共查询到20条相似文献，搜索用时 203 毫秒
1.
采用微波辅助提取技术,以臭牡丹黄酮类化合物的提取率为考察目标,利用溴化1-丁基-3-甲基咪唑溴([bmim]Br)离子液体水溶液为提取剂,提取臭牡丹中黄酮类化合物.分别考察了离子液体浓度、料液比、微波功率、p H值、提取温度和时间对臭牡丹黄酮类化合物提取率的影响.结果显示,臭牡丹黄酮类化合物的最佳提取工艺条件为:离子液体浓度为1.0 mol/L,料液比为1∶30,微波功率为500 W,p H值为8.0,提取温度为70℃,提取时间为6.0 min,在此条件下提取率可达4.318%.与传统乙醇提取法相比,该方法具有快速高效、溶剂使用量少、绿色环保、提取率高等优点. 相似文献
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《河南职业技术师范学院学报(职业教育版)》2020,(1)
为了研究离子液体对作物的毒性效应,以周麦18、百农207和百旱207三种小麦为试验材料,研究了不同质量浓度(0 mg/L、100 mg/L、300 mg/L、500 mg/L和700 mg/L)的离子液体1-己基-3-甲基咪唑溴化盐对三种小麦种子萌发和幼苗生长的影响.结果表明:三种小麦的发芽率、株高和鲜质量都受到抑制作用,当质量浓度达到300 mg/L时,与对照相比都有显著性差异;三种小麦叶片的相对电导率和丙二醛的量与对照相比有显著升高,当质量浓度为700 mg/L时,达到最大值.说明离子液体对三种小麦都有一定的毒害作用,且随着离子液体质量浓度增加毒害作用也逐渐增大;三种小麦对离子液体的响应也不同,相对而言,百农207耐受性更强. 相似文献
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本文讨论了离子强度对盐类水解浓度平衡常数影响 ,指出在一定温度下 ,离子强度的增大 ,对一元弱酸强碱盐和强酸弱碱盐的水解浓度平衡常数趋向无影响 ;使一元弱酸弱碱盐的水解浓度平衡常数Kch 减小 ;对多元弱酸强碱盐的最后一级水解浓度平衡常数趋向无影响 ,其余各级水解浓平衡浓度平衡常数减小 ,以及相邻两级水解浓度平衡常数Kchi与Kch(i 1 ) 的比值减小 相似文献
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对教师期望效应的反思 总被引：1，自引：0，他引：1
罗森塔尔的“教师期望效应”实验表明,教师期望是教学过程中对学生的影响的一个重要因素。但事实上,教师期望所产生的效应是有正负之分的。本文详细分析了教师期望负效应的表现及相关原因,并提出一些避免教师期望负效应的对策。 相似文献
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主要探讨4-AAP分光光度法测定痕量酚过程中各种因素对其测定结果的影响,并通过比较实验考察不同影响因素对测量精确度的影响程度。除探讨了pH值、4-AAP用量、温度等传统的影响因素外,同时还讨论了金属离子、有机物等因素对测定结果的影响,实验结果表明:pH值、锌离子、苯胺会对测定结果产生较大影响,而4-AAP用量、温度、铜离子和甲醛对测定结果的影响较小。 相似文献
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影响高强高模聚乙烯醇（PVA）纤维原液可纺性的关键因素有PVA的醋酸根含量及聚合度;纺丝原液中的PVA浓度及溶解程度、添加剂及硼酸加入量,纺丝过程中喷丝头的电位及电化学腐蚀;凝固浴中钙镁离子含量等。本文在多年生产过程中研究了上述控制参数对原液可纺性的影响,并提出了防范措施。比如在PVA中残存醋酸根含量≤0．05％、聚合度1850＋50、PVA浓度15．8％时可纺性较好,同时也对PVA的浸泡时间、浸泡温度、纺丝过程中喷丝头的处理等提出了指导建议。没有发现聚乙烯醇的其它指标与高强高模PVA纤维原液的可纺性有直接的关系。 相似文献
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《浙江大学学报(A卷英文版)》2016,(5)
目的:探讨矿渣固化氯盐渍土强度变化规律及作用机理,为氯盐渍土有效固化提供依据。创新点:评价矿渣固化高含盐量氯盐渍土的效果,分析矿渣固化氯盐渍土固化机理,提出具有一定适用性的拟合关系式。方法:通过固化土无侧限抗压强度试验、X射线衍射、能谱分析、热重及液相离子浓度测试对固化氯盐渍土强度及微观结构进行分析。结论:1.氯化钠是影响矿渣固化氯盐渍土强度的主因;2.矿渣固化氯盐渍土强度随土中含氯量增加而增强,铝酸钙与氯化钠反应生成的水化氯铝酸钙填充孔隙及氢氧化钠提高液相碱度是增强固化土强度的主因;3.通过固化土强度增量曲线拟合分析,得到矿渣固化氯盐渍土强度增量与含氯量关系式。 相似文献
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不同施氮量配施饼肥对烤烟生长及产质量的影响 总被引：3，自引：0，他引：3
研究了不同施氮量配施饼肥处理对烟株生长及产质量的影响,结果表明,烟株农艺性状主要受施氮量的影响,增施饼肥对不同施氮量处理农艺性状影响较小.烟叶产量、上等烟比例、上中等烟比例、均价、单位面积产值、单叶重、烟碱、总氮、还原糖/烟碱比和总氮/总烟碱比同时受施氮量和饼肥的影响,但施氮量对其影响较大,饼肥对其作用仅在较低施氮量时表现较为明显.总糖、还原糖含量和总钾/总氯比仅受施氮量影响,受饼肥影响较小. 相似文献
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张志刚 《福建工程学院学报》2014,(6):557-561
采用柚子皮制备生物吸附剂用于去除水中的Cr(VI),考察了p H值、柚子皮投加量、柚子皮粒径、溶液离子强度、反应温度等因素对吸附效果的影响。结果表明,当溶液中Cr(VI)离子初始浓度15mg/L、p H 1.5、反应温度25℃、柚子皮投加量1.0g/100 m L、吸附时间7 h时,Cr(VI)离子去除率可达90%以上。柚子皮对Cr(VI)离子的吸附过程可以用Langmuir和Freundlich吸附等温模型来描述,吸附等温线线性相关性均较显著,吸附过程符合准二级动力学方程。柚子皮对水中Cr(VI)离子吸附性能较好,且运行成本低,可推广应用于水中重金属离子的治理。 相似文献
11.
The effects of the concentration of dissolved total organic carbon(TOC),the TOC/Br-ratio,bromide ion levels,the chlorine to ammonia-N ratio(Cl:N),the monochloramine dose and the chlorine dose on the formation of trihalomethanes(THMs)(including chloroform,bromodichloromethane,chlorodibromomethane,and bromoform)from chlorination were investigated using aqueous humic acid(HA)solutions.The profile of the chloramine decay was also studied under various bromide ion concentrations.Monochloramine decayed in the presence of organic material and bromide ions.The percentage of chloroform and brominated THMs varied according to the TOC/Br-ratio.Total THMs(TTHMs)formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from 0.67 to 6.72 mg/L,but the chlorine-substituted THMs were replaced by bromine-substituted THMs.A strong linear correlation was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1.These ratios had a distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane.The presence of bromide ions increased the rate of monochloramine decay. 相似文献
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The effects of the concentration of dissolved total organic carbon (TOC), the TOC/Br- ratio, bromide ion levels, the chlorine to ammonia-N ratio (Cl:N), the monochloramine dose and the chlorine dose on the formation of trihalomethanes (THMs) (including chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) from chlorination were investigated using aqueous humic acid (HA) solutions. The profile of the chloramine decay was also studied under various bromide ion concentrations. Monochloramine decayed in the presence of organic material and bromide ions. The percentage of chloroform and brominated THMs varied according to the TOC/Br- ratio. Total THMs (TTHMs) formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from 0.67 to 6.72 mg/L, but the chlorine-substituted THMs were replaced by bromine-substituted THMs. A strong linear correlation was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1. These ratios had a distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane. The presence of bromide ions increased the rate of monochloramine decay. 相似文献
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原油中的氯分为有机氯和无机氯两种形态。在原油加工过程中,原油中的无机氯和有机氯水解生成大量的HCl,在水存在时具有强腐蚀性,它给加工装置的防腐蚀工作和安全生产带来了很大的压力。文章针对常减压蒸馏装置塔顶氯离子偏高的实际问题,对试用TLV-1原油氯转移剂的过程进行分析,对试验效果进行总结和讨论。 相似文献
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To guarantee the safety of drinking water quality after chlorination, the formation, distribution and factors influencing the concentrations of haloacetic acids (HAAs) in a water distribution system (WDS) were investigated both on a full-scale WDS (FWDS) and pilot-scale WDS (PWDS) within a city in northern China. The results of both investigations showed that trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were the dominating types of HAAs. In the FWDS, variations in the HAA content showed negative correlations with total residual chlorine, pH and non-purgeable organic carbon (NPOC) and positive correlations with temperature and UV254. In the PWDS, the concentration of HAAs after rechlorination followed the rule of ‘first rise and then fall’; therefore, locating an appropriate rechlorination point and lowering the single chlorine dosage could be used as effective measures to control the HAA content in WDSs. 相似文献
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通过对衡水湖水体的氯离子含量、磷含量,COD含量、溶解氧量,水温分析,结果显示:香蒲对水体的氟离子含量的变化没有明显影响;对水域中COD含量的影响也不是主要的;但香蒲可使水域中磷含量升高、使水中的溶解氧量提高;秋季由于香蒲的遮荫作用,水温升高较慢. 相似文献
16.
王艳 《武汉工程职业技术学院学报》2002,14(4):5-8
本文根据现有文献中的实验数据，应用数值计算方法中的曲线拟合的最一乘法，建立了溴化锂吸收式制冷机发生器放热系数的数学模型，使离散数据连续化，为溴化锂吸收式制冷机组的计算机控制打下了基础。此外，本文首次定量地揭示了水在溴化锂溶液中的含量对放热系数的影响。 相似文献
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Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion. 相似文献
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Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion. 相似文献
19.
Huan Wang Dong-mei Liu Zhi-wei Zhao Fu-yi Cui Qi Zhu Tong-mian Liu 《浙江大学学报(A卷英文版)》2010,11(2):143-150
The formation of brominated trihalomethanes （THMs-Br） which is proved more carcinogenic than their chlorinated analogues reported was very different at various water qualities. This study was performed to assess the effects of water quality parameters （bromide concentration, pH value and ammonia concentration）, chlorination conditions （chlorine dose, reaction time） and ratios of Br^-/DOC and Br^-/Cl2 consumption on the formation and distribution of THMs-Br in chlorination. The results showed good correlation between the bromine incorporation factor （BIF） n（Br） and Br^-/Cl2 consumption ratio. The formation of total THM （TTHM） was found to＇ decrease with increasing ammonia concentration but to increase with bromide concentration and pH value. The n（Br） trends were significantly affected by the presence of bromide concentration. The effects on the molar yields of THMs were more strongly influenced by bromide concentration and dissolved organic carbon （DOC） concentration than pH value and natural organic matter （NOM） source. High Br^-/DOC and Br^-/Cl2 favor the formation of THMs-Br over chlorinated THMs （THMs-Cl）. The experimental data including the main parameters such as bromide, DOC, ammonia, pH and reaction time were used for developing the predictive model for THMs-Br. 相似文献
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为了研究不同环境下二氧化氯的消毒效果及其稳定性,试验以大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、白色念珠菌为测试菌株,采用菌悬液定量杀菌试验、压缩雾化法和平板计数的方法,对二氧化氯的杀菌效果进行试验。结果表明：在菌液密度为5×10^6 CFU/mL的条件下,90 mg/L的二氧化氯作用5 min,即可对测试菌株达到100%的杀灭效果。不同的pH值、温度及不同浓度有机物存在的条件下,二氧化氯同样具有极强的消毒效果。雾化的二氧化氯对空气自然菌及雾化菌液气溶胶的杀灭效果同样可以达到100%。试验表明二氧化氯作为一种高效、稳定的广谱消毒剂具有良好的杀菌效果。 相似文献