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排序方式: 共有279条查询结果,搜索用时 31 毫秒
71.
N. Canha M. C. Freitas H. M. Anawar I. Dionísio H. M. Dung C. Pinto-Gomes A. Bettencourt 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(2):577-582
This study aims to find out a vascular plant species that accumulate relatively high concentrations of arsenic (As) for its use as phytoremediator at abandoned and contaminated mining areas, such as São Domingos mines (Portugal). The assessment of As contamination levels in soils and plants of other similar sites in the north of the country (Castromil and Poço de Freitas) was also conducted; and the sample analyses were made by instrumental neutron activation analysis. Agrostis genera have shown higher As transfer coefficients than other studied plant species and, in particular, Agrostis curtisii has shown a reasonable ability to accumulate high concentration of this toxic element. 相似文献
72.
Based on a unified approach to macroscopic QED that allows for the inclusion of amplification in a limited space and frequency
range, we study the Casimir force as a Lorentz force on an arbitrary partially amplifying system of linearly locally responding
(isotropic) magnetoelectric bodies. We demonstrate that the force on a weakly polarisable/magnetisable amplifying object in
the presence of a purely absorbing environment can be expressed as a sum over the Casimir-Polder forces on the excited atoms
inside the body. As an example, the resonant force between a plate consisting of a dilute gas of excited atoms and a perfect
mirror is calculated. 相似文献
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Dao Viet Dung J. Marien E. De Pauw J. Decuyper 《Journal of mass spectrometry : JMS》1984,19(6):276-279
SIMS using 6 keV Cs+ ions has been performed on glycerol solutions of various promazines. Fragmentation patterns are compared to those obtained by other ionization methods. The photochemical degradation of chlorpromazine has been observed directly in the glycerol droplet, showing the potentiality of SIMS for the direct study of photochemical reactions in solution. 相似文献
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商用纯钛试片实地悬挂于排烟脱硫 (FGD)系统中的冷却器、除尘塔、吸收塔、加热器等不同位置 ,经历 2 71d现场重量损失试验后 ,观察得知商用纯钛在 4个位置均有良好之耐蚀性 (腐蚀速率 1mpy) ,且以在除尘塔中的腐蚀速率最低 (mpy值为 0 ) ,加热器中的腐蚀速率最高 (mpy值为0 .58) .SEM观察结果显示钛在加热器中有孔蚀现象 .ESCA分析结果得知 :在加热器位置中钛生成硝酸盐 ,在除尘塔位置中钛表面未发现钛化物而有碳酸钙厚膜覆盖 .在通氮气及通氧气之绿色溶液中进行直流电动态极化以探讨钛在FGD系统中不同位置腐蚀行为之差异 相似文献
77.
Trung Dung Dao Hyung-il Lee Han Mo Jeong Byung Kyu Kim 《Colloid and polymer science》2013,291(10):2365-2374
The syntheses of water-dispersible graphene via graphene oxide colloid dispersion and/or using functionalizations that disrupt the π-bond system of graphene or contaminate a graphene surface with big amounts of undesired impurities face some challenges in practical applications. Approaches based on thermally exfoliated graphene might be promising for many applications in which flat and perfect single-layer graphene is not mandatory and productivity is more than important. In this paper, for the first time, we report a simple and effective method to prepare water-dispersible graphene directly from thermally exfoliated graphene by covalent modification utilizing the inherent defects of graphene as active sites. That is, the epoxide groups on graphene were reacted with ethanolamine and then with n-butyl bromide to prepare the graphene decorated with cationic ammonium ions (alkylated graphene, AAG). Elemental analysis, thermogravimetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy demonstrated that the reactions have proceeded as designed. The Raman spectra showed that the π-electronic system of sp 2-bonded carbons of the graphene was not damaged by the modification. The homogeneous colloidal dispersion of AAG in water remained stable for at least 6 months, showing that the wrinkled nature of the graphene as well as the electrostatic repulsion and steric hindrance between the graphene sheets caused by the bulky ammonium moieties on the graphene’s surface efficiently prevented the graphene from restacking and aggregating. The AAG dispersed stably in a poly(vinyl alcohol) matrix produced an extraordinarily high modulus increase of 236 % with just 1 phr (about 0.5 vol%) of AAG. 相似文献
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