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分别将N-(β氨乙基)-?-氨丙基三甲氧基硅烷(AEAPTMS)、3-巯丙基三甲氧基硅烷(MPTMS)与四乙氧基硅烷(TEOS)水解共聚,制备氨基\巯基键合的硅胶材料。将此材料作为固相萃取(SPE)小柱的填充材料,建立了固相萃取快速分离富集海产品样品中五价砷As(Ⅴ)和三价砷As(Ⅲ)电感耦合等离子体质谱法(ICP-MS)测定海产品中无机砷的方法。研究了固相萃取小柱对无机砷的吸附原理、性能和洗脱条件,在pH3~4范围内固相萃取小柱材料有良好的选择吸附性,利用2%硝酸可将As(Ⅴ)洗脱,利用2%硝酸+0.1mol/L KIO3可将As(Ⅲ)洗脱。实际样品检测的加标回收率在72~103%之间,方法实现了海产品样品中无机砷形态快速、方便、准确的检测。 相似文献
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A power and wavelength detuning-dependent hysteresis loop in a single mode Fabry-Prot laser diode 下载免费PDF全文
In this paper, we observe experimentally the optical bistability induced by the side-mode injection power and wave-length detuning in a single mode Fabry-Prot laser diode (SMFP-LD). Results show that the bistability characteristics of the dominant and injected modes are strongly dependent on the injected input optical power and wavelength detuning in an SMFP-LD. We observe three types of hysteresis loops: counterclockwise, clockwise, and butterfly hysteresis with various loop widths. In the case of a bistability loop caused by injection power, the transition from counterclockwise to clockwise in the hysteresis direction with the wavelength detuning from 0.028 nm to 0.112 nm is observed in a way of butterfly hysteresis for the dominant mode by increasing the wavelength detuning. The width of hysteresis loop, induced by wavelength detuning is also changed while the injection power is enhanced from 7 dBm to 5 dBm. 相似文献
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熊果苷是从植物中分离到的一种成分,据报道具有低毒性镇咳、利尿、抗菌和尿道消毒作用等生物活性。由于熊果苷水溶性好,便于机体吸收,有希望成为临床的新型镇咳药,它的结构式如下式所示。为了研究构(包括端基异构)效(镇咳作用)关系,作者以熊果苷为模型化合物,对糖基和配糖体分别进行有限的修饰,合成了一些熊果 相似文献