共查询到20条相似文献，搜索用时 140 毫秒
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建立一种快速溶剂萃取—高效液相色谱检测橡胶中的2-巯基苯并噻唑(MBT)含量的方法.采用超声波辅助丙酮溶解橡胶样品,再采用C18固相萃取小柱萃取其中的MBT,并选择合适的高效液相色谱条件分离测定MBT.选用Zorbax eclipse XDB C18液相色谱柱,V甲醇∶V水∶V0.1%甲酸=60∶35∶5为流动相,紫外波长320 nm进行检测.通过考察最佳预处理萃取条件和高效液相色谱条件下MBT含量的色谱图,根据色谱峰面积采用外标法进行定量分析,MBT的浓度在1.0～12.0 ppm范围内呈良好线性,回归方程为A=-15.1+71.2C(C的单位为ppm),相关系数:r=0.99951,标准回收率为95%～106%.该方法可用于橡胶样品中MBT的测定. 相似文献
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采用高效液相色谱法对小麦中尿囊素含量进行测定.色谱柱为Kromasil C18,流动相为V甲醇∶V水=5∶95,柱温30℃,流速0.5 mL/min,HPLC测定尿囊素含量变异系数小于1.1%,回收率为95.80%～105.4%,最低检出限0.5μg/mL. 相似文献
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目的:用高效液相色谱法测定注射用肌苷的含量.方法:采用Kromasil C18柱(5μm 4.6mm×250mm),以甲醇-水(10∶90)作流动相,在248nm紫外波长检测.结果肌苷在4.23～63.48μg/ml范围内有良好的线性关系(r=0.9999).低、中、高3个浓度的平均回收率(n=2)分别为101.4%、101.8%、101.1%,RSD为0.46%.结论:该法简便、快速、准确,可作为测定注射用肌苷中肌苷的含量. 相似文献
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建立一种用高效液相色谱法测定茶叶中儿茶素的含量.方法:样品经乙醇提取,超声30min后,过C18小柱净化,样品溶液经0.45μm滤膜过滤后,用于HPLC分析.使用C18(5 um,150 mm×6.0 mm)色谱柱进行分离,用不同体积比混合的流动相A及流动相B的混合液作梯度淋洗,流速为1.0 ml/min,检测波长为280 nm,柱温为40℃.以甲醇∶水∶乙酸-26∶73.5∶0.5(体积比)为流动相.儿茶素在0.02～0.3 g/L范围内线性关系良好,回收率在98.2%～100.3%之间,相对标准偏差为1.6643%.该方法具有操作简便、快速、精密度高、回收率好、重现性较好、检测限低等优点. 相似文献
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目的:建立状元深海龙酒中丹参酮ⅡA的含量测定方法.方法:用C18柱(4.0×250mm,5μm),以甲醇-水(85∶15)为流动相,检测波长270nm.结果:丹参酮ⅡA的线性范围为0.06～0.18mg/ml;丹参酮ⅡA平均回收率为99.81%,RSD=1.08%(n=5).结论:本方法准确、快速、重现性好,可用于本品的质量控制. 相似文献
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目的:建立状元深海龙酒中丹参酮ⅡA的含量测定方法.方法:用C18柱(4.0×250 mm,5 μm),以甲醇-水(85∶15)为流动相,检测波长270 nm.结果:丹参酮ⅡA的线性范围为0.06～0.18 mg/ml;丹参酮ⅡA平均回收率为99.81%,RSD=1.08%(n=5).结论:本方法准确、快速、重现性好,可用于本品的质量控制. 相似文献
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高效液相色谱法测定辣椒中维生素C的含量 总被引：3，自引：0，他引：3
文章建立了一种高效液相色谱测定辣椒中维生素C含量的方法.采用0.1%的草酸作为提取剂,色谱中采用Hypersil-C18色谱柱,pH=6,0.05mol/L磷酸二氢钾缓冲溶液:甲醇=95∶5(v/v)作流动相.流速1.0 ml/min,DAD检测器,检测波长254 nm.维生素C在20—100 mg/L内有良好的线性关系,线性回归方程为y=29.664x-12.37,相关系数为0.9953,方法回收率为91.24%-105.6%,相对标准偏差小于2%.本文测定方法简便,快速,能准确测定辣椒中维生素C的含量. 相似文献
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目的:建立高效液相色谱法测定一清颗粒中黄芩苷的含量.方法:采用Hypersil C18(250×4.6mm,5um)色谱柱,以甲醇一0.2mol/L磷酸二氢钠缓冲液(用磷酸调节pH值至2.7)(42∶58)为流动相;流速为1.000mL/moL,检测波长275nm,柱温29℃.结果:黄芩苷在0.0916～0.7608 ug范围内成良好的线性.(r=0.9945),平均回收率98.9%,RSD=0.31%.结论:方法简便、快速、适用性好,可用于该制剂的质量控制. 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