检索结果-南通市图书馆

初次双极髋关节成形术治疗髋退变性关节炎10年以上随访研究

在线全文

学校读者我要写书评

暂无评论

骨科动态 2006年第4期2卷 198-204页

作者： VINCENT D pellegrini jr BRADKET A HEICES BRIAN BIXLER ERIK B LEHMAN CHARLES M DAVIS Ⅲ 陈百成（译） Investigation performed at the Department of Orthopaedics and Rehabilitation The Pennsylvania State University College of Medicine Hershey Pennsylvania 河北医科大学第三医院骨科 050051

背景：部分学者建议用双极髋关节成形术替代全髋关节置换术来治疗髋退变性关节炎。我们通过对患者至少10年的随访来评价这种手术的效果。方法：我们回顾性随访了在1983至1987年间采用非骨水泥型股骨柄双极髋关节成形术治疗退变性髋关节... 详细信息

背景：部分学者建议用双极髋关节成形术替代全髋关节置换术来治疗髋退变性关节炎。我们通过对患者至少10年的随访来评价这种手术的效果。方法：我们回顾性随访了在1983至1987年间采用非骨水泥型股骨柄双极髋关节成形术治疗退变性髋关节炎患者152例（173髋），对其中92例（104髋）术后进行了平均12．2年的临床和影像学随访。在末次随访中用Harris髋关节问卷调查患者疼痛、运动、活动水平和手术满意度。通过髋关节X线检查对双极假体外壳移位情况、骨质溶解和股骨柄固定情况进行评估。结果：末次随访时有19例（19髋）因假体位置不良而行全髋关节翻修术，3例（3髋）因X线片示假体位置欠佳并有临床症状正在等待翻修。12例因骨溶解或继发假体移位的髋关节发生内陷并已经实施或拟实施髋臼翻修术。髋臼重建需要骨移植、大型号的臼杯和（或）重建骨盆环。总的假体位置不良率为21．2％（104髋中有22髋），这22髋中91％（20髋）涉及髋臼病变。初次置换时扩大髋臼可致关节翻修的危险增加6．4倍。在平均12．2年随访中因为假体位置不良而翻修的股骨假体生存率为94．2％，髋臼假体为80．8％。关节假体存活的69例（81髋）中有17例（24．6％）患侧关节存在中度至重度疼痛。即使假体位置正常的患者，也有近30％需要按时服用止痛药物。有58髋（包括所有髋关节有中、重度疼痛的患者）在至少10年以上的随访中接受了放射学检查，其中28髋显示髋臼假体移位。结论：对于有症状的髋关节炎患者采用双极髋关节成形术会出现高比例不可接受的术后疼痛、假体移位、骨质溶解，甚至须行全髋关节翻修术，特别是术中曾扩臼的患者。使用类似传统聚乙烯材料设计的假体术后均有这些症状，我们认为初次治疗髋退变性关节炎不宜使用双极髋关节成形术。可信水平：治疗性研究Ⅳ监。进一步可信度参见作者介绍。

关键词：髋关节成形术退变性关节炎随访研究初次治疗双极全髋关节翻修术中度至重度疼痛全髋关节置换术

Stabilization and detection of labile reaction intermediates in supramolecular containers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第6期35卷 47-52页

作者： Rui Wang Yang Liang Julius Rebek jr. Yang Yu Center for Supramolecular Chemistry&Catalysis and Department of Chemistry College of ScienceShanghai UniversityShanghai 200444China Skaggs Institute for Chemical Biology and Department of Chemistry The Scripps Research InstituteLa JollaCA 92037United States

Detection and observation of reactive intermediates is an essential step in investigation of reaction ***,most reactive intermediates are unstable and present at low concentrations;their short lifetimes make them difficult to detect and *** containers offer opportunities for the stabilization and characterization of those labile species,through isolation from the media and protection inside the cavity of the *** this review,we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular *** container compounds include carcerands,deep cavitands and amide *** focus on unstable guest species-cyclobutadiene,benzocyclopropenone,o-benzyne,1,2,4,6-cycloheptatetraene,anti-Bredt's olefin,fluorophenoxycarbene,O-acylisoamide,and hemiaminalthat act as intermediates in certain organic reactions.

关键词： Supramolecular containers Reaction intermediates Labile species stabilization Short-lived species detection Supramolecular chemistry

Reflections on four decades of physical activity epidemiology

在线全文

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2024年第5期13卷 608-610页

作者： Barbara Sternfeld David R.Jacobs jr. Division of Research Kaiser Permanente Northern CaliforniaOaklandCA 94610USA Division of Epidemiology and Community Health School of Public HealthUniversity of MinnesotaMinneapolisMN 55454USA

In 1985,Public Health Reports published a series of papers prepared for a workshop sponsored by the Centers for Disease Control and Prevention(CDC).1 Building on the seminal work of Jeremy Morris and Ralph Paffenbarger jr.,who were among the first to use epidemiological methods to study physical activity(PA),2,3 the workshop itself was the result of a growing scientific understanding of the importance of“physical fitness and exercise for improving the health of the public”.

关键词： semi workshop Ralph

Enhancement of mechanical properties of GTAW joints for ZC63 magnesium alloy by post-weld heat treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第2期169卷 251-263页

作者： Weiyang Zhou Qichi Le Ye Shi Qiyu Liao Tong Wang Qi Zou Clodualdo Aranas jr Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Key Laboratory of Lightweight Structural Materials Liaoning ProvinceNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Department of Mechanical Engineering University of New BrunswickFrederictonE3B 5A3New BrunswickCanada

To further improve the microstructure and mechanical properties of gas tungsten arc welded(GTAW)welded joints for ZC63 magnesium alloy,post-weld heat treatment is carried *** is found that the majority of the MgZnCu phase in the fusion zone(FZ)is dissolved in theα-Mg matrix under suitable heat treatment *** remainder is diffusely distributed as rods or granules at the grain *** excessive heat treatment temperature(460℃)leads to abnormal grain growth(AGG)in the *** substructure gradient between the abnormally grown grains and the surrounding small grains pro-vides the driving force for ***,the dissolution of the MgZnCu phase weakens the hindering effect of the second phase on grain boundary migration,setting the stage for *** addition,the detri-mental impact of the continuous MgZnCu phase on the mechanical properties of the welded joint is also lessened by its *** ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)of the welded joints are 255 MPa,119 MPa and 27.0%,respectively,under the post-weld heat treatment process of 440℃×12 *** welding coefficient of the welded joint reaches 97.0%,satisfying the service criteria set forth by the mechanical properties of the welded joints.

关键词： GTAW FZ Heat treatment AGG Mechanical properties

SnRK1a1, a new player in the sucrose-Opaque2 network during endosperm filling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2024年第8期17卷 1172-1174页

作者： Kelly Mayrink Balmant Marcio F.R.Resende jr. Horticultural Sciences Department University of FloridaGainesvilleFLUSA

Maize(Zea mays)endosperm is an important food source for humans and *** addition,it is considered an excellent model for research on seed development because of its relatively large size for both embryo and endosperm compared to those of other crop species,such as rice(Oryza sativa)and wheat(Triticum aestivum).After double fertilization,early maize endosperm development includes three stages:(i)a multinucleate coenocyte stage;(i)a cellularization stage,in which the cellular endosperm is formed;and(ii)a stage of differentiation into distinct *** early differentiation,four major cell types with specific functions differentiate within the endosperm:starchy endosperm,aleurone layer,basal endosperm transfer layer(BETL),and embryo surrounding *** subaleurone,conducting zone,basal intermediate zone,and endosperm adjacent to scutellum arise in late differentiation(Sabelli and Larkins 2009).After the main cell types are established,maize endosperm undergoes intensive cell proliferation,which marks the transition to the endosperm-filling *** the endosperm-flling stage,the maternal sucrose products are transported to seeds through the BETL region,where they will act as the main carbon substrate for storage products such as starch and proteins(Chen et al.,2023).In fact,the endosperm of maize seeds accounts for approximately 90%of the total grain weight,serving as an important nutrient reservoir(Flint-Garcia et al.,2009).

关键词： endosperm reservoir Flint

Microstructure and forming mechanism of metals subjected to ultrasonic vibration plastic forming: A mini review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1322-1332页

作者： Qinghe Cui Xuefeng Liu Wenjing Wang Shaojie Tian Vasili Rubanik Vasili Rubanik jr. Dzmitry Bahrets Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Institute of Technical Acoustics National Academy of SciencesVitebsk 210009Belarus

Compared with traditional plastic forming,ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the *** technology has a very broad application prospect in industrial *** have conducted extensive research on the ultrasonic vibration plastic forming of metals and laid a deep foundation for the development of this *** this review,metals were classified according to their crystal *** effects of ultrasonic vibration on the microstructure of face-centered cubic,body-centered cubic,and hexagonal close-packed metals during plastic forming and the mech-anism underlying ultrasonic vibration forming were *** main challenges and future research direction of the ultrasonic vibra-tion plastic forming of metals were also discussed.

关键词： ultrasonic vibration plastic forming crystal structure microstructure forming mechanism

Climate bonds toward achieving net zero emissions and carbon neutrality:Evidence from machine learning technique

在线全文

学校读者我要写书评

暂无评论

Journal of Management Science and Engineering 2024年第1期9卷 1-15页

作者： Hermas Abudu Presley K.Wesseh jr. Boqiang Lin College of Overseas Education Chengdu UniversityChengdu610106SichuanChina School of Management China Institute for Studies in Energy PolicyCollaborative Innovation Center for Energy Economics and Energy PolicyXiamen UniversityFujian361005China Center for African Development Strategy(CFADS) MonroviaLiberia

The Conference of the Parties(COP26 and 27)placed significant emphasis on climate financing policies with the objective of achieving net zero emissions and carbon ***,studies on the implementation of this policy proposition are *** address this gap in the literature,this study employs machine learning techniques,specifically natural language processing(NLP),to examine 77 climate bond(CB)policies from 32 countries within the context of climate *** findings indicate that“sustainability”and“carbon emissions control”are the most outlined policy objectives in these CB ***,the study highlights that most CB funds are invested toward energy projects(i.e.,renewable,clean,and efficient initiatives).However,there has been a notable shift in the allocation of CB funds from climate-friendly energy projects to the construction sector between 2015 and *** shift raises concerns about the potential redirection of funds from climate-focused investments to the real estate industry,potentially leading to the greenwashing of climate ***,policy sentiment analysis revealed that a minority of policies hold skeptical views on climate change,which may negatively influence climate ***,the findings highlight that the effective implementation of CB policies depends on policy goals,objectives,and ***,this study contributes to the literature by employing NLP techniques to understand policy sentiments in climate financing.

关键词： Climate bonds funds utilization Climate bonds policy text mining Machine learning technique Net zero emissions Policy sentiment analysis

Sickle cell retinopathy and systemic disease

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Annals of Eye Science 2024年第2期9卷 53-61页

作者： Oladipupo O.Anibire Daniel ABrill Basil K.Williams jr Meharry Medical College NashvilleTNUSA Department of Ophthalmology University of Cincinnati College of MedicineCincinnatiOHUSA Cincinnati Eye Institute CincinnatiOHUSA Bascom Palmer Eye Institute University of Miami Miller School of MedicineMiamiFLUSA

Sickle cell disease(SCD)is a widespread hemoglobinopathy that results in significant patient morbidity and *** occlusion can cause acute pain,acute chest syndrome,and avascular necrosis,while hemolysis and endothelial disruption can cause ischemic stroke,leg ulcers,pulmonary hypertension,and *** ocular and orbital structures can be affected by SCD ischemic events,including orbital bone infarction,ischemic optic neuropathy,retinal artery occlusion,hyphema,secondary glaucoma,sickle cell maculopathy,and sickle cell *** sickle cell retinopathy(PSR)is the most common cause of vision *** PSR can lead to macular ischemia,vitreous hemorrhage,and tractional retinal *** screening exams and multimodal imaging can lead to earlier detection of sickle cell retinopathy and improved patient *** patients undergoing vitreoretinal surgery may require coordination of care with hematologists to avoid ischemic *** hydroxyurea was the only United States Food and Drug Administration approved treatment for several decades,patients with SCD now have several more treatment *** the United States screening all infants for SCD,there can be delays in diagnosis and *** review article aims to provide an overview of sickle disease for the ophthalmologist,and to discuss emerging treatment options and current management of SCD ocular complications.

关键词： Sickle cell anemia sickle cell disease(SCD) sickle cell retinopathy retinal detachment vitreous hemorrhage(VH)

Capacitorless Solid-state Power Filter for Single-phase DC-AC Converters

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CES Transactions on Electrical Machines and Systems 2024年第3期 367-377页

作者： Haitham Kanakri Euzeli C. Dos Santos, jr. IEEE Purdue University Electrical and Computer Engineering Department

Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power electronics. Traditional filtering methods involve a dual inductor-capacitor(LC) cell or an inductor-capacitor-inductor(LCL) T-circuit. However, capacitors are susceptible to wear-out mechanisms and failure modes. Nevertheless, the necessity for monitoring and regular replacement adds to an elevated cost of ownership for such systems. The utilization of an active output power filter can be used to diminish the dimensions of the LC filter and the electrolytic dc-link capacitor, even though the inclusion of capacitors remains an indispensable part of the system. This paper introduces capacitorless solid-state power filter(SSPF) for single-phase dc-ac converters. The proposed configuration is capable of generating a sinusoidal ac voltage without relying on capacitors. The proposed filter, composed of a planar transformer and an H-bridge converter operating at high frequency, injects voltage harmonics to attain a sinusoidal output voltage. The design parameters of the planar transformer are incorporated, and the impact of magnetizing and leakage inductances on the operation of the SSPF is illustrated. Theoretical analysis, supported by simulation and experimental results, are provided for a design example for a single-phase system. The total harmonic distortion observed in the output voltage is well below the IEEE 519 standard. The system operation is experimentally tested under both steady-state and dynamic conditions. A comparison with existing technology is presented, demonstrating that the proposed topology reduces the passive components used for filtering.

关键词：