production systems by replacing the pre-harvest burning (PB) and manual harvest with mechanized harvesting followed by residue deposition. The aim of this study was to evaluate different management systems with respect to C cycling carbon dioxide and soil parameters (chemical, physical and biological) which were determined over the season. Three sugarcane cultivation systems were evaluated at the following periods: (a) PB, (b) 5-year green harvest and (c) 10-year green harvest. The results indicated that CO2 emission was 36% greater in the 10-year sugarcane green harvest system than in the PB system. The bulk density and macroporosity were the factors that were most affected by the different sugarcane management systems and that significantly influenced soil CO2 emissions. The principal component analysis showed that soil CO2 emission was 18% influenced by base saturation (V%) and 14% by pH, especially in the PB area. Additionally, 19% was affected by carbon and macroporosity in the 5- and 10-year green harvest areas, respectively. From our results, it can be concluded that the most CO2 emissions are in the areas of sugarcane green, this is due to the higher carbon concentration when compared with the area of burning sugarcane. The parameters that most influenced the CO2 emissions were bulk density, porosity, macroporosity, pH and V%. 相似文献
58.
赵鹏 《湖南农业大学学报(自然科学版)》2013,39(5):458-462
为了明确烤烟不同生育期气候资源对烟叶品质的贡献率,以陕西安康烟区2002—2011年气象资料和烟叶化学成分为材料,采用主成分分析法,对烤烟不同生育期的平均温度、降水量和日照时数进行分析,构建不同生育期的气候综合指数(CCI);采用相关分析、通径分析和决策分析对各生育期CCI与烟叶化学成分的关系进行分析。结果表明:不同生育期CCI对烟碱含量的影响以采烤前期最大,旺长期最小,对采烤前期的影响主要为直接作用;对烟叶总糖含量的影响以采烤后期最大,采烤前期最小,对采烤后期的影响主要为直接作用和通过旺长期的间接作用;对烟叶糖碱比的影响以采烤后期最大,旺长期最小,采烤后期的影响主要为直接作用和通过采烤前期的间接作用。 相似文献
59.
祁连山是我国西部重要的生态屏障,拥有大量的草地资源。研究草地土壤细菌群落组成及其与土壤环境因子间的关系,可对维持草地生态及了解祁连山土壤细菌群落组成提供一定的数据基础。采用高通量测序技术检测并分析了祁连山默勒镇3种类型草地 (高寒草甸、人工草地、沼泽化草甸)0~10 cm土壤细菌群落结构及多样性,并对上述土壤细菌群落与土壤理化因子的相关性进行了系统的研究。结果表明:1)沼泽化草甸土壤全氮、全磷、有机质碳、含水量和硝态氮显著高于高寒草甸和人工草地(P<0.05)。2)3地共测得有效序列1022446条,以97%的一致性将序列聚类,高寒草甸、人工草地、沼泽化草甸OTU聚类均值分别是4917、5233、5075条。3)Shannon和Simpson多样性指数3地间差异不显著,Chao1指数表现为人工草地>高寒草甸>沼泽化草甸(P<0.05)。4)在门水平上,3地均以变形菌门、酸杆菌门、放线菌门和浮霉菌门为主要类群;在属水平上,表现出不同类型草地细菌富集类型不同。5)有机质碳、全磷、土壤含水量与土壤细菌群落的组成表现出极显著相关(P<0.01)。综上,祁连山地区小生境内3种草地土壤微生物群落存在差异,有机质碳、全磷、土壤含水量是影响群落的主要驱动因子。 相似文献
60.
为研究不同利用方式对藏北高寒草甸建植一年生燕麦(Avena sativa Linn.)人工草地的土壤理化性质及土壤细菌群落的影响,本试验于8月份植物生长旺季,在持续利用人工草地(AG)、撂荒人工草地(AC)和对照天然草地(NG)采集土壤样品,分析了土壤理化性质、土壤细菌群落组成和结构特征变化。结果表明,AG样地土壤有机质、全钾含量和pH与NG样地相比无显著性变化,土壤全氮、速效氮和速效钾含量显著降低;AC样地与NG样地相比土壤pH显著升高,土壤有机质、全氮、速效氮和速效钾含量显著降低。AG样地土壤细菌群落Chao1,Shannon和Pielou均匀度指数显著高于NG样地,AC样地酸杆菌门和变形菌门丰度显著升高。土壤理化性质是土壤细菌群落结构组成门、属相对丰度变化主要影响因子。综上所述,高寒草甸一年生燕麦人工草地长期利用应科学补充肥料,保持土壤肥力;草地撂荒需谨慎,应及时采取恢复措施避免草地发生退化。 相似文献