期刊文献+
共找到1,592篇文章
< 1 2 80 >
每页显示 20 50 100
低温等离子治疗儿童鼻咽部第二鳃裂囊肿分析
1
作者 温鑫 黄爱萍 +5 位作者 张爱英 许敏 宋英鸾 崔莉 耿江桥 史静 《中国耳鼻咽喉头颈外科》 CSCD 2024年第1期54-56,共3页
目的探讨儿童鼻咽部第二鳃裂囊肿的临床特征和治疗方式,提高诊治能力。方法回顾性分析河北省儿童医院收治的4例儿童鼻咽部第二鳃裂囊肿的临床资料,包括年龄、性别、症状、影像学资料和治疗过程。总结分析病变部位特点,B超、CT或MRI特征... 目的探讨儿童鼻咽部第二鳃裂囊肿的临床特征和治疗方式,提高诊治能力。方法回顾性分析河北省儿童医院收治的4例儿童鼻咽部第二鳃裂囊肿的临床资料,包括年龄、性别、症状、影像学资料和治疗过程。总结分析病变部位特点,B超、CT或MRI特征,术后病理结果及治疗方式。结果4例鼻咽部第二鳃裂囊肿患儿均表现为鼻咽侧壁咽鼓管咽口与腭咽弓后上方连线上的囊性肿物,囊壁较厚,影像学检查结果均为囊性病变。4例患儿选择内镜下低温等离子病变切除术,其中2例为内侧囊壁大部分切除术,将囊腔充分敞开,2例为囊肿全部切除术。术后病理提示衬覆纤毛柱状上皮或复层上皮,周围淋巴组织增生。术后随访1.5~3年无复发。结论儿童鼻咽部第二鳃裂囊肿临床罕见,诊断主要依靠病变部位及术后病理结果,内镜下低温等离子切除病变组织是微创、安全、有效的治疗方式。 展开更多
关键词 儿童(Child) 外科手术(Surgical Procedures Operative) 鼻咽部第二鳃裂囊肿(nasopharyngeal cyst of second branchial cleft) 低温等离子(low temperature plasma)
下载PDF
基于Tv-SECOND的自动驾驶场景下的3D目标检测
2
作者 魏海跃 杨奎河 毕江峰 《无线电通信技术》 北大核心 2024年第4期823-830,共8页
针对自动驾驶场景中复杂环境下的3D目标检测任务,特别是远距离和遮挡条件下,为提高模型的检测准确率,在SECOND的基础上提出了Tv-SECOND两阶段算法。该算法提出一种基于Transformer架构的提案框特征提取模块,并在传统体素特征编码基础上... 针对自动驾驶场景中复杂环境下的3D目标检测任务,特别是远距离和遮挡条件下,为提高模型的检测准确率,在SECOND的基础上提出了Tv-SECOND两阶段算法。该算法提出一种基于Transformer架构的提案框特征提取模块,并在传统体素特征编码基础上提出可变形的体素特征编码模块。在KITTI数据集上进行测试,结果显示,所提出的算法相比SECOND在远距离和遮挡严重的情况下分别提高了7.49%、9.72%。同时与其他先进的两阶段方法相比,检测精度有不同程度的提升,证明了Tv-SECOND算法的有效性。新算法能够建立特征之间的依赖关系,聚合周边广域的上下文信息,增强模型的学习推理能力,有效提升了模型在远距离和遮挡的情况下的检测性能。 展开更多
关键词 自动驾驶 3D目标检测 TRANSFORMER SECOND
下载PDF
UV-B irradiation enhances the accumulation of beneficial glucosinolates induced by melatonin in Chinese kale sprout
3
作者 Mengyu Wang Jiansheng Wang +6 位作者 Yuhe Yang Zhiqing Li Ghazala Mustafa Yubo Li Lihong Liu Zuofa Zhang Qiaomei Wang 《Horticultural Plant Journal》 SCIE CAS CSCD 2024年第4期995-1006,共12页
Cruciferous sprout is a new form of vegetable product rich in bioactive compounds,especially glucosinolates.Previous studies have focused on increasing the accumulation of glucosinolates in cruciferous sprouts by appl... Cruciferous sprout is a new form of vegetable product rich in bioactive compounds,especially glucosinolates.Previous studies have focused on increasing the accumulation of glucosinolates in cruciferous sprouts by applying different chemical regulators,with a particular focus on their contribution to nutritional quality and health benefits.Nevertheless,the effects of melatonin and UV-B irradiation on glucosinolate biosynthesis remain unclear.In this study,it was found that changes in melatonin concentrations significantly affected the contents of individual as well as total aliphatic and indolic glucosinolates.The 5μmol·L^(-1)melatonin was decided as the optimum concentration that could increase the content of beneficial glucosinolates including glucoraphanin and 4-methoxy glucobrassicin in Chinese kale sprouts.Notably,the enhancement of glucosinolate accumulation by melatonin treatment could be further amplified by UV-B irradiation.Furthermore,our results showed that R2R3-MYB transcription factor BoaMYB28 and BoaMYB51,which are central regulators of aliphatic and indolic glucosinolate biosynthesis respectively,were both involved in the regulation of glucosinolate biosynthesis by melatonin and UV-B irradiation.Additionally,the expression of glucosinolate biosynthetic genes,including BoaCYP79F1,BoaCYP83A1,BoaSUR1,BoaUGT74B1,BoaCYP79B2,BoaCYP79B3,and BoaCYP83B1 participated in the formation of core structures and BoaFMOGS-OX5,BoaAOP2,BoaCYP81F2,and BoaIGMT1 involved in the sidechain modification of aliphatic and indolic glucosinolate,was regulated by melatonin or UV-B irradiation.Taken together,these findings provide a potential strategy for improving the nutritional quality and resistance of Chinese kale sprouts. 展开更多
关键词 MELATONIN Chinese kale SPROUTS UV-B GLUCOSINOLATES Nutritional quality Second metabolism
下载PDF
Understanding the catalytic performance and deactivation behaviour of second-promoter doped Pt/WO_(χ)/γ-Al_(2)O_(3) catalysts in the glycerol hydrogenolysis for selective and cleaner production of 1,3-propanediol
4
作者 Rafik Rajjak Shaikh Sittichai Damruang +2 位作者 Rais Ahmad Khan Supareak Praserthdam Piyasan Praserthdam 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第7期486-507,共22页
The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the ca... The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the catalyst deactivation via sintering,metal leaching,and coking can predominantly occur in the aqueous phase reaction.In this work,the effect of reaction temperature,pressure and second promoter(Cu,Fe,Rh,Mn,Re,Ru,Ir,Sn,B,and P)on catalytic performance and deactivation behaviour of Pt/WOx/-Al2O3 was investigated.When doped with Rh,Mn,Re,Ru,Ir,B,and P,the second promoter boosts catalytic activity by promoting great dispersion of Pt on support and increasing Pt surface area.The increased Bronsted acid sites lead to selective synthesis of 1,3-PDO than 1,2-propanediol(1,2-PDO).The characterization studies of fresh and spent catalysts reveal that the main cause of catalyst deactivation is the Pt sintering,as interpreted based on XRD,CO chemisorption,and TEM analyses.The Pt sintering is affected depending on the second promoter that can either or reduce the interaction between Pt,WO_(χ)/γ and Al_(2)O_(3).As an electron acceptor of Pt in Pt/WO_(χ)/γ-Al_(2)O_(3),Re and Mn as second promoters resulted in increased Pt^(2+) on the catalytic surface,which strengthens the contact between Pt andγ-Al_(2)O_(3) and WO_(χ),resulting in a decrease in Pt sintering.The metal leaching and coking are not affected by the presence of second promoter.The catalyst modified with a second promoter possesses improved catalytic activity and 1,3-PDO production,however the stability continues to remain a challenge.The present work unrav-elled the determining parameters of catalytic activity and deactivation,thus providing a promising pro-tocol toward effective catalysts for glycerol hydrogenolysis. 展开更多
关键词 Glycerol hydrogenolysis 1 3-PROPANEDIOL Metal-support interaction Second promoter Liquid phase Catalyst deactivation
下载PDF
Applications of a Single Molecule Theory of Protein Dynamics
5
作者 Yi Fang 《Journal of Biosciences and Medicines》 2024年第6期311-335,共25页
A single molecule theory for protein dynamics has been developed since 2012. It consists of the concepts of conformational Gibbs free energy function (CGF) and single molecule thermodynamic hypothesis (STH) that claim... A single molecule theory for protein dynamics has been developed since 2012. It consists of the concepts of conformational Gibbs free energy function (CGF) and single molecule thermodynamic hypothesis (STH) that claims that all stable conformations are (local or global) minimizers of CGF. These are enough to give a unified explanations and mechanisms to many aspects of protein dynamics such as protein folding;allostery;denaturation;and intrinsically disordered proteins. Formulas of CGF in water environment had been derived via quantum statistics. Applications of them to soluble proteins are: docking Gibbs free energy difference formula and a practical way to search better docking site;single molecule binding affinity;predicting and explaining why structures of a monomeric globular protein looks like a globule and is tightly packed with a hydrophobic core;a representation of the hydrophobic effect;and a wholistic view to structures of water soluble proteins. 展开更多
关键词 FOLDING DENATURATION BINDING Post-Binding Deformation ALLOSTERY Dynamic Second Law of Thermodynamics
下载PDF
A Case Report of Kissing Molars Class II
6
作者 Toshiyuki Inou Keiichi Uchida +6 位作者 Keiko Kaneko Anna Fuji Nina Wakimoto Tatsuo Takaya Hiroyuki Kitamura Hiroshi Mori Yuji Kurihara 《Open Journal of Stomatology》 2024年第5期249-254,共6页
Kissing molars (KMs) is a condition of occlusal molar surfaces in a single follicular space with roots extending in opposite directions. Here, we have reported a case of KMs in a 58-year-old woman. The patient complai... Kissing molars (KMs) is a condition of occlusal molar surfaces in a single follicular space with roots extending in opposite directions. Here, we have reported a case of KMs in a 58-year-old woman. The patient complained of pain in the right mandibular molar region and was diagnosed with KMs consisting of the right mandibular second and third molars. Because of the patient’s pain having subsided at the time of the visit and her unwillingness to undergo tooth extraction, the patient was followed up. KMs is classified into three classes (I-III) and is either true-KMs or pseudo-KMs and presents with or without cystic variants of dental follicles. The presents as true-KMs class II without a cystic variant. With reference to the literature and based on our analysis, the mean age of patients affected by this specific case of KMs is 31.7 years and unilateral KMs is relatively more common (85.7%). Histopathological findings of dentigerous cysts are more often indicated (42.9%). The treatment policy for KMs should therefore be based on the classification of KMs. Importantly, the focus should be on preserving the first and second molars as much as possible. The treatment approach, such as the employment of surgical removal or orthodontics, should be determined by considering the associated factors such as the crowns, tissues, and age of the patient. 展开更多
关键词 Kissing Molars Mandibular Second Molar Mandibular Third Molar Cone-Beam Computed Tomography
下载PDF
Researching Creativity in Second Language Acquisition:Book Review
7
作者 SHEN Rong-xi ZENG Hai-xiang 《Journal of Literature and Art Studies》 2024年第3期215-219,共5页
In the realm of psychology and language acquisition,the exploration of“individual differences”-encompassing attributes such as personality traits,motivation,and language aptitude-has long been a focal point of schol... In the realm of psychology and language acquisition,the exploration of“individual differences”-encompassing attributes such as personality traits,motivation,and language aptitude-has long been a focal point of scholarly investigation.Within this sphere,the book“Researching Creativity in Second Language Acquisition”by Ashleigh Pipes offers a fresh perspective on the role of creativity as a significant individual difference in Second Language Acquisition(SLA).Positioned against the backdrop of extensive empirical research on individual differences,this book stands out by focusing on the often overlooked aspect of creativity,which Pipes argues,holds paramount importance in SLA. 展开更多
关键词 Second Language Acquisition(SLA) CREATIVITY
下载PDF
Convergence Phenomenon with Fourier Series of tg(x2)and Alike
8
作者 Alfred Wünsche 《Advances in Pure Mathematics》 2024年第7期556-595,共40页
The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generali... The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. . 展开更多
关键词 Gibbs Phenomenon Generalized Functions Weak Convergence Chebyshev Polynomials of First and Second Kind Even and Odd Generating Functions for Chebyshev Polynomials POLYLOGARITHMS Completeness Relations
下载PDF
Error Analysis of English Pronunciation Acquisition by Chinese Non-English Majors
9
作者 Lin Tao Haiying Liang 《Journal of Contemporary Educational Research》 2024年第2期34-47,共14页
Chinese non-English majors are a large group of English learners.In the process of English pronunciation acquisition,issues such as incomplete phonological knowledge,transfer of mother tongue,and overgeneralization,le... Chinese non-English majors are a large group of English learners.In the process of English pronunciation acquisition,issues such as incomplete phonological knowledge,transfer of mother tongue,and overgeneralization,lead to confusion of phonemes and stress,misunderstanding of syllable structure,and errors of assimilation,drop,and epenthesis.The accuracy of English pronunciation can only be improved by knowing both English and Chinese phonological systems,strengthening the teaching of English phonological knowledge,and adopting various phonological training activities. 展开更多
关键词 English pronunciation acquisition Non-English majors Error analysis INVESTIGATION Second language acquisition
下载PDF
A Review of Research on Second Language Acquisition from a Positive Psychology Perspective
10
作者 Yanhui Wu 《Journal of Contemporary Educational Research》 2024年第6期189-193,共5页
This paper reviews the research on second language acquisition from the perspective of positive psychology.First,it introduces the background and purpose of the study and discusses the significance of the application ... This paper reviews the research on second language acquisition from the perspective of positive psychology.First,it introduces the background and purpose of the study and discusses the significance of the application of positive psychology in the field of language acquisition.Then,the basic theories of positive psychology,including the core concepts and principles of positive psychology,are summarized.Subsequently,the theory of second language acquisition is defined and outlined,including the definition,characteristics,and related developmental theories of second language acquisition.On this basis,the study of second language acquisition from the perspective of positive psychology is discussed in detail.By combing and synthesizing the literature,this paper summarizes the current situation and trend of second language acquisition research under the perspective of positive psychology and puts forward some future research directions and suggestions. 展开更多
关键词 Positive psychology Second language acquisition Language learning motivation Positive emotion Positive mindset
下载PDF
Research on Practical Teaching of Ideological and Political Courses in Colleges and Universities and Collaborative Education in the Second Classroom
11
作者 Luhua Xiao Pingping Liu Zimeng Li 《Journal of Contemporary Educational Research》 2024年第1期214-220,共7页
In today’s society,the need for talent training is of utmost importance due to rapid development.To achieve high-quality talent training,we need to focus on building a collaborative education mechanism.Practical teac... In today’s society,the need for talent training is of utmost importance due to rapid development.To achieve high-quality talent training,we need to focus on building a collaborative education mechanism.Practical teaching and the second classroom,which serve as important carriers of educational talents,must align their educational goals and complement each other.This article explores the collaborative education mechanism of the second classroom and practical teaching for the ideological and political courses in colleges and universities.It proposes reasonable construction measures to provide some guidelines for teaching work. 展开更多
关键词 Colleges and universities Ideological and political courses Practical teaching Second classroom Collaborative education
下载PDF
Research on Learner Needs Analysis and Listening Activities
12
作者 Ruohan Xu 《Journal of Contemporary Educational Research》 2024年第4期247-254,共8页
Listening is the primary method to access language information.It is an essential part of L2(second language)teaching but also the most difficult skill to master for L2 learners.Based on this,it is necessary to analyz... Listening is the primary method to access language information.It is an essential part of L2(second language)teaching but also the most difficult skill to master for L2 learners.Based on this,it is necessary to analyze learners’needs in listening.This article aims to conduct a needs analysis of a selected learner from Iraq and describe course material selection and design.Methods including questionnaires,interviews,and observation were used to collect data.Additionally,targeted 60-minute online listening activities were designed.It was found that listening activities can improve both listening and speaking skills.Thus,language teaching should be student-oriented,and subsequent course materials and activity design should be selected based on the analysis of students’needs. 展开更多
关键词 Listening skills Needs analysis Second language teaching
下载PDF
Research on the Application of Second Language Acquisition Theory in College English Speech Teaching
13
作者 Hui Zhang 《Journal of Contemporary Educational Research》 2024年第3期173-178,共6页
The teaching of English speeches in universities aims to enhance oral communication ability,improve English communication skills,and expand English knowledge,occupying a core position in English teaching in universiti... The teaching of English speeches in universities aims to enhance oral communication ability,improve English communication skills,and expand English knowledge,occupying a core position in English teaching in universities.This article takes the theory of second language acquisition as the background,analyzes the important role and value of this theory in English speech teaching in universities,and explores how to apply the theory of second language acquisition in English speech teaching in universities.It aims to strengthen the cultivation of English skilled talents and provide a brief reference for improving English speech teaching in universities. 展开更多
关键词 Second language acquisition theory Teaching English speeches in universities Practical strategies
下载PDF
Low-temperatures synthesis of CuS nanospheres as cathode material for magnesium second batteries 被引量:2
14
作者 Qin Zhang Yaobo Hu +1 位作者 Jun Wang Fusheng Pan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期192-200,共9页
Rechargeable magnesium batteries(RMBs),as one of the most promising candidates for efficient energy storage devices with high energy,power density and high safety,have attracted increasing attention.However,searching ... Rechargeable magnesium batteries(RMBs),as one of the most promising candidates for efficient energy storage devices with high energy,power density and high safety,have attracted increasing attention.However,searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge.Cu S submicron spheres,made by a facile low-temperature synthesis strategy,were applied as the high-performance cathode for RMBs in this work,which can deliver a high specific capacity of 396mAh g^(-1)at 20 mA g^(-1) and a remarkable rate capacity of 250 m Ah g^(-1)at 1000 mA g^(-1).The excellent rate performance can be assigned to the nano needle-like particles on the surface of Cu S submicron spheres,which can facilitate the diffusion kinetics of Mg^(2+).Further storage mechanism investigations illustrate that the Cu S cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process.This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg2+and the reaction mechanism of RMBs. 展开更多
关键词 Magnesium second batteries Cathode material CUS Submicron spheres Low-temperature synthesis.
下载PDF
Temporal electric field of a helium plasma jet by electric field induced second harmonic(E-FISH)method 被引量:2
15
作者 李旭 晋绍珲 +3 位作者 宋珂 聂兰兰 刘大伟 卢新培 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第1期43-52,共10页
Electric field is an important parameter of plasma,which is related to electron temperature,electron density,excited species density,and so on.In this work,the electric field of an atmospheric pressure plasma jet is d... Electric field is an important parameter of plasma,which is related to electron temperature,electron density,excited species density,and so on.In this work,the electric field of an atmospheric pressure plasma jet is diagnosed by the electric field induced second harmonic(E-FISH)method,and the time-resolved electric field under different conditions is investigated.When positive pulse voltage is applied,the electric field has a peak of about 25 kV cm-1at the rising edge of the voltage pulse.A dark channel is left behind the plasma bullet and the electric field in the dark channel is about 5 kV cm-1.On the other hand,when negative pulse voltage is applied,the electric field has a peak of-16 kV cm-1when the negative voltage is increased to-8 kV.A relatively bright channel is left behind the plasma head and the electric field in this relatively bright channel is about-6 kV cm-1.When the pulse rising time increases from 60 to 200 ns,the peak electric field at both the rising edge and the falling edge of the voltage decreases significantly.When 0.5%of oxygen is added to the main working gas helium,the peak electric field at the rising edge is only about 15 kV cm-1.On the other hand,when 0.5%nitrogen is added,the peak electric field increases especially at the falling edge of the voltage pulse,where it increases reversely from-12 to-16 kV cm-1(the minus sign only represents the direction of electric field). 展开更多
关键词 atmospheric pressure plasma jet electric field electric field induced second harmonic
下载PDF
Towards Innovative Research Approaches to Investigating the Role of Emotional Variables in Promoting Language Teachers’ and Learners’ Mental Health 被引量:2
16
作者 Ali Derakhshan Yongliang Wang +1 位作者 Yongxiang Wang José Luis Ortega-Martín 《International Journal of Mental Health Promotion》 2023年第7期823-832,共10页
The adequacy of language education largely depends on the favorable and unfavorable emotions that teachers and students experience throughout the education process.Simply said,emotional factors play a key role in impr... The adequacy of language education largely depends on the favorable and unfavorable emotions that teachers and students experience throughout the education process.Simply said,emotional factors play a key role in improving the quality of language teaching and learning.Furthermore,these emotional factors also promote the well-being of language teachers and learners and place them in a suitable mental condition.In view of the favorable impact of emotional factors on the mental health of language teachers and learners,many educational scholars around the world have studied these factors,their background,and their pedagogical consequences.Nonetheless,the majority of previous studies have employed traditional research methods in assessing these variables and their influences on language teachers’and learners’mental health.Because of the complex and dynamic quality of emotional factors,traditional research approaches often fail to evaluate these factors and their dynamic,non-linear connections with teachers’and learners’mental health and well-being.Accordingly,some novel research approaches are required to measure the dynamicity and complexity of emotional factors in language education settings.To address this call,the current state-of-the-art conceptual article seeks to provide new insights for investigating emotional factors and their potential impact on language teachers’and learners’mental states.This study also intends to offer a comprehensive list of emerging methods that take into account the complex and dynamic nature of emotional variables.Finally,the study outlines the potential implications of this review for educational researchers. 展开更多
关键词 COMPLEXITY dynamicity emotional factors mental health WELL-BEING innovative research approaches second and foreign language education
下载PDF
Comparative study of extrudability, microstructure, and mechanical properties of AZ80 and BA53 alloys 被引量:1
17
作者 Sang-Cheol Jin Jae Won Cha +2 位作者 Jongbin Go Jun Ho Bae Sung Hyuk Park 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期249-258,共10页
The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)alloy.When AZ80 is extr... The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)alloy.When AZ80 is extruded at 400℃,severe hot cracking occurs at exit speeds of 4.5 m/min or more.In contrast,BA53 is successfully extruded without any surface cracking at 400℃ and at high exit speeds of 21–40 m/min.When extruded at 3 m/min(AZ80–3)and 40 m/min(BA53–40),both AZ80 and BA53 exhibited completely recrystallized microstructures with a<10–10>basal texture.However,BA53–40 has a coarser grain structure owing to grain growth promoted by the high temperature in the deformation zone.AZ80–3 contains a continuous network of Mg_(17)Al_(12) particles along the grain boundaries,which form via static precipitation during natural air-cooling after the material exits the extrusion die.BA53–40 contains coarse Mg_(3)Bi_(2) particles aligned parallel to the extrusion direction along with numerous uniformly distributed fine Mg_(3)Bi_(2) particles.AZ80–3 has higher tensile strength than BA53–40 because the relatively finer grains and larger number of solute atoms in AZ80–3 result in stronger grain-boundary and solid-solution hardening effects,respectively.Although BA53 is extruded at a high temperature and extrusion speed of 400℃ and 40 m/min,respectively,the extruded material has a high tensile yield strength of 188 MPa.This can be primarily attributed to the large particle hardening effect resulting from the numerous fine Mg_(3)Bi_(2) particles. 展开更多
关键词 Mg-Bi-Al alloy EXTRUSION Hot cracking Second phase Tensile properties
下载PDF
The impact of ChatGPT on foreign language teaching and learning: Opportunities in education and research 被引量:7
18
作者 Wilson Cheong Hin Hong 《教育技术与创新》 2023年第1期37-45,共9页
The revolutionary online application ChatGPT has brought immense concerns to the education field.Foreign language teachers being some of those most reliant on writing assessments were among the most anxious,exacerbate... The revolutionary online application ChatGPT has brought immense concerns to the education field.Foreign language teachers being some of those most reliant on writing assessments were among the most anxious,exacerbated by the extensive media coverage about the much-fantasized functionality of the chatbot.Hence,the article starts by elucidating the mechanisms,functions and common misconceptions about ChatGPT.Issues and risks associated with its usage are discussed,followed by an in-depth discussion of how the chatbot can be harnessed by learners and teachers.It is argued that ChatGPT offers major opportunities for teachers and education institutes to improve second/foreign language teaching and assessments,which similarly provided researchers with an array of research opportunities,especially towards a more personalized learning experience. 展开更多
关键词 Large Language Model second language education flip classroom personalized learning formative assessment
下载PDF
Color Edge Detection Using Multidirectional Sobel Filter and Fuzzy Fusion
19
作者 Slim Ben Chaabane Anas Bushnag 《Computers, Materials & Continua》 SCIE EI 2023年第2期2839-2852,共14页
A new model is proposed in this paper on color edge detection that uses the second derivative operators and data fusion mechanism.The secondorder neighborhood shows the connection between the current pixel and the sur... A new model is proposed in this paper on color edge detection that uses the second derivative operators and data fusion mechanism.The secondorder neighborhood shows the connection between the current pixel and the surroundings of this pixel.This connection is for each RGB component color of the input image.Once the image edges are detected for the three primary colors:red,green,and blue,these colors are merged using the combination rule.Then,the final decision is applied to obtain the segmentation.This process allows different data sources to be combined,which is essential to improve the image information quality and have an optimal image segmentation.Finally,the segmentation results of the proposed model are validated.Moreover,the classification accuracy of the tested data is assessed,and a comparison with other current models is conducted.The comparison results show that the proposed model outperforms the existing models in image segmentation. 展开更多
关键词 SEGMENTATION edge detection second derivative operators data fusion technique fuzzy fusion CLASSIFICATION
下载PDF
Development of high-strength magnesium alloys with excellent ignition-proof performance based on the oxidation and ignition mechanisms: A review
20
作者 Jing Ni Li Jin +5 位作者 Jian Zeng Jing Li Fulin Wang Fenghua Wang Shuai Dong Jie Dong 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期1-14,共14页
High reactivity and ease of ignition are the major obstacles for the application of Mg alloys in aerospace.Thus,the ignition mechanisms of Mg alloys should be investigated systematically,which can guide the ignition-p... High reactivity and ease of ignition are the major obstacles for the application of Mg alloys in aerospace.Thus,the ignition mechanisms of Mg alloys should be investigated systematically,which can guide the ignition-proof alloy design.This article concludes the factors influencing the ignition resistance of Mg alloys from oxide film and substrate microstructure,and also the mechanisms of alloying elements improving the ignition resistance.The low strength is another reason restricting the development of Mg alloys.Therefore,at the last section,Mg alloys with the combination of high strength and good ignition-proof performance are summarized,including Mg-Al-Ca based alloys,SEN(Mg-Al-Zn-Ca-Y)alloys as well as Mg-Y and Mg-Gd based alloys.Besides,the shortages and the future focus of theses alloys are also reviewed.The aim of this article is to promote the understanding of oxidation and ignition mechanisms of Mg alloys and to provide reference for the development of Mg alloys with high strength and excellent ignition-proof performance at the same time. 展开更多
关键词 High-strength and ignition-proof Mg alloys High temperature oxidation Oxide film Second phases ALLOYING
下载PDF
上一页 1 2 80 下一页 到第
使用帮助 返回顶部