期刊文献+
共找到564篇文章
< 1 2 29 >
每页显示 20 50 100
Unlocking Opportunities Xinjiang celebrates seven decades of sea change
1
作者 LU YAN 《ChinAfrica》 2025年第11期37-39,共3页
Aquiet revolution is underway in the vast cotton fields of Bortala Mongolian Autonomous Prefecture in north Xinjiang where harvesting machines,guided by digital sensors,operate with minimal human intervention.Accordin... Aquiet revolution is underway in the vast cotton fields of Bortala Mongolian Autonomous Prefecture in north Xinjiang where harvesting machines,guided by digital sensors,operate with minimal human intervention.According to Aoqierbate,head of the prefecture’s Bureau of Agriculture and Rural Affairs,now hundreds of hectares of cotton can be harvested by just one or two machine operators. 展开更多
关键词 digital sensors REVOLUTION cotton fields sea change unlocking opportunities machine operators minimal human intervention aquiet revolution
原文传递
Competing reduction induced homogeneous oxygen doping to unlock MoS_(2)basal planes for faster polysulfides conversion 被引量:2
2
作者 Da Lei Wenzhe Shang +10 位作者 Xu Zhang Yongpeng Li Xiaoshan Shi Shaoming Qiao Qian Wang Qiang Zhang Ce Hao Hui Xu Guohua Chen Gaohong He Fengxiang Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第10期26-34,I0002,共10页
The parasitic polysulfides shuttle effect greatly hinders the practical application of lithium sulfur batteries,and this issue can be addressed by promoting polysulfides conversion with catalytic materials such as Mo ... The parasitic polysulfides shuttle effect greatly hinders the practical application of lithium sulfur batteries,and this issue can be addressed by promoting polysulfides conversion with catalytic materials such as Mo S_(2).However,the catalytic activity of Mo S_(2)mainly relies on edge sites,but is limited by inert basal planes.We herein report a novel,facile,ethylene glycol enabled competing reduction strategy to dope Mo S_(2)homogeneously with oxygen atoms so that its inert basal planes can be unlocked.Ethylene glycol works as a reducing agent and competes with thiourea to react with ammonium molybdate,leading to insufficient sulfuration of Mo,and consequent formation of O-Mo S_(2).Our theoretical and experimental investigations indicate that the homogeneously distributed O dopants can create abundant adsorption/-catalytic sites in the Mo S_(2)basal planes,enlarge the inter-plane distance to promote ion transport,and thus enhance the catalytic conversion of polysulfides.The oxygen doped Mo S_(2)(O-Mo S_(2))is supported on carbon nanosheets(CNS)and the composite(O-Mo S_(2)/CNS)is employed to modify the separator of Li-S battery.It gives the battery an initial discharge capacity of 1537 m Ah g-1at 0.2 C,and the battery retains a discharge capacity of 545 m Ah g-1after ultra-long 2000 cycles at 1 C,corresponding to a very small cyclic decay rate of 0.0237%.Even under a raising sulfur loading of 8.2 mg cm^(-2),the Li-S battery also delivers a high discharge capacity(554 m Ah g^(-1))with outstanding cycle stability(84.6%capacity retention)after 100 cycles at 0.5 C.Our work provides a novel,facile approach to fabricate highly catalytically active oxygen-doped Mo S_(2)for advanced Li-S batteries. 展开更多
关键词 Competing reduction One-pot Oxygen-doped MoS_(2) unlocked basal plane Li-S batteries
在线阅读 下载PDF
Partial Unlock for COVID-19-Like Epidemics Can Save 1 - 3 Million Lives Worldwide
3
作者 Robert L. Shuler Theodore Koukouvitis Dyske Suematsu 《Open Journal of Epidemiology》 2020年第3期283-302,共20页
<strong>Background:</strong> A large percentage of deaths in an epidemic or pandemic can be due to overshoot of population (herd) immunity, either from the initial peak or from planned or unplanned exit fr... <strong>Background:</strong> A large percentage of deaths in an epidemic or pandemic can be due to overshoot of population (herd) immunity, either from the initial peak or from planned or unplanned exit from lockdown or social distancing conditions. <strong>Objectives:</strong> We study partial unlock or reopening interaction with seasonal effects in a managed epidemic to quantify overshoot effects on small and large unlock steps and discover robust strategies for reducing overshoot. <strong>Methods:</strong> We simulate partial unlock of social distancing for epidemics over a range of replication factor, immunity duration and seasonality factor for strategies targeting immunity thresholds using overshoot optimization. <strong>Results:</strong> Seasonality change must be taken into account as one of the steps in an easing sequence, and a two-step unlock, including seasonal effects, minimizes overshoot and deaths. It may cause undershoot, which causes rebounds and assists survival of the pathogen. <strong>Conclusions:</strong> Partial easing levels, even low levels for economic relief while waiting on a vaccine, have population immunity thresholds based on the reduced replication rates and may experience overshoot as well. We further find a two-step strategy remains highly sensitive to variations in case ratio, replication factor, seasonality and timing. We demonstrate a three or more step strategy is more robust, and conclude that the best possible approach minimizes deaths under a range of likely actual conditions which include public response. 展开更多
关键词 Epidemic Partial unlock Social Distancing OVERSHOOT COVID-19 SARS-CoV-2
在线阅读 下载PDF
We should Focus on Ways to Unlock Investment
4
作者 Bill Winters 《China's Foreign Trade》 2016年第5期15-,共1页
The summit’s theme reflects the shared aspiration of G20 member states to steer the world economy towards a more sustainable path.A key success of the G20 in the aftermath of the financial crisis has been to signific... The summit’s theme reflects the shared aspiration of G20 member states to steer the world economy towards a more sustainable path.A key success of the G20 in the aftermath of the financial crisis has been to significantly strengthen the resilience of the global financial system.Now we need to focus on ways in 展开更多
关键词 We should Focus on Ways to unlock Investment
在线阅读 下载PDF
删除有理 UnLocker痛删顽固文件
5
作者 唐风 《电脑与电信》 2006年第Z2期64-64,共1页
笔者是一个软件爱好者,几乎每天都会安装、测试一些新软件,由于软件质量良莠不齐,重装系统是常有的事,这本来没什么,但自从碰到某个文件夹加密的软件后(在这里就不公布软件的名称了,免得大家同时中招),这个软件在硬盘上留下了一些顽固... 笔者是一个软件爱好者,几乎每天都会安装、测试一些新软件,由于软件质量良莠不齐,重装系统是常有的事,这本来没什么,但自从碰到某个文件夹加密的软件后(在这里就不公布软件的名称了,免得大家同时中招),这个软件在硬盘上留下了一些顽固的垃圾文件。 展开更多
关键词 软件质量 垃圾文件 重装系统 unlocker
在线阅读 下载PDF
VoIP Market Intensified,the Government Control Still Won't Be Unlocked In the Near Future
6
作者 Xu Xiaoying 《数字通信世界》 2006年第12期94-95,共2页
The traditional telecommunications operator of China has entered into a substantive network construction stage of NGN and new VoIP service in 2006. As the increasing understanding and the consideration of cost to VoIP... The traditional telecommunications operator of China has entered into a substantive network construction stage of NGN and new VoIP service in 2006. As the increasing understanding and the consideration of cost to VoIP, VoIP has become more acceptable for CIO of large-scale enterprises. Small and medium-scale enterprises are sensitive to communication cost, but influenced by the maturity of VoIP technology and reduction of VoIP equipment price, the market is intensified. All these drive the VoIP equipment entering into the actual purchase stage and promote the stable growth of VoIP equipment scale. 展开更多
关键词 VoIP Market Intensified the Government Control Still Won’t Be unlocked In the Near Future In more As BE VolP
在线阅读 下载PDF
Unlocking Potential
7
作者 Hannah Edinger Simon Schaefer 《ChinAfrica》 2013年第2期28-29,共2页
IN December 2012, as corporate South Africa closed down for the holiday season, more than 4,500 members of the ruling African National Congress (ANC) descended on the city of Mangaung to elect their leadership for t... IN December 2012, as corporate South Africa closed down for the holiday season, more than 4,500 members of the ruling African National Congress (ANC) descended on the city of Mangaung to elect their leadership for the next five years, and ultimately determine the future of South Africa's development. 展开更多
关键词 ANC unlocking Potential
原文传递
Unlocking Africa’s Potential
8
作者 Simon Freemantle 《ChinAfrica》 2011年第12期28-28,共1页
Investment remains the vital ingredient for Africa’s success WHILE there are meaningful objections to the nature and structure of much of the new investment in African agriculture,it is clear that the introduction of... Investment remains the vital ingredient for Africa’s success WHILE there are meaningful objections to the nature and structure of much of the new investment in African agriculture,it is clear that the introduction of new capital,skills and technology is an essential component in unlocking the continent’s ultimate allure. 展开更多
关键词 In unlocking Africa’s Potential
原文传递
Unlocking Potential
9
作者 Ge Lijun Fran?ois Dubé 《ChinAfrica》 2018年第10期28-29,共2页
China's ongoing commitment to Africa at the FOCAC Beijing Summit encourages businesses taking part in the Belt and Road Initiative on the continent
关键词 unlocking Potential
原文传递
数智融合如何影响“碳解锁”?
10
作者 邝嫦娥 黄嘉信 狄亚轩 《审计与经济研究》 北大核心 2025年第5期118-127,共10页
随着全球气候变化的加剧和环境问题的日益突出,中国经济正面临从传统碳基技术路径向绿色低碳经济转型的巨大挑战。如何有效打破这种“碳锁定”,实现“碳解锁”,已成为中国乃至全球经济可持续发展的重要课题。基于中国2011—2022年279个... 随着全球气候变化的加剧和环境问题的日益突出,中国经济正面临从传统碳基技术路径向绿色低碳经济转型的巨大挑战。如何有效打破这种“碳锁定”,实现“碳解锁”,已成为中国乃至全球经济可持续发展的重要课题。基于中国2011—2022年279个地级及以上城市数据,实证检验了数智融合对“碳解锁”的影响。实证结果表明:(1)数智融合发展有利于促进“碳解锁”,该促进作用在非资源型城市和非老工业基地城市中表现更为突出。从“碳解锁”的不同维度来看,数智融合发展的促进程度由高到低依次为科技维度、制度维度、产业维度与文化维度。(2)机制检验表明,数智融合可以通过提高市场一体化水平促进“碳解锁”。(3)进一步研究发现,新型数字基础设施建设、宽带中国建设等硬环境政策支持以及数据要素市场化和公共数据开放等软环境政策支持都有助于增强数智融合对“碳解锁”的促进作用。研究旨在深入探讨数智融合如何通过影响市场一体化促进“碳解锁”,以期为中国经济绿色低碳转型和“双碳”目标的实现提供新的视角和理论支持。 展开更多
关键词 数智融合 市场一体化 碳解锁 碳锁定 绿色低碳 经济转型 数字化发展
在线阅读 下载PDF
中国碳解锁效率时空演进、区域差异及影响因素分析——基于八大综合经济区视角
11
作者 崔和瑞 张芙宇 《生态经济》 北大核心 2025年第10期13-23,共11页
碳解锁效率衡量了经济发展能力与生态文明效益的综合水平,对我国加快构建绿色低碳循环发展经济体系具有重要意义。在对碳解锁理论机制分析的基础上,该研究将能源、技术、制度与社会因素融入碳解锁效率评价指标体系,以2010—2020年中国... 碳解锁效率衡量了经济发展能力与生态文明效益的综合水平,对我国加快构建绿色低碳循环发展经济体系具有重要意义。在对碳解锁理论机制分析的基础上,该研究将能源、技术、制度与社会因素融入碳解锁效率评价指标体系,以2010—2020年中国八大综合经济区为研究对象,运用非期望产出超效率SBM模型测算其碳解锁效率并基于ML指数、Dagum基尼系数和Tobit面板模型对其时空演进、动态变化、空间差异及影响因素进行实证分析。结果显示:(1)研究期内中国整体碳解锁效率平均提升了19.5%,沿海地区效率水平大于内陆地区,西南地区效率水平增速最快,技术进步是各区域碳解锁效率提升的主要影响因素。(2)中国碳解锁效率空间分布呈“东南—西北—中部阶梯分化”特征,北京、上海等直辖市碳解锁效率稳居全国前列,山西、辽宁等以工业为主导产业省份效率落后。(3)中国碳解锁效率总体差异较大但呈小幅度波动下降趋势,主要来源于区域间差异,且沿海与内陆区域间差异最为严峻。(4)经济发展、城镇化、社会消费、产业结构升级对中国碳解锁效率有显著正向作用,人口规模、外资依存、政府干预呈显著负向作用,影响因素的区域异质性存在并具有一定规律。 展开更多
关键词 碳解锁效率 八大综合经济区 时空特征 影响因素
原文传递
长江中游城市群碳解锁空间关联网络及影响因素
12
作者 李华金 黄嘉信 狄亚轩 《生态学报》 北大核心 2025年第14期7065-7079,共15页
长江中游城市群在我国区域发展格局中占据重要地位,其碳解锁水平对推动长江经济带绿色发展、助力实现碳达峰碳中和目标意义重大。以2011—2022年长江中游城市群27个城市为研究对象,运用社会网络分析和空间杜宾模型等方法,从产业、制度... 长江中游城市群在我国区域发展格局中占据重要地位,其碳解锁水平对推动长江经济带绿色发展、助力实现碳达峰碳中和目标意义重大。以2011—2022年长江中游城市群27个城市为研究对象,运用社会网络分析和空间杜宾模型等方法,从产业、制度、科技、文化四个维度构建碳解锁水平指标体系,探究碳解锁空间关联网络及影响因素。研究结果表明:①在空间格局演变上,环鄱阳湖城市群碳解锁水平相对武汉城市圈和环长株潭城市群更高,南昌、武汉对周边城市存在技术溢出的辐射效应。②区域差异特征上,泰尔指数经历先升后降的动态过程,总体差异以区域内差异为主导,其中环鄱阳湖城市群的区域内差异贡献率最高,武汉城市圈贡献率波动显著,环长株潭城市群贡献率呈下降趋势,而区域间差异贡献率虽低但近年呈递增态势。③网络联系方面,长江中游城市群碳解锁网络关联度保持高位,强连通性显著,网络密度持续攀升、效率下降、等级度降低;以武汉和南昌代表的环鄱阳湖城市群和武汉城市圈的核心城市构成的“净溢出板块”通过技术、政策辐射带动周边发展;萍乡、武汉、宜昌和黄冈等市在网络中发挥着中介作用。④在影响因素方面,富裕程度与互联网发展对本地碳解锁产生显著正向直接效应,社会消费则具有负向作用;产业结构、技术水平、人口规模、互联网发展及富裕程度存在负向空间溢出效应,而产业结构与技术水平的总效应表现为正向驱动,人口规模与互联网的总效应呈现负向抑制。 展开更多
关键词 长江中游城市群 碳解锁 STIRPAT模型 空间杜宾模型 社会网络分析
在线阅读 下载PDF
穴结探析
13
作者 吴小丽 陈冬玲 +4 位作者 丘鸿 吴娇娟 李晓璐 刘宇 刘清国 《上海中医药大学学报》 2025年第1期87-89,共3页
在中医学中,“结”是无形邪气与有形物质发生病理反应的产物,经络系统中腧穴内结节、条索等被认为是该产物,但此对于穴结的认识并不够全面。“结”非邪侵即成,其是在正邪斗争过程中有形之物与无形邪气日久交织结聚而成的病理产物。其在... 在中医学中,“结”是无形邪气与有形物质发生病理反应的产物,经络系统中腧穴内结节、条索等被认为是该产物,但此对于穴结的认识并不够全面。“结”非邪侵即成,其是在正邪斗争过程中有形之物与无形邪气日久交织结聚而成的病理产物。其在穴内有散结、聚结两种形式,因其常碍气血运行而引发痹证,进而影响机体活动,故探“结”之所在以解之在临床诊疗中尤为重要。在相关文献基础上,从穴结释义、病理表现、病机、针下感及临床运用等方面进行阐述,以期为临床针刺提供指导和理论依据。 展开更多
关键词 穴结 痹证 邪盛 久病入络 解结
原文传递
Functional central nervous system regeneration:Challenges from axons to circuits
14
作者 Apolline Delaunay Mickael Le Boulc’h +1 位作者 Stephane Belin Homaira Nawabi 《Neural Regeneration Research》 2026年第5期1983-1984,共2页
The mature central nervous system(CNS,composed of the brain,spinal cord,olfactory and optic nerves)is unable to regenerate spontaneously after an insult,both in the cases of neurodegenerative diseases(for example Alzh... The mature central nervous system(CNS,composed of the brain,spinal cord,olfactory and optic nerves)is unable to regenerate spontaneously after an insult,both in the cases of neurodegenerative diseases(for example Alzheimer's or Parkinson's disease)or traumatic injuries(such as spinal cord lesions).In the last 20 years,the field has made significant progress in unlocking axon regrowth. 展开更多
关键词 parkinsons disease unlocking axon regrowth neurodegenerative diseases central nervous system cnscomposed functional regeneration axon regrowth spinal cord lesions central nervous system
暂未订购
Closed Reduction and Minimally Invasive Fixation for the Treatment of Bilateral Displaced Posterior Pelvic Ring Disruption
15
作者 Zhen Wang Zhe Xu +5 位作者 Peng-hui Xiang Mei-qi Gu Rui Zhang Hua Chen Li He Cheng-la Yi 《Current Medical Science》 2025年第1期137-145,共9页
Objective Close reduction and internal fixation have gained popularity for the treatment of pelvic fractures.However,the closed reduction of bilateral displaced posterior pelvic ring disruption is a great challenge ev... Objective Close reduction and internal fixation have gained popularity for the treatment of pelvic fractures.However,the closed reduction of bilateral displaced posterior pelvic ring disruption is a great challenge even for the most experienced surgeon.In this study,we describe in detail a novel unlocking closed reduction technique(UCRT)frame that allows strong traction for bilateral posterior pelvic ring displacement and presents preliminary clinical outcomes.Methods We retrospectively reviewed 32 patients with bilateral displaced posterior pelvic ring disruptions(AO/OTA 61-C2 and C3)who were initially treated with this technique between July 2017 and July 2022.According to the AO/OTA clas-sification,there were 9 cases(28.12%)of 61-C2,and 23 cases(71.88%)of 61-C3.There were 11 males,21 females,with an average age of 38.1 years.The interval from injury to operation was 4-27 days,with a cut-off of 12.5 days(receiver operat-ing characteristic curve).Operative time,blood loss,and postoperative radiographic findings were recorded.The functional outcomes and complications were followed.Results A total of 30(93.8%)patients achieved successful closed reduction,whereas 2 required open reduction.The success-ful closed reduction rate was 95.5%(21/22)in patients whose injury-to-operation time was less than 12.5 days.The vertical displacement percent correction of the obviously displaced hemipelvis was 70.20%±16.79%on average.The average degree of pelvic deformity correction was 64.86%±17.71%.Thirty patients were followed up for at least 12 months(12-36 months),and no complications of nonunion or redisplacement were observed.The Matta-Tornetta scoring standard revealed that the excellent(25/30)and good(4/30)rate was 96.7%.The Majeed clinical efficacy score revealed that the overall excellent and good rate was 100%.One patient had INFIX-related infection,and 2 reported numbness in the lateral thigh.The numbness was improved after INFIX removal.Conclusions This study presents an updated technique for closed reduction using a UCRT frame for bilateral posterior pelvic ring disruption,which has been shown to be effective,as indicated by excellent surgical and functional outcomes. 展开更多
关键词 Pelvic fractures unlocking closed reduction technique Minimally invasive internal fixation
暂未订购
中国城市尺度下建筑业碳排放锁定状态及解锁路径 被引量:2
16
作者 蒯林沂 安敏 +1 位作者 宋孟斐 安慧 《环境科学》 北大核心 2025年第8期4803-4812,共10页
中国当前正处于推动绿色低碳发展的关键阶段,建筑业作为能源消耗排放和碳排放的关键行业,深入探讨建筑业碳锁定问题并提出可行的解锁路径具有重大意义.研究基于2011~2020年中国272个城市建筑业的面板数据,深入分析了城市建筑业碳锁定现... 中国当前正处于推动绿色低碳发展的关键阶段,建筑业作为能源消耗排放和碳排放的关键行业,深入探讨建筑业碳锁定问题并提出可行的解锁路径具有重大意义.研究基于2011~2020年中国272个城市建筑业的面板数据,深入分析了城市建筑业碳锁定现象.通过技术、经济、制度和社会这4个维度探讨碳排放的主要驱动因素,进一步分析建筑业待解锁城市相应的解锁路径.结果发现:(1)2011~2020年中国城市建筑碳排放总量大致呈增长趋势,碳排放由17 030万t上升至69 603万t扩大了4倍,呈现出“东高西低”的特征;(2)2011~2020年,中国272个城市建筑业锁定状态随时间呈现出先波浪式减小后逐渐上升的趋势,锁定城市呈现由聚集北部、中部到块状分布再逐渐扩散到全国范围的空间格局变化;(3)技术、制度和经济因素为主要的中国城市建筑业碳排放驱动因素,均呈正向作用,根据主要驱动因素指标,将2011~2020年中国209个待解锁城市对于不同因素进行了不同程度的技术、制度和经济碳解锁路径分析.研究成果有助于地方政府根据不同类型城市的碳锁定程度和驱动因素制定低碳绿色发展战略,可为实现区域自主探索低碳发展路径和“双碳”目标提供了重要参考. 展开更多
关键词 建筑业 碳排放 碳锁定状态 驱动因素 解锁路径
原文传递
数字技术锁定:侵蚀效应与解锁策略研究——基于逆向锁定视角 被引量:1
17
作者 茹慧超 邓峰 《科技进步与对策》 北大核心 2025年第2期1-10,共10页
数字技术研发应用推动创新内涵嬗变。探讨数字技术创新潜藏逆向锁定风险,基于技术路径依赖理论,结合2011—2021年中国上市公司数字技术专利申请数据,采用非径向超效率SBM方法测度我国数字技术锁定,检验数字技术锁定对数字经济发展的侵... 数字技术研发应用推动创新内涵嬗变。探讨数字技术创新潜藏逆向锁定风险,基于技术路径依赖理论,结合2011—2021年中国上市公司数字技术专利申请数据,采用非径向超效率SBM方法测度我国数字技术锁定,检验数字技术锁定对数字经济发展的侵蚀效应。研究发现:(1)数字技术锁定对数字经济发展存在显著侵蚀效应,且该影响遵循“显著侵蚀—侵蚀效果收敛—侵蚀效果强化”这一非线性轨迹;(2)受技术空间扩散影响,数字技术锁定对数字经济发展具有“邻地侵蚀”效应;(3)与内部技术引进相比,外部技术引进能显著打破数字技术逆向锁定演进轨道,处于弱制度创新环境的地区通过技术模仿遏制数字技术锁定的边际收益更高;(4)技术消化吸收对数字技术锁定的遏制效果在区域间存在非对称性特征,知识产权保护能为知识吸收和数字技术成果转化提供坚实的制度保障。研究结论可为数字经济时代下化解数字逆向锁定风险、突破“数字锁定枷锁”提供策略指引。 展开更多
关键词 数字技术锁定 侵蚀效应 逆向锁定 解锁策略 知识产权保护
在线阅读 下载PDF
可折叠式集成化行军固定器的设计研究
18
作者 李银河 田亚锋 +2 位作者 王华亭 雷凯文 孙耀东 《火力与指挥控制》 北大核心 2025年第5期117-123,共7页
作为火炮锁定和解脱重要装置,行军固定器小型化、智能化成为一种重要趋势。某中口径高炮使用具备方位和高低锁定功能独立液压行军固定器,占用空间大,自动化程度低,总体方案设计难度高。提出和设计了新型可折叠式集成化行军固定器,对其... 作为火炮锁定和解脱重要装置,行军固定器小型化、智能化成为一种重要趋势。某中口径高炮使用具备方位和高低锁定功能独立液压行军固定器,占用空间大,自动化程度低,总体方案设计难度高。提出和设计了新型可折叠式集成化行军固定器,对其运动学及力学进行仿真,并且随战车联调进行验证,结果表明,行军固定器可实现150~600mm的高度尺寸变化,以及方位和高低同步锁紧和解脱,其执行时间短,性能可靠。 展开更多
关键词 折叠 集成化 行军固定器 锁定解脱 性能可靠
在线阅读 下载PDF
A comparative analysis of distal locked and unlocked long proximal femoral nail antirotation (PFNA-II) in the fixation of stable intertrochanteric fractures 被引量:6
19
作者 Atmananda Hegde Vikrant Khanna +2 位作者 Prajwal Mane Chethan Shetty Nitin Joseph 《Chinese Journal of Traumatology》 CAS CSCD 2023年第2期111-115,共5页
Purpose:Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures,especially in osteoporotic patients.The purpose of this study is to prospecti... Purpose:Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures,especially in osteoporotic patients.The purpose of this study is to prospectively investigate the effect of distal locking in long PFNA-II fixation of stable intertrochanteric fractures.Methods:A total of 58 patients with isolated stable intertrochanteric fractures and treated in our hospital during the study period of 2017–2019 by distal locked or unlocked long PFNA-II fixation were included in this study.Patients who had multiple injuries or open fractures were excluded.There were 40 female and 18 male patients,with 33 affecting the left side and 25 the right side.Of them,31 belonged to the distal locked group (group A) and 27 to the unlocked group (group B).Surgical procedures and implants used in both groups were similar except for the distal locking of the nails.General data (age,gender,fracture side,etc.) showed no significant difference between two groups (allp > 0.05).The intraoperative parameters like operative time,radiation exposure and follow-up parameters like functional and radiological outcomes were recorded and compared.Statistical tests like the independent samplest-test Fischer’’s exact and Chi-square test were used to analyze association.Results:The distribution of the fractures according to AO/OTA classification and 31A1.2 type of intertrochanteric fractures were most common in our study.All the included fractures united and the average functional outcome in both groups were good and comparable at the end of one year.The operative time (mL,107.1 ± 12.6vs.77.0 ± 12.0,p < 0.001) and radiation exposure (s,78.6 ± 11.0vs.40.3 ± 9.3,p < 0.001) were significantly less among the patients in group B.Fracture consolidation,three months after the operative procedures,was seen in a significantly greater proportion of patients in group B (92.6%vs.67.7%,p = 0.025).Hardware irritation because of distal locking bolt was exclusively seen in group A,however this was not statistically significant (p = 0.241).Conclusion:We conclude that,in fixation of stable intertrochanteric fractures by long PFNA-II nail,distal locking not only increases the operative time and radiation exposure but also delays the fracture consolidation and increases the chances of hardware irritation,and hence is not required. 展开更多
关键词 Intertrochanteric fractures Hip fractures Proximal femoral nail Distal locked unlocked intramedullary nail Intramedullary nail
原文传递
深海水下采油树油管悬挂器结构设计研究 被引量:1
20
作者 朱军龙 李育房 汝梦奇 《西南石油大学学报(自然科学版)》 北大核心 2025年第2期175-184,共10页
水下采油树是深海油气开发的关键设备,油管悬挂器作为油气通道、电通道,支撑油管柱并密封油管和套管之间环形空间,是采油树的核心部件,其结构强度关系到油气的安全生产。以南海某油气田油管悬挂器为例,结合对国外油管悬挂器的分析,进行... 水下采油树是深海油气开发的关键设备,油管悬挂器作为油气通道、电通道,支撑油管柱并密封油管和套管之间环形空间,是采油树的核心部件,其结构强度关系到油气的安全生产。以南海某油气田油管悬挂器为例,结合对国外油管悬挂器的分析,进行了水下采油树油管悬挂器主体结构尺寸设计。采用有限元分析方法,建立了油管悬挂器的有限元模型,并对其在下放过程、安装就位过程、正常生产过程及锁紧解锁过程中进行了数值模拟分析。结果表明,在下放过程中,油管悬挂器的最大应力为310.43 MPa,最大变形为0.45009 mm;在安装就位过程中,最大应力为310.43 MPa,最大变形为0.40885 mm;在正常生产过程中,69 MPa、64℃时,油管悬挂器出油口的最大应力为311.13 MPa,最大变形为0.58148 mm;在69 MPa、121℃时,最大应力为586.93 MPa,最大变形为1.33470 mm。所设计油管悬挂器结构强度满足安全要求,变形较小,具有良好的结构安全性。该油管悬挂器已成功应用于中国首个自主研发的水下采油树系统,对推动中国水下油气生产系统的国产化具有重要意义。 展开更多
关键词 水下采油树 油管悬挂器 结构计算 锁紧 解锁
在线阅读 下载PDF
上一页 1 2 29 下一页 到第
使用帮助 返回顶部