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111.
地质样品中金的化学发光测定法 总被引:5,自引:0,他引:5
本文使用含十二烷基苯磺酸钠,β-环糊精和丙酮的水溶液作稳定剂,解决了低含量金试液的稳定性问题。同时发现,以此稳定剂作为洗脱剂,可以定量洗脱吸附在泡塑上的金,而且得到的洗脱液可以直接用于金的化学发光测定。在此基础上,建立了一个灵敏,简便,实用的地质样品中痕量金的化学发光测定法。 相似文献
112.
Ying Wang Xiaoqing Cao Zhe Fu Siyuan Wang Xiaojie Li Naixin Liu 《Natural product research》2020,34(6):754-758
AbstractAmphibian skin is known to secrete gene-encoded antioxidant peptides of small molecular weight, which play important roles in host defense. However, recognition of such peptides is still in its infancy. Here, we discovered a novel gene-encoded antioxidant peptide (named OM-GF17) from skin secretions of amphibian species, Odorrana margaretae. Produced by the post-translational processing of a 61-residue prepropeptide, the amino acid sequence of OM-GF17 was 'GFFKWHPRCGEEHSMWT', with a molecular mass of 2135.7?Da. Functional analysis revealed that OM-GF17 scavenged ABTS+, DPPH, NO and decreased iron oxidation. Our results also implied that five amino acid residues, including Cys, Pro, Met, Trp, and Phe, be related to the antioxidant activity of OM-GF17. Furthermore, OM-GF17 did not exhibit direct microbe-killing activity. This novel gene-encoded antioxidant peptide could help in the development of new antioxidant agents and increase our understanding of the biological functions of amphibian skin. 相似文献
113.
114.
An efficient sodium bicarbonate promoted aerobic oxidation reaction to prepare N-monosubstituted α-keto amides in the presence of n-tetrabutylammonium hydrogensulfate (TBAHS) was described. This reaction provides a very simple and convenient synthetic route to N-monosubstituted α-keto amides from easily available aryl- or heteroarylacetamides in good to high yields without using toxic reagents and harsh conditions. 相似文献
115.
116.
利用代谢组学技术研究全氟辛酸的人肝脏毒性机制 总被引:3,自引:0,他引:3
采用超高效液相色谱-飞行时间质谱联用系统研究暴露于不同浓度全氟辛酸(PFOA)72 h的正常人L-02肝细胞内代谢谱的变化。将主成分分析法用于数据分析和生物标志物的初步筛选。在正离子和负离子扫描模式下,对照组和暴露组均可得到较好区分并呈现出明显的剂量-效应关系,筛选鉴定了18种与全氟辛酸毒性密切相关的潜在生物标志物,包括肉碱和酰肉碱、核苷及其同源物、氨基酸及其同源物等。在暴露组中,在脂肪酸代谢中起关键作用的肉碱类代谢物的含量变化显著,其中肉碱含量随剂量的升高呈现明显的下降趋势,而酰肉碱则呈现相反的变化趋势,表明全氟辛酸可通过诱导胆固醇等脂类物质代谢相关基因的异常表达从而扰乱胆碱类物质的正常合成和代谢。除了变化最显著的胆碱代谢通路之外,全氟辛酸的肝脏毒性还与三羧酸循环、嘌呤代谢、氨基酸代谢和核酸代谢等多个通路相关。这些结果表明,PFOA在体内经过长时间累积可通过干扰众多的代谢通路从而破坏人体的正常生理机能,造成潜在的健康危害。 相似文献
117.
118.
Zhang S Zong Y Wan M Yu X Fu Q Ding T Zhou F Wang S 《The Journal of the Acoustical Society of America》2012,131(6):4845-4855
This paper compares the efficiency of flowing polymer- and lipid-shelled microbubbles (MBs) in the heating and cavitation during focused ultrasound exposures. Temperature and cavitation activity were simultaneously measured as the two types of shelled MBs and saline flowing through a 3 mm diameter vessel in the phantom with varying flow velocities (0-20 cm/s) at different acoustic power levels (0.6-20 W) with each exposure for 5 s. Temperature and cavitation for the lipid-shelled MBs were higher than those for the polymer-shelled MBs. Temperature rise decreased with increasing flow velocities for the two types of shelled MBs and saline at acoustic power 1.5 W. At acoustic power 11.1 W, temperature rise increased with increasing flow velocities for the lipid-shelled MBs. For the polymer-shelled MBs, the temperature rise increased with increasing flow velocities from 3-15 cm/s and decreased at 20 cm/s. Cavitation increased with increasing flow velocity for the two shelled MBs and there were no significant changes of cavitation with increasing flow velocities for saline. These results suggested that lipid-shelled MBs may have a greater efficiency than polymer-shelled MBs in heating and cavitation during focused ultrasound exposures. 相似文献
119.
Influence of satellite vibration on optical communication performance for intersatellite laser links
For intersatellite laser links, vibration-induced pointing jitter severely influences the communication quality as a result
of intensity fluctuation. In this paper the probability density function of normalized intensity at the receiver is derived
in the presence of pointing jitter taking consideration of bias error. Accordingly, the scintillation index is developed to
identify the impact of bias error on intensity fluctuation. Furthermore the bit error rate (BER) is obtained as a function
of the beam divergence angle and vibration variance. Qualitative analysis is also given, and the numerical simulation is carried
out for demonstration. Results suggested that bias error has a significant detrimental impact on optical terminals which should
be considered in system design. This work can benefit the intersatellite optical system design. 相似文献
120.
We report a method for estimating the positions of charge transfer (CT) bands in Eu3+-doped complex crystals. The environmental factor (h(e)) influencing the CT energy is presented. h(e) consists of four chemical bond parameters: the covalency, the bond volume polarization, the presented charge of the ligand in the chemical bond, and the coordination number of the central ion. These parameters are calculated with the dielectric theory of complex crystals. The relationship between the experimental CT energies and calculated environmental factors was established by an empirical formula. The calculated values are in good agreement with the experimental results. Such a relationship was confirmed by detailed analysis. In addition, our method is also useful to predict the charge-transfer position of any other rare earth ion. 相似文献