Results 1 to 10 of about 541,783 (130)
Gaoya dianqi, 2023 研究发现单断口或者常规串联双断口真空断路器，无法有效提高电容器组开断参数、降低重击穿概率的原因为无法避免高频涌流电弧对触头表面的烧蚀破坏，从而导致断口绝缘强度大为降低。研究获得了高频涌流电弧烧蚀对真空断口绝缘强度和串联断口分压特性的影响规律；高频涌流电弧烧蚀对单个真空灭弧室和串联双真空断口绝缘强度的影响规律及串联断口的分压规律。实验结果表明，真空灭弧室受到涌流电弧烧蚀后场致发射电流大大增加，触头表面破坏越严重场致发射电流越大。触头都受到烧蚀后的串联双断口各自分压约50 ...
赵峰, 杨和, 李玲
doaj
Developmental Medicine &Child Neurology, Volume 61, Issue 3, Page E1-E35, March 2019., 2019 目的 本国际临床指南由欧洲残疾儿童学会（the European Academy of Childhood Disability，EACD）牵头制定，旨在解决发育性协调障碍（developmental coordination disorder，DCD）的定义、诊断、评估、干预以及与社会心理方面的临床应用关键问题。 方法 本指南针对五个领域的关键问题，通过文献综述和专家团队的正式讨论达成共识。为保证指南的循证基础，以“机制”、“评估”和“干预”为检索词, 对2012年更新以来提出的最新建议以及新增的“社会心理问题”和“青少年/成人”为检索词进行检索。根据牛津大学循证医学中心证据等级 (证据水平 [level of evidence, LOE]1–4) 将结果进行分类，最终转化为指南建议。并由国际 ...
Jing Hua +6 more
wiley +1 more source
, 2015 断裂力学是固体力学的一个分支，人们说“断裂力学是破解结构低应力破坏的金钥匙”。这里，我们就来谈谈断裂力学发展过程中的一些趣事吧。 一．“彗星号”大型客机失事惨剧促发断裂力学的诞生 1954年1月10日，一架英国海外航空公司（BOAC）的一架“彗星”1型客机（航班编号781号）从意大利罗马起飞，飞往目的地是英国伦敦。飞机起飞后26分钟，机身在空中解体，坠入地中海，机上所有乘客和机组人员全部遇难。这次事故震惊了全世界 ...
张双寅
core +2 more sources
, 1992 本文对反应烧结氦化硅 Si_3N_4陶瓷的断裂韧性进行实验研究,用三种不同试件进行了测试,这三种试件是:山形切口双悬臂粱试件,山形切口三点弯曲梁试件和直穿透切口三点弯曲梁试件.用有限元方法分析了直穿透切口三点弯曲梁切口宽度对应力强度因子的影响,结合断裂载荷测定值估算了材料的断裂韧性值 ...
王俊表, 向小运, 张双寅
core +2 more sources
How much biotic nativeness matters across human demographic groups
Conservation Biology, Volume 40, Issue 2, April 2026.Abstract Many central concepts of conservation biology—such as nativeness—are structured by ecological and social factors. However, the social consequences of using these concepts to make conservation decisions remain inadequately understood. Some researchers argue that nativeness, rather than acting as an objective proxy for important ecological ...
Harold N. Eyster, Rachelle K. Gould
wiley +1 more source
Ultrasound in Obstetrics &Gynecology, Volume 66, Issue 1, Page 41-50, July 2025.ABSTRACT Objectives Monochorionic diamniotic (MCDA) twins with selective fetal growth restriction (sFGR) and either continuous (cAREDF) or intermittent (iAREDF) absent or reversed end‐diastolic flow in the umbilical artery face significant fetal and neonatal risks.
A. T. R. Noll +19 more
wiley +1 more source
Including the urbanization gradient in people‐centered wildlife conservation in Amazonia
Conservation Biology, Volume 39, Issue 3, June 2025.Abstract Conservation policy in the Amazon traditionally focuses on rural areas, overlooking the socioecological roles of urban populations. This oversight can hinder sustainability by neglecting rural–urban connections. We compared the prevalence and quantity of wild meat consumed, bartered, and traded commercially in rural, peri‐urban, and urban ...
Lísley P. Lemos +3 more
wiley +1 more source
, 2002 用超声波断口图和扫描电镜(SEM)研究了聚甲基丙烯酸甲酯(PMMA)的失稳断裂与断口形态,发现了两个断裂临界速度。当裂纹速度达到第一临界值时,出现二次曲线记号;裂纹扩展速度超过第二临界速度时,断口表面留下二级微裂纹丛 ...
赵亚溥, 盛季生
core +2 more sources
Gaoya dianqi, 2020 为了满足GIS扩建对接及现场耐压时不停电所需的高绝缘裕度扩建断口要求,文中介绍了一种252 kV GIS双隔离断口的不停电扩建装置,采用两个隔离断口串联方式构成扩建断口,由于受断口等效电容和对地杂散电容的影响,两个断口分压比并非1:1关系。为校验双隔离断口的绝缘性能,首先分析确定不停电扩建断口最大承受电压;再建立等值电路模型进行理论计算公式推导;然后以Ansys有限元软件为计算工具,以理论公式与仿真计算相结合的研究分析方法,得出断口电压分布情况。结果表明,高压侧隔离断口电压明显高于低压侧 ...
李忠富 +4 more
doaj
Ultrasound in Obstetrics &Gynecology, Volume 65, Issue 3, Page 372-383, March 2025.ABSTRACT Objective To assess whether premenopausal women diagnosed with deep or ovarian endometriosis on transvaginal sonography (TVS) were more likely to suffer from dyspareunia and pelvic pain symptoms, and have a lower quality of life, compared to women without sonographically diagnosed deep or ovarian endometriosis.
P. Chaggar +5 more
wiley +1 more source