共查询到20条相似文献，搜索用时 78 毫秒
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基于亚硝酸根与碘化钾反应生成单质碘，碘可使异硫氰酸荧光素发生荧光猝灭的原理，采用流动注射连续可更新液滴荧光法测定亚硝酸根．体系的激发和发射波长分别为492nm和516nm，亚硝酸根含量在25～100μg／L范围内有良好的线性关系，检测限为3．9μg／L．本方法灵敏度高，选择性好，操作简单．用于环境水样中痕量亚硝酸根的测定，结果满意． 相似文献
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基于亚硝酸根与碘化钾反应生成单质碘,碘可使异硫氰酸荧光素发生荧光猝灭的原理,采用流动注射连续可更新液滴荧光法测定亚硝酸根.体系的激发和发射波长分别为492nm和516nm,亚硝酸根含量在25~100μg/L范围内有良好的线性关系,检测限为3.9μg/L.本方法灵敏度高,选择性好,操作简单.用于环境水样中痕量亚硝酸根的测定,结果满意. 相似文献
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采用流动注射化学发光法测定甲磺酸酚妥拉明的含量，得出：KMnO4在酸性介质中直接氧化酚妥拉明产生化学发光，相对发光强度与酚妥拉明的浓度在5～1000μg/L范围内呈线性关系，其中r≥0．9993，最低检出限为0．82μg/L，相对标准偏差为2．4％（n=11）．该方法简单、快速、准确，具有较高的灵敏度和较宽的线性范围，已成功应用于注射液和血清样中酚妥拉明的测定． 相似文献
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在过硫酸钾存在下的近中性介质中,头孢噻肟钠能够增强荧光桃红的荧光强度,从而建立了荧光法测定头孢噻肟钠含量的新方法。头孢噻肟钠的质量浓度与荧光强度的变化在0．6～3．0μg/mL范围内呈良好的线性关系（1=0．9984）,对浓度为1．0μg／mL的头孢噻肟钠试液连续测定11次,相对标准偏差（RSD）为1．25％,检出限为0．0376μg／mL。该法简便、快速,结果可靠,并应用于药物制剂中头孢噻肟钠含量的测定,结果令人满意。 相似文献
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汪凤云 《商丘师范学院学报》2008,24(3):83-84
目的：建立一种准确、方便、易操作的水碘测定方法,方法：利用碘化物对砷-铈氧化还原反应的催化作用进行分光光度法测定,结果：取水样0．25mL,最低检测浓度31．μg／L,碘浓度在0—600μg／L的范围内呈良好的线性关系,相关系数r=-0．9998,回收率范围98．71％～101．44％,精密度与准确度均符合要求,多种离子均不干扰测定结果,结论：操作及计算简单快速,结果准确可靠。 相似文献
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赵晓辉 《山东教育学院学报》2008,23(2):89-91
本文建立了用1,3-环己二酮-甲醛作为荧光衍生试剂测定多巴胺的方法。多巴胺与1,3-环已二酮-甲醛反应生成一种强荧光物质。其最大激发波长是393nm,最大发射波长是450nm。多巴胺浓度在10～40μg/ml范围内与相对荧光强度存在线性关系,线性方程为C=0．1732F-29．6873,线性相关系数为0．9993,相对标准偏差为2．5％,检出限为18ng/ml,回收率为97．9-101．7％。实验了pH值,温度,放置时间,干扰离子等对测定的影响。此法可用于注射液中多巴胺含量的测定。 相似文献
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翁文婷 《泉州师范学院学报》2007,25(2):71-74
在pH为3.0~4.0的范围内,Cu2 会氧化I-并定量析出单质碘,I2与4,6-二溴荧光素反应,使其荧光发生猝灭.据此可建立一种荧光光谱间接测定微量Cu2 的方法.初步讨论了I2对二溴荧光素的荧光猝灭机理,认为主要是静态猝灭的作用.该体系的荧光发射波长为λem=531 nm.在铜含量12~170μg/mL范围内呈现良好的线性关系,回归方程为ΔIF=0.347 3C 1.546 6(C:μg/mL),相关系数r=0.998 9,检出限为5.3μg/mL.将该方法用于水样中铜离子的测定,得到较好的结果. 相似文献
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建立采用涡旋辅助浊点萃取滇重楼提取物中4个偏诺皂苷类成分,以非离子表面活性剂脂肪醇聚氧乙烯醚 AEO －9为萃取剂,V（乙腈）∶V（水）＝38∶62为流动相,对富集的偏诺皂苷进行高效液相色谱快速分离的方法．最优实验条件为,AEO －9用量为110μL,正戊酸用量为150μL,pH 为9,平衡温度为40℃,平衡时间为15 min．结果表明,检测出滇重楼中4个偏诺皂苷 VI,VII,Pa 及 H 的质量分数分别为0．9923％,1．3603％,3．3444％及1．6663％,检测限达3．2～4．0μg／L,RSD 低于0．5％,定量限为6．6～8．3μg／L,线性范围为10～500μg／L,萃取的富集倍数达到23倍,萃取的回收率为98．68％～102．46％． 相似文献
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通过使用荧光光谱法，研究了新合成的化合物2，6-吡啶二甲酰（氨基酸）胺与竞争过渡金属离子及稀土离子的配位性质。发现在pH=2.0-12.0以及溴化十六烷基吡啶存在下，该化合物可以和铜离子形成稳定的配合物，其最大激发和发射波长分别位于310nm和420nm，组成比为2：1(铜离子：配体）。当铜离子的浓度介于1.1μg/ml-32.0μg/ml范围时，配合物荧光强度与铜离子浓度呈良好的线性关系，线性方程为F=0.44757 3.98388CCu^2 (10^-3mol/L）。通过新化合物与铜离子的配位反应，初步考察了新试剂的配位特征。 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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《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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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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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献