检索结果-南通市图书馆

Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by (27)Al NMR

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第6期14卷 605-608页

作者： shu Hua HAN Wan Guo HOU Wen Xiu dang Jun XU Key Lab of Colloid and Interface Chemistry of State Education Ministry Shandong UniversityJinan 250100

The coordination structure of aluminum in magnesium aluminum hydroxide was studied by 27Al NMR. The result showed that tetrahedral aluminum (AlIV) existed in magnesium aluminum hydroxide, and the contents of AlIV increased with the increase of the ratio of Al/Mg and with the peptizing temperature. AlIV originated from the so-called Al13 polymer with the structure of one Al tetrahedron surrounded by twelve Al octahedrons.

关键词： Coordination structure magnesium aluminum hydroxide 27Al NMR.

Electronic structures and optical properties of Si-and Sn-doped β-Ga_2O_3: A GGA+U study

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第1期28卷 502-510页

作者： Jun-Ning dang shu-wen Zheng Lang Chen Tao Zheng[] Institute of Opto-electronic Materials and Technology South China Normal University

The electronic structures and optical properties of β-Ga_2O_3 and Si-and Sn-doped β-Ga_2O_3 are studied using the GGA + U method based on density functional theory. The calculated bandgap and Ga 3d-state peak of β-Ga_2O_3 are in good agreement with experimental results. Si-and Sn-doped β-Ga_2O_3 tend to form under O-poor conditions, and the formation energy of Si-doped β-Ga_2O_3 is larger than that of Sn-doped β-Ga_2O_3 because of the large bond length variation between Ga–O and Si–O. Si-and Sn-doped β-Ga_2O_3 have wider optical gaps than β-Ga_2O_3, due to the Burstein–Moss effect and the bandgap renormalization effect. Si-doped β-Ga_2O_3 shows better electron conductivity and a higher optical absorption edge than Sn-doped β-Ga_2O_3, so Si is more suitable as a dopant of n-type β-Ga_2O_3, which can be applied in deep-UV photoelectric devices.

关键词： density functional theory GGA + U method Si-doped β-Ga2O3 Sn-doped β-Ga2O3 electronic structure optical property

Theoretical investigations on the thiol–thioester exchange steps of different thioesters

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2015年第10期26卷 1259-1264页

作者： Xiao-Hui Sun Hai-Zhu Yu shu-Qi Pei Zhi-Min dang Department of Polymer Science and Engineering University of Science and Technology Beijing Department of Chemistry and Centre for Atomic Engineering of Advanced Materials Anhui University

As the rate-determining step in native chemical ligation reactions, the thiol–thioester exchange step is important in determining the efficiency of the ligations of peptides. In the present study, systematic theoretical calculations were carried out on the relationships between the structure of different thioesters and the free energy barriers of the thiol–thioester exchange step. According to the calculation results, the thiol–thioester exchange step is disfavored by the steric hindrance around the carbonyl center, while the electronic effect（i.e. conjugation and hyper-conjugation effects） becomes important when the steric hindrance is insignificant.

关键词： Native chemical ligation Thiol–thioester exchange Density functional theory

Spatiotemporal Trend Analysis of Precipitation Extremes in Ho Chi Minh City, Vietnam During 1980–2017

在线全文

学校读者我要写书评

暂无评论

International Journal of Disaster Risk Science 2021年第1期12卷 131-146页

作者： Nguyen Trong Quan Dao Nguyen Khoi Nguyen xuan Hoan Nguyen Ky Phung Thanh Duc dang Faculty of Environmental and Food Engineering Nguyen Tat Thanh UniversityHo Chi Minh City 700000Vietnam Faculty of Environment University of ScienceHo Chi Minh City 700000Vietnam Vietnam National University Ho Chi Minh City 700000Vietnam Ho Chi Minh City University of Food Industry Ho Chi Minh City 700000Vietnam Institute for Computational Science and Technology Ho Chi Minh City 700000Vietnam Engineering Systems and Design Pillar Singapore University of Technology and DesignTampines 487372Singapore

In this study,the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980–2017 was analyzed based on several core extreme precipitation indices(Rx1 day,Rx5 day,CDD,CWD,R20 mm,R25 mm,R95 p,and SDII).The nonparametric Mann–Kendall and Sen’s slope methods were used to compute the statistical strength,stability,and magnitude of trends in annual rainfall,as well as the extreme precipitation *** found that 64%of the stations had statistically significant upward trends in yearly rainfall,with high magnitudes frequently observed in the northern and southern regions of the *** the extreme precipitation indices,only SDII and R25 mm showed dominantly significant ***,there were increasing trends in the frequency and duration at the southern and central regions of the city during the study ***,El Ni?o-Southern Oscillation and Pacific Decadal Oscillation positively correlated with the duration and negatively correlated with the intensity and frequency of extreme ***,water management plans should be adjusted appropriately to reduce the severe impacts of precipitation extremes on communities and ecosystems.

关键词： Spatiotemporal trend Extreme precipitation Extreme precipitation indices Ho Chi Minh City

Impact of Energy Transition on CO2 Emissions in China's Cities

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2025年第2期 250-261页

作者： dang Niu WANG Qiang KWAN Mei-po LIN Jian School of Geographical Sciences Fujian Normal University Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education School of Geographical Sciences Fujian Normal University Department of Geography and Resource Management and Institute of Space and Earth Information Science The Chinese University of Hong Kong School of Geography Nanjing Normal University

Reducing global carbon dioxide（CO2） emissions is essential for meeting climate change mitigation goals, especially in urban areas. In this regard, this study used CO2emissions and energy transition data from 296 China's cities in 2020 and the extended Stochastic Impacts by Regression on Population, Affluence, and Technology（STIRPAT） model to explore the relationship between energy transition and CO2emissions at the city-scale. The findings indicate a spatial distribution of energy transition magnitude that is high in the west and low in the east, which does not align with economic status and total CO2emissions, posing significant challenges for China's energy transition and urban CO2reduction. The STIRPAT model reveals that urban CO2emissions are significantly driven by increases in population size, levels of economic development, and the expansion of transportation infrastructure. Conversely, investments in science and education, the expansion of the tertiary sector, and the disruptive effects of the COVID-19（Coronavirus Disease 2019） pandemic are associated with notable reductions in CO2emissions. Specifically, the analysis estimates that a 1.00% increase in the energy transition degree is associated witha 0.90% decrease in urban CO2emissions. However, regional assessments underscore considerable spatial heterogeneity in the energy transition effect, with CO2reduction benefits being less pronounced in central and western cities. These findings suggest that future clean energy initiatives should be strategically concentrated in eastern China, where the demand and potential for CO2mitigation are greater. This study deepens the understanding of the complex relationship between energy transition and urban CO2emissions, offering valuable insights to inform targeted policy interventions for carbon reduction at the city level.

关键词：

计及天然气非等温特性的气电互联系统连锁故障评估

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

电力系统自动化 2025年第3期49卷 103-113页

作者：刘雨濛李佳松顾雪平党玉洁华北电力大学电气与电子工程学院河北省保定市071003

在电网与天然气网耦合关系趋于紧密的同时,故障跨异质能源系统传播为气电互联系统连锁故障引入了新的风险。然而,现阶段已开展的相关研究中均未计及天然气输送过程中气体温度变化的特性,或将难以反映连锁故障实际的演化过程和进行准确... 详细信息

在电网与天然气网耦合关系趋于紧密的同时,故障跨异质能源系统传播为气电互联系统连锁故障引入了新的风险。然而,现阶段已开展的相关研究中均未计及天然气输送过程中气体温度变化的特性,或将难以反映连锁故障实际的演化过程和进行准确的影响评估。文中首先推导了天然气管道稳态下的非等温传输公式并建立对应模型,通过理论分析和仿真证明管道内的气流量、气体温度及管道始末端压强差三者之间存在相互制约的关系;在此基础上,提出计及天然气非等温特性的气电互联系统连锁故障评估模型,以更为准确地评估天然气系统对电力系统连锁故障所造成的影响;最后,以IEEE 39节点和改进的比利时20节点天然气系统组成的测试算例对所提模型的有效性进行了验证,并与基于等温假设开展的相关研究进行了对比和分析。结果表明,所提模型可充分反映天然气系统非等温的特性,且兼顾其对电力系统连锁故障所造成影响评估的准确性和实用性。

关键词：天然气非等温特性气电互联系统连锁故障

同方期刊数据库

中药在病原体诱导的代谢重编程及免疫抑制中的作用

在线全文

学校读者我要写书评

暂无评论

四川大学学报(医学版) 2025年第1期56卷 10-18页

作者：党怡雄孙鑫蒋静文四川大学华西公共卫生学院/四川大学华西第四医院成都610041 四川大学华西医院中国循证医学中心成都610041

中药作为我国传统医学的重要组成部分,在抗击病原体感染性疾病和多种肿瘤方面展现出独特的疗效,尤其在增强机体免疫功能、维持内环境稳态和改善代谢平衡方面发挥了重要作用。然而,由于中药成分复杂,作用靶点广泛,其作用机制尚缺乏整体... 详细信息

中药作为我国传统医学的重要组成部分,在抗击病原体感染性疾病和多种肿瘤方面展现出独特的疗效,尤其在增强机体免疫功能、维持内环境稳态和改善代谢平衡方面发挥了重要作用。然而,由于中药成分复杂,作用靶点广泛,其作用机制尚缺乏整体解析的切入点。此外,目前中药作用机制在分子和细胞水平上的研究仍显不足,限制了其在现代医学领域的广泛应用。近年来,越来越多的研究表明,中药不仅能够直接抑制包括细菌、真菌、病毒和肿瘤细胞等在内的病原体的活性,还能通过调控病原体代谢、宿主代谢对免疫重塑产生重要影响。因此,全面认识中药在调控代谢方面的作用对于认识中药的抗病原体作用至关重要。本文以病原体的代谢途径及其诱导的宿主代谢重编程为切入点,系统综述了中药在调控病原体代谢、病原体诱导的宿主代谢重编程及病原体导致的免疫抑制中的作用机制,为从分子水平解析中药在疾病发生发展中的机制研究提供了新思路。

关键词：中药病原体代谢重编程免疫分子机理综述

Caveolin-1与视网膜新生血管性疾病

在线全文

学校读者我要写书评

暂无评论

眼科新进展 2025年第2期45卷 156-160页

作者：汤婉玉张睿党亚龙河南科技大学临床医学院河南科技大学第一附属医院眼科河南省洛阳市476600 河南科技大学临床医学院河南科技大学附属三门峡中心医院眼科河南省三门峡市472000

视网膜新生血管是许多致盲性眼病的共同病理特征,这些新生血管通常比较脆弱,容易破裂出血,引发严重的视力障碍。而Caveolin-1是一种重要的膜蛋白,参与细胞信号转导、脂质代谢和细胞骨架的调控。目前,Caveolin-1已被证实在多种视网膜细... 详细信息

视网膜新生血管是许多致盲性眼病的共同病理特征,这些新生血管通常比较脆弱,容易破裂出血,引发严重的视力障碍。而Caveolin-1是一种重要的膜蛋白,参与细胞信号转导、脂质代谢和细胞骨架的调控。目前,Caveolin-1已被证实在多种视网膜细胞中表达,能够通过调控多种信号通路参与视网膜新生血管形成过程。本文主要综述了国内外关于Caveolin-1在新生血管形成中的作用及机制的相关研究,并展望了Caveolin-1在视网膜新生血管性眼病中的治疗前景,以期为探索疾病的发病机制和寻求潜在的靶向干预措施提供思路。

关键词： Caveolin-1 视网膜新生血管作用机制

维普期刊数据库博看期刊

Graph Designs for all Graphs with Six Vertices and Eight Edges

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2005年第3期21卷 469-484页

作者： Qing-de Kang Lan-dang Yuan shu-xia Liu Institute of Mathematics Hebei Normal University Shijiazhuang 050016 China College of Mathematics & Statistic Hebei University of Economics and Trade Shijiazhuang 050061 China

Graph designs for all graphs with six vertices and eight edges are discussed. The existence of these graph designs are completely solved except in two possible cases of order 32.

关键词： Graph design holey graph design quasi-group