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排序方式: 共有3156条查询结果,搜索用时 31 毫秒
31.
Xianhao Lv Mizhen Sun Lei Xu Runzhe Wang Huayi Zhou Yuyu Pan Shitong Zhang Qikun Sun Shanfeng Xue Wenjun Yang 《Chemical science》2020,11(19):5058
Designing a donor–acceptor (D–A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D–π–A fluorescent molecule (triphenylamine–anthracene–phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as a light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L''Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A−1, power efficiency of 12.35 lm W−1, luminescence of ≈29 900 cd cm−2, and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m−2 with a low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.A new pure fluorescent blue HLCT-emitter was designed and synthesized. Highly efficient non-doped blue OLEDs with low efficiency roll-off were achieved. 相似文献
32.
Jun Chu Qiulan Lv Chunliang Guo Dazhuang Xu Ke Wang Meiying Liu Hongye Huang Xiaoyong Zhang Yen Wei 《中国科学:化学(英文版)》2016,59(8):1003-1009
The synthesis of amphiphilic aggregation-induced emission(AIE) dyes based organic nanoparticles has recently attracted increasing attention in the biomedical fields. These AIE dyes based nanoparticles could effectively overcome the aggregation caused quenching effect of conventional organic dyes, making them promising candidates for fabrication of ultrabright organic luminescent nanomaterials. In this work, AIE-active luminescent polymeric nanoparticles(4-NH_2-PEG-TPE-E LPNs) were facilely fabricated through Michael addition reaction between tetraphenylethene acrylate(TPE-E) and 4-arm-poly(ethylene glycol)-amine(4-NH_2-PEG) in rather mild ambient. The 4-NH_2-PEG can not only endow these AIE-active LPNs good water dispersibility, but also provide functional groups for further conjugation reaction. The size, morphology and luminescent properties of 4-NH_2-PEG-TPE-E LPNs were characterized by a series of techniques in detail. Results suggested that these AIE-active LPNs showed spherical morphology with diameter about 100–200 nm. The obtained 4-NH_2-PEG-TPE-E LPNs display high water dispersibility and strong fluorescence intensity because of their self assembly and AIE properties of TPE-E.Biological evaluation results demonstrated that 4-NH_2-PEG-TPE-E LPNs showed negative toxicity toward cancer cells and good fluorescent imaging performance. All of these features make 4-NH_2-PEG-TPE-E LPNs promising candidates for biological imaging and therapeutic applications. 相似文献
33.
Seed‐Mediated Synthesis of Gold Tetrahedra in High Purity and with Tunable,Well‐Controlled Sizes 下载免费PDF全文
Yiqun Zheng Wenying Liu Tian Lv Ming Luo Dr. Hefei Hu Dr. Ping Lu Dr. Sang‐Il Choi Chao Zhang Dr. Jing Tao Prof. Yimei Zhu Prof. Zhi‐Yuan Li Prof. Younan Xia 《化学:亚洲杂志》2014,9(9):2635-2640
We report a facile synthesis of Au tetrahedra in high purity and with tunable, well‐controlled sizes via seed‐mediated growth. The success of this synthesis relies on the use of single‐crystal, spherical Au nanocrystals as the seeds and manipulation of the reaction kinetics to induce an unsymmetrical growth pattern for the seeds. In particular, the dropwise addition of a precursor solution with a syringe pump, assisted by cetyltrimethylammonium chloride and bromide at appropriate concentrations, was found to be critical to the formation of Au tetrahedra in high purity. Their sizes could be readily tuned in the range of 30–60 nm by simply varying the amount of precursor added to the reaction solution. The current strategy not only enables the synthesis of Au tetrahedra with tunable and controlled sizes but also provides a facile and versatile approach to reducing the symmetry of nanocrystals made of a face‐centered cubic lattice. 相似文献
34.
Determination of hydroxysafflor yellow A in biological fluids of patients with traumatic brain injury by UPLC‐ESI‐MS/MS after injection of Xuebijing 下载免费PDF全文
Yong Guo Yang Wang Xi. Huang Huiying Lv Rong Fan Wei Huang Pingping Gan Wei Liu Kuipo Yan Zian Xia Jinfang Liu 《Biomedical chromatography : BMC》2014,28(8):1090-1095
A simple, novel, specific, rapid and reproducible ultra‐performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for the determination of hydroxysafflor yellow A (HSYA) in biological fluids (plasma, urine and cerebrospinal fluid) of patients with traumatic brain injury after intravenous injection of Xuebijing (XBJ). Liquid–liquid extraction was performed, and separation was carried out on an Acquity UPLC? BEH C18 column, with gradient elution using a mobile phase composed of methanol and 0.1% formic acid at a flow rate of 0.3 mL/min. A triple quadrupole tandem mass spectrometer with electrospray ionization was used for the detection of HSYA. The mass transition followed was m/z 611.0 → 491. The retention time was less than 3.0 min. The calibration curve was linear in the concentration range from 2 to 6125 ng/mL for cerebrospinal fluid, plasma and urine. The intra‐ and inter‐day precisions were <10%, and the relative standard deviation of recovery was <15% for HSYA in biological matrices. The method was successfully applied for the first time to quantify HSYA in the biological fluids (especially in cerebrospinal fluid) of patients with traumatic brain injury following intravenous administration of XBJ. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
35.
Stephen G. Davies Ai M. Fletcher Linlu Lv Paul M. Roberts James E. Thomson 《Tetrahedron: Asymmetry》2012,23(11-12):910-925
The conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to a range of β-fluoroaryl-α,β-unsaturated esters gave the corresponding β-amino esters with high diastereoselectivity and in good isolated yields. Sequential treatment of the resultant β-fluoroaryl-β-amino esters under optimised hydrogenolysis conditions, followed by ester hydrolysis with 2.0 M aq HCl, provided access to a range of β-fluoroaryl-β-amino acids in good yield. 相似文献
36.
37.
In this study, BiOCl samples were synthesized under different pH values and characterized by XRD, SEM, UV‐vis DRS, BET, photoelectrochemical measurement and PL. The photocatalytic performances of the as‐prepared samples were evaluated through the decomposition of trichloroethylene (TCE) under UV irradiation. The influences of several parameters such as solution pH and common inorganic anions on TCE removal were investigated. Results indicated that BiOCl‐0.6 exhibited better photocatalytic performance than BiOCl‐6.0 because of its higher migration ability of photo‐induced carrier. The photocatalytic degradation of TCE over BiOCl‐0.6 followed pseudo first‐order kinetics and appeared to be more efficient in acidic solution than in alkaline. TCE was almost completely dechlorinated in 120 minutes. The inhibiting effect of naturally occurring anions was in the order of HCO3‐ >SO42‐ >NO3‐, while Cl‐ exhibited a dual effect. Moreover, BiOCl‐0.6 exhibited superior reusability after three cycles of repetition tests. 相似文献
38.
We develop the wave-optics approach for calculating the diffraction distribution of gradient refractiveindex lenses and observing the diffraction pattern of gradient refractive-index lenses in the experiments. The results of our calculation are in good agreement with the experimental results obtained. We show that the diffraction can be regarded as a method to check the quality of the refractive-index distributions of gradient refractive-index lenses. 相似文献
39.
40.
The dynamic characteristics of drilling shaft in deep hole drilling influenced by minimal quantity lubrication (MQL) is investigated. According to the features of the compressible fluid Reynolds equation in oil/air feature, a time-dependent mathematical model is established to describe the pressure distribution of cutting fluid with nonlinearity in MQL deep hole drilling. By introducing the differential transformation approach, the time-dependent pressure equation arising from cutting fluid is solved by the use of direct integral method. The influences of the rotational speed, the transverse displacement ratio, and radial clearance on the hydrodynamic pressure distribution of cutting fluid are obtained. The advantage of this method is to overcome much of the computational cost and has its rapid convergence rate. Furthermore, the nonlinear responses of drilling shaft influenced by MQL are analyzed, and the instability rotational speeds of drilling tool are discussed while the design parameters of drilling shaft system changing. 相似文献