检索结果-南通市图书馆

Supertetragonal BaZrS: A promising perovskite sulphide with giant ferroelectricity and low band gap

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年

作者： Menglu Li sa Zhang Chenhan Liu Xiaotao Zu Liang Qiao Haiyan Xiao School of Physics University of Electronic Science and Technology of China College of Mathematics and Physics Chengdu University of Technology Micro-and Nano-scale Thermal Measurement and Thermal Management Laboratory Ministry of Education Key Laboratory of Numerical Simulation of Large-Scale Complex Systems School of Energy and Mechanical Engineering Nanjing Normal University

Over the past century, ferroelectricity has offered exciting opportunities for fundamental research and device ***, most of the discovered excellent ferroelectrics are oxide materials with large band gaps, limiting their potential for optoelectronics applications. Here using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e., ferroelectric perovskite sulphide BaZrS3. under large compressive strains, BaZrS3can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16 μC/cm2, which is even stronger than that of conventional oxide ferroelectrics. Excitingly, the supertetragonal BaZrS3exhibits a direct narrow band gap of 1.2 eV and excellent electronic properties. Based on the chemical bonding analysis, we attribute the formation of supertetragonal phase to charge re-ordering in which the π bond overlap along the long ?Zr-S? bond completely vanishes and the antibonding states of the σ bond appear below the Fermi level. Our work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.

关键词：

The first record of dermochelyid turtles in the Eocene of Tierra del Fuego:new insights on the evolution of the Weddellian faunas

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Advances in Polar Science 2024年第1期35卷 63-77页

作者： Paula BONA Juliana STERLI Marcelo saúl de la FuENTE Eduardo OLIVERO Marta S.FERNÁNDEZ Marcelo REGuERO División Paleontología Vertebrados Museo de La Plata-Anexo IIFacultad de Ciencias Naturales y MuseoUniversidad Nacional de La PlataLa Plata B1900FWAArgentina Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET) Ciudad Autónoma de Buenos Aires C1425FQBArgentina Museo Paleontológico Egidio Feruglio Trelew U9100Argentina Instituto de Evolución Ecología Histórica y Ambiente-CONICETSan Rafael CP5600Argentina Centro Austral de Investigaciones Científicas-CONICET Universidad Nacional de Tierra del FuegoUshuaia CP 9410Argentina División Paleontología Vertebrados Museo de La PlataUniversidad Nacional de La PlataLa Plata B1900FWAArgentina

The Antarctic Paleogene marine fossil record has been the key to reconstructing the evolution of the Weddellian Sea and final dismemberment of Southern *** this context,Eocene marine vertebrates from Seymour(Marambio)Island have provided valuable *** present the first Eocene record of marine reptiles from the southern Atlantic Coast of South *** corresponds to several postcranial turtle remains represented by a proximal end of the right humerus,three caudal and one thoracic vertebrae,a fragment of the left pubis,and ten ossicles of the dorsal carapace,coming from the Leticia Formation(late-mid Eocene)at Cabo Tiburones,Tierra del Fuego,*** materials show severalfeatures such as the size and general morphology of the humerus and vertebrae,and the presence of relatively small,irregular,smooth,and unkeeled ossicles,which allow us to assign them to Dermochelyidae *** are a cosmopolitan group ofcryptodiran turtles,registered from the late Cretaceous up to the recent,with some physiological-biological peculiarities(e.g.,endothermy and an exclusive jellyfish-based diet)and characterized by the presence of an osseous carapace formed by *** new finding from the Leticia Formation is an addition to the scarce and extremely fragmentary record of Eocene dermochelyids from the southern seas like those from the La Meseta and Submeseta formations(Antarctica)and the Waihao and Burnside formations(New Zealand).This new information allows us to discuss the presence of these turtles in such high latitudes in the past and its implication in the evolution of the Weddellian fauna.

关键词： marine reptiles sea turtles Dermochelyidae Paleogene La Meseta Formation Submeseta Formation Leticia Formation

同方期刊数据库

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第2期33卷 108-114页

作者： u.S.Mahabaleshwar G.P.Vanitha L.M.Pérez Emad H.Aly I.Pop Department of Studies in Mathematics Davangere UniversityShivagangothriDavangereIndia Departamento de F´ısica FACIUniversidad de Tarapac´aCasilla 7DAricaChile Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt Department of Mathematics Babes-Bolyai University400084 Cluj-NapocaRomania

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked *** the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is *** resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity *** transformed differential equations are solved *** of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted *** skin friction and Nusselt number were also *** addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching ***,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O ***,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

关键词： magnetohydrodynamic nanofluid stretching/shrinking sheet axisymmetric flow analytical solution suction/injection

salinity Distribution at Canal Istanbul and Its Possible Impacts on the Northern Marmara Sea

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第6期34卷 881-888页

作者： Şehriban sa.u Tarkan ERDIK OlgayŞEN Istanbul Technical university MaslakIstanbul 34467Turkey

Turkey has announced its plan to construct a new waterway, Canal Istanbul, parallel to the Bosphorus. In this study,the influence of Canal Istanbul on salinity distribution in the northern Marmara Sea is investigated using a previously calibrated 3 D hydrodynamic and salinity model. Moreover, the salinity field of the canal and its propagation are examined based on various meteorological cases. Finally, the flow structure of the canal is determined. It is calculated that at the southern end of the canal, mainly unidirectional flow(from the Black Sea to the Marmara Sea)occurs during 68% of the simulation period. A two-layer flow is seen only 28% of the time with a weak lower layer flow, whereas this value decreases to 4% at the north end of the canal. In the southward direction(to the Marmara Sea), velocities higher than 1.5 m/s are rarely observed along the canal. The average surface salinity difference in the northern Marmara Sea due to the construction of the canal is calculated to be smaller than 0.50 ppt. The salinity difference gradually diminishes as water depth increases and after 25 m(from the surface) almost no difference is observed.

关键词： Canal Istanbul Marmara Sea salinity distribution hydrodynamic modeling

Developing Weibull-based diameter distributions for the major coniferous species in Heilongjiang Province,China

在线全文

学校读者我要写书评

暂无评论

林业研究:英文版 2023年第6期34卷 1803-1815页

作者： Qila sa Xingji Jin Timo Pukkala Fengri Li Key Laboratory of Sustainable Forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin 150040People’s Republic of China university of Eastern Finland 80101 JoensuuFinland

Diameter distribution models play an important role in forest inventories,growth prediction,and *** Weibull probability density function is widely used in *** a number of methods have been proposed to predict or recover the Weibull distribution,their applicability and predictive performance for the major tree species of China remain to be *** in sample plots of three even-aged coniferous species(Larix olgensis,Pinus sylvestris and Pinus koraiensis)were measured both in un-thinned and thinned stands to develop parameter prediction models for the Weibull probability density *** least squares(OLS)and maximum likelihood regression(MLER),as well as cumulative distribution function regression(CDFR)were used,and their performance *** results show that MLER and CDFR were better than OLS in predicting diameter distributions of tree *** produced the best results in terms of fitting *** on the error statistics calculated for different age groups,CDFR was considered the most suitable method for developing prediction models for Weibull parameters in coniferous plantations.

关键词： Parameter prediction Maximum likelihood regression Cumulative distribution function regression

CXCL12/CXCR4轴在HIV感染及艾滋病中医证候中的研究现状

在线全文

学校读者我要写书评

暂无评论

中国免疫学杂志 2024年第6期40卷 1297-1301页

作者：陈晓宇谢世平张淼刘飒马素娜王娟河南中医药大学郑州450046

机体CXCL12/CXCR4的结构及生物学作用是生理病理功能的基础。HIV-1包膜蛋白与CXCR4结合会促进病毒进入宿主细胞,CXCL12能通过快速内吞作用减少CXCR4的数量抑制HIV的复制及传播。CXCL12/CXCR4轴与炎症、自噬的相互作用在HIV感染中发挥重... 详细信息

机体CXCL12/CXCR4的结构及生物学作用是生理病理功能的基础。HIV-1包膜蛋白与CXCR4结合会促进病毒进入宿主细胞,CXCL12能通过快速内吞作用减少CXCR4的数量抑制HIV的复制及传播。CXCL12/CXCR4轴与炎症、自噬的相互作用在HIV感染中发挥重要作用。研究发现艾滋病不同中医证候的基因表达谱不同,CXCR4在艾滋病肺脾气虚证、气阴两虚证和湿热内蕴证中的表达具有差异,涉及趋化因子信号通路;在艾滋病肺脾气虚证患者外周血中差异基因CXCR4与自噬过程相关,对该证型患者进行中药益艾康胶囊干预,CXCR4表达升高,提示中药益艾康胶囊可以调控自噬相关基因的表达。研究CXCL12/CXCR4在艾滋病中医证候中的作用,有利于更好地发挥中医药的治疗优势,为基因的靶向治疗提供新的方向。

关键词： CXCL12/CXCR4 HIV感染艾滋病中医证候研究现状

珠海金鼎工业园地下水水质演变及其对水污染防控的提示

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

中国环境监测 2024年第2期40卷 63-73页

作者：何志东叶珊杨虹王萌王亚肖洒赵新锋广东省珠海生态环境监测站广东珠海519070 广东省生态环境监测中心广东广州510308 中山大学地球科学与工程学院广东珠海519082 广东省地质过程与矿产资源探查重点实验室广东珠海519082 南方海洋科学与工程广东省实验室(珠海) 广东珠海519082

以珠海金鼎工业园这一典型的滨海工业园为研究对象,对比分析了工业园建成后不同时期(2005—2007与2015—2022)园区地下水环境监测数据与稳定氢、氧、氮等多种环境同位素数据,探讨了该园区浅层地下水水质时空演变特征,分析了园区地下水... 详细信息

以珠海金鼎工业园这一典型的滨海工业园为研究对象,对比分析了工业园建成后不同时期(2005—2007与2015—2022)园区地下水环境监测数据与稳定氢、氧、氮等多种环境同位素数据,探讨了该园区浅层地下水水质时空演变特征,分析了园区地下水水质的超标问题与诱因,并识别了园区地下水、主要离子与无机氮等成分的来源,明确了该浅层含水层特征指标对海水入侵的指示,为滨海工业园区地下水污染的管控提供了科学依据。

关键词：滨海工业园地下水水质超标重金属无机氮

Sino -u .S .Relations in Retrospect and Prospect——In Commemoration of the 25th Anniversary for the Establishment of Diplomatic Relations Between the PRC and the u.S.A

在线全文

学校读者我要写书评

暂无评论

和平与发展 2004年第2期 60-64页

作者： sa Benwang

A Throughput-Aware Joint Vehicle Route and Access Network Selection Approach Based on SMDP

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Communications 2020年第5期17卷 243-265页

作者： Jiandong Xie sa Xiao Ying-Chang Liang Li Wang Jun Fang National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 116024China Center for Intelligent Networking and Communications(CINC) University of Electronic Science and Technology of China(UESTC)Chengdu 611731China Research and Development Center Huawei TechnologiesStockholm 16494Sweden

In intelligent transportation system(ITS), the interworking of vehicular networks(VN) and cellular networks(CN) is proposed to provide high-data-rate services to vehicles. As the network access quality for CN and VN is location related, mobile data offloading(MDO), which dynamically selects access networks for vehicles, should be considered with vehicle route planning to further improve the wireless data throughput of individual vehicles and to enhance the performance of the entire ITS. In this paper, we investigate joint MDO and route selection for an individual vehicle in a metropolitan scenario. We aim to improve the throughput of the target vehicle while guaranteeing its transportation efficiency requirements in terms of traveling time and distance. To achieve this objective, we first formulate the joint route and access network selection problem as a semi-Markov decision process(SMDP). Then we propose an optimal algorithm to calculate its optimal policy. To further reduce the computation complexity, we derive a suboptimal algorithm which reduces the action space. Simulation results demonstrate that the proposed optimal algorithm significantly outperforms the existing work in total throughput and the late arrival ***, the heuristic algorithm is able to substantially reduce the computation time with only slight performance degradation.

关键词： mobile data offloading network selection route selection semi-Markov decision process vehicular network