排序方式: 共有34条查询结果,搜索用时 31 毫秒
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利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便. 相似文献
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Hu Eming Lei Zhiwu Wang Hongqiang Su Hao Zhou Wen Wan Qiang Zhu Fangping Wang Qingliang 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(6):2445-2450
Journal of Radioanalytical and Nuclear Chemistry - The uraniferous caustic sludge (UCS) produced in the production of uranium fuel components was hardly to leach directly, due to its very low-grade... 相似文献
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Fangping Zhou Zhao Zhao Ming Xu Prof. Ting Wang Huiru Yang Rong Wang Jiahui Wang Prof. Haibo Li Prof. Ming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(14):e202104157
Perovskite is a promising non-noble catalyst and has been widely investigated for the electrochemical oxygen evolution reaction (OER). However, there is still serious lack of valid approaches to further enhance their catalytic performance. Herein, we propose a spin state modulation strategy to improve the OER electrocatalytic activity of typical perovskite material of LaCoO3. Specifically, the electronic configuration transition was realized by a simple high temperature thermal reduction process. M-H hysteresis loop results reveal that the reduction treatment can produce more unpaired electrons in 3d orbit by promoting the electron transitions of Co from low spin state to high spin state, and thus lead to the increase of the spin polarization. Electrochemical measurements show that the catalytic performance of LaCoO3 is strongly dependent on its electronic configuration. With the optimized reduction treatment, the overpotential for the OER process in 0.5 M KOH electrolyte solution at 10 mA cm−2 current density was 396 mV, significantly lower than that of the original state. Furthermore, it can mediate efficient OER with an overpotential of 383 mV under an external magnetic field, which is attributed to the appropriate electron filling. Our results show that electron spin state regulation is a new way to boost the OER electrocatalytic activity. 相似文献
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Dr. Fangping Ren Ji Xian Zhaowei Jia Zhichun Chen Hongjun Fu Prof. Dr. Rui Wang Prof. Dr. Wen-Dao Chu Prof. Dr. Xiaobo Pan Jincai Wu 《Angewandte Chemie (International ed. in English)》2023,62(44):e202306759
To synthesize high molecular weight poly(phenolic ester) via a living ring-opening polymerization (ROP) of cyclic phenolic ester monomers remains a critical challenge due to serious transesterification and back-biting reactions. Both phenolic ester bonds in monomer and polymer chains are highly active, and it is difficult so far to distinguish them. In this work, an unprecedented selectively bifunctional catalytic system of tetra-n-butylammonium chloride (TBACl) was discovered to mediate the syntheses of high molecular weight salicylic acid-based copolyesters via a living ROP of salicylate cyclic esters (for poly(salicylic methyl glycolide) (PSMG), Mn=361.8 kg/mol, Ð<1.30). Compared to previous catalysis systems, the side reactions were suppressed remarkably in this catalysis system because phenolic ester bond in monomer can be selectively cleaved over that in polymer chains during ROP progress. Mechanistic studies reveal that the halide anion and alkyl-quaternaryammonium cation work synergistically, where the alkyl-quaternaryammonium cation moiety interacts with the carbonyl group of substrates via non-classical hydrogen bonding. Moreover, these salicylic acid-based copolyesters can be recycled to dimeric monomer under solution condition, and can be recycled to original monomeric monomers without catalyst under sublimation condition. 相似文献
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以乙酸-水-甲酸三元体系为研究对象,适当选择甲酸的酯化剂,进行该体系的分离实验。结果表明,用酯化-共沸蒸馏可除去乙酸、水和甲酸混合液中的水和甲酸,从而达到精制醋酸的目的。 相似文献
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固相萃取-高效液相色谱法测定烟草样品中10种多酚 总被引:21,自引:2,他引:21
研究了用固相萃取预分离,高效液相色谱法测定烟草样品中的10种植物多酚。烟草样品中的多酚提取液用SepParkC18固相萃取小柱预分离脱脂,以WatersNovaPakC18(3.9mm×150mm,5μm)色谱柱为固定相,0.05mol/L磷酸二氢钾缓冲溶液和甲醇梯度洗脱为流动相,烟草中主要的植物多酚均达到基线分离;用紫外二级管矩阵检测器检测,得出各组分在其最大吸收波长下的色谱图,根据该色谱图的峰面积定量,并用紫外光谱图对烟草中主要多酚进行辅助定性。标准回收率为94%~105%;RSD为1.3%~1.5%。用该方法测定了烟草样品中的10种植物多酚,结果令人满意。 相似文献
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Fangping Chen 《Applied Surface Science》2008,255(2):270-272
Calcium polyphosphate (CPP) bone substitutes were prepared by gravity sintering crystal transformations. The crystalline structure of CPP was analyzed by Raman spectroscopy and in situ variable temperature XRD. In addition, the variation of CPP in SBF considering as degradation was characterized by monitoring the changes of its compressive strength and weight loss. The results revealed that CPP was inorganic condensed phosphate with linear long chain structure. Amorphous CPP (a-CPP) was initially transformed to crystalline γ-CPP, then crystalline β-CPP with the increase of sintering temperature. The transformation of γ-CPP to β-CPP occurred from 650 to 670 °C. Compressive strength decreased quickly at initial stage for all specimens after immersed in SBF, and thereafter, continued to decrease at a slower rate subsequently. After immersion for 15 and 30 days, the compressive strength of γ-CPP decreased from 13.5 to 7.6 and 4.8 MPa, while β-CPP decreased from 16 to 12 and 8 MPa, respectively. The degradation rate of a-CPP, γ-CPP and β-CPP decreased with time after immersed in SBF. a-CPP had highest degradation rate, which would have been completely degraded in 10 days, and the weight loss ratio of γ-CPP was 28% for 15 days and 35% for 30 days, but the weight loss of β-CPP was only 11% for 30 days. The results therefore revealed that CPPs with different degradation rates could be obtained by controlling crystalline structure. 相似文献
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Ran Zhao Liping Zhu Fangping Cai Zhiguo Yang Xiuquan Gu Jun Huang Ling Cao 《Applied Physics A: Materials Science & Processing》2013,113(1):67-73
We present a new method of synthesizing ZnO/TiO2 core–shell nanowire (NW) arrays for the fabrication of dye-sensitized solar cells (DSSCs). Vertically aligned ZnO NW arrays were obtained on Si substrates, and modified by a TiO2 shell in order to solve the recombination problems via a cost-effective spin-coating method. The structure of the ZnO/TiO2 composite NW arrays was characterized. The experimental results indicate that the TiO2 shell enhances the performance of the DSSCs, through improving the stability of the ZnO NWs and decreasing the recombination of photogenerated electrons on the NW surface. The highest overall conversion efficiency of the cell reaches about 3.0 %. 相似文献