检索结果-南通市图书馆

FeCl3-6H2O-Catalyzed Synthesis of β-Ketothioesters from Chain α-Oxo Ketene Dithioactals

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2017年第5期33卷 746-752页

作者： zhao hui Jilin Province Key Laboratory of Organic Functional Molecular Design ＆ Synthesis Department of Chemistry Northeast Normal University Changchun 130024 P. R. China

A FeCl3-6H2O-catalyzed synthesis of β-ketothioesters from the hydrolysis reaction of chain α-oxoketene dithioacetals was carried out. Subsequently, we explored the FeCl3-6H2O-catalyzed Friedel-Crafts alkylation of the synthesized fl-ketothioesters with alcohols in CH3CN at 25 ℃, affording the desired α-alkylated fl-ketothioesters in excellent yields. Wide scope of the substrates, use of inexpensive reagents, high yields under mild reaction conditions are notable features of these reactions.

关键词： Iron(Ⅲ) chloride Thioester Ketene dithioacetal Hydrolysis Friedel-Crafts alkylation

The quasitriangular structures of biproduct Hopf algebras

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 149-157页

作者： zhao Li-hui zhao Wen-zheng Department of Mathematics Zhejiang University Hangzhou 310027 China Department of Mathematics Henan Normal University Xinxiang 453002 China

The construction of the biproduct of Hopf algebras, which consists of smash product and the dual notion of smash coproduct, was first formulated by Radford. In this paper we study the quasitriangular structures over biproduct Hopf algebras B*H. We show the necessary and sufficient conditions for biproduct Hopf algebras to be quasitriangular. For the case when they are, we determine completely the unique formula of the quasitriangular structures. And so we find a way to construct solutions of the Yang-Baxter equation over biproduct Hopf algebras in the sense of (Majid, 1990).

关键词： Hopf algebra Quasitriangular structure Biproduct

A TWO-STAGE ESTIMATION ALGORITHM FOR A TYPE OF CURRENT STATUS DATA

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2012年第3期25卷 556-566页

作者： hui zhao Ningning JIANG School of Mathematics and Statistics Central China Normal University Institute of Systems Science Academy of Mathematics and Systems ScienceChinese Academy of Sciences

Success-failure life tests are widely used in reliability engineering research to evaluate the storage life of products, where the observed data are the current status data, usually summarized as the form of ＂binomial life data＂. For this type of data, this paper proposes a two-stage algorithm to estimate some commonly used lifetime distributions. This Mgorithm is automatic, intuitively appealing and simple to implement. Simulation studies show that compared with some existing methods, the proposed algorithm is more stable and efficient, especially in small sample situations, and it can also be extended to deM with some complicated lifetime distributions.

关键词： Current status data nonparametric maximum likelihood estimation success-failure lifetest.

Optimal Investment with Multiple Risky Assets for an Insurer with Modified Periodic Risk Process

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2015年第4期28卷 997-1014页

作者： zhao hui RONG Ximin School of Science Tianjin University

This paper considers the optimal investment problem for an insurer in the sense of maximizing the adjustment coefficient of the risk *** authors propose a modified periodic risk model in which the periodic risk process is perturbed by a standard Brownian *** insurer can invest in multiple risky assets and one risk-free asset and the correlations between the risky assets and the risk process are *** strategy is obtained explicitly,which is a function of time and related to the risk *** effects of market parameters on the optimal strategy are discussed and a numerical example is also given.

关键词： Adjustment coefficient modified periodic risk model multiple risky assets optimalinvestment ruin probability.

Surface/interface engineering of high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2021年第3期30卷 89-104页

作者： hui zhao Zhong-Yong Yuan School of Materials Science and Engineering Liaocheng UniversityLiaocheng 252000ShandongChina Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) School of Materials Science and EngineeringNankai UniversityTianjin 3000350China

To date,much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen-and oxygen-involving energy conversion reactions,due to their abundance,low cost and ***/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for *** various engineering strategies,heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts,and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts,though the heteroatom-doping can only provide limited active *** of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free *** addition,surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties,being as a promising complement or substitute for offering materials with catalytic *** paper gives the insights into the diverse strategies of surface/interface engineering of the highefficiency noble metal-free electrocatalysts for energy-related electrochemical *** significant advances are *** unique advantages and mechanisms for specific applications are *** current challenges and outlook of this growing field are also discussed.

关键词： Noble metal-free electrocatalysts Electrocatalysis Surface/interface engineering Metal-air battery Overall water splitting

基于改进DeblurGAN-v2的运动模糊农作物害虫图像复原方法

在线全文

学校读者我要写书评

暂无评论

光电子·激光 2025年第1期36卷 46-52页

作者：赵辉黄镖王红君岳有军天津理工大学电气工程与自动化学院天津市复杂系统控制理论与应用重点实验室

为对巡检机器人在巡检过程中产生的运动模糊图像进行高效精准识别，提出了一种基于改进DeblurGAN-v2的运动模糊农作物害虫图像复原方法。为有效提取图像重要特征，该方法将通道注意力(channel attention, CA)机制集成到DeblurGAN-v2主... 详细信息

为对巡检机器人在巡检过程中产生的运动模糊图像进行高效精准识别，提出了一种基于改进DeblurGAN-v2的运动模糊农作物害虫图像复原方法。为有效提取图像重要特征，该方法将通道注意力(channel attention, CA)机制集成到DeblurGAN-v2主干网格中，使模型更加关注细节特征，提高对运动模糊图像的复原能力；此外，在原模型特征提取网络顶层引入空间金字塔池化(spatial pryamid pooling, SPP)缓解图像多尺度变化造成对图像复原的负面影响，提高模型对图像复原的性能。基于实际农田环境建立的数据集所做的实验结果表明，改进后算法的PSNR、SSIM指标分别为26.281 8 dB、0.947 3,较原模型提升了8、7.2个百分点。与其他主流模型的对比实验结果表明，本文方法对模糊图像的实际复原效果更优，对解决运动模糊农作物害虫的图像复原问题具有实际应用价值。

关键词：运动模糊深度学习图像复原 DeblurGAN-v2 通道注意力(CA)机制空间金字塔池化(SPP)模块

Analysis of the Paper Entitled Traditional Chinese Medicine Use in the Treatment of Acute Heart Failure in Western Medicine Hospitals in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2020年第3期26卷 165-167页

作者：无 zhao hui China Center for Evidence Based Traditional Chinese Medicine CCEBTCM China Academy of Chinese Medical Sciences Beijing100700China

On July 31st 2019,a paper entitled'Traditional Chinese Medicine Use in the Treatment of Acute Heart Failure in Western Medicine Hospitals in China:Analysis from the China PEACE Retrospective Heart Failure Study'was published on the Journal of the American Association,which has gained a lot of media attention and has caused extensive discussion inside and outside the medical health-care *** retrospectively reviewed the use of Chinese herbal medicine(CHM)during acute heart failure(AHF)hospitalisation in Western medicine hospitals in China,and analyzed the association of Chinese pate nt medicine(especially injections)with inpatient bleeding and *** careful reading and analysis of the original text,we(China Center for Evidenee Based Traditional Chinese Medicine,CCEBTCM)believed that the following conclusions can be drawn.

关键词： Medicine herbal mortality

Grain-size Age Model in Reconstructing Orbital-and Suborbital-scale Climate Changes on the Northeastern Tibetan Plateau Since the Late Glacial

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2020年第3期94卷 698-706页

作者： LI Yuan zhao hui Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Western China’s Environmental Systems(MOE) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

Reconstructions of past climatic changes on the northeastern Tibetan Plateau(NETP) can provide insights into the Asian summer monsoon(ASM) variability. However, the regional climate changes on both orbital and suborbital time scales since the late Glacial remain controversial. Here we present the results of high-resolution geochemical and grain-size analyses of a sediment core from Genggahai Lake, a small, shallow lake in this area. Changes of the accumulation rate of the core sediments show a similar trend with variations of the coarse fraction. Accordingly, the chronological framework is constructed using a grain-size age model. In addition, the histories of chemical weathering and aeolian activity since the late Glacial are reconstructed based on the Al/Ti ratios and coarse fractions, respectively. The results suggest that an enhanced chemical weathering and a weakened aeolian activity occurred on the NETP under a warmer, wetter climate during the early to mid-Holocene(11.3–6.3 ka cal BP), compared with the late Glacial(17.1–11.3 ka cal BP) and the late Holocene(6.3 ka cal BP to present), which responded mainly to the strengthened ASM on orbital time scale. In addition, the synchronous occurrences of weakened chemical weathering, low lake level and intense aeolian activity on suborbital time scale reflect several episodes of weakened ASM. Furthermore, these episodes largely coincide with the centennial-to millennial-scale cold events in the North Atlantic, which demonstrates the close connection between the ASM and the cooling at high latitudes.

关键词： climate change lake sediment grain-size age model monsoon Holocene China

Aseismic ridge subduction and flat subduction:Insights from three-dimensional numerical models

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2023年第2期7卷 269-281页

作者： hui zhao Wei Leng Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China

Flat subduction can significantly influence the distribution of volcanism,stress state,and surface topography of the overriding ***,the mechanisms for inducing flat subduction remain *** two-dimensional(2-D)numerical models and laboratory analogue models suggested that a buoyant impactor(aseismic ridge,oceanic plateau,or the like)may induce flat ***,three-dimensional(3-D)systematic studies on the relationship between flat subduction and buoyant blocks are still ***,we use a 3-D numerical model to investigate the influence of the aseismic ridge,especially its width(which is difficult to consider in 2-D numerical models),on the formation of flat *** model results suggest that the aseismic ridge needs to be wide and thick enough to induce flat subduction,a condition that is difficult to satisfy on the *** also find that the subduction of an aseismic ridge parallel to the trench or a double aseismic ridge normal to the trench has a similar effect on super-wide aseismic ridge subduction in terms of causing flat subduction,which can explain the flat subduction observed beneath regions such as Chile and Peru.

关键词： flat subduction aseismic ridge oceanic plateau 3-D numerical simulation