共查询到20条相似文献，搜索用时 62 毫秒
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研究载氟氧化铝中氟含量的测定方法,采用氟离子选择电极在PH为6～7的总离子强度调节缓冲溶液介质中,氟离子浓度在0.475～4.75ug/ml之间呈现良好线性关系,方法灵敏性和选择性较好,回收率在96.8%～101.6%之间.能够很好的应用于载氟氧化铝中氟含量的测定. 相似文献
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《赤峰学院学报(自然科学版)》2020,(2)
气相色谱法可测定牙膏中可溶性氟、氟化物的含量.本实验是用氢氧化钠溶液溶解牙膏,得到牙膏中氟化钠待测液,配置氟化钠标准溶液和牙膏标准溶液,通过气相色谱对标准溶液的峰高、峰宽和峰面积的测定,以峰面积-浓度绘制标准曲线,利用标准曲线计算牙膏中可溶性氟和氟化物的含量.实验结果表明:牙膏中可溶性氟的含量≧400mg/kg,氟化物的含量≦1500mg/kg,符合国家规定.该方法快速简便,准确性高,可作为牙膏中可溶性氟和氟化物含量测定的方法. 相似文献
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曾琪 《四川职业技术学院学报》2013,23(3):151-153
本文用直接电位法测定了牙膏中的氟.用预先煮沸并冷却的蒸馏水溶解样品,在溶液pH值为5.5~6.5的条件下进行测定,用标准曲线法计算出样品中的氟含量.线性回归方程为Y=61.693x-79.529,线性相关系数为R=0.9991,样品的加标回收率为99.15%～102.05%,方法操作简单、选择性好、成本低、准确度高. 相似文献
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离子选择性电极在氟离子测定中的应用 总被引：1，自引：0，他引：1
本文利用氟离子选择性电极对氟离子的高选择性,建立了对运城市盐湖区自来水和绿茶中氟含量的测定方法.实验测定了F-的选择性系数,并选择了测定F-的适宜pH范围.结果表明,F-测定的线性范围为0.05~10mg/L,根据IUPAC建议,计算出该方法测定F-的检出限为3×10-5mg/L,对浓度为0.05mg/L的F-标准溶液进行11次平行测定的精密度为0.26%.该法具有灵敏度高,选择性好等优点,可以用于样品中氟含量的测定,结果令人满意. 相似文献
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为了测定开封市不同地点水源中氟的分布,采用氟离子选择电极作指示电极的直接电位法对7个地点水源中的氟进行了测定。该测定所建立的回归方程为E=-54.45pF-160.8,r=0.9991,线性范围0.4～2mg.L-1。平均回收率为100.8%,RSD=2.58%。开封市不同地点水源中氟的含量在0.5875～2.2744mg.L-1之间。 相似文献
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氟电极毫伏值数据转换方法研究 总被引：1，自引：0，他引：1
改进、统一、量化氟电极毫伏值转换为样品氟含量数据处理方法,使各种样品的氟化物测定结果更接近真值,方法间的测定结果具有可比性;选用标准加入法、标准加入微量曲线法、标准加入常量曲线法,对氟离子选择电极测得毫伏值转换为样品氟含量的数据处理方法进行了研究和改进;改进后方法的回收率达99%;变异系数小于2.73%氟离子选择电极测定微量氟不仅实验方法要定标准,而其测定所得毫伏值转换为样品氟含量的数据处理方法也应规定统一的标准。 相似文献
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研究了在高含量钙溶液中用氟离子选择性电极标准曲线法测定氟的条件．实验表明,以大于0.01mo·L-1 EDTA为掩蔽剂可以有效排除Ca2 离子的干扰．在F-浓度为10-2 ～10-6 mol·L-1浓度范围,可得到EF-～logCF-直线关系．该法可用于含钙溶液中氟的准确测定． 相似文献
8.
《嘉应学院学报》2020,(3):38-42
pH值为2～9的Fe(Ⅲ)溶液中,加入对乙酰氨基酚,将Fe(Ⅲ)定量还原为Fe(Ⅱ),Fe(Ⅱ)离子与邻菲罗啉形成橘红色配合物(λmax=511 nm).结果表明,对乙酰氨基酚含量(ρ)4.00～48.00μg·mL~(-1)范围内,配合物溶液吸光度与对乙酰氨基酚含量呈良好的线性关系,其线性回归方程为A=0.021ρ+0.052 8,线性相关系数r=0.999 7.方法用于感冒药中对乙酰氨基酚含量的测定,测定的相对标准偏差为0.3%～0.7%(n=10),加标回收率为95.6%～101.6%(n=10),方法检出限为0.71μg·mL~(-1),测定结果与药典法相近. 相似文献
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水中微量氟的电位法测定 总被引：1，自引：0，他引：1
刘丹萍 《郧阳师范高等专科学校学报》2002,22(3):88-89
通过对氟离子在氟电极上电位响应 ,提出了电位分析法测定水中微量氟的方法 .该方法简单、快捷、灵敏 .用此法对水样中微量氟进行了测定 ,获得满意效果 . 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
14.
Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
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正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
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《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献
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《重庆大学学报(英文版)》2014,(2)
正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof. 相似文献