共查询到20条相似文献，搜索用时 78 毫秒
1.
在酸性介质中,抗坏血酸对溴酸钾-酸性铬兰K-钒催化体系具有显著的活化作用,据此建立了测定抗坏血酸的新方法,并探讨了动力学条件.方法的测定范围为0.8μg～30μg/mL,检出限为2.09×10-7g/mL.方法用于药品中抗坏血酸的测定,结果满意. 相似文献
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在醋酸钠体系中,以α-α联吡啶为活化剂,用镍催化过硫酸钾氧化二氯荧光素,建立了测量海产品中的痕量镍催化动力学荧光法的分析方法.实验相关系数R=0.993 23,线性范围为0.5～5μg/L,相对标准偏差为2.94%,检出限为3.7×10-6μg/L.用该方法测定文蛤汁中的镍含量,结果令人满意. 相似文献
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本文建立了同时测定工业废水中微量的萘、α-萘酚及蒽的毛细管气相色谱方法。以二氯乙烷和氯化钠的混合液萃取水样,利用毛细管柱气相色谱-FID进行检测,以外标法定量。该方法测定的萘、α-萘酚、蒽的标准工作曲线方程分别为y=23.091x＋0.688（r=0.9996）,y=17.788x-13.136（r=0.9992）,y=25.123x-10.756（r=0.9991）,检出限（S/N=3）分别是5.3×10-4μg.mL^-1,6.9×10-4μg.mL^-1,4.9×10-4μg.m^L-1,线性范围分别是1.8×10^-3 - 40μg.mL^-1、2.3×10^-3 - 60μg.mL^-1、1.6×10^-3 - 50μg.mL^-1。对此多环芳烃体系标准混合物溶液进行了3个不同水平的添加,每个水平重复6次进样,萘、α-萘酚、蒽的平均加标回收率分别为89%-104%、97%-113%、90%-106%,相对标准偏差分别为1.7%-2.6%、1.9%-3.7%、1.8%-3.5%。相同条件下,实际工业废水样品经富集后检测,萘,α-萘酚,蒽的平均浓度分别为196.7μg.mL^-1、20.65μg.mL^-1、100.8μg.mL^-1。实验结果表明：本方法操作简便、快速、准确、灵敏度高、线性范围较宽,测定结果令人满意。 相似文献
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基于在NaOH碱性介质中,铁氰化钾可以直接氧化芦丁和槲皮素产生强的化学发光这一现象,在Hypersil ODS色谱柱上,以乙醇-0.01%醋酸铵(体积比)=2:1为流动相的条件下,实现了对芦丁和槲皮素的分离测定,建立了测定芦丁和槲皮素的方法。该法简单、灵敏度高、选择性好,可用于检测红花中的芦丁和槲皮素。芦丁和槲皮素浓度在2.0×10-7g/mL～2.5×10-5g/mL和5.1×10-7g/mL～1.3×10-4g/mL范围内与化学发光强度呈良好的线性关系,检出限(3δ)为1.20×10-8g/mL和2.50×10-8g/mL。对浓度为5.0×10-6g/mL的芦丁和槲皮素溶液进行6次平行测定,相对标准偏差(RSD)为1.4%、2.3%。用于红花中芦丁和槲皮素的同时测定,结果令人满意。 相似文献
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催化动力学光度法测定生物样品中痕量钒 总被引：1，自引：0，他引：1
研究了在硫酸溶液中钒催化溴酸钾氧化偶氮胂Ⅲ的褪色反应及其动力学条件,提出了分光光度法测定痕量钒的新方法。方法的检测限为8.0×10-3μg·ml-1,线性范围为0.25～2.0μg钒/25ml,样品加标准回收率为90%～109%。用于茶叶、河水等生物样品中钒的测定,结果满意。 相似文献
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吴永军 《廊坊师范学院学报(自然科学版)》2010,10(2)
在聚合电位-0.15～0.7V、扫速20mV/s、聚合时间为25次循环下制得的PAn膜电极对邻苯二酚和对苯二酚进行测定,其线性范围均为2×10-6g/mL～45×10-6g/mL,用卡尔曼滤波对数据进行处理,平均回收率为100.6%和97.53%. 相似文献
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建立HPLC同时定量刺五加叶中原儿茶酸、绿原酸、刺五加苷E、金丝桃苷及槲皮苷五种主要成分的方法。方法:色谱柱:Agilent Extend C18(4.6mm×25mm,5μm),柱温:30℃;流速1 mL/min;进样量:10μL;流动相A:0.3%磷酸-水溶液,流动相B:0.3%磷酸-乙腈;梯度洗脱,洗脱条件:0～3 min,95%A;3～10 min,95%～80%A;10～35 min,80%～70%A;35～40 min,70%～10%A;40～50 min,10%A;紫外检测波长:265 nm。结果:金丝桃苷和槲皮苷在20～240μg/mL,原儿茶酸、绿原酸、刺五加苷E分别在5～60μg/mL、167.2～2010μg/mL及6～72μg/mL下与峰面积呈良好的线性关系;平均加样回收率在99.6%～103.1%,RSD为1.5%～2.7%。结论:本方法简便可靠,适用于刺五加叶中的多成分含量测定。 相似文献
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基于鲁米诺在氢氧化钠介质中能被磷钼钒杂多酸氧化产生较强的化学发光,头孢曲松钠能强烈地抑制其化学发光,建立了磷钼钒杂多酸-鲁米诺-头孢曲松钠化学发光抑制法测定头孢曲松钠的新体系.结合流动注射分析技术,头孢曲松钠的浓度在4.0×10-7～4.0×10-5g/ml范围内与相对化学发光强度呈线性关系;检出限为8×10-5g/ml;对8.0×10-6g/ml的头孢曲松钠进行11次连续测定,相对标准偏差为2.8%.该方法已经被成功地应用于头孢曲松钠药品的测定. 相似文献
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铈（Ⅳ）-罗丹明6G流动注射化学发光法测定盐酸氟奋乃静 总被引：1，自引：0，他引：1
张韬顺 《Journal of Zhangzhou Technical Institute》2009,11(3):63-66
本实验研究在盐酸-硫酸介质中,盐酸氟奋乃静和铈(Ⅳ)、罗丹明6G的化学发光行为,并对影响化学发光强度的多种因素进行试验,据此建立了流动注射化学发光法检测盐酸氟奋乃静的新方法,检测的线性范围为1.0×10-7～1.0×10-5g/mL,检出限为3×10-8g/mL;对浓度为2.0×10-6g/mL盐酸氟奋乃静连续11次测定,其相对标准偏差为1.2%,该方法应用于盐酸氟奋乃静含量测定并与标准方法(中国药典法)比较,结果令人满意. 相似文献
11.
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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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 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
14.
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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《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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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献