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排序方式: 共有4534条查询结果,搜索用时 171 毫秒
1.
为进一步提高对偏硼酸钠电催化还原的效率,采用化学镀的方法,以铜片为基体,PdCl2乙醇胶体溶液为活化剂,乙醇为化学镀溶剂,制备了稀土复合电极La-Ni-B.并采用XRD、SEM、EDS方法对催化剂进行表征分析,结果表明稀土合金以纳米颗粒的形式附着在基体表面,所得合金膜是非晶态的.通过循环伏安法研究了复合电极La-Ni-B用于电解偏硼酸钠制备硼氢化钠的可行性.以硼氢化钠实际生产量为指标,探讨了直流、脉冲两种不同供电方式、脉冲电流频率、电解时间对电解行为的影响.结果表明稀土镧对电解偏硼酸钠有催化作用,以20 mL镀液制备的复合电极,在脉冲频率阳极时间T1=1 s,阴极时间T2=1 s时,最佳电解时间为4h.复合电极在重复使用3次的情况下,硼氢化钠产量降低15;,催化剂的重复使用性能良好. 相似文献
2.
De-en Han Yanmei Shi Ping Tian Hengchao Wei Mingsan Miao Xiu-min Li 《Biomedical chromatography : BMC》2020,34(7):e4838
A rapid and sensitive method was developed and validated for the quantitative determination of xanthopurpurin (XPP) in rat plasma using ultra-performance liquid chromatography-electrospray ionization-Orbitrap mass spectrometry. XPP inhibits IgE production and prevents peanut-induced anaphylaxis. The XPP and emodin (internal standard) were determined in negative ion mode with m/z 239.0350 → 211.0400 and 269.0455 → 241.0507, respectively. The separation process was achieved using an ACQUITY UPLC HSS T3 column with acetonitrile and 0.1% formic acid in water (85:15). The linear range was 0.5–100 ng/mL, and the correlation coefficient (r2) was > 0.993. The inter-day and intra-day precision was within an acceptable range of 15%. The extraction recovery and matrix effect were 78.9–87.2% and 94.3–98.5%, respectively. Under different conditions, the XPP was stable in the range of 5.6–10.6%. This method was successfully applied to study the pharmacokinetics of XPP with an oral dose of 10.0 mg/kg and intravenous dose of 2.0 mg/kg in rats. The absolute oral bioavailability of XPP was 4.6%. 相似文献
3.
Zhengyang Yang Jiafeng Wang Song Liu Feng Sun Ji Miao En Xu Liang Tao Yuxin Wang Shichao Ai Wenxian Guan 《Particle & Particle Systems Characterization》2019,36(7)
Photothermal therapy (PTT) is an emerging noninvasive and precise localized therapeutic modality; however, it is deeply limited by its poor tumor accumulation, inadequate photothermal conversion efficiency, and the thermoresistance of cancer cells. Aimed at these shortcomings, tumor‐targeting nanoparticles (iRGD‐W18O49‐17AAG) comprising carboxyl‐group‐functionalized W18O49 nanoparticles, integrin‐targeting peptide iRGD, and HSP90‐inhibitor 17AAG are developed. The W18O49 nanoparticles act as excellent PTT carriers and computed tomography (CT) imaging contrast agents. The ring type polypeptide iRGD promotes the accumulation of nanoparticles in the tumour and further penetration into cancer cells. The introduction of 17AAG can inhibit the heat‐shock response and overcome the thermoresistance, thus increasing the curative effect of PTT and reducing the chance of tumor recurrence. The W18O49 nanoparticles can also be used to monitor and guide the phototherapeutic through CT and near‐infrared fluorescence imaging after modification with Cy5.5. In addition, superior biosafety is also indicated in both preliminary in vitro and in vivo assessments. The potential of iRGD‐W18O49‐17AAG in tumor targeting, dual modality imaging‐guided and remarkable enhanced PTT of gastric cancer with ignorable side effect both in vitro and in vivo, which may be further applied in clinic, is highlighted. 相似文献
4.
Yijie Yang Shu‐Qi Wang Haoming Wen Tao Ye Jing Chen Cheng‐Peng Li Miao Du 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15506-15510
The electrochemical nitrogen reduction reaction (NRR) offers an energy‐saving and environmentally friendly approach to produce ammonia under ambient conditions. However, traditional catalysts have extremely poor NRR performances because of their low activity and the competitive hydrogen evolution reaction. The high catalytic activity of nanoporous gold (NPG) and the hydrophobicity and molecular concentrating effect of the zeolitic imidazolate framework‐8 (ZIF‐8) were incorporated in the NPG@ZIF‐8 nanocomposite so that the ZIF‐8 shell could weaken hydrogen evolution and retard reactant diffusion. A highest Faradaic efficiency of 44 % and an excellent rate of ammonia production of (28.7±0.9) μg h?1 cm?2 were achieved, which are superior to traditional gold nanoparticles and NPG. Moreover, the composite catalyst shows high electrochemical stability and selectivity (98 %). The superior NRR performance makes NPG@ZIF‐8 one of the most promising water‐based NRR electrocatalysts for ammonia production. 相似文献
5.
6.
Xuan Zhang Xianhe Fang Miao Xu Yibo Lei Zibo Wu Xiangdong Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7927-7931
Enantioselective total syntheses of pseudopteroxazole ( 1 ) and ileabethoxazole ( 2 ) are presented. The two original stereocenters were constructed in excellent enantioselectivity and good diastereoselectivity through Carreira's asymmetric dual catalytic allylation, which shows potential for accessing diastereoisomers at C2 and C3 of 1 and 2 . Cationic cyclizations of 13 and 24 demonstrated an effective pathway for the construction of the opposite configurations at C1 in 1 and 2 . Additionally, an approach for the introduction of methyl at C4 is a feasible solution for structural modifications at C4 in 1 and 2 . 相似文献
7.
Miao Yan Hai-Ru Li Xiao-Yun Zhao Xiao-Qin Lu Yue-Wen Mu Hai-Gang Lu Si-Dian Li 《Journal of computational chemistry》2019,40(9):966-970
Based on detailed bonding analyses on the fluxional behaviors of planar B19−, tubular Ta@B20−, and cage-like B39−, we propose the concept of fluxional bonds in boron nanoclusters as an extension of the classical localized bonds and delocalized bonds in chemistry. © 2018 Wiley Periodicals, Inc. 相似文献
8.
Dr. Liangqi Gui Xiaoyun Miao Chengjun Lei Kailin Wang Dr. Wei Zhou Dr. Beibei He Prof. Qing Wang Dr. Ling Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(47):11007-11014
Implementing sustainable energy conversion and storage technologies is highly reliant on crucial oxygen electrocatalysis, such as the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). However, the pursuit of low cost, energetic efficient and robust bifunctional catalysts for OER and ORR remains a great challenge. Herein, the novel Na-ion-deficient Na2−xCoP2O7 catalysts are proposed to efficiently electrocatalyze OER and ORR in alkaline solution. The engineering of Na-ion deficiency can tune the electronic structure of Co, and thus tailor the intrinsically electrocatalytic performance. Among the sodium cobalt phosphate catalysts, the Na1.95CoP2O7 (NCPO5) catalyst exhibits the lowest ΔE (EJ10,OER−EJ−1,ORR) of only 0.86 V, which favorably outperforms most of the reported non-noble metal catalysts. Moreover, the Na-ion deficiency can stabilize the phase structure and morphology of NCPO5 during the OER and ORR processes. This study highlights the Na-ion deficient Na2−xCoP2O7 as a promising class of low-cost, highly active and robust bifunctional catalysts for OER and ORR. 相似文献
9.
10.
Dr. Hongming He Qian-Qian Zhu Jia-Nan Zhao Dr. Hongming Sun Jing Chen Dr. Cheng-Peng Li Prof. Miao Du 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11474-11480
CO2 is considered as the primary greenhouse gas, resulting in a series of serious environmental problems that affect people's life and health. Carbon capture and sequestration has been implemented as one of the most appealing pathways to control and use CO2. Here, we rationally integrate various functional sites within the confined nanospace of a microporous metal–organic framework (MOF) material, which is constructed by mixed-ligand strategy based on metal-adeninate vertices. It not only exhibits excellent stability but also can efficiently transform CO2 and epoxides to cyclic carbonates under mild and cocatalyst-free conditions. Additionally, this catalyst shows extraordinary recyclability for the CO2 cycloaddition reaction. 相似文献