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CAUSES OF OUTBREAK OF THE LARCH CATERPILLAR(Dendrolimus superans Butler) IN DAXINGAN MOUNTAIN AND ITS CONTROL STRATEGY 被引量:3
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作者 刘宽余 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1994年第1期34-40,共7页
In 1991, in Daxingan Mountain, an outbreak of larch caterpillar (Dendrolim us superans Butler) happened on large areas of more than one million hectares, where stands of larch were seriously damaged because needles on... In 1991, in Daxingan Mountain, an outbreak of larch caterpillar (Dendrolim us superans Butler) happened on large areas of more than one million hectares, where stands of larch were seriously damaged because needles on the trees were almost eaten up by the pest. causing enormous economic losses. Analysis of data collected indicated that the main cause of the outbreak of larch caterpillar on large areas was that, after thirty years of exploitation, mature and overmature forests decreased rapidly. middle-aged and young forests incresed in large amount. significant changes occurred in individual ecological conditions of stands, especially those tended. with decreasing canoPy density and better light condition in the forest, and all these were adventageous to the outbreak of the pest. In addition, in recent years, the climatic condition in Daxingan Mountain changed significantly. The yearly average temperature raised gradually and the soil surface temperature in April and October increased year by year, which were advantageous to the outbreak of larch caterpillars. In short. the significant changes in the ecological conditions in Daxingan Mountain provided suitable conditions for the outbreak of the larch caberpill ar, and after several years of increase in population number, the larch caterpillar outbroke into a serious disaster on vast areas. In the paper, composite control strategy was also discussed. 展开更多
关键词 LARCH CATERPILLAR CAUSE of outBREAK control strategy
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Analysis on Current Situation,Formation Causes and Control Countermeasures of Acid Rain Pollution in China 被引量:3
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作者 万玉山 王皖蒙 《Meteorological and Environmental Research》 CAS 2010年第10期92-95,共4页
Environmental problem is one of three major issues of common concern in the world today.Being a developing socialist country,the environmental problems in china are even more prominent,mainly in population expansion,s... Environmental problem is one of three major issues of common concern in the world today.Being a developing socialist country,the environmental problems in china are even more prominent,mainly in population expansion,sharp decrease of global forest areas,soil erosion,acid rain pollution,water pollution and so on.This essay is to introduce the present status,formation causes and hazardous condition of acid rain pollution in china.Some feasible and effective control measures are put forward according to the actual situation in China. 展开更多
关键词 Acid rain pollution causes of pollution Hazards control measures China
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Analysis of the Causes of Continuous Cropping Obstacles for Atractylodes macrocephala Koidz in Pingjiang County and Its Control Methods 被引量:1
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作者 宋荣 邓凯 +2 位作者 朱校奇 周佳民 曹亮 《Agricultural Science & Technology》 CAS 2015年第3期462-466,共5页
First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provi... First at all, it introduced the concept and the damages of continuous cropping obstacle. Then, it analyzed the causes of continuous cropping obstacles for Atractylodes macrocephala Koidz. In the end, in order to provide guidance for pro- moting sustainable development of Atractylodes macrocephala Koidz industry in Pingjiang County, it put forward some control methods for eliminating continuous cropping obstacles of Atractylodes macrocephala Koidz, including breeding varieties with high resistance; applying rotation cropping and intercropping reasonable; rational fertilization and soil disinfection; introducing antagonistic bacterial and eliminating au- tointoxication. 展开更多
关键词 Atractylodes macrocephala Koidz Continuous cropping obstacles CAUSE DAMAGE control method Pingjiang County
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CAUSES AND CONTROL COUNTERMEASURES OF EUTROPHICATION IN CHAOHU LAKE, CHINA 被引量:26
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作者 SHANG Guang-ping SHANG Jin-cheng 《Chinese Geographical Science》 SCIE CSCD 2005年第4期348-354,共7页
Chaohu Lake, located in the central Anhui Province, is one of the five largest fresh lakes in China. Now it is one of the three most eutrophication lakes in China. The deterioration of its water quality has influenced... Chaohu Lake, located in the central Anhui Province, is one of the five largest fresh lakes in China. Now it is one of the three most eutrophication lakes in China. The deterioration of its water quality has influenced the sustainable development of society, economy and environment of Hefei City, the capital of Anhui Province. A series of measures have been carried out to control its eutrophication, but it is still serious. On the basis of the lake water quality data from 1984 to 2003, the causes of the eutrophication of Chaohu Lake are analyzed. Studies indicated that the suitable natural conditions and human activities played a crucial role in the process of the eutrophication of Chaohu Lake. A great amount of industrial, agricultural and domestic sewage discharged into the lake is the main cause of eutrophication in the lake. Land use, soil erosion and shoreline collapse destroyed the watershed eco-environment and the terrestrial ecosystem of Chaohu Lake. And the building of Yuxi Gate extends the sluggish of the nutritious substance and speeds up the process of the eutrophication. From the view of systematic engineering and watershed ecology, a series of the countermeasures have been put forward to control the eutrophication. 展开更多
关键词 causes of eutrophication eutrophication control non-engineering measures watershed management Chaohu Lake
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Micro-geological causes and macro-geological controlling factors of low-resistivity oil layers in the Puao Oilfield 被引量:5
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作者 Tan Fengqi Li Hongqi +2 位作者 Liu Hongtao Jiang Fucong Yu Hongyan 《Petroleum Science》 SCIE CAS CSCD 2009年第3期246-253,共8页
Low-resistivity oil layers are often missed in logging interpretation because of their resistivity close to or below the resistivity of nearby water layers. Typical low-resistivity oil layers have been found in the pa... Low-resistivity oil layers are often missed in logging interpretation because of their resistivity close to or below the resistivity of nearby water layers. Typical low-resistivity oil layers have been found in the past few years in the Putaohua reservoir of the Puao Oilfield in the south of the Daqing placanticline by detailed exploration. Based on a study of micro-geological causes of low-resistivity oil layers, the macro-geological controlling factors were analyzed through comprehensive research of regional depositional background, geological structure, and oil-water relations combined with core, water testing, well logging, and scanning electron microscopy data. The results showed that the formation and distribution of Putaohua low-resistivity oil layers in the Puao Oilfield were controlled by depositional environment, sedimentary facies, diagenesis, motive power of hydrocarbon accumulation, and acidity and alkalinity of reservoir liquid. The low-resistivity oil layers caused by high bound-water saturation were controlled by deposition and diagenesis, those caused by high free-water saturation were controlled by structural amplitude and motive power of hydrocarbon accumulation. Those caused by formation water with high salinity were controlled by the ancient saline water depositional environment and faulted structure and those caused by additional conductivity of shale were controlled by paleoclimate and acidity and alkalinity of reservoir liquid. Consideration of both micro-geological causes and macro-geological controlling factors is important in identifying low-resistivity oil layers. 展开更多
关键词 Daqing placanticline Puao Oilfield Putaohua oil layer low-resistivity oil layers microgeological causes macro-geological controlling factors
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Causes of Recurrence of Rice Chilo suppressalis( Walker) in Longyou County and Prevention and Control Measures 被引量:2
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作者 Ying WANG Yong ZHANG +3 位作者 Chenguang ZHANG Runzhong LOU Xinxin XU Xiaowei XU 《Asian Agricultural Research》 2019年第2期111-113,116,共4页
In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice productio... In recent years,the occurrence of rice Chilo suppressalis( Walker) in Longyou County of Zhejiang Province has increased year by year and has become aggravated. This poses a great threat to the safety of rice production. In order to curb the recurrence momentum of rice C. suppressalis,according to the dynamic monitoring and field system survey of rice C. suppressalis in Longyou County since 2015,the causes of the annual increase of rice C. suppressalis in recent years were analyzed,and the recurrence area of C. suppressalis was introduced,and finally some prevention and control measures were put forward. 展开更多
关键词 CHILO SUPPRESSALIS (Walker) causes of RECURRENCE Prevention and control measures
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Causes and Prevention and Control of Rice Lodging 被引量:1
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作者 Zhou Hui 《Plant Diseases and Pests》 CAS 2018年第3期23-26,28,共5页
Rice lodging is a major restraint for high-yield, stable and quality production of rice. The corresponding preventive measures and remedies are given by analyzing variety selection, field management, diseases and pest... Rice lodging is a major restraint for high-yield, stable and quality production of rice. The corresponding preventive measures and remedies are given by analyzing variety selection, field management, diseases and pests, natural disasters, etc. 展开更多
关键词 RICE LODGING CAUSE Prevention and control
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Causes and typical control model of wind-drift sandy lands in abandoned channel of the Yellow River 被引量:1
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作者 Zhang Guo-zhen Yang Li +1 位作者 Xu Wei Sun Bao-ping 《Forestry Studies in China》 CAS 2006年第1期59-64,共6页
The historical formation and development of the abandoned channel of the Yellow River is reviewed and its causes of formation and present condition of prevention and control are analyzed in this paper. Based on this a... The historical formation and development of the abandoned channel of the Yellow River is reviewed and its causes of formation and present condition of prevention and control are analyzed in this paper. Based on this analysis, some ideas about control, critical problems and countermeasures in the next period are proposed with two typical control models as examples. We suggest that in preventing and controlling the wind-drift sandy lands in the region, the emphasis should be to develop, with a greatly expanded effort, a recycling economy. This should realize a combination of two ideas, i.e. integrate combating desertification with a structural adjustment of agricultural and an increase in the income of farmers. 展开更多
关键词 wind-drift sandy land cause of formation control model the abandoned channel of the Yellow River
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Controlling Methods and Causes of Wall Cracks of Civil and Industrial Construction Projects
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作者 Zhiqi Guan 《Journal of World Architecture》 2020年第6期19-21,共3页
Since the reform and opening up,Chinese economy has developed rapidly.Industrial and civil construction projects have made significant progress.That said,it is of great significance to further strengthen the construct... Since the reform and opening up,Chinese economy has developed rapidly.Industrial and civil construction projects have made significant progress.That said,it is of great significance to further strengthen the construction management of industrial and civil construction projects for the longterm development of construction industry in China.In terms of reality,one of the common problems in the current industrial and civil construction is wall cracks,which will have an important impact on the appearance of the building and the overall construction quality.Therefore,it is necessary to analyze the reasons and put forward corresponding measures on it.That is how we can continuously improve the construction quality in civil and industrial construction projects,thereby achieving the enhancement of building safety and stability. 展开更多
关键词 Industrial and civil construction projects Wall cracks causes control methods
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Cause of over Water Quality Standard and Control Measures of State-controlled Sections in Northern Water-deficient Area of Jiangsu 被引量:5
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作者 胡永定 韩宝平 +1 位作者 钱新 袁兴程 《Meteorological and Environmental Research》 CAS 2010年第2期91-94,99,共5页
Taking state-controlled section of Xuzhou Peiyan river as an example,the current water quality was monitored,and the cause of over water quality standard was analyzed.The results showed that the pollutants of Peiyan r... Taking state-controlled section of Xuzhou Peiyan river as an example,the current water quality was monitored,and the cause of over water quality standard was analyzed.The results showed that the pollutants of Peiyan river were mainly from the urban river segment,and the immediate cause of over standard was tributary pollutants in urban river segment with the runoff into rivers.So we should strengthen the maintenance of drainage control and gate-han,accelerate the construction of urban wastewater treatment facilities and supporting pipe network,promote rural decentralized sewage treatment,prevent and control livestock and poultry pollution,pesticides and fertilizers pollution,and intercept non-point source pollution by using eco-technology. 展开更多
关键词 State-controlled sections Cause analysis control measures Water-deficient area China
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Treatment of Atherosclerotic Disease of the Femoral Artery: Randomized Controlled Trials and Meta-Analyses. Should You Be Sceptical?
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作者 Raymond Englund 《Surgical Science》 2019年第7期235-254,共20页
A narrative review of the data provided by Randomised Controlled clinical trials and meta-analyses was undertaken to assess how much reliance a clinician could place on these in selecting a treatment for patients with... A narrative review of the data provided by Randomised Controlled clinical trials and meta-analyses was undertaken to assess how much reliance a clinician could place on these in selecting a treatment for patients with disease of the Femoral artery. An attempt was made to detect and review every clinical trial and meta-analysis published on treatments relating to disease of the femoral artery but not relating to drug treatment. Disease of the femoral artery in >65 years age group occurs in approximately 20% of the population but symptomatology was present in 40%. In almost all trials the predominant (>90%) indication for treatment was intermittent claudication. In this setting, clinical benefit was limited and did not extend beyond 12 months. Mortality, from co-morbidities was high. The Basil Trial was the only one to examine intervention for critical limb ischemia. The results for Bypass surgery and Percutaneous transarterial balloon angioplasty (PTA) were equivalent. There is little evidence to support the use of PTA or stenting other than in the treatment of patients with critical limb ischemia. 展开更多
关键词 Femoral Artery Stent (Nitinol DRUG-ELUTING Covered) Percutaneous Balloon Angioplasty Drug Eluting BALLOONS RANDOMISED controlled Trials META-analyses Intermittent CLAUDICATION Critical Limb Ischemia PATENCY Clinical Benefit
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A review of control loop monitoring and diagnosis:Prospects of controller maintenance in big data era 被引量:7
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作者 Xinqing Gao Fan Yang +1 位作者 Chao Shang Dexian Huang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第8期952-962,共11页
Owing to wide applications of automatic control systems in the process industries, the impacts of controller performance on industrial processes are becoming increasingly significant. Consequently, controller maintena... Owing to wide applications of automatic control systems in the process industries, the impacts of controller performance on industrial processes are becoming increasingly significant. Consequently, controller maintenance is critical to guarantee routine operations of industrial processes. The workflow of controller maintenance generally involves the following steps: monitor operating controller performance and detect performance degradation, diagnose probable root causes of control system malfunctions, and take specific actions to resolve associated problems. In this article, a comprehensive overview of the mainstream of control loop monitoring and diagnosis is provided, and some existing problems are also analyzed and discussed. From the viewpoint of synthesizing abundant information in the context of big data, some prospective ideas and promising methods are outlined to potentially solve problems in industrial applications. 展开更多
关键词 control LOOP performance assessment Industrial ALARM system Process knowledge ROOT CAUSE diagnosis BIG data
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Occurrence of Rice Dry Straight Head Disease and Its Control
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作者 黄自安 刘小林 +2 位作者 倪春耕 胡宏云 王振荣 《Plant Diseases and Pests》 CAS 2010年第2期1-4,9,共5页
[Objective] Cause of disease and control measures of rice dry straight head disease in Chuzhou area was discussed. [Method] Field investigation and comprehensive analysis of the literature were conducted to study the ... [Objective] Cause of disease and control measures of rice dry straight head disease in Chuzhou area was discussed. [Method] Field investigation and comprehensive analysis of the literature were conducted to study the reason of dry straight head disease in Chuzhou area, some common control measures were summarized. [Result] The characteristic of main symptoms included incidence of single plant, incidence of cluster, inclusive incidence between clusters. Sporadic normal rice grains existed in diseased spikes under the incidence of grains. The main pathogenic factors of dry straight head disease were concentration of arsenic or lack of elements, belonging to physiological disease, while the effect of other pathogenic factors could not be excluded. Heavy application of organic fertilizer and crop rotation should be conducted, white soil field should be paid more attention about the changes of disease condition with more wet and dry roasting over fields. Application time of micro fertilizer should be chosen properly, while tillering final stage and pollen formation stage must be adjusted to avoid high temperature, irrigation management should also be improved. [Conclusion] The study could provide reference for preventing rice dry straight head disease. 展开更多
关键词 Rice dry straight head disease Research SYMPTOM Cause of disease Arsenic concentration Prevention and control measure
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Damage of Apriona swainsoni(Hope)on Sophora japonica Linn.in Pingdingshan Area
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作者 Li Shihong 《Plant Diseases and Pests》 CAS 2016年第1期16-18,共3页
The damage status of Apriona swainsoni (Hope) in Pingdingshan area is investigated combined with historical data, and the causes of heavy occurrence are analyzed. Moreover, according to production practice, it is pr... The damage status of Apriona swainsoni (Hope) in Pingdingshan area is investigated combined with historical data, and the causes of heavy occurrence are analyzed. Moreover, according to production practice, it is proposed that forecast of pests and annual control countermeasures are important for the control of A. swainsoni. 展开更多
关键词 Apriona swainsoni (Hope) Damage status Cause of heavy occurrence Annual control
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Measurement of Mechanical Quantities
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《计量学报》 CSCD 1991年第S1期56-63,共8页
03001 Controlled Behaviour of the Meniscus LiquidSurface and its Applications. Sheng Yitang. XuJiangyong.Fang Jingfu: 1(1 ). 1980. pp.36--45An expression of the meniscus liquid surface which isin contact with a solid ... 03001 Controlled Behaviour of the Meniscus LiquidSurface and its Applications. Sheng Yitang. XuJiangyong.Fang Jingfu: 1(1 ). 1980. pp.36--45An expression of the meniscus liquid surface which isin contact with a solid wall is derived.The principlethat controls the behaviour of the meniscus Surface bymeans of different Shapes of the solid wall is proposed.and the controlled condition or the meniscus surface isalso calculated Finally it is applied to achieve stablebuoyancy of a specified float. 展开更多
关键词 BEHAVIOUR BEHAVIOUR controlLED FLOAT Sheng specified analysed GAUGE dynam RESONANT
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Analysing the cause of sever blood transfusion reaction caused by mixed anti-body of anti-Jk^b and anti-E
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《中国输血杂志》 CAS CSCD 2001年第S1期381-,共1页
关键词 body Analysing the cause of sever blood transfusion reaction caused by mixed anti-body of anti-Jk^b and anti-E
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Empowering women to combat osteoporosis:unveiling the causes,consequences,and control strategies
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作者 Seyi Samson Enitan Babatunde Ishola Gabriel Adejumo +4 位作者 Esther Ngozi Adejumo Temitope Oyewole Olusanya Eguagie Osareniro Osakue Oluwakemi Anike Ladipo Comfort Bosede Enitan 《Aging Communications》 2023年第3期8-17,共10页
Osteoporosis is a common bone disease in women worldwide, leading to decreased bone density and an accelerated risk of fractures. The causes of osteoporosis in women include age (senile osteoporosis), menopause-associ... Osteoporosis is a common bone disease in women worldwide, leading to decreased bone density and an accelerated risk of fractures. The causes of osteoporosis in women include age (senile osteoporosis), menopause-associated hormonal changes, deficiencies in calcium and vitamin D, genetics, lifestyle factors, medical conditions, and some type of medications. The consequences of osteoporosis are colossal, consisting of fractures, decreased quality of life, psychological impacts, and economic burden. To effectively control the menace of osteoporosis in women, numerous strategies are advocated. Adequate calcium and vitamin D consumption through diet or supplements is vital. Regular weight-bearing activities and strength training that promote bone density. Maintaining a healthy life-style through avoiding smoking, limiting alcohol in-take and maintaining a wholesome body weight is essential. Hormone replacement therapy and some medications may be recommended in certain cases. Early detection through regular bone density and blood tests is crucial to lowering its impact. Creating a supportive network through educational programs and resources fosters awareness and empowerment. By engaging these strategies, women can be empowered to combat osteoporosis, reduce fracture risk, and build stronger bones for their overall well-being. 展开更多
关键词 WOMEN AGING OSTEOPOROSIS causes consequences control strategies
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Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review 被引量:38
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作者 Sasmita Poudel Adhikari Sha Meng +8 位作者 Yu-Ju Wu Yu-Ping Mao Rui-Xue Ye Qing-Zhi Wang Chang Sun Sean Sylvia Scott Rozelle Hein Raat Huan Zhou 《Infectious Diseases of Poverty》 SCIE 2020年第2期90-91,共2页
Background:The coronavirus disease(COVID-19)has been identified as the cause of an outbreak of respiratory illness in Wuhan,Hubei Province,China beginning in December 2019.As of 31 January 2020,this epidemic had sprea... Background:The coronavirus disease(COVID-19)has been identified as the cause of an outbreak of respiratory illness in Wuhan,Hubei Province,China beginning in December 2019.As of 31 January 2020,this epidemic had spread to 19 countries with 11791 confirmed cases,including 213 deaths.The World Health Organization has declared it a Public Health Emergency of International Concern.Methods:A scoping review was conducted following the methodological framework suggested by Arksey and O'Malley.In this scoping review,65 research articles published before 31 January 2020 were analyzed and discussed to better understand the epidemiology,causes,clinical diagnosis,prevention and control of this virus.The research domains,dates of publication,journal language,authors'affiliations,and methodological characteristics were included in the analysis.All the findings and statements in this review regarding the outbreak are based on published information as listed in the references.Results:Most of the publications were written using the English language(89.2%).The largest proportion of published articles were related to causes(38.5%)and a majority(67.7%)were published by Chinese scholars.Research articles initially focused on causes,but over time there was an increase of the articles related to prevention and control.Studies thus far have shown that the virus7 origination is in connection to a seafood market in Wuhan,but specific animal associations have not been confirmed.Reported symptoms include fever,cough,fatigue,pneumonia,headache,diarrhea,hemoptysis,and dyspnea.Preventive measures such as masks,hand hygiene practices,avoidance of public contact,case detection,contact tracing,and quarantines have been discussed as ways to reduce transmission.To date,no specific antiviral treatment has proven effective;hence,infected people primarily rely on symptomatic treatment and supportive care.Conclusions:There has been a rapid surge in research in response to the outbreak of COVID-19.During this early period,published research primarily explored the epidemiology,causes,clinical manifestation and diagnosis,as well as prevention and control of the novel coronavirus.Although these studies are relevant to control the current public emergency,more high-quality research is needed to provide valid and reliable ways to manage this kind of public health emergency in both the short-and long-term. 展开更多
关键词 COVID-19 EPIDEMIOLOGY causes Prevention and control Review
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急性后循环缺血性脑卒中患者睡眠状态变化与预后影响因素的研究
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作者 张萍淑 薛晶 +4 位作者 邢爱君 王连辉 马倩 符永山 元小冬 《中国全科医学》 CAS 北大核心 2025年第5期548-553,共6页
背景脑卒中患者通常伴有睡眠状态紊乱失衡,这在临床治疗中极易被忽视,且目前针对睡眠状态是否对该类疾病预后产生影响的研究较少。目的探究急性后循环缺血性脑卒中患者睡眠状态变化与预后影响的因素。方法选取2019年12月—2023年12月在... 背景脑卒中患者通常伴有睡眠状态紊乱失衡,这在临床治疗中极易被忽视,且目前针对睡眠状态是否对该类疾病预后产生影响的研究较少。目的探究急性后循环缺血性脑卒中患者睡眠状态变化与预后影响的因素。方法选取2019年12月—2023年12月在华北理工大学附属开滦总医院诊治的急性后循环缺血性脑卒中患者60例为病例组,根据患者出院时改良Rankin(mRS)评分,将病例组分为预后良好亚组45例,预后不良亚组15例。选取同时期无脑血管狭窄且无急性缺血性脑卒中患者52例作为对照组。收集患者一般及临床资料,比较病例组与对照组患者昼夜睡眠-觉醒节律、日间睡眠-觉醒节律、夜间睡眠-觉醒节律指标以及预后良好亚组与预后不良亚组梗死脑区分布的差异性。采用多因素Logistic回归分析探讨急性后循环缺血性脑卒中患者预后不良的影响因素。结果病例组睡眠呼吸暂停低通气指数(AHI)高于对照组(P<0.05)。病例组睡眠周期颠倒、日间睡眠增多、夜间入睡困难所占比例高于对照组(P<0.05)。病例组日间总睡眠时间、入睡后清醒时间、浅睡眠期、深睡眠期、非快速眼动(NREM)睡眠期、快速眼动(REM)睡眠期、REM睡眠期占比、深睡眠期占比高于对照组,NREM睡眠期占比、浅睡眠期占比低于对照组(P<0.05)。病例组夜间总睡眠时间、浅睡眠期、NREM睡眠期高于对照组(P<0.05)。预后不良亚组桥脑梗死占比高于预后良好亚组(P<0.05)。多因素Logistic回归分析结果显示,日间深睡眠期(OR=1.203,95%CI=1.032~1.401)、桥脑梗死(OR=16.497,95%CI=1.142~238.391)是急性后循环缺血性脑卒中预后不良的影响因素(P<0.05)。结论急性后循环缺血性脑卒中患者AHI增高,睡眠状态特征为睡眠周期颠倒、日间睡眠增多、夜间入睡困难,且日间深睡眠期、桥脑梗死是患者预后不良的影响因素。 展开更多
关键词 卒中 脑梗死 后循环 睡眠状态 预后 病例对照研究 影响因素分析
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Parametric analyses on dynamic stall control of rotor airfoil via synthetic jet 被引量:10
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作者 Qijun ZHAO Yiyang MA Guoqing ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第6期1818-1834,共17页
The effects of synthetic jet control on unsteady dynamic stall over rotor airfoil are investigated numerically. A moving-embedded grid method and an Unsteady Reynolds Averaged Navier-Stokes(URANS) solver coupled wit... The effects of synthetic jet control on unsteady dynamic stall over rotor airfoil are investigated numerically. A moving-embedded grid method and an Unsteady Reynolds Averaged Navier-Stokes(URANS) solver coupled with k-x Shear Stress Transport(SST) turbulence model are established for predicting the complex flowfields of oscillatory airfoil under jet control. Additionally, a velocity boundary condition modeled by sinusoidal function has been developed to fulfill the perturbation effect of periodic jet. The validity of present CFD method is evaluated by comparisons of the calculated results of baseline dynamic stall case for rotor airfoil and jet control case for VR-7 B airfoil with experimental data. Then, parametric analyses are conducted emphatically for an OA212 rotor airfoil to investigate the effects of jet control parameters(jet location, dimensionless frequency, momentum coefficient, jet angle, jet type and dual-jet) on dynamic stall characteristics of rotor airfoil. It is demonstrated by the calculated results that efficiency of jet control could be improved with specific momentum coefficient and jet angle when the jet is located near separation point of rotor airfoil. Furthermore, the dual-jet could improve control efficiency more obviously on dynamic stall of rotor airfoil with respect to the unique jet, and the influence laws of dual-jet's angles and momentum coefficients on control effects are similar to those of the unique jet. Finally,unsteady aerodynamic characteristics of rotor via synthetic jet which is located on the upper surface of rotor blade in forward flight are calculated, and as a result, the aerodynamic characteristics of rotor are improved compared with the baseline. The results indicate that synthetic jet has the capability in improving aerodynamic characteristics of rotor. 展开更多
关键词 AIRFOIL Dynamic stall characteristics:Flow control Moving-embedded gridmethodology Navier-Stokes equations Parametric analyses ROTOR Synthetic jet
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