期刊文献+
共找到121,284篇文章
< 1 2 250 >
每页显示 20 50 100
Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials
1
作者 Rui Zhao Jian Zheng +4 位作者 Jin Guo Yunbo Shi Hengzhen Feng Jun Tang Jun Liu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期217-224,共8页
In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation pr... In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment. 展开更多
关键词 star-shaped metamaterials BROADBAND Vibration attenuation Low-frequency ultrasound vibration Transmission loss
下载PDF
Practice patterns among ophthalmic surgeons in treating concomitant oculoplastic conditions in preoperative period:A questionnaire-based study
2
作者 Bijnya Birajita Panda Chitaranjan Mishra +3 位作者 Bhagabat Nayak Avik Kumar Roy Logesh Balakrishnan Priyadarshini Mishra 《World Journal of Clinical Cases》 SCIE 2025年第1期29-37,共9页
BACKGROUND Addressing oculoplastic conditions in the preoperative period ensures both the safety and functional success of any ophthalmic procedure.Some oculoplastic conditions,like nasolacrimal duct obstruction,have ... BACKGROUND Addressing oculoplastic conditions in the preoperative period ensures both the safety and functional success of any ophthalmic procedure.Some oculoplastic conditions,like nasolacrimal duct obstruction,have been extensively studied,whereas others,like eyelid malposition and thyroid eye disease,have received minimal or no research.AIM To investigate the current practice patterns among ophthalmologists while treating concomitant oculoplastic conditions before any subspecialty ophthalmic intervention.METHODS A cross-sectional survey was disseminated among ophthalmologists all over India.The survey included questions related to pre-operative evaluation,anaesthetic and surgical techniques preferred,post-operative care,the use of adjunctive therapies,and patient follow-up patterns.RESULTS A total of 180 ophthalmologists responded to the survey.Most practitioners(89%)felt that the ROPLAS test was sufficient during pre-operative evaluation before any subspecialty surgery was advised.The most common surgical techniques employed were lacrimal drainage procedures(Dacryocystorhinostomy)(63.3%),eyelid malposition repair(36.9%),and ptosis repair(58.7%).Post-operatively,47.7%of respondents emphasized that at least a 4-week gap should be maintained after lacrimal drainage procedures and eyelid surgeries.Sixty-seven percent of ophthalmologists felt that topical anaesthetic procedures should be preferred while performing ocular surgeries in thyroid eye disease patients.CONCLUSION Approximately 50%of ophthalmologists handle prevalent oculoplastic issues themselves,seeking the expertise of an oculoplastic surgeon under particular conditions.Many ophthalmologists still favor using ROPLAS as a preliminary screening method before proceeding with cataract surgery.Eyelid conditions and thyroid eye disease are not as commonly addressed before subspecialty procedures compared to issues like nasolacrimal duct obstruction and periocular infections. 展开更多
关键词 Oculoplasty Ophthalmic plastic surgery Nasolacrimal duct obstruction Practice patterns SURVEY
下载PDF
Synthesis and characterization of novel star-shaped pyridine cored compounds with alternating carbazole and triphenylamine moieties 被引量:2
3
作者 Ji Bing Yuan Zhi Guo Zhang +1 位作者 Louis Man Leung Ke Li Zhang 《Chinese Chemical Letters》 SCIE CAS CSCD 2008年第6期647-650,共4页
Amorphous 2,4,6-trissubstituted pyridines containing three peripheral carbazole or two triphenylamine and one carbazole moieties, respectively, have been synthesized and characterized. The properties of the compounds ... Amorphous 2,4,6-trissubstituted pyridines containing three peripheral carbazole or two triphenylamine and one carbazole moieties, respectively, have been synthesized and characterized. The properties of the compounds are investigated by UV-vis absorption, photoluminescence spectroscopy, thermal analysis as well as cyclic voltammetry. The results show that the compounds have high thermal stability, emit blue light. Also, the compounds possess the HOMO and LUMO energy levels comparable to those of NPB. The effects of different substituents on the electronic properties of the materials have been discussed. 展开更多
关键词 star-shaped CARBAZOLE Tdphenylamine PYRIDINE
下载PDF
SYNTHESIS OF HETEROARM STAR-SHAPED POLYMER BY THE USE OF POLYFUNCTIONAL CHAIN-TRANSFER AGENT via CONVENTIONAL FREE RADICAL POLYMERIZATION 被引量:2
4
作者 石艳 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2008年第3期321-329,共9页
Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methac... Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methacrylate was carried out in the presence of a polyfunctional chain transfer agent,pentaerythritol tetrakis(3-mercaptopropinate).At appropriate monomer conversions,two-arm PMMA having two residual thiol groups at the chain center or three-arm PMMA having one residual thiol group at the core were o... 展开更多
关键词 Heteroarm star-shaped polymer Conventional free radical polymerization Polyfunctional chain-transfer agent
下载PDF
Fiber-based joint time and frequency dissemination via star-shaped commercial telecommunication network 被引量:1
5
作者 袁一博 王波 王力军 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第8期96-101,共6页
A fiber-based, star-shaped joint time and frequency dissemination scheme is demonstrated. By working in cooperation with the existing commercial telecommunication network. Our scheme enables the frequency, time, and d... A fiber-based, star-shaped joint time and frequency dissemination scheme is demonstrated. By working in cooperation with the existing commercial telecommunication network. Our scheme enables the frequency, time, and digital data networks to be integrated together and could represent an ideal option of interconnection among scientific institutions.The compensation functions of the time and frequency transfer scheme are set at the client nodes. The complexity of the central node is thus reduced, and future expansion by the addition of further branches will be accomplished more easily.During a performance test in which the ambient temperature fluctuation is 30℃/day, timing signal dissemination stability is achieved to be approximately ±50 ps along 25-km-long fiber spools. After calibration, a timing signal synchronization accuracy of 100 ps is also realized. The proposed scheme offers an option of the construction of large-scale fiber-based frequency and time transfer networks. 展开更多
关键词 time synchronization telecommunication network frequency transfer star-shaped network
下载PDF
SYNTHESIS,CHARACTERIZATION AND NANOPARTICLE FORMATION OF STAR-SHAPED POLY(L-LACTIDE)WITH SIX ARMS 被引量:1
6
作者 董常明 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2008年第2期161-169,共9页
Well-defined star-shaped poly(L-lactide)with six arms(sPLLA)was synthesized via the ring-opening polymerization of L-lactide using dipentaerythritol as initiator and stannous octoate as catalyst in bulk at 125~C.The e... Well-defined star-shaped poly(L-lactide)with six arms(sPLLA)was synthesized via the ring-opening polymerization of L-lactide using dipentaerythritol as initiator and stannous octoate as catalyst in bulk at 125~C.The effects of molar ratios of both monomer to initiator and monomer to catalyst on the molecular weights of as-synthesized sPLLA polymers were in detail investigated.The molecular weights of sPLLA polymers linearly increased with the molar ratio of monomer to initiator,and the molecular weight dist... 展开更多
关键词 star-shaped poly(L-Lactide) Ring-opening polymerization Nanoparticles Drug delivery.
下载PDF
pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages for enhanced MDR reversal and chemotherapy 被引量:1
7
作者 Yong Xu Shi Wang +4 位作者 Longshun Yang Yuhang Dong Yafang Zhang Guoqing Yan Rupei Tang 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2021年第3期363-373,共11页
TPGS approved by FDA can be used as a P-gp inhibitor to effectively reverse multi-drug resistance(MDR)and as an anticancer agent for synergistic antitumor effects.However,the comparatively high critical micelle concen... TPGS approved by FDA can be used as a P-gp inhibitor to effectively reverse multi-drug resistance(MDR)and as an anticancer agent for synergistic antitumor effects.However,the comparatively high critical micelle concentration(CMC),low drug loading(DL)and poor tumor target limit its further clinical application.To overcome these drawbacks,the pH-sensitive star-shaped TPGS copolymers were successfully constructed via using pentaerythritol as the initial materials,ortho esters as the pH-triggered linkages and TPGS active-ester as the terminated MDR material.The amphiphilic star-shaped TPGS copolymers could self-assemble into free and doxorubicin(DOX)-loaded micelles at neutral aqueous solutions.The micelles exhibited the lower CMC(8.2×10^(−5) mg/ml),higher DL(10.8%)and long-term storage and circulation stability,and showed enhanced cellular uptake,apoptosis,cytotoxicity,and growth inhibition for in vitro MCF-7/ADR and/or MCF-7/ADR multicellular spheroids and in vivo MCF-7/ADR tumors via efficiently targeted drug release at tumoral intracellular pH(5.0),MDR reversal of TPGS,and synergistic effect of DOX and TPGS.Therefore,the pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages are potentially useful to clinically transform for enhanced MDR cancer treatment. 展开更多
关键词 TPGS Ortho esters star-shaped copolymers MDR reversal
下载PDF
PREPARATION AND CHARACTERIZATION OF INCLUSION COMPLEXES OF TWO-ARM LINEAR AND FOUR-ARM STAR-SHAPED POLY(ε-CAPROLACTONE)S WITHα-CYCLODEXTRIN 被引量:1
8
作者 Lu Wang Jing-liang Wang 董常明 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2006年第3期245-252,共8页
Both four-ann star-shaped poly(ε-caprolactone) (4sPCL) and two-ann linear PCL (2LPCL) were synthesized and their inclusion complexation with α-cyclodextrin (α-CD) were studied. The inclusion complexes (ICs... Both four-ann star-shaped poly(ε-caprolactone) (4sPCL) and two-ann linear PCL (2LPCL) were synthesized and their inclusion complexation with α-cyclodextrin (α-CD) were studied. The inclusion complexes (ICs) formed between the PCL polymers and α-CD were characterized by ^1H-NMR, DSC, TGA, WAXD, and FT-1R, respectively. Both branch ann number and molecular weight of the PCL polymers have apparent effect on the stoichiometry (CL:CD, mol:mol) of these ICs. All these analytical results indicate that the branch arms of the PCL polymers are incorporated into the hydrophobic α-CD cavities and their original crystalline properties are completely suppressed. Moreover, the inclusion complexation between two-ann linear or four-ann star-shaped PCL polymers and α-CD not only enhances the thermal stability of the guest PCL polymers but also improves that of α-CD. 展开更多
关键词 Inclusion complexes Linear poly(ε-caprolactone) star-shaped poly(ε-caprolactone) Thermal stability.
下载PDF
FIXED POINTS OF NONEXPANSIVE MAPPINGS ON STAR-SHAPED SUBSETS OF A CONVEX METRIC SPACE
9
作者 邓磊 丁协平 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1992年第2期135-141,共7页
In this paper, we give some characteristic properties of star-shaped sets which include a subset of a convex metric space. Using the characteristic properties, we discuss the existence problems of fixed points of none... In this paper, we give some characteristic properties of star-shaped sets which include a subset of a convex metric space. Using the characteristic properties, we discuss the existence problems of fixed points of nonexpansive type mappings on star-shaped subsets of convex metric spaces, which generalize the recent results obtained by Ding Xie-ping, Beg and Azam. Finally, we give an example which shows that our generalizations are essential. 展开更多
关键词 star-shaped set star centre normal structure of a star-shaped set
下载PDF
Star-shaped Differentiable Functions and Star-shaped Differentials
10
作者 PAN SHAO-RONG ZHANG HONG-WEI ZHANG LI-WEI 《Communications in Mathematical Research》 CSCD 2010年第1期41-52,共12页
Based on the isomorphism between the space of star-shaped sets and the space of continuous positively homogeneous real-valued functions, the star-shaped differential of a directionally differentiable function is defin... Based on the isomorphism between the space of star-shaped sets and the space of continuous positively homogeneous real-valued functions, the star-shaped differential of a directionally differentiable function is defined. Formulas for star-shaped differential of a pointwise maximum and a pointwise minimum of a finite number of directionally differentiable functions, and a composite of two directionaUy differentiable functions are derived. Furthermore, the mean-value theorem for a directionaUy differentiable function is demonstrated. 展开更多
关键词 The space of star-shaped sets gauge function isometrical isomorphism directionally differentiable function star-shaped differential mean-value theorem
下载PDF
Corrigendum to“Migration pattern of a population of Barn Swallows(Hirundo rustica)breeding in East Asian tropical region”[Avian Res.15(2024)100192] 被引量:1
11
作者 Li Tian Yu Liu +3 位作者 Yang Wu Zimei Feng Dan Hu Zhengwang Zhang 《Avian Research》 SCIE CSCD 2024年第3期402-402,共1页
The authors regret that the caption of Fig.4 should be replaced as below.
关键词 BREEDING pattern TROPICAL
下载PDF
Clinical manifestation,lifestyle,and treatment patterns of chronic erosive gastritis:A multicenter real-world study in China 被引量:2
12
作者 Ying-Yun Yang Ke-Min Li +18 位作者 Gui-Fang Xu Cheng-Dang Wang Hua Xiong Xiao-Zhong Wang Chun-Hui Wang Bing-Yong Zhang Hai-Xing Jiang Jing Sun Yan Xu Li-Juan Zhang Hao-Xuan Zheng Xiang-Bin Xing Liang-Jing Wang Xiu-Li Zuo Shi-Gang Ding Rong Lin Chun-Xiao Chen Xing-Wei Wang Jing-Nan Li 《World Journal of Gastroenterology》 SCIE CAS 2024年第9期1108-1120,共13页
BACKGROUND Although chronic erosive gastritis(CEG)is common,its clinical characteristics have not been fully elucidated.The lack of consensus regarding its treatment has resulted in varied treatment regimens.AIM To ex... BACKGROUND Although chronic erosive gastritis(CEG)is common,its clinical characteristics have not been fully elucidated.The lack of consensus regarding its treatment has resulted in varied treatment regimens.AIM To explore the clinical characteristics,treatment patterns,and short-term outcomes in CEG patients in China.METHODS We recruited patients with chronic non-atrophic or mild-to-moderate atrophic gastritis with erosion based on endoscopy and pathology.Patients and treating physicians completed a questionnaire regarding history,endoscopic findings,and treatment plans as well as a follow-up questionnaire to investigate changes in symptoms after 4 wk of treatment.RESULTS Three thousand five hundred sixty-three patients from 42 centers across 24 cities in China were included.Epigastric pain(68.0%),abdominal distension(62.6%),and postprandial fullness(47.5%)were the most common presenting symptoms.Gastritis was classified as chronic non-atrophic in 69.9%of patients.Among those with erosive lesions,72.1%of patients had lesions in the antrum,51.0%had multiple lesions,and 67.3%had superficial flat lesions.In patients with epigastric pain,the combination of a mucosal protective agent(MPA)and proton pump inhibitor was more effective.For those with postprandial fullness,acid regurgitation,early satiety,or nausea,a MPA appeared more promising.CONCLUSION CEG is a multifactorial disease which is common in Asian patients and has non-specific symptoms.Gastroscopy may play a major role in its detection and diagnosis.Treatment should be individualized based on symptom profile. 展开更多
关键词 Chronic erosive gastritis SYMPTOM Endoscopic findings Treatment pattern Real-world
下载PDF
Synthesis and Physicochemical Characterization of Biodegradable Star-Shaped Poly Lactide-Co-Glycolide-<i>β</i>-Cyclodextrin Copolymer Nanoparticles Containing Albumin
13
作者 Soodabeh Davaran Akbar Rezaei +4 位作者 Somayeh Alimohammadi Amir Ahmad Khandaghi Kazem Nejati-Koshki Hamid Tayefi Nasrabadi Abolfazl Akbarzadeh 《Advances in Nanoparticles》 2014年第1期14-22,共9页
The purposes of this research were to synthesize and characterize star-shaped poly lactide-co-glycolide-β-cyclo-dextrin (PLGA-β-CD) copolymer by reacting L-lactide, glycolide and β-cyclodextrin in the presence of s... The purposes of this research were to synthesize and characterize star-shaped poly lactide-co-glycolide-β-cyclo-dextrin (PLGA-β-CD) copolymer by reacting L-lactide, glycolide and β-cyclodextrin in the presence of stannous octoate as a catalyst. The structure of PLGA-β-CD copolymer was confirmed with 1H-NMR, 13C-NMR and FT-IR spectra. Albumin as a model peptide drug was encapsulated within nanoparticles made of PLGA-β-CD with a modified double emulsion method. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) photomicrographs showed that the nanoparticles have the mean diameter within the range of 80 - 210 nm. Also they were almost spherical in shape. Effects of the experimental parameters, such as copolymer composition, copolymer concentration, and reaction temperature, on particular size and encapsulation efficiency were investigated. 展开更多
关键词 ALBUMIN star-shaped Poly Lactide-Co-Glycolide β-Cyclodextrin Nanoparticles
下载PDF
Plant-based dietary patterns and risk of esophageal cancer:A prospective cohort study spanning 17 years 被引量:1
14
作者 Xiaorui Zhang Feifan He +6 位作者 Jiayue Li Ru Chen Xinqing Li Li Li Fen Liu Shaoming Wang Wenqiang Wei 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2024年第1期36-45,共10页
Objective: Plant-based diets have multiple health benefits for cancers;however, little is known about the association between plant-based dietary patterns and esophageal cancer(EC).This study presents an investigation... Objective: Plant-based diets have multiple health benefits for cancers;however, little is known about the association between plant-based dietary patterns and esophageal cancer(EC).This study presents an investigation of the prospective associations among three predefined indices of plant-based dietary patterns and the risk of EC.Methods: We performed endoscopic screening for 15,709 participants aged 40-69 years from two high-risk areas of China from January 2005 to December 2009 and followed the cohort until December 31, 2022. The overall plant-based diet index(PDI), healthful plant-based diet index(h PDI), and unhealthful plant-based diet index(u PDI), were calculated using survey responses to assess dietary patterns. We applied Cox proportional hazard regression to estimate the multivariable hazard ratios(HRs) and 95% confidence intervals(95% CIs) of EC across 3plant-based diet indices and further stratified the analysis by subgroups.Results: The final study sample included 15,184 participants in the cohort. During a follow-up of 219,365person-years, 176 patients with EC were identified. When the highest quartile was compared with the lowest quartile, the pooled multivariable-adjusted HR of EC was 0.50(95% CI, 0.32-0.77) for h PDI. In addition, the HR per 10-point increase in the h PDI score was 0.42(95% CI, 0.27-0.66) for ECs. Conversely, u PDI was positively associated with the risk of EC, and the HR was 1.80(95% CI, 1.16-2.82). The HR per 10-point increase in the u PDI score was 1.90(95% CI, 1.26-2.88) for ECs. The associations between these scores and the risk of EC were consistent in most subgroups. These results remained robust in sensitivity analyses.Conclusions: A healthy plant-based dietary pattern was associated with a reduced risk of EC. Emphasizing the healthiness and quality of plant-based diets may be important for preventing the development of EC. 展开更多
关键词 Esophageal cancer DIET dietary pattern EPIDEMIOLOGY NUTRITION prospective cohort study
下载PDF
Surface Patterning of Metal Zinc Electrode with an In‑Region Zincophilic Interface for High‑Rate and Long‑Cycle‑Life Zinc Metal Anode 被引量:2
15
作者 Tian Wang Qiao Xi +8 位作者 Kai Yao Yuhang Liu Hao Fu Venkata Siva Kavarthapu Jun Kyu Lee Shaocong Tang Dina Fattakhova‑Rohlfing Wei Ai Jae Su Yu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第6期192-209,共18页
The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially im... The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries(ZMBs).Herein,we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium(Zn-In)interface in the microchannels.The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities.Meanwhile,electron aggregation accelerates the dissolution of non-(002)plane Zn atoms on the array surface,thereby directing the subsequent homoepitaxial Zn deposition on the array surface.Consequently,the planar dendrite-free Zn deposition and long-term cycling stability are achieved(5,050 h at 10.0 mA cm^(−2) and 27,000 cycles at 20.0 mA cm^(−2)).Furthermore,a Zn/I_(2) full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C,demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs. 展开更多
关键词 Zn metal anode Surface patterning Directional Zn deposition Aqueous Zn-I_(2)batteries
下载PDF
Extreme Meteorological Drought Events over China(1951-2022):Migration Patterns,Diversity of Temperature Extremes,and Decadal Variations 被引量:1
16
作者 Zhenchen LIU Wen ZHOU Xin WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第12期2313-2336,共24页
Recently,extreme meteorological droughts have affected China,causing terrible socioeconomic impacts.Despite previous research on the spatiotemporal characteristics and mechanisms of drought,two crucial issues remain s... Recently,extreme meteorological droughts have affected China,causing terrible socioeconomic impacts.Despite previous research on the spatiotemporal characteristics and mechanisms of drought,two crucial issues remain seldom explored.First,an event-oriented drought chronology with detailed spatiotemporal evolutions is urgently required.Second,the complex migration patterns and diversity of synchronous temperature extremes need to be quantitatively investigated.Accordingly,the main achievements of our investigation are as follows.We produced an event-oriented set of extreme meteorological droughts over China through the application of a newly developed 3D DBSCAN-based detection method(deposited on https://doi.org/10.25452/figshare.plus.25512334),which was verified with a historical atlas and monographs on a case-by-case basis.In addition,distinctive migration patterns(i.e.,stationary/propagation types)are identified and ranked,considering the differences in latitudinal zones and coastal/inland locations.We also analyze the diversity of synchronous temperature extremes(e.g.,hotness and coldness).Notably,an increasing trend in hot droughts occurred over China since the late 1990s,predominantly appearing to the south of 30°N and north of 40°N.All drought events and synchronous temperature extremes are ranked using a comprehensive magnitude index,with the 2022 summer-autumn Yangtze River hot drought being the hottest.Furthermore,Liang-Kleeman information flow-based causality analysis emphasizes key areas where the PDO and AMO influenced decadal variations in coverages of droughts and temperature extremes.We believe that the achievements in this study may offer new insights into sequential mechanism exploration and prediction-related issues. 展开更多
关键词 3D DBSCAN event-oriented drought set migration pattern compound climate extremes
下载PDF
Acute effect of foot strike patterns on in vivo tibiotalar and subtalar joint kinematics during barefoot running 被引量:1
17
作者 Dongqiang Ye Lu Li +4 位作者 Shen Zhang Songlin Xiao Xiaole Sun Shaobai Wang Weijie Fu 《Journal of Sport and Health Science》 SCIE CSCD 2024年第1期108-117,共10页
Background:Foot kinematics,such as excessive eversion and malalignment of the hindfoot,are believed to be associated with running-related injuries.The maj ority of studies to date show that different foot strike patte... Background:Foot kinematics,such as excessive eversion and malalignment of the hindfoot,are believed to be associated with running-related injuries.The maj ority of studies to date show that different foot strike patterns influence these specific foot and ankle kinematics.However,technical deficiencies in traditional motion capture approaches limit knowledge of in vivo joint kinematics with respect to rearfoot and forefoot strike patterns(RFS and FFS,respectively).This study uses a high-speed dual fluoroscopic imaging system(DFIS)to determine the effects of different foot strike patterns on 3D in vivo tibiotalar and subtalar joints kinematics.Methods:Fifteen healthy male recreational runners underwent foot computed tomography scanning for the construction of 3-dimensional models.A high-speed DFIS(100 Hz)was used to collect 6 degrees of freedom kinematics for participants’tibiotalar and subtalar joints when they adopted RFS and FFS in barefoot condition.Results:Compared with RFS,FFS exhibited greater internal rotation at 0%-20%of the stance phase in the tibiotalar joint.The peak internal rotation angle of the tibiotalar joint under FFS was greater than under RFS(p<0.001,Cohen’s d=0.92).RFS showed more dorsiflexion at 0%-20%of the stance phase in the tibiotalar joint than FFS.RFS also presented a larger anterior translation(p<0.001,Cohen’s d=1.28)in the subtalar joint at i nitial contact than FFS.Conclusion:Running with acute barefoot FFS increases the internal rotation of the tibiotalar joint in the early stance.The use of high-speed DFIS to quantify the movement of the tibiotalar and subtalar joint was critical to revealing the effects of RF S and FFS during running. 展开更多
关键词 Foot strike patterns High-speed dual fluoroscopic imaging system In vivo kinematics Running
下载PDF
Surface crack evolution patterns in freeze-thaw damage of fissured rock bodies 被引量:1
18
作者 KANG Zhiqiang WANG Zhilei +2 位作者 SHAO Luhang FENG Jiangjiang YAO Xulong 《Journal of Mountain Science》 SCIE CSCD 2024年第9期3094-3107,共14页
To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to char... To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to characterize the changes in the physical and mechanical properties of fissured sandstone caused by freeze‒thaw cycles.The crack evolution and crack change process on the surface of the fissured sandstone were recorded and analysed in detail via digital image technology(DIC).Numerical simulation was used to reveal the expansion process and damage mode of fine-scale cracks under the action of freeze‒thaw cycles,and the simulation results were compared and analysed with the experimental data to verify the reliability of the numerical model.The results show that the mass loss,porosity,peak stress and elastic modulus all increase with increasing number of freeze‒thaw cycles.With an increase in the number of freeze‒thaw cycles,a substantial change in displacement occurs around the prefabricated cracks,and a stress concentration appears at the crack tip.As new cracks continue to sprout at the tips of the prefabricated cracks until the microcracks gradually penetrate into the main cracks,the displacement cloud becomes obviously discontinuous,and the contours of the displacement field in the crack fracture damage area simply intersect with the prefabricated cracks to form an obvious fracture.The damage patterns of the fractured sandstone after freeze‒thaw cycles clearly differ,forming a symmetrical"L"-shaped damage pattern at zero freeze‒thaw cycles,a symmetrical"V"-shaped damage pattern at 10 freeze‒thaw cycles,and a"V"-shaped damage pattern at 20 freeze‒thaw cycles.After 20 freeze‒thaw cycles,a"V"-shaped destruction pattern and"L"-shaped destruction pattern are formed;after 30 freeze‒thaw cycles,an"N"-shaped destruction pattern is formed.This shows that the failure mode of fractured sandstone gradually becomes more complicated with an increasing number of freeze‒thaw cycles.The effects of freeze‒thaw cycles on the direction and rate of crack propagation are revealed through a temperature‒load coupled model,which provides an important reference for an in-depth understanding of the freeze‒thaw failure mechanisms of fractured rock masses. 展开更多
关键词 Freeze‒thaw cycles Fissured sandstone Particle flow software Rock mechanics Crack extension pattern DIC technique
下载PDF
Nondoped-type White Organic Light-Emitting Diode Using Star-Shaped Hexafluorenylbenzene as an Energy Transfer Layer
19
作者 Jun-sheng Yu Tao Ma +2 位作者 Shuang-ling Lou Ya-dong Jiang Qing Zhang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2008年第5期500-504,共5页
White organic light-emitting diodes (WOLEDs) with a structure of indium-tin-oxide (ITO)/N,N'-bis- (1-naphthyl)-N,N'-diphenyl- (1, 1'-biphenyl)-4,4'-diamine (NPB)/1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluor... White organic light-emitting diodes (WOLEDs) with a structure of indium-tin-oxide (ITO)/N,N'-bis- (1-naphthyl)-N,N'-diphenyl- (1, 1'-biphenyl)-4,4'-diamine (NPB)/1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2- yl)benzene (HKEthFLYPh)/5,6,11,12-tetraphenylnaphtacene (rubrene)/tris(8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag were fabricated by vacuum deposition method, in which a novel star-shaped hexafluorenyl- benzene HKEthFLYPh was used as an energy transfer layer, and an ultrathin layer of rubrene was inserted between HKEthFLYPh and Alq3 layers as a yellow light-emitting layer instead of using a time-consuming doping process. A fairly pure WOLED with Commissions Internationale De L'Eclairage (CIE) coordinates of (0.32, 0.33) was obtained when the thickness of rubrene was 0.3 nm, and the spectrum was insensitive to the applied voltage. The device yielded a maximum luminance of 4816 cd/m2 at 18 V. 展开更多
关键词 White organic light-emitting diode diethyl-9H-fluoren-2-yl)benzene Energy transfer star-shaped hexafluorenylbenzene 1 2 3 4 5 6-hexakis(9 9- Ultrathin layer
下载PDF
Venous Doppler flow patterns,venous congestion,heart disease and renal dysfunction:A complex liaison 被引量:1
20
作者 Alessio Di Maria Rossella Siligato +1 位作者 Marta Bondanelli Fabio Fabbian 《World Journal of Cardiology》 2024年第1期5-9,共5页
The World Journal of Cardiology published an article written by Kuwahara et al that we take the pleasure to comment on.We focused our attention on venous congestion.In intensive care settings,it is now widely accepted... The World Journal of Cardiology published an article written by Kuwahara et al that we take the pleasure to comment on.We focused our attention on venous congestion.In intensive care settings,it is now widely accepted that venous congestion is an important clinical feature worthy of investigation.Evaluating venous Doppler profile abnormalities at multiple sites could suggest adequate treatment and monitor its efficacy.Renal dysfunction could trigger or worsen fluid overload in heart disease,and cardio-renal syndrome is a well-characterized spectrum of disorders describing the complex interactions between heart and kidney diseases.Fluid overload and venous congestion,including renal venous hypertension,are major determinants of acute and chronic renal dysfunction arising in heart disease.Organ congestion from venous hypertension could be involved in the development of organ injury in several clinical situations,such as critical diseases,congestive heart failure,and chronic kidney disease.Ultrasonography and abnormal Doppler flow patterns diagnose clinically significant systemic venous congestion.Cardiologists and nephrologists might use this valuable,noninvasive,bedside diagnostic tool to establish fluid status and guide clinical choices. 展开更多
关键词 Cardio-renal syndrome Fluid overload Venous congestion Acute kidney injury ULTRASOUND Doppler flow patterns
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部