共查询到19条相似文献，搜索用时 281 毫秒
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Fe^3＋、Fe^2＋离子对叶绿素的稳定性影响研究 总被引：1，自引：0，他引：1
叶绿素铁钠盐与叶绿素亚铁钠盐在生产制备中易受皂化溶液的PH值、温度、时间,铁代处理时间,离子浓度等的影响.因此,我们对皂化和铁代条件进行筛选并对色素的稳定性进行了研究.结果表明,用5%NaOH溶液,在60℃加热60min皂化完全,Fe3+离子在酸化PH为3.0,铁代温度为60℃,铁代时间为60min,Fe3+离子浓度为0.4moVL时铁代最完全.Fe2+离子在酸化PH为4.0,铁代温度为40℃,铁代时间为40min,Fe2+离子浓度为0.5mol.L时铁代最完全.所得叶绿素铁钠盐与叶绿素亚铁钠盐在PH值为3～6时稳定性较好,对室内光、热稳定性好. 相似文献
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刘振 《西安文理学院学报》2015,(2):17-19
以电导率法测定乙酸乙酯皂化反应速率常数是大学物理化学专业必修动力学实验之一,但在实际操作过程中,溶液反应的起始与终了浓度均难以精确测定.通过对该实验的改进,通过模拟电导滴定的方式准确测定皂化反应起始与终了浓度,较传统方法相比具有操作简便、测量结果准确的优点. 相似文献
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唐美春 《邵阳学院学报(社会科学版)》1997,(2)
本文介绍了二反应物初始浓度不同时,乙酸乙酯皂化反应速度常数k和活化能E_α的测定方法,并且在不需知道乙酸乙酯的初始浓度情况下,利用电导法所测得的数据进行处理,所得结果与文献值一致. 相似文献
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杨雁波 《佳木斯教育学院学报》2012,(5):471-472,477
研究了从黎蒿叶中提取叶绿素及制备叶绿素铜钠盐的最佳条件,结果表明黎蒿叶叶绿素提取的最佳条件为:乙醇浓度85%;料液比1:8;提取温度为80℃;浸提时间为4h;叶绿素铜钠盐制备条件为:皂化pH为11-12,65℃皂化30 min,酸化pH为2-3,65℃酸化20min;15%硫酸铜,铜代1h。 相似文献
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积屑瘤是在切削塑性金属材料时,在一定切削速度范围内形成带状切屑情形下,切屑底层金属粘在前刀面上经过加工硬化并参与切削形成的.那么其存在的条件有两个,一是切屑与前刀面有足够的冷焊面积,二是积屑瘤有足够的加工硬化强度,足以代替刀具进行切削.故只要我们选用润滑性能好的切削液,降低切削温度,减小刀具与切屑的冷焊面积,或者是提高切削速度,提高切削温度,降低切屑底层金属的屈服强度,再就是增大刀具前角在35°以上,就能防止积屑瘤的产生. 相似文献
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根据超声光栅测量声速的原理,使用超声光栅声速仪测量并计算出超声波在不同浓度和温度条件下该溶液中的传播速度.通过对比不同浓度、不同温度的NaC1溶液中的声速并对其进行数据拟合,得出声速与溶液浓度、声速与溶液温度的关系.实验结果表明,在相同温度,浓度3％ ～15％,声速随溶液浓度的增加而增加,并显现出良好的线性关系;利用温度递增研究了3％ NaCl溶液和清水中超声传播的速度,声速与温度显现出良好的线性关系,声速随液体温度的增加而递增. 相似文献
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以自制的大豆油基微乳化切削液为研究对象,在对国内外微乳化切削液生物降解性试验方法研究现状和发展趋势进行综述的基础上,参照OECD301D的方法,以市售SC3209型微乳化切削液为对比液,拟通过测定CODcr、BOD5值及计算两者的比值,来确定所研究的微乳化切削液的生物降解性.实验结果表明,研制的微乳化切削液BOD5/CODcr为0.36,大于0.30,可以生物降解.即这种微乳化液的废液渗入陆地或流入水体中是可生物降解的.研制的微乳化切削液的基础油为大豆油属于天然的植物油,而各添加剂基本上都是易生物降解的. 相似文献
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To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to evaluate the influence of cutting fluid properties on the machinability of glass. The sodium carbonate solution of 10.5% concentration was chosen as cutting fluid. Then the critical depths in scratching experiments with and without cutting fluid were examined. Based on this, turning experiments were carried out, and the surface quality of SF6 was assessed. Compared with the process of dry cutting, the main indexes of surface roughness decrease by over 70% totally. Experimental results indicated that the machinability of glass SF6 can be improved by using the sodium carbonate solution as cutting fluid. 相似文献
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KHAN M.M.A DHAR N.R. 《浙江大学学报(A卷英文版)》2006,7(11):1790-1799
In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication （MQL） has been suggested since a decade ago as a means of addressing the issues of environmental intrusiveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction. 相似文献
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赵淑玲 《漯河职业技术学院学报》2013,12(5):43-45
阐述了不锈钢的加工特点,并从化学和物理的角度对其难切削加工的特性进行了分析,对切削不锈钢所使用的刀具材料、刀具几何参数的确定进行了说明,对切削用量的选择进行了具体的描述,并对切削液的使用提出了建设性的看法。 相似文献
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吕世国 《广东技术师范学院学报》2010,(9)
根据薄壁零件加工特点,对黄铜薄壁件原有工艺方案所存在的问题,结合装夹方案、切削液、切削参数与刀具选择等因素进行分析,并进行工艺改善得出适合的加工方案.从而指出,这种薄壁零件的加工方法,稳定可靠,工件的安装、加工方便,能有效地保证加工质量. 相似文献
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In order to improve the present aviation ejection escape system, the application of explosion cutting technique to aviation escape system is proposed to weaken the strength of canopy before ejecting it. A series of mini cutting explosives are designed to investigate the process of splitting PMMA plate. The phenomenon of spallation in PMMA is observed. The effects of different parameters of mini cutting explosives on the cutting depth are obtained. Consequently the appropriate material of half-circular metal covers, explosive types and the ranges of charge quantities are determined. On the other hand, the cutting process of aviation PMMA plate by mini cutting explosives is simulated by means of nonlinear dynamic analysis code LS-DYNA. In finite element analysis,Arbitrary Lagrangian Euler (ALE) algorithm is used to depict the fluid property of high energy explosives. Continuous damage material model is used to simulate the complicate dynamic damage behavior of PMMA due to explosion shock waves. Only sliding contact option is defined to fulfill the fluid-structure interaction between explosives and PMMA plate by distributed parameter methods. Phenomenon of spallation observed in the experiment is presented in the simulation. The relationship between the penetration depth of PMMA plate and charge linear density obtained by numerical simulation agrees well with experimental result. 相似文献
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为了使物理化学实验中的数据计算、处理、作图更加便捷,以乙酸乙酯皂化反应为例,使用电子表格进行处理,首先对Excel电子表格进行了数学计算模式设计,然后根据数学计算要求编制了计算公式,给出了具体处理方法的详细过程,研究了具体实例的数据处理.结果表明该方法处理二级反应——乙酸乙酯皂化数据,方法简单,操作步骤少,处理速度快,避免了人为误差. 相似文献
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用电导法测定乙酸乙酯皂化反应速率常数是物理化学动力学部分的一个重要实验．电导率仪作为一种常用的电化学分析仪器有着广泛的用途,但使用中一般都需要手工绘制电导率——时间变化图,数据处理工作量大且准确度受到影响,这在一定程度上限制了电导测定方法的普遍应用．本实验采用手持技术仪器,通过计算机处理数据,具有定量、便携、实时、准确、直观、综合性强等特点,是实现改革扣发展的有效手段,也为深刻理解乙酸乙酯皂化反应提供了技术条件． 相似文献