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排序方式: 共有216条查询结果,搜索用时 15 毫秒
91.
Leng W Zhou S You B Wu L 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):17836-17839
Styrene-acrylic acid copolymer was synthesized via solution polymerization and then sulfonated by concentrated sulfuric acid. This sulfonated copolymer displays an obvious pH-responsive color change in aqueous solutions (1 g/L) from yellow (pH <6) to khaki (pH 6 to 7)/red (pH 7 to 8) to purple (pH >8). This response is as quick as for small-molecule pH indicators such as methyl orange and phenolphthalein within 1 s and can be reversible. The lowest critical concentration of this pH-responsive copolymer solution is around 0.1 g/L, which is about 50-500 times the necessary amount used for conventional small-molecule pH indicators. An intramolecular cyclization mechanism between a neighboring carboxyl group and a benzene ring to form a sulfonated aromatic ketone is proposed to explain this pH-responsive color change behavior. The molar ratio of 1:1 for styrene to acrylic acid is the most favorable for forming neighboring benzene and carboxyl group pairs in the copolymer chains and subsequently yields sulfonated aromatic ketone chromophores at full capacity. 相似文献
92.
Amino‐Assisted Anchoring of CsPbBr3 Perovskite Quantum Dots on Porous g‐C3N4 for Enhanced Photocatalytic CO2 Reduction 下载免费PDF全文
Man Ou Dr. Wenguang Tu Dr. Shengming Yin Weinan Xing Shuyang Wu Haojing Wang Shipeng Wan Prof. Dr. Qin Zhong Prof. Dr. Rong Xu 《Angewandte Chemie (International ed. in English)》2018,57(41):13570-13574
Halide perovskite quantum dots (QDs) have great potential in photocatalytic applications if their low charge transportation efficiency and chemical instability can be overcome. To circumvent these obstacles, we anchored CsPbBr3 QDs (CPB) on NHx‐rich porous g‐C3N4 nanosheets (PCN) to construct the composite photocatalysts via N?Br chemical bonding. The 20 CPB‐PCN (20 wt % of QDs) photocatalyst exhibits good stability and an outstanding yield of 149 μmol h?1 g?1 in acetonitrile/water for photocatalytic reduction of CO2 to CO under visible light irradiation, which is around 15 times higher than that of CsPbBr3 QDs. This study opens up new possibilities of using halide perovskite QDs for photocatalytic application. 相似文献
93.
A transition metal-free, direct one-pot domino allylation reaction of 2-pyridinyl Grignard reagents with polysubstituted allyl chlorides for the regioselective synthesis of pyridinyl-substituted 1,5-diene derivatives has been disclosed. The reaction presumably proceeded through the coupling of polysubstituted allyl chloride to 2-PyMgX, which was in situ generated from 2-bromopyridine with i-PrMgCl·LiCl. 相似文献
94.
以Sm2O3、Gd2O3与Ce2(CO3)3.nH2O为原料,采用Sol-Gel法制备了二元稀土掺杂(Sm2O3)0.04(Gd2O3)0.06Ce0.8O2.δ纳米粉体.测定了pH值对0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3水溶胶体系zeta电位的影响.pH值约为7.0时,体系的Zeta电位为0,即体系的等电点(IEP)为7.0.pH值为10.0时,Zeta电位达到最大值-18.5my,说明此时该体系的稳定性最好.DTA/TG热分析表明,0.80Ce(OH)4·0.08Sm(OH)3·0.12Gd(OH)3粉体的热分解温度约为232℃.由粉末XRD分析可知,经750℃焙烧的二元稀土掺杂CeO2粉末为立方萤石结构,说明Sm2O3与Gd2O3已完全固溶到CeO2中形成了CeO2基固溶体.由TEM照片可以看出,粉末具有良好的分散性,呈软团聚状态,粒径在5-10nm之间.经BET测试计算的平均颗粒尺寸为11nm,与TEM结果是一致的. 相似文献
95.
For the purpose of structural health monitoring, a damage detection method combined with optimum sensor placement is proposed in this paper. The back sequential sensor placement(BSSP) algorithm is introduced to optimize the sensor locations with the aim of maximizing the 2-norm of information matrix, since the EI method is not suitable for optimum sensor placement based on eigenvector sensitivity analysis. Structural damage detection is carried out based on the respective advantages of mode shape and frequency. The optimized incomplete mode shapes yielded from the optimal sensor locations are used to localize structural damage. After the potential damage elements have been preliminarily identified, an iteration scheme is adopted to estimate the damage extent of the potential damage elements based on the changes in the frequency. The effectiveness of this method is demonstrated using a numerical example of a 31-bar truss structure. 相似文献
96.
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98.
补硒对预防原发性肝癌的作用 总被引:2,自引:2,他引:2
原发性肝癌病因为多因素协同作用的结果,我国肝癌病因以乙型肝炎病毒(HBV)、黄曲霉毒(AFB1)、饮水污染和遗传等因素为主。某些微量元素缺乏,促进了肝癌的发生、发展。科学工作者针对肝癌病因采取以“防治肝炎、管粮防霉、改良饮水、适量补硒”为中心的综合防治措施,已取得初步成效,本硒进一步阐明在肝癌高发现场应用补硒肝癌的作用。通过四年前瞻研究结果表明,食硒盐补硒组较对照组血硒GSH-px升高,UDS、微 相似文献
99.
A white substance was got by directly heating TiSi powder on Ti foil, under Ar+O2 atmosphere. ED, EDX, SEM and HRTEM studies reveal that the white substance consists of amorphous SiO2nanowires of smooth surface and uniform diameter (40-90 nm). X-ray-induced luminescent emission experiment shows that two broad peaks are at 430 and 570 nm. A one-dimensional growth mechanism, on the basis of the one-dimensional thermal flow during nanowire formation, is discussed. 相似文献
100.
Kuan Wang Danyang Chen Zhuoya Wang Jianhai Yang Wenguang Liu 《Macromolecular bioscience》2023,23(10):2300142
The imbalance of extrinsic and intrinsic healing of tendon is thought to be the main cause of peritendinous adhesions. In this work, an injectable supramolecular poly(N-(2-hydroxypropyl) acrylamide) (PHPAm) hydrogel is prepared merely via side chain hydrogen-bonding crosslinks. This PHPAm exhibits good antifouling and self-healing properties. The supramolecular hydrogel simultaneously loaded with Prussian blue (PB) nanoparticles and platelet lysate (PL) is explored as a functional physical barrier, which can significantly resist the adhesion of fibrin and fibroblasts, attenuate the local inflammatory response, and enhance the tenocytes activity, thus balancing extrinsic and intrinsic healing. The PHPAm hydrogel is shown to prevent peritendinous adhesions considerably by inhibiting NF-κB inflammatory pathway and TGF-β1/Smad3-mediated fibrosis pathway, thereby significantly improving tendon repair by releasing bioactive factors to regulate the tenocytes behavior. This work provides a new strategy for developing physical barriers to prevent peritendinous adhesions and promote tissue repair effectively. 相似文献