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用塞曼石墨炉原子吸收光谱法测定贝类中的微量砷,以硝酸钯为基体改进剂,灰化温度1 100℃,原子化温度2 300℃。本方法具有较高的精密度（检出限为0.18μg/L）和较高的回收率（93.0%-101%）,操作简便、快速,可用于贝类中总砷的准确检测。 相似文献
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本文研究了海水基体和共存离子对镍和钒的影响,选用酒石酸、乙酸铵分别作为镍和钒的基体改进剂。未加基体改进剂前,海水镍回收率只有77％,钒的测量精度为11％;加人改进剂后均有改善。采用塞曼效应背景校正技术,热解涂层石墨管,建立了石墨炉原子吸收直接测定海水镍和钒的分析方法。镍和钒的特征质量值(mo)分别为8.4pg和17pg;实际检测限:镍为0.25μgL~(-1)和钒为0.41μgL~(-1)。回收率镍为86～110％,钒为88～106％范围。最大相对标准偏差为谋5.5％,钒4.2％。 相似文献
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石墨炉原子吸收法测定自来水中的有害元素铅 总被引：1，自引：0，他引：1
采用石墨炉原子吸收光谱法,水样处理后加入基体改进剂,测定水中有害元素痕量铅.实验优化了石墨炉原子吸收光谱法的测定条件.重点讨论了铅的灰化温度、原子化温度以及基体改进剂的选用对铅测定结果的影响,结果表明,以磷酸二氢盐、钯盐为基体改进剂可提高灰化温度,消除样品中的钙、镁、钠等复杂基体的干扰,相对标准偏差为2.23%,回收率为94.0%-102.0%,具有良好的精密度和回收率.方法简便快速、结果准确. 相似文献
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平台石墨炉原子吸收光谱法测定水中的重金属 总被引：3，自引：0，他引：3
居红芳 《常熟理工学院学报》2003,17(2):47-50
利用SIPF技术，直接测定水样中10种重金属元素，通过对灰化温度、背景扣除、基体改进剂等三方面的研究，得出了各被测重金属元素的最佳灰化温度，确定了测定海水或其它水样中重金属元素的方法，即用硝酸调节水样的PH值为1，在最佳灰化温度下，用D2扣除背景，用氩气作护气进行测定。该方法测定各重金属的加标回收率为91．3－108．4％，相对欲望 为3．49－9．12％，具有准确度和精确度高等优点。 相似文献
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采用原子荧光光谱法,用浓盐酸和5%硫脲+5%抗坏血酸混合试剂处理样品,并以1.0%硼氢化钾和0.5%氢氧化钾为还原剂,在5%的盐酸介质中测定水样中的痕量砷.砷的检出限为0.20μg/L.本方法具有操作简便、快速、基体干扰少、灵敏度高等优点,可广泛应用于水样中痕量砷的测定. 相似文献
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本文探讨了用塞曼效应石墨炉原子吸收法测定饮用水中痕量铅, 研究了石墨炉升温程序及基体改进剂对测定的影响。测定结果表明, 采用塞曼扣背景的方法, 以硝酸为基体改进剂, 使水样中基体干扰大大减少, 回收率达到97 %以上, 可获得满意的测定结果. 相似文献
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薛行爱 《福建师大福清分校学报》2005,(2):9-14
应用AFS-2202a型原子荧光光度计对地表水和海水中的砷、汞联合测定方法进行有苴的研究。通过实验，探讨总结出了合理有效的水样前处理方法和实用测定步骤。并对其最低检出下限、精密度和准确度进行了全面评估，结果表明：该方法具有操作简便、快速、干扰少、灵敏度高等优点，适用于地表水和海水中微量砷、汞元素的联合测定，具有很好的可行性和适用性。 相似文献
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本文提出了一种简便、快速直接测定海水Co的石墨炉原子吸收光谱方法。研究了几种不同的有机基体改进剂及石墨炉升温程序对消除基体干扰的效果。管壁原子化、酒石酸为基体改进剂、积分吸收测量、一次进样20μl(或多次进样以提高灵敏度)以及严格控制狭缝宽度在0.4nm可以获得最佳分析结果。海水Co的检测限(3σ)为0.1μgL~(-1),特征质量mo为4.6pg/0.0044A.S。11个海水样品及4个河水样品的平均回收率为98％,平均相对标准偏差为4.6％。 相似文献
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试验表明用石墨炉原子吸收光谱法直接测定海水Pb时,抗坏血酸—HNO_3是消除海水基体干扰的有效基体改进剂。样品从石墨管壁原子化,不同商标的热解涂层石墨管效果不一。分析结果通过“质控海水”和“极谱分析法”的验证,结果是满意的,回收率在95～99％范围。对含Pb lμg/L以内的海水可直接测定。 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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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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《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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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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《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