共查询到20条相似文献，搜索用时 441 毫秒
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采用火焰原子吸收法,对比测定了采于千山地区的油松及扫帚松中的几种金属元素含量;并对样品的处理和测定条件进行了讨论.实验表明,用该方法测定生物体中无机矿物质含量,具有灵敏度高、精密度好、试样耗量小、操作简单等优点. 相似文献
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标准加入原子吸收法连续测定镍粉中微量Co、Fe、 Cu、Ca、Mn、Zn、Mg和Pb的含量 总被引：1，自引：0，他引：1
用HNO3溶解试样，在几个相同量的试液中，分别加入浓度依次递增的8种元素的标准溶液，再加入释放剂SrCl2溶液，用空气—乙炔火焰原予吸收法连续测定Co、Fe、Cu、Ca、Mn、Zn、Mg和Pb的含量．建立了优化的仪器测定条件，并进行了相关的干扰实验．方法的回收率为98．4％—102．6％，相对标准偏差为1．2％—2．7％． 相似文献
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本文探索了火焰原子吸收法测定保险丝中的铜、铁、锌的方法.样品采用盐酸和过氧化氢分解,对测定条件进行了探讨,不用分离保险丝中的主要成分铅和锌,直接测定铜、铁、锌.方法简便,能胜任保险丝测定的要求.相对标准偏差1.0%-2.8%,回收率95%-107%. 相似文献
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中华稻蝗（Oxya chinensis Thunb）是一种常见的农业害虫，它的个体较大，易采并便于进行观察和实验。为了便于学生更直观地认识蝗虫的呼吸知识，笔者用人工溺水的方法来进行对呼吸现象的观察，并测定特定温度条件下，蝗虫溺水窒息死亡时间，及窒息多长时间后还能通过人工呼吸使其复活。通过测定，蝗虫在18℃条件下，溺水约20min窒息死亡，窒息18min以内能通过人工呼吸使其复活。 相似文献
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稀土类热稳定剂合成条件研究及性能测试 总被引：1，自引：0，他引：1
本对热稳定剂的合成条件进行了研究，确定了硬脂酸镧的最佳配方。对硬脂酸盐类热稳定剂的性能进行了测定，摸索了测定硬脂酸镧的分析方法。 相似文献
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本文介绍了人血中微量铬的化学发光测定法，并讨论了酸度、共存离子、测定时间等因素对测定结果的影响及适合于ｌｕｍｉｎｏｌ—Ｈ２Ｏ２－Ｃｒ（Ⅲ）体系进行发光测定的条件。该法具有灵敏度高、精密度好、选择性好、良好的线性关系等特点，对不同人血样品进行了发光测定及回收率试验，结果令人满意。 相似文献
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为建立测定桔梗茎、叶中总黄酮含量的方法,通过对比亚硝酸钠-硝酸铝-氢氧化钠比色法、三氯化铝-缓冲溶液比色法、盐酸-镁粉法、二氯氧锆比色法的紫外可见光谱图的手段,发现亚硝酸钠-硝酸铝-氢氧化钠比色法更适合测定桔梗茎、叶中总黄酮含量,并对该方法的显色条件进行了优化,同时对其方法学进行验证。 相似文献
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包晓玉 《南都学坛(南阳师专学报)》1996,16(3):55-58
用钼蓝法分别测定磷和硅的含量多有报导〔１〕〔２〕〔３〕，但用该法对其进行同时测定未见报导。本文探讨了用钼蓝法同时测定磷和硅，确定了其测定条件，本法具有简便、快速、不需特殊试剂等特点，可用于水等试样中磷和硅的同时测定。 相似文献
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在101.325kPa下,用新型泵式沸点仪测定了水-甲醇二元系在不同液相组成时的沸点,并用非分析法由tpx推算了与之平衡的汽相组成y.用最小二乘法分别求出了甲醇-水二元体系的液相活度系数Wilson、NRTL、Margules和Van Laar模型参数,由这些模型参数推算的此二元系的泡点与实验值能很好的吻合.这些模型参数求得的结果,用面积检验法检验得到很好的热力学一致性. 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｐｈａｓｅｉｓａｎｉｍｐｏｒｔａｎｔｃｏｎｃｅｐｔｉｏｎｉｎｏｐｔｉｃｓ.Ｉｔｓｄｅｆｉｎｉ ｔｉｏｎｉｓｅｘｐｌｉｃｉｔｉｎｃｌａｓｓｉｃｏｐｔｉｃｓ,ｂｕｔｉｔｉｓｄｉｆｆｉｃｕｌｔｔｏｇｉｖｅｉｔｓｄｅｆｉｎｉｔｅｍｅａｎｉｎｇｉｎｑｕａｎｔｕｍｏｐｔｉｃｓ.Ｔｈｅｒｅｈａｖｅｂｅｅｎｓｅｖｅｒａｌｄｅｆｉｎｉｔｉｏｎｓ,ｗｈｉｃｈｈａｖｅｄｉｆｆｅｒｅｎｔｃｈａｒａｃｔｅｒｉｓｔｉｃｒｅｓｐｅｃｔｉｖｅｌｙ.ＳｏｍｅｏｆｔｈｅｍａｒｅＳｕｓｓｋｉｎｄ Ｇｌｏｇｏｗｅ… 相似文献
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张青松 《兰州石化职业技术学院学报》2014,(1):30-33
分析了电加热器的结构特点与SolidWorks软件的三维建模步骤。在几何模型上直接定义了载荷和边界条件,对电加热器温度场与速度场进行了模拟,模拟结果与工程实际吻合较好。探索了有无折流板对电加热器换热的影响,结果显示无折流板的出口温度高于有折流板情况,这对电加热管不利,局部温度过高,长时间工作,容易导致电加热管烧坏。可见利用SolidWorks软件可为电加热器的结构优化与换热等性能的研究提供新的设计手段。 相似文献
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本文叙述了在国际公认的三大检索系统中１９９２年我国科技论文的发展情况及我国高校科技论文的数量及增长速度；详细介绍了清华大学在三大检索系统中当年科技论文的数量及在我国高样名的排名。 相似文献
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采用同时蒸馏萃取法提取玉米及加食用碱后玉米的挥发性成分,并用气-质联用仪对提取液进行分离鉴定.初步确定了玉米挥发性成分中的32种化合物,占总峰面积的92.2%;加食用碱玉米挥发性成分中的26种化合物,占总峰面积的88.5%.玉米挥发性成分含量较高的是棕榈酸（39.4%）、亚油酸（15.0%）,3,4-二甲基己烷（5.7%）.但加入食用碱后玉米的挥发性成分主要为2,4-戊二醇（19.4%）,1,1-二乙氧基辛烷（18.9%）,2,2-二乙硫基丙烷（5.3%）. 相似文献
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Anne F. Marrelli 《Performance Improvement》2008,47(4):39-45
This 10th article in the Performance Technologist's Toolbox series describes the data collection method of focus groups. Several variations in structure and facilitation techniques are summarized and common misconceptions are explained. Multiple applications of focus groups in performance technology are illustrated with examples. The advantages and disadvantages of using focus groups are then reviewed. The article concludes with guidelines for planning and conducting effective focus groups. 相似文献
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《Journal of College Student Psychotherapy》2013,27(1):83-96
Some theories of family psychotherapy and adolescent development are reviewed. The suitability of family and couples techniques for brief psychotherapy with college students is discussed. Four cases are described in which family psychotherapy techniques were used with college students. In each, these techniques were used in conjunction with ongoing individual psychotherapy. The participants in conjoint sessions were either family members or close friends. Determination of participants in conjoint sessions, benefits of family psychotherapy techniques, and the use of dreams are discussed. Suggestions are offered on when to use family psychotherapy techniques with college students. 相似文献
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This article draws on work undertaken as part of the Economic and Social Research Council's Learning Society Programme. The project from which data are drawn, entitled 'The Meaning of the Learning Society for Adults with Learning Difficulties', focused on lifelong learning opportunities available to people with learning difficulties and experiences of these services. The article begins by examining theories of late modernity, their use by feminist and disability studies theorists and their relationship to ideas of a learning society. Subsequently, using case study material, it is argued that the identities of people with learning difficulties are not chosen freely from a range of options but are socially ascribed. The status of learning difficulties is used as a dominant category to justify deprivation of basic political and economic rights. In addition, the lives of people with learning difficulties are structured by gender and class, and these intersect with the category of learning difficulties. For both women and men, the advantages of middle-class social and economic capital are overridden by the negative category of learning difficulties. In relation to gender, men with learning difficulties are more likely to receive post-school training, but in inappropriate areas of the labour market. Their domestic needs are also likely to be attended to by others, but in the absence of employment, they find themselves without any valued social role. Women with learning difficulties are also likely to be excluded from the labour market, but are more likely to be involved in reciprocal, albeit limited, social relationships. It is concluded that postmodernist theories are inadequate to describe the structuring of the lives of people with learning difficulties. 相似文献
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防爆局扇是我总厂新开发的高效率、低能耗的新型井下通风设备。其铸铝扇叶要求精度高，尺寸公差小。叶片为流线型，按坐标定位，最小壁厚尺寸为0.62mm，国内无生产成功先例。我们经过分析研究和多次试验采用了数控切割样板，水玻璃砂造型，分体组芯，表面涂滑石粉，提高浇注温度，去气精炼和变质处理等方法，解决了该件所存在的技术难题。并试制出合格的产品。 相似文献