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Dynamic response mechanism and precursor characteristics of gneiss rockburst under different initial burial depths 被引量:1
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作者 LIU Dongqiao SUN Jie +4 位作者 MENG Wen HE Manchao ZHANG Chongyuan LI Ran CAO Binghao 《Journal of Mountain Science》 SCIE CSCD 2024年第3期1004-1018,共15页
To investigate the influence mechanism of geostress on rockburst characteristics,three groups of gneiss rockburst experiments were conducted under different initial geostress conditions.A high-speed photography system... To investigate the influence mechanism of geostress on rockburst characteristics,three groups of gneiss rockburst experiments were conducted under different initial geostress conditions.A high-speed photography system and acoustic emission(AE)monitoring system were used to monitor the entire rockburst process in real time.The experimental results show that when the initial burial depth increases from 928 m to 1320 m,the proportion of large fracture scale in rockburst increases by 154.54%,and the AE energy increases by 565.63%,reflecting that the degree and severity of rockburst increase with the increase of burial depth.And then,two mechanisms are proposed to explain this effect,including(i)the increase of initial geostress improves the energy storage capacity of gneiss,and then,the excess energy which can be converted into kinetic energy of debris ejection increases,consequently,a more pronounced violent ejection phenomenon is observed at rockburst;(ii)the increase of initial geostress causes more sufficient plate cracks of gneiss after unloading ofσh,which provides a basis for more severe ejection of rockburst.What’s more,a precursor with clear physical meaning for rockburst is proposed under the framework of dynamic response process of crack evolution.Finally,potential value in long term rockburst warning of the precursor obtained in this study is shown via the comparison of conventional precursor. 展开更多
关键词 Traffic Engineering Gneiss Rockburst Crack propagation Excess energy Precursor characteristic
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Excess non-COVID-19-related mortality among inflammatory bowel disease decedents during the COVID-19 pandemic 被引量:1
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作者 Sarah Rotondo-Trivette Xin-Yuan He +9 位作者 Jamil S Samaan Fan Lv Emily Truong Michaela Juels Anthony Nguyen Xu Gao Jian Zu Yee Hui Yeo Fan-Pu Ji Gil Y Melmed 《World Journal of Gastroenterology》 SCIE CAS 2024年第20期2677-2688,共12页
BACKGROUND The coronavirus disease 2019(COVID-19)pandemic disrupted healthcare in the United States.AIM To investigate COVID-19-related and non-COVID-19-related death and characteristics associated with excess death a... BACKGROUND The coronavirus disease 2019(COVID-19)pandemic disrupted healthcare in the United States.AIM To investigate COVID-19-related and non-COVID-19-related death and characteristics associated with excess death among inflammatory bowel disease(IBD)decedents.METHODS We performed a register-based study using data from the National Vital Statistics System,which reports death data from over 99%of the United States population,from January 1,2006 through December 31,2021.IBD-related deaths among adults 25 years and older were stratified by age,sex,race/ethnicity,place of death,and primary cause of death.Predicted and actual age-standardized mortality rates(ASMRs)per 100000 persons were compared.RESULTS 49782 IBD-related deaths occurred during the study period.Non-COVID-19-related deaths increased by 13.14%in 2020 and 18.12%in 2021[2020 ASMR:1.55 actual vs 1.37 predicted,95%confidence interval(CI):1.26-1.49;2021 ASMR:1.63 actual vs 1.38 predicted,95%CI:1.26-1.49].In 2020,non-COVID-19-related mortality increased by 17.65%in ulcerative colitis(UC)patients between the ages of 25 and 65 and 36.36%in non-Hispanic black(NHB)Crohn’s disease(CD)patients.During the pandemic,deaths at home or on arrival and at medical facilities as well as deaths due to neoplasms also increased.CONCLUSION IBD patients suffered excess non-COVID-19-related death during the pandemic.Excess death was associated with younger age among UC patients,and with NHB race among CD patients.Increased death at home or on arrival and due to neoplasms suggests that delayed presentation and difficulty accessing healthcare may have led to increased IBD mortality. 展开更多
关键词 Inflammatory bowel disease Ulcerative colitis Crohn’s disease COVID-19 Excess death Race SEX DISPARITIES
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Excess pore pressure behavior and evolution in deep coalbed methane reservoirs
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作者 Changqing Liu Zhaobiao Yang +3 位作者 Yong Qin Xia Yan Yunhai Wang Zhe Wang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第6期763-781,共19页
Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some prod... Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some production data analysis techniques have been adapted from conventional oil and gas wells,there remains a gap in the understanding of pore pressure generation and evolution,particularly in wells subjected to large-scale hydraulic fracturing.To address this gap,a novel technique called excess pore pressure analysis(EPPA)has been introduced to the coal seam gas industry for the first time to our knowledge,which employs dual-phase flow principles based on consolidation theory.This technique focuses on the generation and dissipation for excess pore-water pressure(EPWP)and excess pore-gas pressure(EPGP)in stimulated deep coal reservoirs.Equations have been developed respectively and numerical solutions have been provided using the finite element method(FEM).Application of this model to a representative field example reveals that excess pore pressure arises from rapid loading,with overburden weight transferred under undrained condition due to intense hydraulic fracturing,which significantly redistributes the weight-bearing role from the solid coal structure to the injected fluid and liberated gas within artificial pores over a brief timespan.Furthermore,field application indicates that the dissipation of EPWP and EPGP can be actually considered as the process of well production,where methane and water are extracted from deep coalbed methane wells,leading to consolidation for the artificial reservoirs.Moreover,history matching results demonstrate that the excess-pressure model established in this study provides a better explanation for the declining trends observed in both gas and water production curves,compared to conventional practices in coalbed methane reservoir engineering and petroleum engineering.This research not only enhances the understanding of DCBM reservoir behavior but also offers insights applicable to production analysis in other unconventional resources reliant on hydraulic fracturing. 展开更多
关键词 Deep coalbed methane CONSOLIDATION Excess pore-water pressure Excess pore-gas pressure Production data analysis
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Density of excess modes below the first phonon mode in four-dimensional glasses
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作者 王利近 胥鼎 张世允 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期483-489,共7页
Glasses are known to possess low-frequency excess modes beyond the Debye prediction.For decades,it has been assumed that evolution of low-frequency density of excess modes D(ω) with frequency ω follows a power-law s... Glasses are known to possess low-frequency excess modes beyond the Debye prediction.For decades,it has been assumed that evolution of low-frequency density of excess modes D(ω) with frequency ω follows a power-law scaling:D(ω)~ω~γ.However,it remains debated on the value of γ at low frequencies below the first phonon-like mode in finitesize glasses.Early simulation studies reported γ=4 at low frequencies in two-(2D),three-(3D),and four-dimensional(4D)glasses,whereas recent observations in 2D and 3D glasses suggested γ=3.5 in a lower-frequency regime.It is uncertain whether the low-frequency scaling of D(ω)~ω^(3.5) could be generalized to 4D glasses.Here,we conduct numerical simulation studies of excess modes at frequencies below the first phonon-like mode in 4D model glasses.It is found that the system size dependence of D(ω) below the first phonon-like mode varies with spatial dimensions:D(ω) increases in2D glasses but decreases in 3D and 4D glasses as the system size increases.Furthermore,we demonstrate that the ω^(3.5)scaling,rather than the ω~4 scaling,works in the lowest-frequency regime accessed in 4D glasses,regardless of interaction potentials and system sizes examined.Therefore,our findings in 4D glasses,combined with previous results in 2D and 3D glasses,suggest a common low-frequency scaling of D(ω)~ ω^3.5) below the first phonon-like mode across different spatial dimensions,which would inspire further theoretical studies. 展开更多
关键词 vibrational density of states excess modes four-dimensional glasses SCALING computer simulation
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Effect of Aggregate Gradation on the Properties of 3D Printed Recycled Coarse Aggregate Concrete
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作者 DING Yahong TONG Jiaqi +3 位作者 ZHANG Meixiang GUO Shuqi ZHANG Yaqi ZHAO Yu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第6期1541-1554,共14页
A simplex centroid design method was employed to design the gradation of recycled coarse aggregate.The bulk density was measured while the specific surface area and average excess paste thickness were calculated with ... A simplex centroid design method was employed to design the gradation of recycled coarse aggregate.The bulk density was measured while the specific surface area and average excess paste thickness were calculated with different gradations.The fluidity,dynamic yield stress,static yield stress,printed width,printed inclination,compressive strength and ultrasonic wave velocity of 3D printed recycled aggregate concrete(3DPRAC)were further studied.The experimental results demonstrate that,with the increase of small-sized aggregate(4.75-7 mm)content,the bulk density initially increases and then decreases,and the specific surface area gradually increases.The average excess paste thickness fluctuates with both bulk density and specific surface area.The workability of 3DPRAC is closely related to the average excess paste thickness.With an increase in average paste thickness,there is a gradual decrease in dynamic yield stress,static yield stress and printed inclination,accompanied by an increase in fluidity and printed width.The mechanical performance of 3DPRAC closely correlates with the bulk density.With an increase in the bulk density,there is an increase in the ultrasonic wave velocity,accompanied by a slight increase in the compressive strength and a significant decrease in the anisotropic coefficient.Furthermore,an index for buildability failure of 3DPRAC based on the average excess paste thickness is proposed. 展开更多
关键词 3D printed recycled coarse aggregate concrete aggregate gradation excess paste WORKABILITY mechanical performance
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Oxygen and hydrogen isotope characteristics of different water bodies in the Burqin River Basin of the Altay Mountains,China
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作者 XIE Yida WANG Feiteng LIU Shuangshuang 《Journal of Arid Land》 SCIE CSCD 2024年第10期1365-1379,共15页
Characterization of the spatial and temporal variability of stable isotopes in surface water is essential for interpreting hydrological processes.In this study,we collected the water samples of river water,groundwater... Characterization of the spatial and temporal variability of stable isotopes in surface water is essential for interpreting hydrological processes.In this study,we collected the water samples of river water,groundwater,and reservoir water in the Burqin River Basin of the Altay Mountains,China in 2021,and characterized the oxygen and hydrogen isotope variations in different water bodies via instrumental analytics and modeling.Results showed significant seasonal variations in stable isotope ratios of oxygen and hydrogen(δ18O andδ2H,respectively)and significant differences inδ18O andδ2H among different water bodies.Higherδ18O andδ2H values were mainly found in river water,while groundwater and reservoir water had lower isotope ratios.River water and groundwater showed differentδ18O-δ2H relationships with the local meteoric water line,implying that river water and groundwater are controlled by evaporative enrichment and multi-source recharge processes.The evaporative enrichment experienced by reservoir water was less significant and largely influenced by topography,recharge sources,local moisture cycling,and anthropogenic factors.Higher deuterium excess(d-excess)value of 14.34‰for river water probably represented the isotopic signature of combined contributions from direct precipitation,snow and glacial meltwater,and groundwater recharge.The average annual d-excess values of groundwater(10.60‰)and reservoir water(11.49‰)were similar to the value of global precipitation(10.00‰).The findings contribute to understanding the hydroclimatic information reflected in the month-by-month variations in stable isotopes in different water bodies and provide a reference for the study of hydrological processes and climate change in the Altay Mountains,China. 展开更多
关键词 water bodies stable isotopes deuterium excess(d-excess) Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model Burqin River Basin Altay Mountains
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Ultrasound unveiling:Decoding venous congestion in heart failure for precision management of fluid status
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作者 Davide Ramoni Federico Carbone Fabrizio Montecucco 《World Journal of Cardiology》 2024年第6期306-309,共4页
This editorial discusses the manuscript by Di Maria et al,published in the recent issue of the World Journal of Cardiology.We here focus on the still elusive pathophysiological mechanisms underlying cardio-renal syndr... This editorial discusses the manuscript by Di Maria et al,published in the recent issue of the World Journal of Cardiology.We here focus on the still elusive pathophysiological mechanisms underlying cardio-renal syndrome(CRS),despite its high prevalence and the substantial worsening of both kidney function and heart failure.While the measure of right atrial pressure through right cardiac catheterization remains the most accurate albeit invasive and costly procedure,integrating bedside ultrasound into diagnostic protocols may substantially enhance the staging of venous congestion and guide therapeutic decisions.In particular,with the assessment of Doppler patterns across multiple venous districts,the Venous Excess Ultrasound(VExUS)score improves the management of fluid overload and provides insight into the underlying factors contributing to cardio-renal interactions.Integrating specific echocardiographic parameters,particularly those concerning the right heart,may thus improve the VExUS score sensitivity,offering perspective into the nuanced comprehension of cardio-renal dynamics.A multidisciplinary approach that consistently incorporates the use of ultrasound is emerging as a promising advance in the understanding and management of CRS. 展开更多
关键词 Cardio-renal syndrome Fluid overload Heart failure Ultrasound assessment Venous congestion Venous excess ultrasound score
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Compensatory Damages in Personal Information Public Interest Litigation in China: Challenges and Prospects
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作者 Qi Haixia 《科技与法律(中英文)》 CSSCI 2024年第6期138-148,共11页
In contrast to private interest litigation,public interest litigation provides a more potent solution to personal information infringements marked by extensive scope,unspecified victims,and limited individual loss.How... In contrast to private interest litigation,public interest litigation provides a more potent solution to personal information infringements marked by extensive scope,unspecified victims,and limited individual loss.However,com⁃pensatory damages remain a contentious issue,both in theory and in practice,within the legal framework of personal in⁃formation public interest litigation.Through an empirical study conducted within China's judicial practice,this paper reveals that the pending issue concerning the nature and function of compensatory damages has caused highly contra⁃dictory verdicts regarding their calculation and allocation,as well as their relationship with other forms of pecuniary li⁃abilities.Only by acknowledging the role of compensatory damages imposed in personal information public interest liti⁃gation as"Skimming off Excess Profits",and affirming their function as deterrence rather than compensation can they truly achieve the broader objective of safeguarding personal information security and promoting public welfare,as well as avoid disrupting the harmony of the existing legal landscape. 展开更多
关键词 personal information protection compensatory damages public interest litigation skimming-off excess profits equal liability
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Portal vein pulsatility:An important sonographic tool assessment of systemic congestion for critical ill patients
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作者 Stavros Dimopoulos Michael Antonopoulos 《World Journal of Cardiology》 2024年第5期221-225,共5页
In this editorial we comment on the article by Kuwahara et al,published in the recent issue of the World Journal of Cardiology.In this interesting paper,the authors showed a correlation between portal vein pulsatility... In this editorial we comment on the article by Kuwahara et al,published in the recent issue of the World Journal of Cardiology.In this interesting paper,the authors showed a correlation between portal vein pulsatility ratio,examined by bedside ultrasonography,and prognosis of hospitalized patients with acute heart failure.Systemic congestion is being notoriously underdetected in the acutely ill population with conventional methods like clinical examination,biomarkers,central venous pressure estimation and X-rays.However,congestion should be a key therapeutic target due to its deleterious effects to end organ function and subsequently patient prognosis.Doppler flow assessment of the abdominal veins is gaining popularity worldwide,as a valuable tool in estimating comprehensively congestion and giving a further insight into hemodynamics and patient management. 展开更多
关键词 Systemic congestion Organ perfusion Hemodynamics Central venous pressure Point of care ultrasound Venous excess ultrasound
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Point-of-care ultrasonography spotlight:Could venous excess ultrasound serve as a shared language for internists and intensivists?
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作者 Anosh Aslam Khan Hasham Saeed +3 位作者 Ibtehaj Ul Haque Ayman Iqbal Doantrang Du Abhilash Koratala 《World Journal of Critical Care Medicine》 2024年第2期126-136,共11页
Point-of-care ultrasonography(POCUS),particularly venous excess ultrasound(VExUS)is emerging as a valuable bedside tool to gain real-time hemodynamic insights.This modality,derived from hepatic vein,portal vein,and in... Point-of-care ultrasonography(POCUS),particularly venous excess ultrasound(VExUS)is emerging as a valuable bedside tool to gain real-time hemodynamic insights.This modality,derived from hepatic vein,portal vein,and intrarenal vessel Doppler patterns,offers a scoring system for dynamic venous congestion assessment.Such an assessment can be crucial in effective management of patients with heart failure exacerbation.It facilitates diagnosis,quantification of congestion,prognostication,and monitoring the efficacy of decongestive therapy.As such,it can effectively help to manage cardiorenal syndromes in various clinical settings.Extended or eVExUS explores additional veins,potentially broadening its applications.While VExUS demonstrates promising outcomes,challenges persist,particularly in cases involving renal and liver parenchymal disease,arrhythmias,and situations of pressure and volume overload overlap.Proficiency in utilizing spectral Doppler is pivotal for clinicians to effectively employ this tool.Hence,the integration of POCUS,especially advanced applications like VExUS,into routine clinical practice necessitates enhanced training across medical specialties. 展开更多
关键词 Point-of-care ultrasonography ULTRASOUND Venous excess ultrasound Doppler Congestion Heart failure
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Application of Non-Fuel Power Generation Technology in Steel Industry
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作者 Ganglie Zhu Sizhuo Cai Yuxi Wang 《Frontiers of Metallurgical Industry》 2024年第2期1-4,共4页
Through continuous equipment technology transformation and full utilization of Ma Steel's abundant gas,the boiler no longer relies on fuel oil for stable combustion during boiler startup,sliding parameter shutdown... Through continuous equipment technology transformation and full utilization of Ma Steel's abundant gas,the boiler no longer relies on fuel oil for stable combustion during boiler startup,sliding parameter shutdown,and RB,thus achieving safe and stable operation of the boiler under any abnormal working conditions,and achieving good economic and social benefits. 展开更多
关键词 fuel oil excess gas BENEFIT
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A Discussion on the Issue of Excessive Academic Burden among Middle School Students
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作者 Pinghui Tu 《Journal of Contemporary Educational Research》 2024年第11期6-15,共10页
At present,the heavy academic workload of middle school students is a common problem,which is still questioned by parents,concerned by the government,and hotly debated by society.This paper summarizes the following ei... At present,the heavy academic workload of middle school students is a common problem,which is still questioned by parents,concerned by the government,and hotly debated by society.This paper summarizes the following eight aspects:the difficult content of subject courses,excessive class hours,heavy homework burden,complicated exams,overwhelming study materials,fierce subject competition,prevalent off-campus tutoring,and poor physical and mental health.Recognizing these problems can help to optimize the education and teaching environment and achieve a sustainable enrollment rate. 展开更多
关键词 Middle school students Excessive academic burden DISCUSSION
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ARCADE 2 Spatial Roar, What Theory of Relation Reveals
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作者 Russell Bagdoo 《Journal of Modern Physics》 2024年第5期690-719,共30页
The theory of Relation provides an explanation for the Arcade 2 excess. It assumes that the isotropic radio emission measured by the Arcade 2 Collaboration, which is 5 - 6 times brighter than the expected contribution... The theory of Relation provides an explanation for the Arcade 2 excess. It assumes that the isotropic radio emission measured by the Arcade 2 Collaboration, which is 5 - 6 times brighter than the expected contributions from known extra-galactic sources, is the residue of an immense primitive energy of ordinary matter released by a relativistic bang almost 100 million years after the big bang, which gave the mass-energy the missing gravity to activate contraction. This relativistic bang, via a Lorentz energy transformation, would have released enormous energy held to be the source of the powerful radio noise detected by the NASA researchers. This transformation would have simultaneously triggered the formation of the first stars from dense gas and the reionization of less dense neutral gas. This departs from the idea that continuous reionization began after the formation of the first stars. We emphasize the importance of primordial magnetic fields, which would have generated significant density fluctuations during recombination and acted as a direct seed for cosmic structures. The first stars and galaxies were bathed in strong magnetic fields that gave rise to the radio microwave din (boom) discovered by Arcade 2. These intense magnetic fields alter the trajectory of charged particles zooming near the speed of light, triggering the space roar and emitting radiation that forms a synchrotron radio background. The theory of Relation offers an alternative to the Lambda-CDM cosmological model, which has become the standard model of the big bang, which leads straight to the vacuum catastrophe. 展开更多
关键词 Arcade 2 Excess Relativistic Bang Theory of Relation Lorentz Energy Transformation Cosmic Statics Cosmic Boom Synchrotron Radio Background Primordial Magnetic Fields
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A Case Report on Treating Progressive Supranuclear Palsy with a Combination of Chinese and Western Medicine
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作者 Kai Wu Yongjie Gong +1 位作者 Shan Yang Yalan Yu 《Journal of Clinical and Nursing Research》 2024年第5期23-29,共7页
A case of progressive supranuclear palsy in a 66-year-old woman is presented.The patient complained of“progressive stiffness of both lower limbs for five years,accompanied by choking and coughing for more than 1 year... A case of progressive supranuclear palsy in a 66-year-old woman is presented.The patient complained of“progressive stiffness of both lower limbs for five years,accompanied by choking and coughing for more than 1 year,”and was diagnosed with paralysis in traditional Chinese medicine(TCM),which was characterized by a deficiency of liver and kidney,and phlegm and blood stasis blocking the collaterals.Western medicine diagnosed it as progressive supranuclear palsy.The patient was diagnosed with“Parkinson’s disease”several times in the past and was given“polybasic hydrazide”and“amantadine hydrochloride tablets,”etc.The patient did not have significant symptomatic relief,so she sought further treatment with a combination of traditional Chinese and Western medicine.Based on the concept of deficiency and excess,this disease is categorized as a paralytic disease in Chinese medicine,and the onset of the disease is closely related to the deficiency of the body after a long period of illness,with wind,phlegm,blood stasis,and deficiency as the main pathogenetic mechanism.The treatment is based on the combination of disease and evidence,with traditional Chinese medicine and acupuncture as the main treatments,supplemented by intermediate-frequency pulsed electrical stimulation,transcranial repetitive magnetic stimulation,medicated canisters,wax therapy,traditional Chinese medicine guasha,and acupoint injections.Western medicine is based on symptomatic treatment,and the patient’s symptoms were relieved significantly after the combination of Chinese and Western medicine. 展开更多
关键词 Progressive supranuclear palsy Paralytic disease Diagnosis and treatment Deficiency and excess Combination of Chinese and Western medicine
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小Excess与开流形的拓扑(英文) 被引量:4
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作者 徐森林 王作勤 杨芳云 《应用数学》 CSCD 北大核心 2002年第4期7-12,共6页
本文中 ,我们应用比较几何的方法研究开流形的Excess与其拓扑之间的关系 .我们证明了对于一个曲率下有界的开流形 ,当它的Excess被其临界半径的某个函数所界定时 ,它就有有限拓扑型或微分同胚于n维z欧氏空间 .
关键词 Excess函数 开流形 有限拓扑型 临界点 比较定理
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次大体积增长的流形的曲率与拓扑研究 被引量:1
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作者 薛琼 陈欢欢 +1 位作者 陈爱云 肖小峰 《华中师范大学学报(自然科学版)》 CAS 北大核心 2016年第5期652-655,共4页
该文研究了一类具有非负Ricci曲率和α(α∈[0,2])次衰减截曲率下界的完备非紧黎曼流形.利用Toponogov型比较定理和临界点理论,证明了该流形在一定次大体积增长条件下具有有限拓扑型,从而推广了J.Sha、Z.Shen和C.Xia的关于这类流形的一... 该文研究了一类具有非负Ricci曲率和α(α∈[0,2])次衰减截曲率下界的完备非紧黎曼流形.利用Toponogov型比较定理和临界点理论,证明了该流形在一定次大体积增长条件下具有有限拓扑型,从而推广了J.Sha、Z.Shen和C.Xia的关于这类流形的一系列结果. 展开更多
关键词 RICCI曲率 次大体积增长 Excess函数 BUSEMANN函数
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Ricci曲率,共轭半径和大体积增长 被引量:1
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作者 薛琼 肖小峰 陈欢欢 《华中师范大学学报(自然科学版)》 CAS 北大核心 2015年第3期331-333,共3页
研究了一类具有非负Ricci曲率和大体积增长的完备非紧黎曼流形.证明了在共轭半径有正下界以及流形M上测地球与欧氏空间上单位球的体积增长相差不大的条件下,流形M微分同胚于Rn.该文将体积增长条件改进,推广了M.Do.Carmo和C.Xia的结果.
关键词 RICCI曲率 大体积增长 共轭半径 Excess函数
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Effect of composition and structure on specific resistivity of SiC fibers 被引量:1
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作者 王得印 宋永才 李永强 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第5期1133-1139,共7页
Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by c... Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by changing the curing and pyrolysis conditions. And the free carbon content and the ability to crystallize no longer affect the specific resistivities notably with the time when the fiber is covered with an excess carbon layer, and the fiber has a low specific resistivity. The excess carbon layer in the circular outer part is originated from the re-pyrolysis and deposition of hydrocarbon volatiles. The removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity can be considerable and should not be neglected. 展开更多
关键词 silicon carbide fiber excess carbon layer specific resistivity
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Impacts of Excessive Soaking on N, P, and K in Substrates Plots and Seedling Growth
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作者 王甲辰 左强 +4 位作者 谷佳林 肖强 邹国元 张琳 王美菊 《Agricultural Science & Technology》 CAS 2012年第1期158-161,180,共5页
[Objective] The aim was to study on impacts of excessive soaking N, P, and K insubstrate plots of and seedling growth. [Method] Substrate was designed to add additional 1/2 water after saturation and expansion. Dispos... [Objective] The aim was to study on impacts of excessive soaking N, P, and K insubstrate plots of and seedling growth. [Method] Substrate was designed to add additional 1/2 water after saturation and expansion. Disposable excessive soak- ing and regression relation of nutrition infusion of substrate plots were studied by design of 13 time gradient. Plant nutrition absorption and growth effects after sub- strate plots immersed by water were investigated by growing tomato. [Result] Con- centration and time of the three nutrition immersed in water had the regression equation of each, as follows: N=-2E-05t2+0.016 lt+2.0553, P=0.002 2t+2.248 5 and K=0.004 7t+0.875 8. With nutrition loss of the three, however, loss amount was al- most same with variance analysis of regression equation, which may result from its volatilization. Regression equations of P and K were: P=0.125 7t-0.117, and K=0.022 5t.1514, which led to adverse impact on plant absorption of N and K above ground, whose equations were N=20.64e-4E-0.4t, and K=E-06t2-0.011 3t+29.055. Meanwhile, un- der the condition, sound seedling index was not impacted a lot by excessive immer- sion. [Conclusion] This study has provided theoretical reference for guidance of sub- strate plot soaking method, cultivation and regulation, and breeding, as well as agri- cultural production. 展开更多
关键词 Substrate plot Saturation and expansion for absorption Excessive water Regression equation
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具有非负Ricci曲率和大体积增长的非紧黎曼流形
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作者 薛琼 肖小峰 《华中师范大学学报(自然科学版)》 CAS 北大核心 2013年第4期451-453,460,共4页
应用Gromov-Hausdorff收敛性和Toponogov型比较定理得到临界半径CP的一个上界估计,结合距离函数与临界点的关系,得到具有非负Ricci曲率且满足αM>12的完备非紧Riemann流形在几个距离函数有限的条件下微分同胚于Rn的结果,从而进一步支... 应用Gromov-Hausdorff收敛性和Toponogov型比较定理得到临界半径CP的一个上界估计,结合距离函数与临界点的关系,得到具有非负Ricci曲率且满足αM>12的完备非紧Riemann流形在几个距离函数有限的条件下微分同胚于Rn的结果,从而进一步支持P.Petersen的猜想. 展开更多
关键词 RICCI曲率 大体积增长 临界半径 Excess函数
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