共查询到20条相似文献，搜索用时 46 毫秒
1.
采用阳极溶出伏安法分离富集铜，并选用盐酸羟胺作发光试剂，结合流动注射技术建立了一种新的电化学发光测定铜的分析方法．该法选择性好、灵敏度高．其线性范围是6．0×10-7~4．0×10-10kg／L铜，RSD是3．2％（n＝11；Cs＝1．0×10－7kg／L），检测限是1．0×10－10kg／L铜，可用于人发中铜的测定． 相似文献
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本文用伏安法对药物中的维生素B6（VB6）进书测定。在0．05mol／L（CH3）4NBr－（CH3）4NOH底液中（pH-6．0～11．0），VB6在-1．88V（VS，SCE）产生一灵敏还原峰，峰高与VB6浓度在8．0×10-7～2．2×10－5mol／L范围内成线性关系，检测下限为2．0×－7mol／L，用本法，可直接测定药物中VB6的含量。 相似文献
3.
任爱萍 《黄冈师范学院学报》1999,(6)
在NH3－NH4Cl缓冲溶液（pH=9．5）中,吲哚乙酸与磷钨杂多酸的还原产物在滴汞电极上于－1．70V（vs．SCE）处产生一灵敏的极谱波,该波波高与吲哚乙酸在1．0×10－7～4．0×10－7mol／L范围内成线性关系,检出限为50×10－8mol／L。加标回收实验5次,测定结果的平均回收率为99．7％,RSD为1．09％． 相似文献
4.
亚铁氰化钾修饰碳黑微电极测定抗坏血酸 总被引：1，自引：0，他引：1
研究了抗坏血酸(AA)在亚铁氰化钾修饰碳黑微电极上的电化学行为。实验结果表明,在pH7．0的磷酸盐中,AA在该电极上的线性范围为2．0×10-6-4．0×10-3mol／L;检出限(3σ)为1．0×10-6mol／L。用这种电极测定抗坏血酸的含量,结果满意。 相似文献
5.
采用半微积分伏安法研究了DAM（L）配位推动La（Ⅲ）离子在水／硝基苯界面的传递行为．在0.01mol/LLaC13(W)－0.05mol/LTBATPB（NB）中,ep与CL成正比,线性范围为3．0×10-5-7．0×10-4mol／L,可作L的定量分析．本文对转移机理进行探讨,测定了配合物的形成常数等． 相似文献
6.
96年全国高考上海化学试题第22题的命题“pH值为4的FeCl3溶液……”．是否存在PH值为4的FeCl3溶液呢？对于这个问题,我们不妨分析一下．在FeCl3溶液中存在水解平衡：Fe3＋＋3H2OFe（OH）3＋3H＋已知KspFe（OH）3＝4×10－38,Kw＝10×10－14设FeCl3溶液中[Fe3＋]＝0．1mol／L,Fe3＋完全沉淀为Fe（OH）3时的[Fe3＋]＝1．0×10－6mol／L根据溶度积公式,可以求得Fe3＋开始形成Fe（OH）3沉淀的pH值为1．87．同理,也可以求得pH值为4时溶液中Fe3＋的浓度．[Fe3＋]＝Ksp／[OH－]3＝4×10-38／（10-10）3＝4×10-8（mol／L）… 相似文献
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本文研究了铅（Ⅱ）-胱氨酸-甘氨酸体系在悬汞电极上的吸附伏安特性。在0．001mol／L甘氨酸溶液中（pH=8．2），加入铅（Ⅱ）溶液后，使胱氨酸的峰电流增大，最佳实验条件下，该峰电流与优氨酸浓度在3．3×10－8～1．0×10－6mol／L范围内呈良好的线性关系，检测限过3．3×10－9mol／L。通过对该峰的性质及反应机理的研究，证明此峰为配合物吸附还原峰，吸附反应物为铅（Ⅱ）与胱氨酸形成的1：1配合物，电机反应为二电子还原。 相似文献
8.
采用巯基棉分离富集痕量铜,用3mol．L-1HCl作洗脱剂洗脱富集在巯基棉上的铜,结合离子选择电权法建立了水饮料中痕量铜的离子选择电极分析方法．该法简单、分析灵敏度高,选择性好,检出限量8．30×10－8mol·L－1铜。相对标准偏差为3．8％（n＝7;Cs＝7．2×10－7mol．L－1Cu2＋）． 相似文献
9.
在酸性溶液中,高锰酸钾可直接氧化安乃近,产生很强的化学发光,由此建立了一各测定安乃近的流动注射化学发光分析法．方法的检出限为3．1×10-8g／mL,相对标准偏差为1．8％（6．0×10－6g／mL安乃近,n＝11）,线性范围为1．0×10－7～1．0×10-4g／mL,此法已用于安乃近针剂和片剂中安乃近含量的测定．并对该反应的机理进行了探讨． 相似文献
10.
基于氟离子对固定于聚氯乙烯(PVC)膜中的8羟基喹啉铝(Alq3)有不可逆的荧光熄灭作用,研制成测定氟离子的选择性光化学敏感膜,并对其性能进行了初步探讨.该膜制作简单,成本低,对于氟离子在5×10-6～5×10-2mol/L浓度范围内时,其荧光强度降低值与氟离子浓度具有良好的线性关系,检出限为2.5×10-6mol/L,相对标准偏差RSD为2.0%,适合于水相中的氟化物测定. 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
12.
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
13.
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
17.
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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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
19.
《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
20.
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