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蒽蒽是煤焦油中一个重要组分,是染料和塑料工业的重要原料,有致癌作用.目前测蒽的方法有GC、LC、荧光光谱法、电离光谱法.试验表明用N,N-二甲基甲酰胺(DMF)溶解的蒽在酸性条件下可被K_2Cr_2O_7氧化成蒽醌,该产物在六次甲基四胺(HXA)和二氧六环(DOX)介质中于-0.4V(vs.SCE)处产生一波形很好的二阶导数极谱波.用以测定煤焦油中蒽的含量获得满意结果. 相似文献
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纯化的沙眼衣原体经各种理化手段处理后,在电子显微镜下观察表明,原体被膜由胞壁外层、胞壁内层及内膜组成.胞壁外层主要由按六角形规则排列的颗粒亚单位构成,可称为“壁体结构蛋白”层.它与胞壁内层共同组成有刚性的细胞壁.内膜即原生质膜,在年青原体中不易被显示.在负染片中可见“壁体结构蛋白”层的外面附有较为脆弱、易被去除的表层.在超薄切片中表层不单独显示.被膜上有褶皱状凹陷,为特殊结构,可能与繁殖有关.此外,还发现了一些分裂中的原体,以及一些具有原体形态特征的大型个体,以二分裂、出芽、“多中心生发”等方式进行繁殖.因此对只有始体才能进行繁殖的传统看法提出了异议. 相似文献
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A non-destructive evaluation system based on high-T_c dc-SQUID (superconducting quantum interference device) incorporating a gradient field excitation has been built. By using this system a 1mm-diameter hole at a depth of 2mm inside an aluminium plate at room temperature can be easily detected and imaged in an unshielded environment. The relation between the spatial resolution, or the smallest detectable flaw size, and experimental parameters is briefly analysed in terms of a simple metal ring model. The result shows that the spatial resolution depends strongly on the sensor-sample separation as well as on some other parameters, such as signal-to-noise ratio of excitation, excitation frequency and material conductivity. 相似文献
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A normalized data-reusing least-mean-square algorithm of noise cancellation for magnetocardiography 下载免费PDF全文
An adaptive filter based on Data-Reusing Least-Mean-Square algorithm has been proposed and applied in magnetocardiography (MCG) to suppress ambient noise, Numerical simulation studies indicate that the adaptive filter is a powerful noise suppresser for correlated interferences, especially for those with amplitude changing and time delay.Also the filter has a wide frequency bandwidth. With this filter, the signal-to-noise ratio of an MCG is improved to the intrinsic noise level, The periodic average method for further improvement of the noise level in MCG is also discussed. 相似文献
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本工作发现,用DSC测定从熔体等速降温时辐照样品的结晶温度Tc随辐照剂量R增加而线性变低,即辐照前后样品的△Tc=Tco-TcR=KR。依据Charlesby-Pinner方程,导出一新关系式,S+S1/2=A+B/△Tc。已经证明,式中的Tc只与聚合物的交联度有关,与辐射交联方法和过程无关。因此,该方程可用于结晶聚合物的强化辐射交联,以获得非无规交联的瞬时G(c,1)值。本文为定量研究结晶聚合物的无规交联与非无规交联提供了一个简便的方法。 相似文献
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