共查询到20条相似文献，搜索用时 78 毫秒
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林宏伟 《郧阳师范高等专科学校学报》2004,24(6):24-26
建立了以银催化过硫酸钾氧化孔雀绿褪色的动力学光度法测定痕量银的新方法.实验确定了反应最佳条件,研究了动力学参数.该方法线性范围20～180μg/L.对40μg/LAg(Ⅰ)测定的相对标准偏差为1.7%(n=11).应用黑白相纸中银的测定,相对标准偏差为1.1%～1.6%,回收率为:97.7%～98.2%. 相似文献
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痕量铜的新催化光度法测定 总被引：1，自引：0，他引：1
研究了铜(Ⅱ)催化双氧水氧化溴百里酚兰褪色的催化效应及动力学条件,建立了测定痕量铜的新催化光度法.该法标准曲线的线性范围为铜(Ⅱ)浓度0～0.5μg/25mL,检出限为0.009μg/25mL,方法简便、快速、准确,用于铝合金中痕量铜的测定,回收率为96.0%～98.3%. 相似文献
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在硝酸介质中,硒(Ⅳ)能催化溴酸钾氧化亚甲蓝使之褪色.利用这一催化反应的动力学条件,建立了一种动力学光度法测定痕量硒(Ⅳ)的方法,其灵敏度为1.06×107g/L Se(Ⅳ).Se(Ⅳ)的含量在0-8μg/L范围内与褪色反应速率lg(A0/A)呈正比.通过萃取纯化,使方法具有良好的选择性和准确度,用于测定富硒平菇中的硒结果满意. 相似文献
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在pH为9.0的NH4Cl-NH3.H2O缓冲介质中,研究了Cu(Ⅱ)-苯基荧光酮(PF)-Triton X-100析相体系的最佳显色条件及其吸收光谱的分析特性.结果表明,Cu(Ⅱ)-PF-Triton X-100胶束溶液在95℃下加热1 h,配合物即被Triton X-100相完全富集,其最大吸收峰为546 nm,铜含量在0.5~8μg/5ml,符合比耳定律,表观摩尔吸光系数ε为4.7×104L.mol-1.cm-1;并尝试以氟化钾、酒石酸钾钠、柠檬酸钠为掩蔽剂,应用于食品中铜含量的测定,结果令人满意. 相似文献
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利用痕量铁在pH=4.0的HAc-NaAc介质中能催化H2O2、氧化苯酚红的反应.在催化条件下,表观活化能增加55%的原理,建立了动力学分光光度法测定痕量铁的新方法.此法线性范围为0.1-0.8 μg/ml. 相似文献
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《赤峰学院学报(自然科学版)》2016,(7)
基于在p H=11.0的NH3-NH4Cl缓冲溶液中,在邻菲啰啉存在下,铜(Ⅱ)对双氧水氧化紫脲酸铵的褪色反应具有催化作用,建立了催化动力学光度法测定微量元素铜(Ⅱ)的新方法.该方法的线性范围为0.01~0.15μg/m L,检出限为1.4×10-3μg/m L.对0.1μg/m L的铜(Ⅱ)进行11次测定,测得相对标准偏差为1.3%,用于样品(海带、延河水)中微量铜的测定,结果满意. 相似文献
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用阳离子交换柱的HPLC法同时测定注射用氨苄西林钠/ 氯唑西林钠中氨苄西林和氯唑西林的含量.色谱条件:采用HypersilSCX柱,磷酸盐缓冲液(0.01mol/ L磷酸氢二铵溶液,用磷酸调节pH值6.0):乙腈(90:10)为流动相,检测波长225nm.氨苄西林和氯唑西林分别在45～134和44～131μg/ml范围内呈良好的线性关系,日内RSD分别为0.5%和0.6%,回收率分别为99.9%和100.0%,含量测定结果与国家药品标准方法所得结果相符. 相似文献
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催化动力学光度法测定红枣中的硒 总被引：2，自引：0，他引：2
在硝酸介质中 ,硒 (IV)能催化溴酸钾氧化亚甲蓝使之褪色。研究了这一催化反应的动力学条件 ,建立了一种动力学光度法测定Se(IV)的新方法。其灵敏度为 4.0 10- 7g/l,se(IV)的含量在 0 - 8μg/L范围内与褪色反应率lg(A0 /A)成正比 ,方法用于红枣中硒的测定 ,结果满意 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 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
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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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