排序方式: 共有16条查询结果,搜索用时 31 毫秒
1.
采用气相分子吸收光谱法测定地下水中的亚硝酸盐氮(NO2^-)、氨氮(NH4^+)、硝酸盐氮(NO3^-)。考察NO2^-,NH4^+和NO3^-测定时的相互干扰,并给出了相应的消除方法。研究结果表明,测定NO2^-时,NH4^+和NO3^-无干扰;NO2^-对测定NH4^+和NO3^-产生干扰,可分别采用分段法和加入2滴10%氨基磺酸溶液的方法消除干扰;对于不含NO2^-或NO2-含量不高的地下水样品,可简化操作步骤直接测定NO3^-。该方法测定结果的相对标准偏差为0.73%~2.74%(n=12),样品加标回收率为97.67%~100.28%。所用检测仪器具有流动注射、自动进样及在线绘制标准曲线的功能,简化了标准方法中的样品前处理过程,减少了样品的损失,实现了自动化分析,大幅提高了检测结果的准确度和工作效率。 相似文献
2.
Xuanwei Wang Jianfeng Chen Qiuyun Li Prof. Lingyun Li Prof. Zanyong Zhuang Dr. Fei-Fei Chen Prof. Yan Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3786-3792
Photocatalytic syngas (CO and H2) production with CO2 as gas source not only ameliorates greenhouse effect, but also produces valuable chemical feedstocks. However, traditional photocatalytic systems require noble metal or suffers from low yield. Here, we demonstrate that S vacancies ZnIn2S4 (VS-ZnIn2S4) nanosheets are an ideal photocatalyst to drive CO2 reduction into syngas. It is found that building S vacancies can endow ZnIn2S4 with stronger photoabsorption, efficient electron–hole separation, and larger CO2 adsorption, finally promoting both hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR). The syngas yield of CO and H2 is therefore significantly increased. In contrast to pristine ZnIn2S4, the syngas yield over VS-ZnIn2S4 can be improved by roughly ≈4.73 times and the CO/H2 ratio is modified from 1:4.18 to 1:1. Total amount of syngas after 12 h photocatalysis is as high as 63.20 mmol g−1 without use of any noble metals, which is even higher than those of traditional noble metal-based catalysts in the reported literatures. This work demonstrates the critical role of S vacancies in mediating catalytic activity and selectivity, and highlights the attractive ability of defective ZnIn2S4 for light-driven syngas production. 相似文献
3.
周轩伟 《高等学校计算数学学报》2000,22(2):175-182
1 引 言由于反应扩散方程涉及的大量问题来自物理学、化学、生物学和人口动力学中众多的数学模型,因而有广阔的实际背景.其行波解引起了人们的兴趣,行波解是某个常微分方程的解,对某些传播速度,利用几何方法可以建立其解的存在性(见[1][2][3]).在文[4]中J.Canosa讨论了Fisher方程ut=2u2x+u(1-u)(1)行波解的存在性、逼近解和误差估计.所谓方程(1)的行波解是指形为u(x,t)=u(x-ct)=u(z)的解.众所周知,行波解u(x,t)=u(x-ct)=u(z)是方程(1)的行波解的充要条件是d2udz2+cdudz+u(1-u)=0(2)若u(z)是单调有界且不恒为常数,则u(z)叫做(1)的波前… 相似文献
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5.
Surface modification with EDTA molecule: A feasible method to enhance the adsorption property of ZnO
Chong Sun Xuanwei WuHao Meng Xinxin XuJunli Xu Xia Zhang 《Journal of Physics and Chemistry of Solids》2014
Surface-functionalized zinc oxide (ZnO) nanoparticles were synthesized with ethylene diamine tetraacetic acid (EDTA) as a modification agent, which were used as adsorbents in the adsorption of Cu2+ at certain conditions. The transmission electron microscopy (TEM) results show that the average size of ZnO particles is about 45 nm, and it exhibits hexagonal wurtzite structure. Fourier transform infrared (FTIR) spectra reveal that the EDTA species are chemically bonded on the surface of ZnO. Compared with bare ZnO particles, the functionalized ZnO nanoparticles have a better activity in the Cu2+ adsorption. The maximum adsorption capacity of functionalized ZnO nanoparticles is 20.97 mg/g, while it is 17.93 mg/g for the bare ZnO. The adsorption isotherm of bare ZnO particles is in accordance with the Freundlich model, and the chemical adsorption is in a dominant position in the adsorption process of Cu2+ on functionalized ZnO particles. 相似文献
6.
ZHANG Guobin PAN Xuelei YU Kesong YAN Mengyu XIONG Fangyu WU Liming DENG Xuanwei ZHANG Haining MAI Liqiang 《高等学校化学研究》2020,36(4):690-693
Li[Ni0.6Co0.2Mn0.2]O2(NCM622) is one of the best commercialized cathodes in the battery field. However, poor cyclability at relatively high temperature hinders its multiple usages. Here, operando tests were performed to investigate the phase transitions and electron/ion transfer process of layered NCM622 at 25 and 55℃. The identified spinel structure resulting in the poor cyclability at 55℃ guides the commercialization of batteries at high temperature. 相似文献
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Liu J Yan J Yuan X Liu K Peng J Fang Y 《Journal of colloid and interface science》2008,318(2):397-404
A novel low-molecular-mass gelator containing a redox-active ferrocenyl group, cholesteryl glycinate ferrocenoylamide (CGF), was intentionally designed and prepared. It was demonstrated that the gelator gels 13 out of the 45 solvents tested. Scanning electron microscopy (SEM) measurements revealed that the gelator self-assembled into different supramolecular network structures in different gels. Chemical oxidation of the ferrocenyl residue resulted in phase transition of the gel from gel state to solution state. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding between the gelator molecules in the gel was one of the main driving forces for the formation of the gels. 相似文献
8.
Qizhang Li Xuefei Wang Yiyuan Chen Juan Lin Xuanwei Zhou 《Applied biochemistry and biotechnology》2010,162(5):1403-1413
Ganoderma sinensis fungal immunomodulatory protein (FIP-gsi) was a new member of FIPs family. Based on the cloning of FIP-gsi gene from G. sinensis, this paper reported that FIP-gsi gene was expressed in Escherichia coli expression system. Then, the recombinant proteins were analyzed by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis
(SDS-PAGE) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Finally, the immunomodulatory activity
was examined by inducing cytokine genes expression. The results showed that the recombinant FIP-gsi protein could be expressed
in E. coli and got the yield of about 25% of the soluble form in the total soluble protein. The FIP-gsi protein was composed of 111
amino acids, and the sequence of homologous rate was 88.6% with FIP-glu (LZ-8). Furthermore, it could enhance the levels of
interleukin (IL)-2, IL-3, IL-4, interferon gamma, tumor necrosis factor alpha, and IL-2 receptor (IL-2R) in mouse spleen cells. 相似文献
9.
对于赋范线性空间中的多目标规划问题,引进了广义KT-真有效解的概念.在一定条件下,得到了广义KT-真有效解和广义H-局部真有效解之间的关系. 相似文献
10.
Water-spray-cooled quasi-isothermal compressed air energy storage aims to avoid heat energy losses from advanced adiabatic compressed-air energy storage (AA-CAES). The compression efficiency increases with injection water spray. However, the energy-generated water spray cannot be ignored. As the air pressure increases, the work done by the piston and the work converted into heat rise gradually in the compression process. Accordingly, the flow rate of the water needed for heat transfer is not a constant with respect to time. To match the rising compression heat, a time sequence of water-spray flow rate is constructed, and the algorithm is designed. Real-time water-spray flow rate is calculated according to the difference between the compression power and heat-transfer power. Compared with the uniform flow rate of water spray, energy consumption from the improved flow rate is reduced. 相似文献