共查询到20条相似文献，搜索用时 62 毫秒
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样品处理后,用火焰原子吸收法连续测定白云石中的氧化钾、氧化钠和氧化镁。氧化钾、氧化钠质量浓度在0-1ug／ml范围内呈良好的线性关系．以镁的202．6nm次灵敏线测定样品中的氧化镁,氧化镁的质量浓度在0—30ug／ml范围内呈良好的线性关系。方法的相对标准偏差（RSD％,n=11）为0．3％~9％,加标回收率为95％-100％。 相似文献
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催化荧光法测定痕量铜(Ⅱ) 总被引：1，自引：0，他引：1
在pH值=8．0的B-R缓冲液中，痕量铜(Ⅱ)(Cu^2 )对过氧化氢与罗丹明B的氧化反应具有催化作用，使罗丹明B的荧光减弱．据此建立了一种测定痕量Cu^2 的新方法．方法检测限为1．52ug／L，测定范围为0．03～O．3mg／L．本法用于测定牡蛎样品中Cu^2 的测定，平均回收率为99％． 相似文献
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本文主要是运用GMS软件,以氯代烃的典型污染区为模拟区,以三氯乙烯和四氯乙烯为模拟对象,在水流模型的基础上建立溶质模型,进行识别和验证,并根据模拟结果分析氯代烃在地下水中的迁移转化规律。模拟的结果表明,四氯乙烯和三氯乙烯的降解主要与氧化还原环境有关。模型中四氯乙烯和三氯乙烯的阻滞系数在地下水中相差不大,分别为6.52和6.34。但四氯乙烯的降解系数约为三氯乙烯的6倍。从整体上看,三氯乙烯和四氯乙烯污染羽的范围有不同程度的扩大,且浓度不断的降低。 相似文献
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分光光度法测定食品中的微量镉 总被引：2，自引：0，他引：2
白晓朝 《宁夏师范学院学报》2004,25(6):30-32
探讨在聚乙烯醇存在下，镉(Ⅱ)—碘化钾—罗丹明B分光光度法测定食品中微量镉的可行性。讨论了影响测定结果的因素，确定了最佳反应条件．镉浓度在0—1．5ug／25mL范围内符合比尔定律，镉的回收率为95％-105％． 相似文献
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建立了牛肉和猪肉中3种有机磷类农药基质固相分散一高效液相色谱分析方法。方法：样品经基质固相分散装柱,乙腈一7．k．（20：80,v／v）洗脱净化,浓缩后c,。分离分析,高效液相色谱紫外检测。结果：检测条件下,3种农药线性良好,线I}生相关系数大于0．9959,对牛肉和猪肉加标1．0ug/kg、5．0．ee＇kg和10．0ug/kg三水平,平均回收率在82．2％～100．9％,变异系数小于7．8％,方法的最低检测限0．03～0．08ug/kg。结论：该方法可以满足实际样品的分析和食品安全控制。 相似文献
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建立固相萃取与UPLC—MS／MS检测食品中黄曲霉毒素M1和黄曲霉毒素B1的方法。样品经乙腈提取和SPE小柱萃取净化,提取液经氮气吹干后,用50％甲醇水溶液定容。超高效液相色谱一串联质谱（UPLC—MS／MS）测定,采用电喷雾正离子（ESI＋）模式电离,多反应监测（MRM）模式检测。流动相为0．1％甲酸水溶液和甲醇,流速0．4ml／min,使用ZORBAX Eclipse XDB—C18色谱柱（100mm×3．0mm×1．8μm）为分析柱。黄曲霉毒素AFM1在0．1～50μg／kg范围内线性关系良好、黄曲霉毒素AFB1在0．1～10ug／kg范围内线性关系良好,相关系数均大于0．999;回收率在83．75％～97．8％之间;检出限AFMl为0．05μg／kg、AFBl0．02μg／kg。该法具有分析速度快,检测准确、灵敏度和回收率高等优点,适合食品中黄曲霉毒素M1、B1含量的检测。 相似文献
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采用离子色谱电导检测法测定皮革制品中Cr（Ⅳ）,选用Metrohm86I型离子色谱仪,Metrosep A Supp5—150型阴离子分析柱,12．8mmol／LNa2C03＋4．0mmol／LNaHC03淋洗液．在10～100μg／L范围内,Cr（Ⅳ）的浓度与色谱峰面积呈线性关系,线性方程为C×100—2893．72×A＋200．136,相关系数为0．9990,最低检测浓度为4μg／L,低、中、高三个浓度的精密度分别为1．60％、1．05％、0．65％,样品加标回收率分别为91．5％、93．6％和92．3％,本方法可用于皮革中Cr（Ⅵ）的测定． 相似文献
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离子色谱法测定饮用水中钠、镁、钙 总被引：1，自引：0，他引：1
本研究了离子色谱法测定饮用水及源水中钠、镁、钙离子的方法。实验表明，该方法灵敏度高，重现性好，操作简便，分析快速。在本方法实验条件下．钠、镁、钙方法检出限，分别为：0．013mg／L；0．013mg／L；0．025mg／L。相对标准偏差分布在0．07-0．76％，加标回收率分布在99-102％。 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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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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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