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主要研究了两类近似凸集的关系和性质.首先,举例说明两类近似凸集没有相互包含关系.其次,在近似凸集(nearly convex)条件下,证明了在一定条件下函数上图是近似凸集与凸集的等价关系.同时,考虑了近似凸函数与函数上图是近似凸集的等价刻画、近似凸函数与函数水平集是近似凸集的必要性,并用例子说明近似凸函数与函数水平集是... 相似文献
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In-situ fabrication of ZnO nanoparticles sensors based on gas-sensing electrode for ppb-level H_2S detection at room temperature 下载免费PDF全文
The zinc oxide(ZnO)nanoparticles(NPs)sensors were prepared in-situ on the gas-sensing electrodes by a one-step simple sol-gel method for the detection of hydrogen sulfide(H2S)gas.The sphere-like ZnO NPs were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),x-ray diffraction(XRD),energy dispersive x-ray analysis(EDX),and their H2S sensing performance were measured at room temperature.Testing results indicate that the ZnO NPs exhibit excellent response to H2S gas at room temperature.The response value of the optimal sample to750 ppb H2S is 73.3%,the detection limit reaches to 30 ppb,and the response value is 7.5%.Furthermore,the effects of the calcining time and thickness of the film on the gas-sensing performance were investigated.Both calcining time and film thickness show a negative correlation with the H2S sensing performance.The corresponding reaction mechanism of H2S detection was also discussed. 相似文献
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建立了一种离子色谱电导检测法测定水基胶黏剂中氨残留的方法。样品经10 mmol/L盐酸水溶液振荡、离心、过滤提取后,采用阳离子交换色谱柱分离和电导检测。在优化实验条件下,样品中的氨在0.05~2.0 mg/L范围内呈良好的线性关系(r2=0.999 8),加标回收率在93%~102%之间,相对标准偏差不高于4.3%,检出限(S/N=3)为0.007 mg/L,定量下限(S/N=10)为0.024 mg/L。结果表明该方法能够达到定量检测的目的。将该方法用于实际样品检测,结果可靠。通过对氨的稳定性实验发现,处理好的样品宜在12 h内测定。 相似文献
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