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91.
An efficient one-step method has been developed to construct furans via a Suzuki–Miyaura cross-coupling reaction of 1,2-oxaborol-2(5H)-ols with carboxylic anhydrides. In the presence of Pd(OAc)2/PCy3, the multi-substituted alkenylboron compounds could couple with anhydrides to obtain furans in moderate-to-good yields. The addition of bases promoted the coupling reaction, and the plausible reaction mechanism was proposed. 相似文献
92.
Qingpei Xiang Dongfeng Tian Fanhua Hao Chengsheng Chu Ge Ding Jun Zeng Fei Luo 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1439-1445
In recent years, the cerium-doped lanthanum bromide, LaBr3 (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr3(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr3(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically. 相似文献
93.
Wang Jin-Lan Liu Zhi-Hua Zhao Ying-Nan Li Jun Shi Zhi-Chun Liang Xin-Rui Zhao Ming Zhang Shu-Jun 《Chemistry of Natural Compounds》2022,58(4):601-603
Chemistry of Natural Compounds - A new lactam, 5-hydroxy-1-[(4-hydroxyphenyl)methyl]-2-pyrrolidinone (1), was isolated from the ethyl acetate extract of Cannabis sativa L. The structure was... 相似文献
94.
Qiang Fu Xianjie Wang Jiecai Han Jun Zhong Tongrui Zhang Tai Yao Chengyan Xu Tangling Gao Shibo Xi Ce Liang Lingling Xu Ping Xu Bo Song 《Angewandte Chemie (International ed. in English)》2021,60(1):259-267
To ensure sustainable hydrogen production by water electrolysis, robust, earth‐abundant, and high‐efficient electrocatalysts are required. Constructing a hybrid system could lead to further improvement in electrocatalytic activity. Interface engineering in composite catalysts is thus critical to determine the performance, and the phase‐junction interface should improve the catalytic activity. Here, we show that nickel diphosphide phase junction (c‐NiP2/m‐NiP2) is an effective electrocatalyst for hydrogen production in alkaline media. The overpotential (at 10 mA cm?2) for NiP2‐650 (c/m) in alkaline media could be significantly reduced by 26 % and 96 % compared with c‐NiP2 and m‐NiP2, respectively. The enhancement of catalytic activity should be attributed to the strong water dissociation ability and the rearrangement of electrons around the phase junction, which markedly improved the Volmer step and benefited the reduction process of adsorbed protons. 相似文献
95.
First-principles calculations are carried out to study photo-oxidation of glucose, as a prototype of polyhydroxyl carbohydrates and alcohols, on TiO2 surfaces. We reveal the microscopic mechanisms for the separation and transfer of photogenerated electrons and holes at the TiO2-molecule interface as detailed from hole trapping, deprotonation, to the formation of an electron-hole recombination center. These revealed mechanisms further lead to the understanding of the light-induced self-assembly mechanism for TiO2-cyclodextrin nanowires. 相似文献
96.
Laser-diode pumped heavy-doped Yb:YAG ceramic lasers 总被引:1,自引:0,他引:1
Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at.% ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb(3+)-ion lasants. 相似文献
97.
Zhiguo Lu Xiangyu Wang Tianlu Zhang Luyao Zhang Jun Yang Yan Li Jie Shen Jianze Wang Yunwei Niu Zuobing Xiao Guiying Liu Xin Zhang 《中国化学快报》2021,31(12):3139-3142
Silk has been widely used in the clothing industry due to their soft and smooth features, good biocompatibility, good heat dissipation, warmth and ultraviolet resistance. The application of fragrance to silk can significantly improve the performance of silk. However, there are two key scientific problems that need to be solved: slowing down the release rate of fragrances and increasing the scent lasting time of silk. In this study, cationic and temperature-sensitive liposomes were designed and prepared to encapsulate eugenol. These fragrance-loaded liposomes significantly slowed down the release rate of the fragrance and controlled the release rate of the fragrance in a thermo-sensitive manner. The liposomes adhered to the silk through electrostatic adsorption interaction. The positive charge on the fragrance-loaded liposomes neutralized much negative charge on silk and thereby increasing the adhesion efficiency. 相似文献
98.
Synthesis of α-Fe2O3 compound with regular hexahedron shape is firstly reported. X-ray diffraction and scan electron microscope are used to characterize the structure and morphology of the prepared sample, respectively. The average edge length of hexahedron is about 0.9 μm. A reaction mechanism has been proposed. The pH value is a crucial factor for the formation and shape of α-Fe2O3. Moreover, electrochemical impedance spectroscopy and charge-discharge test of α-Fe2O3 as anode material in lithium ion batteries are evaluated. The data indicate that the synthesized regular hexahedron α-Fe2O3 can show better electrochemical properties than that of the commercial. 相似文献
99.
Xiande Yang Yongqian Wang Tingting Jiang Jun Yang Yinchang Li Qun Ma 《Crystal Research and Technology》2015,50(4):338-345
In this article, dendritic‐like CdS has been prepared by a hydrothermal method using thiourea as the sulfur source, and the effects of experimental conditions on the morphologies of CdS have been investigated. The performances of CdS have been analyzed by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and the fluorescence and photodegradation properties of CdS have also been investigated. The XRD result indicates that the dendritic‐like CdS are of hexagonal phase and they are highly crystallized. Also, the FESEM results show that the ratio of raw material affects the yield of CdS, the reaction time affects the morphology of CdS. The best morphology of CdS is dendritic structures and the length is about 6 μm. The fluorescence spectrum shows three peaks at 470 nm, 513 nm and 547 nm, which indicates that the dendritic‐like CdS mainly emits green and blue fluorescence. Moreover, the dendritic‐like CdS exhibits good photocatalytic activity and its photodegradation rate to methylene blue can reach 92%. The growth mechanism for the formation of CdS with dendritic structure is also described. 相似文献
100.
A Supercharged Fluorescent Protein as a Versatile Probe for Homogeneous DNA Detection and Methylation Analysis 下载免费PDF全文
Chunyang Lei Dr. Yan Huang Prof. Dr. Zhou Nie Jun Hu Lijun Li Guoyan Lu Yitao Han Prof. Dr. Shouzhuo Yao 《Angewandte Chemie (International ed. in English)》2014,53(32):8358-8362
Supercharged proteins are a new class of functional proteins with exceptional stability and potent ability to deliver bio‐macromolecules into cells. As a proof‐of‐principle, a novel application of supercharged proteins as a versatile biosensing platform for nucleic acid detection and epigenetics analysis is presented. Taking supercharged green fluorescent protein (ScGFP) as the signal reporter, a simple turn‐on homogenous method for DNA detection has been developed based on the polyionic nanoscale complex of ScGFP/DNA and toehold strand displacement. This assay shows high sensitivity and potent ability to detect single‐base mismatch. Furthermore, combined with bisulfite conversion, this ScGFP‐based assay was further applied to analyze site‐specific DNA methylation status of genomic DNA extracted from real human colon carcinoma tissue sample with ultrahigh sensitivity (4 amol methylated DNA). 相似文献