期刊文献+
共找到2,597篇文章
< 1 2 130 >
每页显示 20 50 100
Adherence to Advisory Committee on Immunization Practices in diabetes mellitus patients in Saudi Arabia:A multicenter retrospective study
1
作者 Saleh Fahad Alqifari Aya K Esmail +12 位作者 Dalal M Alarifi Ghalya Y Alsuliman Maram M Alhati May R Mutlaq Mohammed Aldhaeefi Shaden A Alshuaibi Palanisamy Amirthalingam Abrar Abdallah Afaf S Wasel Heba R Hamad Shoroq Alamin Tasneem H Atia Tariq Alqahtani 《World Journal of Diabetes》 SCIE 2024年第3期440-454,共15页
BACKGROUND Patients with diabetes mellitus(DM)are predisposed to an increased risk of infection signifying the importance of vaccination to protect against its potentially severe complications.The Centers for Disease ... BACKGROUND Patients with diabetes mellitus(DM)are predisposed to an increased risk of infection signifying the importance of vaccination to protect against its potentially severe complications.The Centers for Disease Control and Prevention/Advisory Committee on Immunization Practices(CDC/ACIP)issued immunization recommendations to protect this patient population.AIM To assess the adherence of patients with DM to the CDC/ACIP immunization recommendations in Saudi Arabia and to identify the factors associated with the vaccine adherence rate.METHODS An observational retrospective study conducted in 2023 was used to collect data on the vaccination records from 13 diabetes care centers in Saudi Arabia with 1000 eligible patients in phase I with data collected through chart review and 709 patients in phase II through online survey.RESULTS Among participants,10.01%(n=71)had never received any vaccine,while 85.89%(n=609)received at least one dose of the coronavirus disease 2019(COVID-19)vaccine,and 34.83%(n=247)had received the annual influenza vaccine.Only 2.96%(n=21),2.11%(n=15),and 1.12%(n=8)received herpes zoster,tetanus,diphtheria,and pertussis(Tdap),and human papillomavirus(HPV)vaccines,respectively.For patients with DM in Saudi Arabia,the rate of vaccination for annual influenza and COVID-19 vaccines was higher compared to other vaccinations such as herpes zoster,Tdap,pneumococcal,and HPV.Factors such as vaccine recommendations provided by family physicians or specialists,site of care,income level,DM-related hospitalization history,residency site,hemoglobin A1c(HbA1c)level,and health sector type can significantly influence the vaccination rate in patients with DM.Among non-vaccinated patients with DM,the most reported barriers were lack of knowledge and fear of side effects.This signifies the need for large-scale research in this area to identify additional factors that might facilitate adherence to CDC/ACIP vaccine recommendations in patients with DM.CONCLUSION In Saudi Arabia,patients with DM showed higher vaccination rates for annual influenza and COVID-19 vaccines compared to other vaccinations such as herpes zoster,Tdap,pneumococcal,and HPV.Factors such as vaccine recommendations provided by family physicians or specialists,the site of care,income level,DM-related hospitalization history,residency site,HbA1c level,and health sector type can significantly influence the vaccination rate in patients with DM. 展开更多
关键词 Diabetes mellitus Vaccine recommendation COVID-19 vaccine Influenza vaccine Pneumococcal vaccine IMMUNIZATION Retrospective study
下载PDF
A BRIEF INTRODUCTION TO THE CHINESE NATIONAL EXAMINATION CENTER FOR TCM AND THE CHINESE INTERNATIONAL EXAMINATION CENTER FOR ACUPUNCTURE & MOXIBUSTION
2
作者 Chinese National Examination Center for TCM Chinese International Examination Center for Acupuncture & Moxibustion 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 1991年第3期236-238,共3页
Traditional Chinese Medicine (TCM)and Acupuncture & Moxibustion (A & M)originated in China,with a history of severalthousand years.They have made great con-tributions to the human health with theunique theoret... Traditional Chinese Medicine (TCM)and Acupuncture & Moxibustion (A & M)originated in China,with a history of severalthousand years.They have made great con-tributions to the human health with theunique theoretical system and excellent clini-al efficacy,and therefore,are drawing greatattention of the international medicalcircles.At present,TCM and A & 展开更多
关键词 ACUPUNCTURE originated drawing friends items CIRCLES trained audio ORGANIZING Nanjing
下载PDF
Introduction of International Research Center on Karst under the Auspices of UNESCO
3
作者 Qu-kan Luo Jian-hua Cao +2 位作者 Mao-yan Hu Bing Bai LiangZhong 《China Geology》 2018年第4期574-576,共3页
On December 15,2008,the International Research Center on Karst under the Auspices of UNESCO (hereinafter referred as IRCK)was formally established in Guilin,China.It is also the first category Ⅱ center concerning geo... On December 15,2008,the International Research Center on Karst under the Auspices of UNESCO (hereinafter referred as IRCK)was formally established in Guilin,China.It is also the first category Ⅱ center concerning geosciences.Since its foundation,it has organized 11 international symposia, attracted over 200 foreign scientists from more than 40 countries for academic exchange,and signed 16 international cooperation agreements with 14 countries.It has played an active role for international exchange,set firm foundation for cooperative projects. 展开更多
关键词 INTERNATIONAL KARST under UNESCO
下载PDF
Biliary fistula and late recurrence of liver hydatid cyst:Role of cystobiliary communication:A prospective multicenter study
4
作者 Tamer A A M Habeeb Mauro Podda +27 位作者 Boris Tadic Vishal G Shelat Yaman Tokat Mohamed Ibrahim Abo Alsaad Abd-Elfattah Kalmoush Mohammed Shaaban Nassar Fawzy Metwally Mustafa Mahmoud Hassib Morsi Badawy Mohamed Sobhy Shaaban Tarek Zaghloul Mohamed Mohammed Ibrahim El Sayed Henish Hamdi Elbelkasi Mahmoud Abdou Yassin Abdelshafy Mostafa Amr Ibrahim Waleed A-Abdelhady TamerMohamed Elshahidy Mohamed Ibrahim Mansour Adel Mahmoud Moursi Mohamed Abdallah Zaitoun EhabShehata Abd-Allah Ashraf Abdelmonem Elsayed Rasha S Elsayed Ahmed M Yehia Amr Abdelghani Mohamed Negm Heba Alhussein Abo-Alella Mostafa M Elaidy 《World Journal of Methodology》 2023年第4期272-286,共15页
BACKGROUND Hydatid cyst disease(HCD)is common in certain locations.Surgery is associated with postoperative biliary fistula(POBF)and recurrence.The primary aim of this study was to identify whether occult cysto-biliar... BACKGROUND Hydatid cyst disease(HCD)is common in certain locations.Surgery is associated with postoperative biliary fistula(POBF)and recurrence.The primary aim of this study was to identify whether occult cysto-biliary communication(CBC)can predict recurrent HCD.The secondary aim was to assess the role of cystic fluid bilirubin and alkaline phosphatase(ALP)levels in predicting POBF and recurrent HCD.AIM To identify whether occult CBC can predict recurrent HCD.The secondary aim was to assess the role of cystic fluid bilirubin and ALP levels in predicting POBF and recurrent HCD.METHODS From September 2010 to September 2016,a prospective multicenter study was undertaken involving 244 patients with solitary primary superficial stage cystic echinococcosis 2 and cystic echinococcosis 3b HCD who underwent laparoscopic partial cystectomy with omentoplasty.Univariable logistic regression analysis assessed independent factors determining biliary complications and recurrence.RESULTS There was a highly statistically significant association(P≤0.001)between cystic fluid biochemical indices and the development of biliary complications(of 16 patients with POBF,15 patients had high cyst fluid bilirubin and ALP levels),where patients with high bilirubin-ALP levels were 3405 times more likely to have biliary complications.There was a highly statistically significant association(P≤0.001)between biliary complications,biochemical indices,and the occurrence of recurrent HCD(of 30 patients with recurrent HCD,15 patients had high cyst fluid bilirubin and ALP;all 16 patients who had POBF later developed recurrent HCD),where patients who developed biliary complications and high bilirubin-ALP were 244.6 and 214 times more likely to have recurrent hydatid cysts,respectively.CONCLUSION Occult CBC can predict recurrent HCD.Elevated cyst fluid bilirubin and ALP levels predicted POBF and recurrent HCD. 展开更多
关键词 Cysto-biliary communication Echinococcus granulosus Hydatid disease recurrence Hydatid fluid analysis LAPAROSCOPY
下载PDF
Simultaneously quantifying hundreds of acylcarnitines in multiple biological matrices within ten minutes using ultrahigh-performance liquid-chromatography and tandem mass spectrometry 被引量:1
5
作者 Jingxian Zhang Qinsheng Chen +4 位作者 Lianglong Zhang Biru Shi Men Yu Qingxia Huang Huiru Tang 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2024年第1期140-148,共9页
Acylcarnitines are metabolic intermediates of fatty acids and branched-chain amino acids having vital biofunctions and pathophysiological significances. Here, we developed a high-throughput method for quantifying hund... Acylcarnitines are metabolic intermediates of fatty acids and branched-chain amino acids having vital biofunctions and pathophysiological significances. Here, we developed a high-throughput method for quantifying hundreds of acylcarnitines in one run using ultrahigh performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS). This enabled simultaneous quantification of 1136 acylcarnitines (C0–C26) within 10-min with good sensitivity (limit of detection < 0.7 fmol), linearity (correlation coefficient > 0.992), accuracy (relative error < 20%), precision (coefficient of variation (CV), CV < 15%), stability (CV < 15%), and inter-technician consistency (CV < 20%, n = 6). We also established a quantitative structure-retention relationship (goodness of fit > 0.998) for predicting retention time (tR) of acylcarnitines with no standards and built a database of their multiple reaction monitoring parameters (tR, ion-pairs, and collision energy). Furthermore, we quantified 514 acylcarnitines in human plasma and urine, mouse kidney, liver, heart, lung, and muscle. This provides a rapid method for quantifying acylcarnitines in multiple biological matrices. 展开更多
关键词 ACYLCARNITINE UPLC-MS/MS Quantitative structure-retention relationship Molecular phenotype
下载PDF
Symmetry transformation of nonlinear optical current of tilted Weyl nodes and application to ferromagnetic MnBi_(2)Te_(4)
6
作者 卢倬成 冯济 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期160-171,共12页
A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-de... A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals. 展开更多
关键词 nonlinear optical response topological Weyl semimetals chiral anomaly
下载PDF
Magnetism and Superconductivity in the t–J Model of La_(3)Ni_(2)O_7 Under Multiband Gutzwiller Approximation
7
作者 薛洁然 王垡 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第5期97-106,共10页
The recent discovery of possible high temperature superconductivity in single crystals of La_(3)Ni_(2)O_(7) under pressure renews the interest in research on nickelates.The density functional theory calculations revea... The recent discovery of possible high temperature superconductivity in single crystals of La_(3)Ni_(2)O_(7) under pressure renews the interest in research on nickelates.The density functional theory calculations reveal that both d_(z^(2)) and d_(x^(2)-y^(2)) orbitals are active,which suggests a minimal two-orbital model to capture the low-energy physics of this system.In this work,we study a bilayer two-orbital t–J model within multiband Gutzwiller approximation,and discuss the magnetism as well as the superconductivity over a wide range of the hole doping.Owing to the inter-orbital super-exchange process between d_(z^(2)) and d_(x^(2)-y^(2)) orbitals,the induced ferromagnetic coupling within layers competes with the conventional antiferromagnetic coupling,and leads to complicated hole doping dependence for the magnetic properties in the system.With increasing hole doping,the system transfers to A-type antiferromagnetic state from the starting G-type antiferromagnetic(G-AFM)state.We also find the inter-layer superconducting pairing of d_(x^(2)-y^(2)) orbitals dominates due to the large hopping parameter ofd_(z^(2)) along the vertical inter-layer bonds and significant Hund’s coupling between d_(z^(2)) and d_(x^(2)-y^(2)) orbitals.Meanwhile,the G-AFM state and superconductivity state can coexist in the low hole doping regime.To take account of the pressure,we also analyze the impacts of inter-layer hopping amplitude on the system properties. 展开更多
关键词 PROPERTIES DOPING ORBITAL
下载PDF
El Niño and the AMO Sparked the Astonishingly Large Margin of Warming in the Global Mean Surface Temperature in 2023
8
作者 Kexin LI Fei ZHENG +1 位作者 Jiang ZHU Qing-Cun ZENG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1017-1022,共6页
In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming ... In 2023,the majority of the Earth witnessed its warmest boreal summer and autumn since 1850.Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming has become one of the hottest topics in the scientific community and is closely connected to the future development of human society.We analyzed the monthly varying global mean surface temperature(GMST)in 2023 and found that the globe,the land,and the oceans in 2023 all exhibit extraordinary warming,which is distinct from any previous year in recorded history.Based on the GMST statistical ensemble prediction model developed at the Institute of Atmospheric Physics,the GMST in 2023 is predicted to be 1.41℃±0.07℃,which will certainly surpass that in 2016 as the warmest year since 1850,and is approaching the 1.5℃ global warming threshold.Compared to 2022,the GMST in 2023 will increase by 0.24℃,with 88%of the increment contributed by the annual variability as mostly affected by El Niño.Moreover,the multidecadal variability related to the Atlantic Multidecadal Oscillation(AMO)in 2023 also provided an important warming background for sparking the GMST rise.As a result,the GMST in 2023 is projected to be 1.15℃±0.07℃,with only a 0.02℃ increment,if the effects of natural variability—including El Niño and the AMO—are eliminated and only the global warming trend is considered. 展开更多
关键词 record-breaking temperature global mean surface temperature El Niño AMO global warming
下载PDF
Uncertainties of ENSO-related Regional Hadley Circulation Anomalies within Eight Reanalysis Datasets
9
作者 Yadi LI Xichen LI +3 位作者 Juan FENG Yi ZHOU Wenzhu WANG Yurong HOU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第1期115-140,共26页
El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement... El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies. 展开更多
关键词 regional Hadley circulation ENSO atmosphere-ocean interaction reanalysis data
下载PDF
Severe Global Environmental Issues Caused by Canada’s Record-Breaking Wildfires in 2023
10
作者 Zhe WANG Zifa WANG +8 位作者 Zhiyin ZOU Xueshun CHEN Huangjian WU Wending WANG Hang SU Fang LI Wenru XU Zhihua LIU Jiaojun ZHU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第4期565-571,共7页
Due to the record-breaking wildfires that occurred in Canada in 2023,unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere.The wildfires had emitted more than 1.3 Pg CO_(2)a... Due to the record-breaking wildfires that occurred in Canada in 2023,unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere.The wildfires had emitted more than 1.3 Pg CO_(2)and 0.14 Pg CO_(2)equivalent of other greenhouse gases(GHG)including CH4 and N_(2)O as of 31 August.The wildfire-related GHG emissions constituted more than doubled Canada’s planned cumulative anthropogenic emissions reductions in 10 years,which represents a significant challenge to climate mitigation efforts.The model simulations showed that the Canadian wildfires impacted not only the local air quality but also that of most areas in the northern hemisphere due to long-range transport,causing severe PM_(2.5)pollution in the northeastern United States and increasing daily mean PM_(2.5)concentration in northwestern China by up to 2μg m-3.The observed maximum daily mean PM_(2.5)concentration in New York City reached 148.3μg m-3,which was their worst air quality in more than 50 years,nearly 10 times that of the air quality guideline(i.e.,15μg m-3)issued by the World Health Organization(WHO).Aside from the direct emissions from forest fires,the peat fires beneath the surface might smolder for several months or even longer and release substantial amounts of CO_(2).The substantial amounts of greenhouse gases from forest and peat fires might contribute to the positive feedback to the climate,potentially accelerating global warming.To better understand the comprehensive environmental effects of wildfires and their interactions with the climate system,more detailed research based on advanced observations and Earth System Models is essential. 展开更多
关键词 CANADA forest fire greenhouse gases PM_(2.5) transboundary air pollution
下载PDF
Trend in seasonal amplitude of northern net ecosystem production:Simulated results from IAP DGVM in CAS-ESM2
11
作者 Jiawen Zhu Xiaodong Zeng 《Atmospheric and Oceanic Science Letters》 CSCD 2024年第2期45-51,共7页
北方陆地净生态系统生产力(NEP)具有明显的季节变化特征,这是大气CO_(2)季节变化的关键驱动.研究这些碳循环过程并理解潜在的驱动因素是气候研究的一个关键问题.本文利用第二代中国科学院地球系统模式(CAS-ESM2)中的全球植被动态模型(IA... 北方陆地净生态系统生产力(NEP)具有明显的季节变化特征,这是大气CO_(2)季节变化的关键驱动.研究这些碳循环过程并理解潜在的驱动因素是气候研究的一个关键问题.本文利用第二代中国科学院地球系统模式(CAS-ESM2)中的全球植被动态模型(IAPDGVM),研究了1990-2014年北方NEP(40°-90°N)的季节振幅及其变化趋势.在初始化试验的基础上,本文开展了一个控制试验来评估模拟的北方NEP季节幅度的变化趋势,同时开展了三个敏感性试验来研究气候和大气CO_(2)的贡献.结果表明:1990-2014年,模拟的北方NEP季节振幅显著增加,趋势为9.69万吨碳/月/年,这主要是由于最大NEP增加所致.当分别排除CO_(2)施肥效应和气候效应时,上述增加趋势大大减弱.这些显著的减少表明大气CO_(2)和气候变化对北方NEP的季节性振幅有重要影响.尽管模式存在不确定性,但这些结果有利于进一步提升IAPDGVM对陆地碳循环的精确模拟,也为CAS-ESM研究碳-气候相互作用的应用提供了重要参考. 展开更多
关键词 净生态系统生产力 北方陆地生态系统 季节变化幅度 CO_(2)施肥效应 气候效应
下载PDF
Magneto-optic Kerr Effect Measurement of TbMn_(6)Sn_(6) at mK Temperature
12
作者 黄代强 汪洋 +2 位作者 王贺 王健 刘阳 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期159-163,共5页
Novel electron states stabilized by Coulomb interactions attract tremendous interests in condensed matter physics.These states are studied by corresponding phase transitions occurring at extreme conditions such as mK ... Novel electron states stabilized by Coulomb interactions attract tremendous interests in condensed matter physics.These states are studied by corresponding phase transitions occurring at extreme conditions such as mK temperatures and high magnetic field.In this work,we introduce a magneto-optical Kerr effect measurement system to comprehensively explore these phases in addition to conventional transport measurement.This system,composed of an all-fiber zero-loop Sagnac interferometer and in situ piezo-scanner inside a dilution refrigerator,operates below 100 m K,with a maximum field of 12 Tesla and has a resolution as small as 0.2μrad.As a demonstration,we investigate TbMn_(6)Sn_(6),where the manganese atoms form Kagome lattice that hosts topological non-trivial Dirac cones.We observed two types of Kerr signals,stemming from its fully polarized ferromagnetic ground state and positive charged carriers within the Dirac-like dispersion. 展开更多
关键词 INTERFEROMETER SCANNER system
下载PDF
New Antibacterial Dihydropyrones Induced by Co-Culture of Penicillium crustosum PRB-2 and Penicillium citrinum HDN11-186
13
作者 YU Guihong ZHOU Luning +1 位作者 WU Guangwei LI Dehai 《Journal of Ocean University of China》 CAS CSCD 2024年第1期216-220,共5页
Two new dihydropyrones,rhytismatones C(1)and D(2),and a known compound,penicillenol A1(3),were isolated from the co-culture broth of the deep-sea-derived fungus Penicillium crustosum PRB-2 and Suaeda salsa-derived end... Two new dihydropyrones,rhytismatones C(1)and D(2),and a known compound,penicillenol A1(3),were isolated from the co-culture broth of the deep-sea-derived fungus Penicillium crustosum PRB-2 and Suaeda salsa-derived endophytic fungus Peni-cillium citrinum HDN11-186.Their structures were elucidated through comprehensive analysis of nuclear magnetic resonance(NMR)spectra and mass spectra.The absolute configurations of new compounds were determined by calculating the electronic circular di-chroism(ECD)spectrum.UPLC-MS data showed that compounds 1–3 could only be detected in the media of co-culture,suggesting new biosynthetic pathways were activated in the co-cultured fungi.Compound 1 showed obvious antibacterial activities against Pro-teus sp.MMBC-1002 and Bacillus subtilis MMBC-1004 with minimum inhibitory concentration(MIC)both at 25μmolL^(-1). 展开更多
关键词 CO-CULTURE Penicillium crustosum Penicillium citrinum dihydropyrones antibacterial activity
下载PDF
Interaction between Surface Acoustic Wave and Quantum Hall Effects
14
作者 刘萧 吴蒙蒙 +6 位作者 王任飞 王兴豪 张文锋 董昱江 杜瑞瑞 刘阳 林熙 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期105-109,共5页
Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its... Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its amplitude,and shifting its velocity,which is described by the relaxation model.In this work,we systematically study this interaction using orders of magnitude lower SAW amplitude than those in previous studies.At high magnetic fields,when electrons form highly correlated states such as the quantum Hall effect,we observe an anomalously large attenuation of SAW,while the acoustic speed remains considerably high,inconsistent with the conventional relaxation model.This anomaly exists only when the SAW power is sufficiently low. 展开更多
关键词 RELAXATION QUANTUM inconsistent
下载PDF
Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea
15
作者 CHANG Jingyi LIU Yujia +4 位作者 LU Hailong LU Jing’an SU Xin YE Jianliang XIE Wenwei 《Journal of Ocean University of China》 CAS CSCD 2024年第1期138-148,共11页
Pyrite is one of the common authigenic minerals in marine sediments.Previous studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it... Pyrite is one of the common authigenic minerals in marine sediments.Previous studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it is formed.To better understand the for-mation mechanism of authigenic pyrite,we analyzed the isotopic composition,morphology,and distribution of pyrite in the sediment at 500m below the seafloor from Xisha Trough,South China Sea.Mineral morphologies were observed by scanning electron micros-copy and Raman spectrography.X-Ray computed tomography was applied to measure the particle size of pyrite.The size of pyrite crystals in the matrix sediment mainly ranged between 25 and 65µm(av.ca.40µm),although crystals were larger(av.ca.50μm)in the veins.The pyrites had a fine-grained truncated octahedral shape with occasionally well-developed growth steps,which implies the low growth rate and weak anaerobic oxidation of methane-sulfate reduction when pyrite was formed.Theδ^(34)S values of pyrites ranged from+20.8‰Vienna-defined Canyon Diablo Troilite(V-CDT)to+33.2‰V-CDT and from+44.8‰V-CDT to+48.9‰,which suggest two growth stages.In the first stage,with the continuous low methane flux,the pyrite possibly formed in an environment with good access to seawater.In the second stage,the pyrites mainly developed in sediment fractures and appeared in veins,probably due to the limited availability of sulfate.The less exposure of pyrite to the environment in the second stage was probably caused by sediment accumulation or perturbation.In this study,an episodic pyritization process was identified,and the paleoenvironment was reconstructed for the sediment investigated. 展开更多
关键词 PYRITE sulfur isotope AOM methane flux Xisha Trough South China Sea
下载PDF
A review on ultra-small undoped MoS_(2) as advanced catalysts for renewable fuel production
16
作者 Guoping Liu Lingling Ding +6 位作者 Yuxuan Meng Ahmad Ali Guifu Zuo Xianguang Meng Kun Chang Oi Lun Li Jinhua Ye 《Carbon Energy》 SCIE EI CAS CSCD 2024年第2期92-112,共21页
Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-... Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-performance catalysts.The synthesis of ultra-small MoS2 particles(<10 nm)is highly desired in various experimental studies.The ultra-small structure could often lead to a distinct S-Mo coordination state and nonstoichiometric composition in MoSx,minimizing in-plane active sites of the 2D structure and making it probable to regulate the atomic and electronic structure of its intrinsic active sites on a large extent,especially in MoSx clusters.This article summarizes the recent progress of catalysis over ultra-small undoped MoS_(2) particles for renewable fuel production.Through a systematic review of their synthesis,structural,and spectral characteristics,as well as the relationship between their catalytic performance and inherent defects,we aim to provide insights into catalysis over this matrix that may potentially enable advancement in the development of high-performance MoS_(2)-based catalysts for sustainable energy generation in the future. 展开更多
关键词 applications CATALYTIC MoS_(2) structure synthesis
下载PDF
Effect of boundary conditions on shakedown analysis of heterogeneous materials
17
作者 Xiuchen GONG Yinghao NIE +1 位作者 Gengdong CHENG Kai LI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第1期39-68,共30页
The determination of the ultimate load-bearing capacity of structures made of elastoplastic heterogeneous materials under varying loads is of great importance for engineering analysis and design. Therefore, it is nece... The determination of the ultimate load-bearing capacity of structures made of elastoplastic heterogeneous materials under varying loads is of great importance for engineering analysis and design. Therefore, it is necessary to accurately predict the shakedown domains of these materials. The static shakedown theorem, also known as Melan's theorem, is a fundamental method used to predict the shakedown domains of structures and materials. Within this method, a key aspect lies in the construction and application of an appropriate self-equilibrium stress field(SSF). In the structural shakedown analysis, the SSF is typically constructed by governing equations that satisfy no external force(NEF) boundary conditions. However, we discover that directly applying these governing equations is not suitable for the shakedown analysis of heterogeneous materials. Researchers must consider the requirements imposed by the Hill-Mandel condition for boundary conditions and the physical significance of representative volume elements(RVEs). This paper addresses this issue and demonstrates that the sizes of SSFs vary under different boundary conditions, such as uniform displacement boundary conditions(DBCs), uniform traction boundary conditions(TBCs), and periodic boundary conditions(PBCs). As a result, significant discrepancies arise in the predicted shakedown domain sizes of heterogeneous materials. Built on the demonstrated relationship between SSFs under different boundary conditions, this study explores the conservative relationships among different shakedown domains, and provides proof of the relationship between the elastic limit(EL) factors and the shakedown loading factors under the loading domain of two load vertices. By utilizing numerical examples, we highlight the conservatism present in certain results reported in the existing literature. Among the investigated boundary conditions, the obtained shakedown domain is the most conservative under TBCs.Conversely, utilizing PBCs to construct an SSF for the shakedown analysis leads to less conservative lower bounds, indicating that PBCs should be employed as the preferred boundary conditions for the shakedown analysis of heterogeneous materials. 展开更多
关键词 heterogeneous material self-equilibrium stress field(SSF) shakedown analysis effect of boundary conditions
下载PDF
Persistent Variations in the East Asian Trough from March to April and the Possible Mechanism
18
作者 Shui YU Jianqi SUN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第4期737-753,I0002-I0004,共20页
The East Asian trough(EAT)profoundly influences the East Asian spring climate.In this study,the relationship of the EATs among the three spring months is investigated.Correlation analysis shows that the variation in M... The East Asian trough(EAT)profoundly influences the East Asian spring climate.In this study,the relationship of the EATs among the three spring months is investigated.Correlation analysis shows that the variation in March EAT is closely related to that of April EAT.Extended empirical orthogonal function(EEOF)analysis also confirms the co-variation of the March and April EATs.The positive/negative EEOF1 features the persistent strengthened/weakened EAT from March to April.Further investigation indicates that the variations in EEOF1 are related to a dipole sea surface temperature(SST)pattern over the North Atlantic and the SST anomaly over the tropical Indian Ocean.The dipole SST pattern over the North Atlantic,with one center east of Newfoundland Island and another east of Bermuda,could trigger a Rossby wave train to influence the EAT in March−April.The SST anomaly over the tropical Indian Ocean can change the Walker circulation and influence the atmospheric circulation over the tropical western Pacific,subsequently impacting the southern part of the EAT in March−April.Besides the SST factors,the Northeast Asian snow cover could change the regional thermal conditions and lead to persistent EAT anomalies from March to April.These three impact factors are generally independent of each other,jointly explaining large variations in the EAT EEOF1.Moreover,the signals of the three factors could be traced back to February,consequently providing a potential prediction source for the EAT variation in March and April. 展开更多
关键词 spring East Asian trough sea surface temperature snow cover
下载PDF
A polarization sensitive interferometer:Delta interferometer
19
作者 卫超奇 刘建彬 +7 位作者 董翼飞 孙雨农 周宇 郑淮斌 刘严严 闫秀生 李福利 徐卓 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期369-377,共9页
A new type of polarization sensitive interferometer is proposed,named the Delta interferometer,inspired by its geometry resembling the Greek letter Delta.The main difference between the Delta interferometer and other ... A new type of polarization sensitive interferometer is proposed,named the Delta interferometer,inspired by its geometry resembling the Greek letter Delta.The main difference between the Delta interferometer and other existing interferometers,such as Michelson,Mach-Zehnder and Young's double-slit interferometers,is that the two interfering paths are asymmetrical in the Delta interferometer.The visibility of the first-order interference pattern observed in the Delta interferometer is dependent on the polarization of the incidental light.Optical coherence theory is employed to interpret this phenomenon and single-mode continuous-wave laser light is employed to verify the theoretical predictions.The theoretical and experimental results are consistent.The Delta interferometer is a perfect tool to study the reflection of electromagnetic fields in different polarizations and may find applications in polarization-sensitive scenarios. 展开更多
关键词 phase sensitive interferometer Fresnel formula first-order interference
下载PDF
Enhanced anomalous Hall effect in kagome magnet YbMn_(6)Sn_(6)with intermediate-valence ytterbium
20
作者 李龙飞 迟晟玮 +3 位作者 马文龙 郭凯臻 徐刚 贾爽 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期43-50,共8页
We report on the magnetization and anomalous Hall effect(AHE)in the high-quality single crystals of the kagome magnet YbMn_(6)Sn_(6),where the spins of the Mn atoms in the kagome lattice order ferromagnetically and th... We report on the magnetization and anomalous Hall effect(AHE)in the high-quality single crystals of the kagome magnet YbMn_(6)Sn_(6),where the spins of the Mn atoms in the kagome lattice order ferromagnetically and the intermediate-valence Yb atoms are nonmagnetic.The intrinsic mechanism plays a crucial role in the AHE,leading to an enhanced anomalous Hall conductivity(AHC)compared with the other rare-earth RMn_(6)Sn_(6)compounds.Our band structure calculation reveals a strong hybridization between the 4f electrons of Yb and conduction electrons. 展开更多
关键词 anomalous Hall effect kagome magnet intermediate valence
下载PDF
上一页 1 2 130 下一页 到第
使用帮助 返回顶部