检索结果-南通市图书馆

Materials Sciences and Applications 2013年第11期4卷 746-750页

作者： Abdelhek Meklid ahmed Boutarfaia Zelikha Necira Hayet Menasra Malika Abba Laboratory of Applied Chemistry Materials Science Department Mohamed Kheider University of Biskra Biskra Algeria Laboratory of Applied Chemistry Materials Science Department Mohamed Kheider University of Biskra Biskra Algeria University of Ouargla Ouargla Algeria

Perovskite PZT variants were synthesized from stoichiometric oxide ratios of Pb, Zr, Ti, Cr, Ni and Sb. The oxide powders were mixed mechanically and calcinated, and then sintered to form the desired perovskite phase. The detailed structural and ferroelectric properties were carried out for sintered specimens. The results of X-ray diffraction showed that all the ceramics specimens have a perovskite phase. The multi-component ceramic system consists of the (0.80?- x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 (PZT-CNS), with 0.30 ≤ x ≤ 0.42, and the ternary system near the rhombohedral/tetragonal morphotropic phase boundary(MPB) was investigated by X-ray diffraction and dielectric properties. In the present system, the MPB that coexists with the tetragonal and rhombohedral phases is a narrow composition region of x = 0.38 - 0.42. The scanning Electron Microscopy (SEM) showed an increase of the mean grain size when the sintering temperature was increased. A sintered density of 92.93% of the theoretical density was obtained for Ti = 42% after sintering at 1180°C. Ceramics sintered at 1180°C with Ti = 42% achieve excellent dielectric properties, which are as follows εr = 4262.48, and Tc = 340°C.

关键词： PZT Calcination Dielectric Properties MPB Ceramic X-Ray Methods

RESEARCH ON MINERAL COMPOSITION OF JILIN CHONDRITE

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1983年第8期28卷 1102-1105页

作者：刘顺生欧阳自远 ahmed EL GORESY Guiyang Institute of Geochemistry Academia Sinica Max-Planck-Institut fr Kernphysik Heidelberg F. R. G.ive different consortium samples (1-2 1-4 4-032 5-033 and Ⅵ-21-057) of the Jilin chondrite were studied in detail with optical microscopy SEM and electron microprobe. Model analyses indicate the following mineralogical composition: silicates (and phosphates) 89.9% metal 7.2% troilite 2% and chromite 0.2%. Miner phases

Five different consortium samples (1—2, 1—4, 4-032, 5-033 and Ⅵ—21-057) of the Jilin chondrite were studied in detail with optical microscopy, SEM and electron microprobe. Model analyses indicate the following min... 详细信息

关键词： Jilin consortium listed ectron Probe Minor ortho inhomogeneous abundant earliest

非目的语与目的语环境下汉语学习者自我叙事研究

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

非目的语与目的语环境下汉语学习者自我叙事研究

作者：大卫（YOUSIF ahmed）山东师范大学

学位级别：硕士

随着中国经济持续而快速的发展,汉语从一门仅由中国人使用的语言成为国际广泛使用的语言,“汉语热”也已经引起了全世界语言学习者的关注。因此,许多国家的人为了更好地学习汉语而来到中国留学,笔者也不例外。本研究以自我叙事为研究方... 详细信息

随着中国经济持续而快速的发展,汉语从一门仅由中国人使用的语言成为国际广泛使用的语言,“汉语热”也已经引起了全世界语言学习者的关注。因此,许多国家的人为了更好地学习汉语而来到中国留学,笔者也不例外。本研究以自我叙事为研究方法,以笔者自身为研究对象,分析和研究其在非目的语与目的语环境下学习汉语的经历,叙述笔者在学习汉语过程中所遇到的细节,并分享其在汉语学习过程中的故事。同时对汉语学习者的学习动机、学习目的、学习方法、学习风格与策略在不同学习环境和不同学习阶段进行分析和研究。论文共有六部分,具体包括以下内容:第一部分为绪论,主要介绍研究缘起,研究目的与意义,相关文献综述;第二部分为研究设计,包括研究问题、研究方法、研究思路、研究对象(包括“笔者自身”基本情况介绍及汉语水平的展示)。第三部分为汉语学习的第一阶段,主要叙述和分析笔者在初级阶段汉语学习过程中的学习动机,汉语学习“课堂与课外”的活动以及学习优势。第四部分为汉语学习的第二阶段,主要讨论分析目的语环境中汉语学习的“输入与输出”、目的语环境对课堂汉语学习的影响、语言学习的“开放性学习者与封闭性学习者”对汉语学习效率的影响,以及汉语学习策略与学习风格。第五部分叙述笔者在目的语环境下的汉语学习过程中的生活适应和文化适应,讨论学习汉语和中国文化的乐趣以及其对汉语学习的影响。第六部分为研究的结语,主要总结笔者在非目的语与目的语环境中的汉语学习经验和对比。本研究通过自我叙事研究,总结了笔者的汉语学习经验和特点,并发现语言学习最重要的功用是学会使用语言进行交流,因此,笔者认为学习某一门语言最重要的部分就是培养运用语言进行交流的能力,故而培养语言交际能力是学习语言的重中之重。因此笔者从开始学习汉语到通过HSK六级考试的学习过程中,一直采用各种各样的可以提高汉语交际能力的学习方法和策略,并保持停课而不停学的汉语学习习惯。通过本研究,笔者期望能帮助汉语学习者掌握学好汉语的技巧,并给汉语教师的教学提供一些启发。

关键词：非目的语与目的语环境下汉语学习者自我叙事

Diapir structure and its constraint on gas hydrate accumulation in the Makran accretionary prism, offshore Pakistan

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

China Geology 2020年第4期3卷 611-622页

作者： Zhen Zhang Gao-wen He Hui-qiang Yao Xi-guang Deng Miao Yu Wei Huang Wei Deng Syed Waseem Haider Naimatullah Sohoo Noor ahmed Kalhoro Ministry of Natural Resources Key Laboratory of Marine Mineral Resources Guangzhou Marine Geological SurveyChina Geological SurveyMinistry of Natural ResourcesGuangzhou 510760China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China National Institute of Oceanography Karachi 75600Pakistan

The Makran accretionary prism is located at the junction of the Eurasian Plate,Arabian Plate and Indian Plate and is rich in natural gas hydrate(NGH)*** consists of a narrow continental shelf,a broad continental slope,and a deformation *** continental slope can be further divided into the upper slope,middle slope,and lower *** are three types of diapir structure in the accretionary prism,namely mud diapir,mud volcano,and gas chimney.(1)The mud diapirs can be grouped into two types,namely the ones with low arching amplitude and weak-medium activity energy and the ones with high arching amplitude and medium-strong activity *** mud diapirs increase from offshore areas towards onshore areas in general,while the ones favorable for the formation of NGH are mainly distributed on the middle slope in the central and western parts of the accretionary prism.(2)The mud volcanoes are mainly concentrated along the anticline ridges in the southern part of the lower slope and the deformation front.(3)The gas chimneys can be grouped into three types,which are located in piggyback basins,active anticline ridges,and inactive anticline ridges,*** are mainly distributed on the middle slope in the central and western parts of the accretionary prism and most of them are accompanied with thrust *** gas chimneys located at different tectonic locations started to be active at different time and pierced different *** mud diapirs,mud volcanoes,and gas chimneys and thrust faults serve as the main pathways of gas migration,and thus are the important factors that control the formation,accumulation,and distribution of NGH in the Makran accretionary *** diapir/gas chimney type hydrate develop in the middle slope,mud volcano type hydrate develop in the southern lower slope and the deformation front,and stepped accretionary prism type hydrate develop on the central and northern lower *** middle slope,lower slope and deformation f

关键词： Natural gas hydrate Mud diapir Mud volcano Gas chimney Makran accretionary prism Marine geological survey engineering Offshore Pakistan

Evaluation of the Quality for the Egyptian Red Sea Coastal Waters during 2011-2013

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Protection 2016年第12期7卷 1810-1834页

作者： Mamdouh A. Fahmy Laila M. Abdel Fattah ahmed M. Abdel-Halim Mohamed A. Aly-Eldeen Ehssan M. Abo-El-Khair Hoda H. Ahdy Hoda H. Ahdy ahmed Hemeilly ahmed Abu El-Soud Mohamed A. Shreadah National Institute of Oceanography and Fisheries Alexandria Egypt Environmental Affairs Agency Ministry of Environmental Affairs Cairo Egypt

To assess the quality of the Egyptian Red Sea coastal waters for the sustainable use and development, due to its importance for the national income, four field campaigns were annually carried out during the period from 2011-2013 to investigate the hydrography, nutrient salts, heavy metals and petroleum hydrocarbons. Except for the area of Bir Shalatein, the results of beach litter cleared out that the shoreline of the studied area is not affected by man-made litter. No sewage could be observed. The results of the present study showed that water temperature followed seasonal changes in air temperature. Red Sea water is more saline than adjacent Arabian Sea. DO revealed high values and presence of well oxygenated waters. Minor changes in the distribution of pH, BOD, DOM and COD, revealed that limited effects of human impacts and depend mainly on the dynamics of its water as well as on the geographical location. Low Chl-a and TSM concentrations and high transparency revealed that also the effect of human impacts is almost negligible. Significantly higher sea water temperatures, TSM, pH, DO, BOD, DOM, and COD were observed in summer season compared to their corresponding values in winter season. Dissolved inorganic nitrogen concentrations were quite low because there is little nutrient input from soil, agriculture and pollution on land. Based on the annual mean values, the pattern concentrations of dissolved inorganic nitrogen forms followed the order: NO3 > NH4 > NO2. The Red Sea coastal waters are classified as oligotrophic to mesotrophic state. A remarkable increase of PO4 concentration was observed in the middle Red Sea stations due to huge amounts of effluents enriched with phosphate from the main shipping and industry of Phosphate Companies. SiO4 displayed a large variability due to the supply of SiO4, which flows in the Red Sea through the strait of Bab El-Mandab, biological consumption, organic ma

关键词： Hydrography Nutrient Salts Heavy Metals Petroleum Hydrocarbons Coastal Water Red Sea

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

面向多规格螺母的自动拧紧机系统

制造技术与机床 2022年第4期 88-93页

作者：郝欣妮高艳 Mohammed ahmed Ebrahim Alaghbari 邹浩扬州市职业大学机械工程学院江苏扬州225009 南通大学机械工程学院江苏南通226019

不同型号的汽车保险丝盒结构上存在较大的差异,装配时需要拧紧的螺母规格和种类繁多,人工装配必须使用多把电批轮换进行,不仅效率低而且拧紧力矩也无法精确控制。设计了一种基于扭矩监测的面向多规格螺母的自动拧紧机,可自动实现多规格... 详细信息

不同型号的汽车保险丝盒结构上存在较大的差异,装配时需要拧紧的螺母规格和种类繁多,人工装配必须使用多把电批轮换进行,不仅效率低而且拧紧力矩也无法精确控制。设计了一种基于扭矩监测的面向多规格螺母的自动拧紧机,可自动实现多规格螺母的上料、定位、拧紧、拧紧力矩实时检测和自动更换扳手功能。经过样机试验测试,系统运行可靠并且拧紧效果良好,生产效率与人工装配相比提高了20%以上,还提高了汽车保险丝盒装配的柔性化水平。

关键词：自动拧紧扭矩检测汽车保险丝盒多规格螺母

A Hybrid Modified Sine Cosine Algorithm Using Inverse Filtering and Clipping Methods for Low Autocorrelation Binary Sequences

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第5期71卷 3533-3556页

作者： Siti Julia Rosli Hasliza A Rahim Khairul Najmy Abdul Rani Ruzelita Ngadiran Wan Azani Mustafa Muzammil Jusoh Mohd Najib Mohd Yasin Thennarasan Sabapathy Mohamedfareq Abdulmalek Wan Suryani Firuz Wan Ariffin ahmed Alkhayyat Advanced Communication Engineering Centre of Excellence(ACE)Universiti Malaysia Perlis(UniMAP)01000 KangarPerlisMalaysia Faculty of Electronic Engineering Technology Universiti Malaysia Perlis(UniMAP)02600 ArauPerlisMalaysia Advanced Computing(AdvCOMP) Centre of ExcellenceUniversiti Malaysia Perlis(UniMAP)02600 ArauPerlisMalaysia Faculty of Electrical Engineering Technology Universiti Malaysia Perlis(UniMAP)02600 ArauPerlisMalaysia Faculty of Engineering and Information Science University of Wollongong in DubaiDubai 20183United Arab Emirates Department of Computer Technical Engineering College of Technical Engineeringthe Islamic University54001 NajafIraq

The essential purpose of radar is to detect a target of interest and provide information concerning the target’s location,motion,size,and other *** knowledge about the pulse trains’properties shows that a class of signals is mainly well suited to digital processing of increasing practical importance.A low autocorrelation binary sequence(LABS)is a complex combinatorial *** main problems of LABS are low Merit Factor(MF)and shorter length ***,the maximum possible MF equals 12.3248 as infinity length is unable to be ***,this study implemented two techniques to propose a new metaheuristic algorithm based on Hybrid Modified Sine Cosine Algorithm with Cuckoo Search Algorithm(HMSCACSA)using Inverse Filtering(IF)and clipping method to achieve better *** proposed algorithms,LABS-IF and HMSCACSA-IF,achieved better results with two large MFs equal to 12.12 and 12.6678 for lengths 231 and 237,respectively,where the optimal solutions belong to the skew-symmetric *** MF outperformed up to 24.335%and 2.708%against the state-of-the-art LABS heuristic algorithm,xLastovka,and Golay,*** results indicated that the proposed algorithm’s simulation had quality solutions in terms of fast convergence curve with better optimal means,and standard deviation.

关键词： Merit factor autocorrelation skew-symmetric sequences combinatorial optimization sine cosine algorithm cuckoo search algorithm radar system wearable antenna antenna and propagation

Phylogenetic and ecological reevaluation of the order Onygenales

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fungal Diversity 2022年第4期115卷 1-72页

作者： Hazal Kandemir Karolina Dukik Marcus de Melo Teixeira J.Benjamin Stielow Fatima Zohra Delma Abdullah M.S.Al‑Hatmi Sarah A.ahmed Macit Ilkit G.Sybren de Hoog Center of Expertise in Mycology Radboud University Medical Center/Canisius Wilhelmina HospitalNijmegenThe Netherlands Division of Medical Mycology Faculty of MedicineUniversity ofÇukurovaAdanaTurkey Westerdijk Fungal Biodiversity Institute UtrechtThe Netherlands Faculdade de Medicina Universidade de BrasíliaBrasíliaBrazil Pathogen and Microbiome Institute Northern Arizona UniversityFlagstaffUSA Thermo Fisher Scientific LandsmeerThe Netherlands Natural&Medical Sciences Research Center University of NizwaNizwaOman Key Laboratory of Environmental Pollution Monitoring and Disease Control Ministry of Education of Guizhou&Key Laboratory of Medical Microbiology and ParasitologySchool of Basic Medical SciencesGuizhou Medical UniversityGuiyangChina

The order Onygenales is classified in the class Eurotiomycetes of the subphylum *** in this order have classically been isolated from soil and dung,and two lineages contain causative agents of superficial,cutaneous and systemic infections in *** ecology and habitat choices of the species are driven mainly by the keratin and cellulose degradation *** present study aimed to investigate whether the ecological trends of the members of Onygenales can be interpreted in an evolutionary sense,linking phylogenetic parameters with habitat preferences,to achieve polyphasic definitions of the main taxonomic *** processes were estimated by multiple gene genealogies and divergence time *** described families,namely,Arthrodermataceae,Ajellomycetaceae,Ascosphaeraceae,Eremascaceae,Gymnoascaceae,Onygenaceae and Spiromastigoidaceae,were accepted in Onygenales,and two new families,Malbrancheaceae and Neogymnomycetaceae,were introduced.A number of species could not be assigned to any of the defined *** study provides a revised overview of the main lines of taxonomy of Onygenales,supported by multilocus analyses of ITS,LSU,TUB,TEF1,TEF3,RPB1,RPB2,and ribosomal protein 60S L10(L1)(RP60S)sequences,combined with available data on ecology,physiology,morphology,and genomics.

关键词： Ancestral reconstruction Evolution Onygenales Taxonomy

Salinity Stress in Wheat:Effects,Mechanisms and Management Strategies

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Phyton-International Journal of Experimental Botany 2022年第4期91卷 667-694页

作者： Mahmoud F.Seleiman Muhammad Talha Aslam Bushra ahmed Alhammad MuhammadUmair Hassan Rizwan Maqbool Muhammad Umer Chattha Imran Khan Harun Ireri Gitari Omer S.Uslu Rana Roy Martin Leonardo Battaglia Plant Production Department College of Food and Agriculture SciencesKing Saud UniversityRiyadh11451Saudi Arabia Department of Crop Sciences Faculty of AgricultureMenoufia UniversityShibin El-kom32514Egypt Department of Agronomy University of AgricultureFaisalabad38040Pakistan Biology Department College of Science and Humanity StudiesPrince Sattam Bin Abdulaziz UniversityRiyadh11942Saudi Arabia Research Center on Ecological Sciences Jiangxi Agricultural UniversityNanchang330045China Department of Agricultural Sciences and Technology School of Agriculture and Enterprise DevelopmentKenyatta UniversityNairobi00100Kenya Department of Field Crops Faculty of AgricultureUniversity of Sutcu ImamKahramanmaras46040Turkey Department of Agroforestry&Environmental Science Faculty of AgricultureSylhet Agricultural UniversitySylhet3100Bangladesh Department of Animal Sciences Cornell UniversityIthaca14850USA

Salinity stress is a major threat to global food production and its intensity is continuously increasing because of anthropogenic *** is a staple food and a source of carbohydrates and calories for the majority of people across the ***,wheat productivity is adversely affected by salt stress,which is associated with a reduction in germination,growth,altered reproductive behavior and enzymatic activity,disrupted photosynthesis,hormonal imbalance,oxidative stress,and yield ***,a better understanding of wheat(plant)behavior to salinity stress has essential implications to devise counter and alleviation measures to cope with salt *** approaches including the selection of suitable cultivars,conventional breeding,and molecular techniques can be used for facing salt stress ***,these techniques are tedious,costly,and *** practices are still helpful to improve the wheat performance under salinity *** of arbuscular mycorrhizal fungi,plant growth-promoting rhizobacteria,and exogenous application of phytohormones,seed priming,and nutrient management are important tools to improve wheat performance under salinity *** this paper,we discussed the effect of salinity stress on the wheat crop,possible mechanisms to deal with salinity stress,and management options to improve wheat performance under salinity conditions.

关键词： Breeding techniques oxidative stress photosynthesis phyto-hormones salinity stress wheat

Spontaneous type 1 pattern, ventricular arrhythmias and sudden cardiac death in Brugada Syndrome： an updated systematic review and meta-analysis

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 Geriatric Cardiology 2017年第10期14卷 639-643页

作者： ahmed Bayoumy Meng-Qi GONG Ka Hou Christien Li Sunny Hei Wong William KK Wu Guang-Ping LI George Bazoukis Konstantinos P Letsas Wing Tak Wong Yun-Long XIA Tong LIU Gary Tse Department of Medicine and Therapeutics Faculty of Medicine Chinese University of Hong Kong Hong Kong China Li Ka Shing Institute of Health Sciences Faculty of Medicine Chinese University of Hong Kong Hong Kong China Faculty of Medicine University of Amsterdam The Netherlands Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease Department of Cardiology Tianjin Institute of Cardiology Second Hospitalof Tianjin Medical University Tianjin China Faculty of Medicine Newcastle University United Kingdom Department of Anaesthesia and Intensive Care Faculty of Medicine Chinese University of Hong Kong Hong Kong China Second Department of Cardiology Evangelismos General Hospital of Athens Athens Greece School of Life Sciences Chinese University of Hong Kong Hong Kong China Department of Cardiology First Affiliated Hospital of Dalian Medical University Dalian China

Brugada syndrome （BrS） is primary electrical disorder characterized by ST segment elevation with right bundle branch block morphology in patients with apparent structurally normal hearts, It predisposes affected individuals to ventricular tachycardia/fibrillation （VT/VF） and sudden cardiac death （SCD）.A number of studies have identified risk factors that are associated with a more malignant course of disease. These include male gender, syncope, a spontaneous type 1 ECG pattern, family history of SCD, family history of Brugada syndrome,

关键词： Brugada syndrome Risk stratification Spontaneous type 1 Sudden cardiac death Ventricular arrhythmia