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Simulating the Saturation Threshold of a Water Environment's Response to Tourist Activities:A Case Study in the Liupan Mountain Eco-tourism Area 被引量:2
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作者 ZHAO Mei-feng XI Jian-chao LIU Sheng-he 《Journal of Mountain Science》 SCIE CSCD 2014年第1期156-166,共11页
The effect of tourism on water environments has received a high degree of interest in the study of eco-tourism.Based on the analysis of the relationship between tourist activities and the water environment in the Liup... The effect of tourism on water environments has received a high degree of interest in the study of eco-tourism.Based on the analysis of the relationship between tourist activities and the water environment in the Liupan Mountain eco-tourism zone,the case study area,a Water Environment of Tourism Area Model(WETAM) is built to simulate the temporal and spatial changes in water quality and the response saturation thresholds under four sewage treatment scenarios.The results imply the following:(1) WETAM performs well in modeling a water environment to represent the dynamic process of water quality change in response to tourist activities.(2) Under four sewage treatment scenarios(fundamental,low,medium,and high),the threshold shows an obvious uptrend.(3) The response threshold of water quality with respect to the interference of tourist activities fluctuates seasonally due to changes in tourist density.(4) The thresholds differ significantly among five tourism functional areas.According to the response saturation threshold of the water environment,effective control based on the scale and intensity of tourist activities is important for a successful transformation of this tourism destination's development strategies.Therefore,the integrated management of water pollution in tourism areas plays a crucial role in sustainable tourism development. 展开更多
关键词 Tourism area Water environment Model simulation response threshold TOURIST ACCOMMODATION Liupan MOUNTAIN
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‘Outbreak Gold Standard’Selection to Provide Optimized Threshold for Infectious Diseases Early-alert Based on China Infectious Disease Automated-alert and Response System 被引量:5
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作者 王瑞平 姜永根 +2 位作者 赵根明 郭晓芹 Engelgau Michael 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2017年第6期833-841,共9页
The China Infectious Disease Automated-alert and Response System(CIDARS) was successfully implemented and became operational nationwide in 2008. The CIDARS plays an important role in and has been integrated into the... The China Infectious Disease Automated-alert and Response System(CIDARS) was successfully implemented and became operational nationwide in 2008. The CIDARS plays an important role in and has been integrated into the routine outbreak monitoring efforts of the Center for Disease Control(CDC) at all levels in China. In the CIDARS, thresholds are determined using the ?Mean+2SD? in the early stage which have limitations. This study compared the performance of optimized thresholds defined using the ?Mean +2SD? method to the performance of 5 novel algorithms to select optimal ?Outbreak Gold Standard(OGS)? and corresponding thresholds for outbreak detection. Data for infectious disease were organized by calendar week and year. The ?Mean+2 SD?, C1, C2, moving average(MA), seasonal model(SM), and cumulative sum(CUSUM) algorithms were applied. Outbreak signals for the predicted value(Px) were calculated using a percentile-based moving window. When the outbreak signals generated by an algorithm were in line with a Px generated outbreak signal for each week, this Px was then defined as the optimized threshold for that algorithm. In this study, six infectious diseases were selected and classified into TYPE A(chickenpox and mumps), TYPE B(influenza and rubella) and TYPE C [hand foot and mouth disease(HFMD) and scarlet fever]. Optimized thresholds for chickenpox(P_(55)), mumps(P_(50)), influenza(P_(40), P_(55), and P_(75)), rubella(P_(45) and P_(75)), HFMD(P_(65) and P_(70)), and scarlet fever(P_(75) and P_(80)) were identified. The C1, C2, CUSUM, SM, and MA algorithms were appropriate for TYPE A. All 6 algorithms were appropriate for TYPE B. C1 and CUSUM algorithms were appropriate for TYPE C. It is critical to incorporate more flexible algorithms as OGS into the CIDRAS and to identify the proper OGS and corresponding recommended optimized threshold by different infectious disease types. 展开更多
关键词 outbreak gold standard optimized threshold algorithms early-alert signal China Infectious Disease Automated-alert and response System
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Hormesis has emerged as a more common and fundamental dose-response model than the threshold or linear-no-threshold(LNT) models 被引量:6
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作者 Edward J. Calabrese Lu Rong-zhu 《毒理学杂志》 CAS CSCD 北大核心 2006年第2期117-118,共2页
在回顾传统的有阈和线性无阈的剂量-反应关系的基础上,分析此类该模型被毒理学领域认同的主要原因和其在预测低剂量效应中的缺陷,进而提出了高剂量接触呈现抑制效应,而低剂量却呈现促进或刺激作用这一全面的激效兴奋性剂量-反应关系,弥... 在回顾传统的有阈和线性无阈的剂量-反应关系的基础上,分析此类该模型被毒理学领域认同的主要原因和其在预测低剂量效应中的缺陷,进而提出了高剂量接触呈现抑制效应,而低剂量却呈现促进或刺激作用这一全面的激效兴奋性剂量-反应关系,弥补了现有模型的不足,并充分论证这种激效性剂量-反应关系在不同种属、接触因素和生物学终点中的普遍性,并探讨了不同物质的激效兴奋作用的可能机制以及激效兴奋模型的三大优点,最后提出了激效模型谋求广泛接受的现实困难和发展趋势。 展开更多
关键词 激效作用 兴奋效应 剂量-反应关系 有阈模型 线性无阈模型
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Genotype and task influence stinging response thresholds of honeybee (<i>Apis mellifera</i>L.) workers of African and European descent
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作者 Jose L. Uribe-Rubio Tatiana Petukhova Ernesto Guzman-Novoa 《Open Journal of Ecology》 2013年第4期279-283,共5页
The stinging response thresholds of individual European and Africanized worker honeybees (Apis mellifera L.) were analyzed. Workers of each genotype performing defense (guard and soldier bees) and non-defense (nest an... The stinging response thresholds of individual European and Africanized worker honeybees (Apis mellifera L.) were analyzed. Workers of each genotype performing defense (guard and soldier bees) and non-defense (nest and forager bees) associated tasks were collected and exposed to an electric stimulus of 0.5 mA, and the time they took to sting a leather substrate was recorded. Africanized bees had significant lower thresholds of response than European bees. Guards and soldiers were faster to sting than nest and forager bees for the Africanized genotype, whereas for the European genotype, guards stung significantly faster than bees of the other three task groups. This is the first study that shows that individual bees specialized in two defensive tasks also have a lower response threshold for stinging. Our results fit a model of division of labor based on differences in response thresholds to stimuli among workers of different genotypes and task groups. 展开更多
关键词 Apis MELLIFERA Africanized HONEYBEES GENOTYPIC Effects Defensive Behavior response thresholds Division of Labor
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Ultrafast Response and Threshold Adjustable Intelligent Thermoelectric Systems for Next‑Generation Self‑Powered Remote IoT Fire Warning
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作者 Zhaofu Ding Gang Li +5 位作者 Yejun Wang Chunyu Du Zhenqiang Ye Lirong Liang Long‑Cheng Tang Guangming Chen 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第11期413-428,共16页
Fire warning is vital to human life,economy and ecology.However,the development of effective warning systems faces great challenges of fast response,adjustable threshold and remote detecting.Here,we propose an intelli... Fire warning is vital to human life,economy and ecology.However,the development of effective warning systems faces great challenges of fast response,adjustable threshold and remote detecting.Here,we propose an intelligent self-powered remote IoT fire warning system,by employing single-walled carbon nanotube/titanium carbide thermoelectric composite films.The flexible films,prepared by a convenient solution mixing,display p-type characteristic with excellent high-temperature stability,flame retardancy and TE(power factor of 239.7±15.8μW m^(-1) K^(-2))performances.The comprehensive morphology and structural analyses shed light on the underlying mechanisms.And the assembled TE devices(TEDs)exhibit fast fire warning with adjustable warning threshold voltages(1–10 mV).Excitingly,an ultrafast fire warning response time of~0.1 s at 1 mV threshold voltage is achieved,rivaling many state-of-the-art systems.Furthermore,TE fire warning systems reveal outstanding stability after 50 repeated cycles and desired durability even undergoing 180 days of air exposure.Finally,a TED-based wireless intelligent fire warning system has been developed by coupling an amplifier,analogto-digital converter and Bluetooth module.By combining TE characteristics,high-temperature stability and flame retardancy with wireless IoT signal transmission,TE-based hybrid system developed here is promising for next-generation self-powered remote IoT fire warning applications. 展开更多
关键词 THERMOELECTRIC SELF-POWERED IoT fire warning Ultrafast response threshold adjustable
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幼苗期梭梭对干旱胁迫的响应及耐旱阈值分析
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作者 于明含 杨蕾 +2 位作者 吕慧 王岳 安骁 《生态学报》 北大核心 2026年第3期1301-1309,共9页
植物幼苗的耐旱能力及耐旱阈值的确定是干旱荒漠区人工植被栽培的关键科学和技术问题,然而,基于植物长势和生理活性等多指标的生长耐旱阈值确定方法尚不成熟,对荒漠地区人工植被建设的水分管理造成限制。以我国北方荒漠生态系统重要建... 植物幼苗的耐旱能力及耐旱阈值的确定是干旱荒漠区人工植被栽培的关键科学和技术问题,然而,基于植物长势和生理活性等多指标的生长耐旱阈值确定方法尚不成熟,对荒漠地区人工植被建设的水分管理造成限制。以我国北方荒漠生态系统重要建群种梭梭(Haloxylon ammodendron)为研究对象,通过水培实验模拟6个干旱梯度(0 MPa至-1.5 MPa),监测梭梭幼苗的生长、生理及生化指标变化,分析梭梭在应对干旱胁迫时的多指标协同响应,并利用主成分分析与Logistic模型相结合的方法明确其生长耐旱阈值。结果表明:(1)随干旱胁迫加剧(水势≤-0.7 MPa),幼苗株高、根长显著下降,根冠比升高,生物量向根系分配,渗透调节物质发生积累且抗氧化酶被显著激活;(2)梭梭幼苗在应对干旱时呈现多生理指标协同响应,表现为超氧化物歧化酶、过氧化氢酶与过氧化物酶的协同作用,脯氨酸与可溶性糖在干旱胁迫下同步升高。(3)基于多生理指标的主成分因子,梭梭生理指标响应水势梯度的Logistic模型表明其生长耐旱阈值为-0.73 MPa,即低于该水势的生境将影响梭梭幼苗长势和活性。量化了幼苗期的生长耐旱阈值,为荒漠区梭梭人工种植的水分管理及抗逆品种筛选提供了依据和借鉴。 展开更多
关键词 幼苗 干旱胁迫 生理响应 耐旱阈值 LOGISTIC模型
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鄂东北大别山区生态环境质量时空演变及归因分析
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作者 潘玉莲 陈大安 +2 位作者 秦苗 陈烨 张斌 《环境科学》 北大核心 2026年第2期916-929,共14页
揭示鄂东北大别山区生态环境质量(EEQ)时空演变规律及其驱动机制,是长江中游生态屏障建设的重要科学依据.研究集成多源遥感、气象及社会经济数据,构建“格局-驱动-阈值”三位一体分析框架,通过融合Theil-Sen Median趋势分析、MannKendal... 揭示鄂东北大别山区生态环境质量(EEQ)时空演变规律及其驱动机制,是长江中游生态屏障建设的重要科学依据.研究集成多源遥感、气象及社会经济数据,构建“格局-驱动-阈值”三位一体分析框架,通过融合Theil-Sen Median趋势分析、MannKendall检验与Hurst指数预测,系统解析2001~2021年EEQ时空分异特征.时空耦合分析表明:①2001~2021年间,研究区多年EEQ均值经历了从0.470上升至峰值0.514后又回落至0.497的波动变化,但整体呈现改善趋势,好转区域面积占比51.95%.②EEQ等级空间分异显著,良好和优秀一级主要分布在西北部、东北部和西南部地区,生态环境质量“较差”级别主要分布在中部和南部沿江平原地区.③研究区生态环境质量驱动因素探究的最佳空间尺度为7.5 km,EEQ在不同年份对不同因素的响应程度存在差异.2001~2021年间,土地利用强度、植被覆盖度、降水量、海拔、温度和建设用地面积占比是研究区EEQ空间分异的主导驱动因素,且土地利用强度的胁迫作用逐年增强,人口密度和人均GDP对EEQ影响较小.EEQ对土地利用强度、温度和建设用地面积占比呈负向非线性响应,与植被覆盖度、海拔和降水量之间呈正向非线性关系.④结合Sen趋势和Hurst指数得到未来区域EEQ改善区域面积占比为39.72%,恶化区域面积占比30.75%.研究成果可为动态优化生态保护红线、实施建设用地强度管控及构建气候适应性管理策略提供定量化决策支持,并为同类型山地生态系统可持续治理提供范式参考. 展开更多
关键词 遥感生态指数(RSEI) 生态环境质量(EEQ) 时空分异 随机森林(RF) 响应阈值
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基坑临边履带式装备动荷载对邻近建筑的响应分析
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作者 赵海涛 梁红忠 +2 位作者 张志红 孙响 朱超 《市政技术》 2026年第2期175-185,共11页
针对密集城区基坑工程中旋挖钻机移动荷载诱发邻近建筑动力响应的问题,该研究依托北京安立路快速化改造工程(建筑距基坑仅2.2 m),通过建立钻机-土体-建筑全耦合数值模型,系统揭示动力响应规律,并提出有效的控制策略。研究结果表明:旋挖... 针对密集城区基坑工程中旋挖钻机移动荷载诱发邻近建筑动力响应的问题,该研究依托北京安立路快速化改造工程(建筑距基坑仅2.2 m),通过建立钻机-土体-建筑全耦合数值模型,系统揭示动力响应规律,并提出有效的控制策略。研究结果表明:旋挖钻机移动荷载作用下的动力响应呈现三阶段特征,包括冲击阶段(建筑沉降峰值4.9 mm)、波动阶段(与履带振动频率匹配的四周期波动)和衰减阶段(82%区域沉降≤1 mm),三者共同构成了完整的“振动—应力—变形”能量传递路径;基于规范要求建立了动荷载安全阈值体系(40 t/低级风险、80 t/中级风险、120 t/高级风险),当动荷载超过40 t时建筑基底振动速度超限104%~138%;提出基于“速度-空间”协同控制的有效措施,行进速度1.0 m/s有效规避能量累积、削弱荷载冲击,移动路径距建筑≥5 m使沉降减少80%、振动速度降低71%,构建了分级控制策略。研究成果为密集城区基坑工程安全施工提供了理论依据和实操指南,实现了安全性与施工效率的协同优化。 展开更多
关键词 深基坑 施工机械 动力响应 数值模拟 邻近建筑 荷载阈值
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战斗部装药在破片撞击下的冲击起爆特性研究
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作者 许伟 段继 《火工品》 北大核心 2026年第1期21-28,共8页
研究了战斗部在破片撞击下的冲击起爆特性,进行了安全性数值仿真和试验。依据美军标MIT-MTD-2105D,使用Φ14.3mm×14.3 mm钢破片撞击战斗部,评估其宏观响应。优化了Lee-Tarver模型,计算了壳体和装药的动力学响应。结果显示:1885,215... 研究了战斗部在破片撞击下的冲击起爆特性,进行了安全性数值仿真和试验。依据美军标MIT-MTD-2105D,使用Φ14.3mm×14.3 mm钢破片撞击战斗部,评估其宏观响应。优化了Lee-Tarver模型,计算了壳体和装药的动力学响应。结果显示:1885,2158m·s^(-1)撞击速度下,战斗部未起爆;峰值压力和最大反应度随速度增加而增大,但破片能量下降,对战斗部威胁效能比降低。不同长径比破片的起爆阈值计算表明,随着破片质量的增加,质量侵蚀比下降,起爆阈值降低12.7%~46.2%。 展开更多
关键词 战斗部安全性 破片撞击 点火增长模型 动态响应 起爆阈值
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基于多特征融合与机器学习的客观听阈评估
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作者 周鑫 高妍 +4 位作者 陈捷敏 刘霞 夏文涛 张麒 陈芳 《自动化仪表》 2026年第2期86-93,共8页
针对传统听觉测听法在法医学鉴定中的局限性,提出基于多特征融合与机器学习的纯音测听(PTA)阈值评估方法。提取40 Hz听觉相关电位(AERP)信号的多域特征,并融合人口统计学信息与听觉反应阈指标,形成多源、异构、高维特征向量。采用F检验... 针对传统听觉测听法在法医学鉴定中的局限性,提出基于多特征融合与机器学习的纯音测听(PTA)阈值评估方法。提取40 Hz听觉相关电位(AERP)信号的多域特征,并融合人口统计学信息与听觉反应阈指标,形成多源、异构、高维特征向量。采用F检验和最小收缩与选择算子进行特征选择。比较四种机器学习模型的PTA阈值预测性能,并使用沙普利加和解释方法评估特征贡献度。试验结果表明,岭回归模型性能最优。特征贡献度分析显示,窄带Claus Elberling啁啾声听觉脑干反应(NB CE-Chirp ABR)高频反应阈和40 Hz AERP低频反应阈贡献最显著,40 Hz AERP信号的频带功率等特征也发挥着重要作用。该方法为客观听阈评估提供了新思路,有助于听力损伤诊断,对法医临床学智能司法鉴定具有重要意义。 展开更多
关键词 客观听阈评估 纯音测听阈值 40 Hz听觉相关电位 窄带Claus Elberling啁啾声听觉脑干反应 特征融合 特征选择 机器学习
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国产人工耳蜗电诱发听性脑干反应与行为测听相关性探究
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作者 徐毓 史文迪 +5 位作者 邱嘉文 高珊仙 郑慧姿 李洋 王旖旎 沈毅 《中华耳科学杂志》 北大核心 2026年第1期52-57,共6页
目的探究国产人工耳蜗植入者使用电诱发听性脑干反应(electrically evoked stem responses,EABR)和行为测听测定人工耳蜗电流级阈值(T值)的相关性,通过EABR测试客观设定T值进行人工耳蜗编程的可行性。方法选取2023年宁波大学附属第一医... 目的探究国产人工耳蜗植入者使用电诱发听性脑干反应(electrically evoked stem responses,EABR)和行为测听测定人工耳蜗电流级阈值(T值)的相关性,通过EABR测试客观设定T值进行人工耳蜗编程的可行性。方法选取2023年宁波大学附属第一医院植入国产人工耳蜗的患者22例(25耳),其中,男性9例,女性13例,平均年龄(21.92±11.30)岁,19例为单侧耳蜗植入,3例为双侧耳蜗植入。分别选取1、7、13、19、24号电极,测定能引出EABR和行为测试的最小电流刺激量;将行为测试测定的电刺激阈值设定为T值,并设置为人工耳蜗植入的程序①;根据EABR测试的电刺激阈值作为T值,设置为程序②,患者分别使用程序①、②进行助听听阈检测,分析两个助听听阈和两个T值之间的相关性。结果第1、7、13、19、24号电极的V波潜伏期分别为(3.30±0.33)ms、(3.41±0.30)ms、(3.52±0.33)ms、(3.59±0.27)ms、(3.54±0.46)ms;EABR测试的T值分别为(83.20±10.40)CL、(89.20±13.52)CL、(101.00±15.48)CL、(102.20±19.26)CL、(110.80±18.97)CL;行为测听测定的T值分别为(79.00±18.91)CL、(80.04±17.04)CL、(86.64±19.38)CL、(90.68±17.37)CL、(104.60±17.91)CL;二者之间存在显著相关性(P<0.05)。两次助听听阈极显著相关(P<0.01)。结论国产人工耳蜗EABR测得的电刺激阈值和行为测听测得的电流级阈值之间存在显著相关性,可使用EABR测试来辅助国产人工耳蜗的编程。 展开更多
关键词 国产人工耳蜗 电刺激诱发听性脑干反应 行为测听 声场助听听阈检测
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Impact of Urban Community Health Resource Allocation on Chronic Disease Management Among Middle-Aged and Older Adults and Planning Responses: Evidence from a Threshold Model
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作者 Zhang Yuzheng Lu Yan +2 位作者 Chen Xiaojian Liu Jinxin(Translated) Lai Yuan(Proofread) 《China City Planning Review》 2025年第2期58-66,共9页
Chronic non-communicable diseases have become a significant threat to the health of middle-aged and older adults in urban areas.The allocation of health resources in urban communities is associated with the prevalence... Chronic non-communicable diseases have become a significant threat to the health of middle-aged and older adults in urban areas.The allocation of health resources in urban communities is associated with the prevalence of chronic diseases.This study conducts an empirical analysis using threshold regression methods based on data from the China Health and Retirement Longitudinal Study(CHARLS).It explores the nonlinear impact of community health resource allocation on chronic disease management among middle-aged and older adults across different age groups.The goal is to allocate health resources scientifically based on the health and activity needs of specific age groups.The results reveal staged differences across distinct age intervals.Specifically,the allocation of community health resources has a negative impact on the management of chronic diseases of respondents under 58 years old,an insignificant impact for those aged between 58 and 73 years,and a significant positive impact for those aged above 73 years old.The threshold effect of age is closely related to the health resource preference and activity pattern of different age groups.The alignment between health resource supply and demand within these groups determines their effectiveness in improving health outcomes.These findings could help optimize the spatial allocation of health resources,enhance planning standards,and address existing disparities across communities,thereby providing an evidence-based solution for urban planning decisions. 展开更多
关键词 urban community health resources chronic diseases planning responses threshold model
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Analysis of the pain threshold at the acupoints on the medial crus in pelvic inflammatory disease 被引量:5
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作者 Jiang-yun WU Yi-ni SUN +4 位作者 Qing-chen ZHOU Lei WANG,Zhi-hong WEN Xue-si HOU Shu-han QU Yi-fan JIAb,Ji-ping ZHAOb 《World Journal of Acupuncture-Moxibustion》 CSCD 2018年第3期204-208,I0006,共6页
Objective: To explore the tenderness response at the acupoints on the medial crus in the patients of pelvic inflammatory disease.Methods: A total of 30 patients of pelvic inflammation and 30 healthy people were incl... Objective: To explore the tenderness response at the acupoints on the medial crus in the patients of pelvic inflammatory disease.Methods: A total of 30 patients of pelvic inflammation and 30 healthy people were included. WAGNER FDX body mechanics algometer was used to determine the score of the visual analogue scale(VAS) and tenderness threshold value at Yīnlíngquán(阴陵泉 SP 9), Sānyīnjiāo(三阴交SP 6) and Lígōu(蠡沟 LR 5).The changes in the tenderness on the body surface at the relevant acupoints were compared and analyzed in the patients of pelvic inflammation.Results: The occurrence rate of tenderness at LR 5 at the pelvic inflammation group was higher significantly than the health group(86% Vs 42%, P0.01). In SP 9, SP 6 and LR 5,the VAS scores at the acupoints in the pelvic inflammation group were higher significantly than the health group(test 1:55.00± 15.12 vs 27.25 ± 10.31,47.07 ± 18.38 vs 29.75 ± 14.30, 47.16 ± 19.4 vs 20.16 ±10.76; test2:53.40± 17.23 vs 33.42± 13.07, 45.95 ± 15.74 vs 29.15± 11.97, 42.50± 21.67 vs 21.05 ± 11.97; test 3:48.50± 14.97 vs 40.08 ± 13.20, 38.24± 15.29 vs 29.29± 12.37, 37.93± 19.17 vs 23.09± 12.26), P〈0.01,P〈0.05.In SP 9, SP 6 and LR 5,the tenderness threshold values at the acupoints in the pelvic inflammation group were higher significantly than the health group(test 1:0.86 ± 0.95 vs 0.53 ± 0.39, 0.86 士 0.95 vs 0.53 ±0.39, 0.85 ± 0.77 vs 0.47 ± 0.47; test 2:0.88 ± 0.81 vs 0.44 ± 0.32, 0.98 ± 0.83 vs 0. 44 ± 0. 32,0.85±0.77 vs 0.47±0.47; test 3:0.98±0.80 vs 0.36±0.26, 1.11 ±0.92 vs 0. 36±0. 26,0.85±0.77 vs0.47 ± 0.47), P〈0.01,P〈0.05(P〈0.05).Conclusion: The VAS scores and tenderness threshold values at SP 9, SP 6 and LR 5 in the patients of pelvic inflammation are higher significantly than those in the healthy people. The occurrence rate of tenderness at LR 5 is higher significantly as compared with the healthy people. 展开更多
关键词 Pelvic inflammation Pain response Visual analogue scale Tenderness threshold value
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Context Dependent Auditory Thresholds Determined by Brainstem Audiometry and Prepulse Inhibition in Mongolian Gerbils 被引量:2
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作者 Markus Walter Konstantin Tziridis +1 位作者 Sonke Ahlf Holger Schulze 《Open Journal of Acoustics》 2012年第1期34-49,共16页
Information on hearing thresholds is not always reliable as differences in these thresholds have been described even for the same species. This may partially be due to different methods used by different labs. A frequ... Information on hearing thresholds is not always reliable as differences in these thresholds have been described even for the same species. This may partially be due to different methods used by different labs. A frequently used approach to obtain an estimate of hearing threshold is the electrophysiological recording of auditory brainstem responses (ABR). They are usually recorded under deep anesthesia and represent the auditory evoked far-field potentials at various levels in the central auditory pathway. Alternatively, several behavioral approaches are employed. These commonly use operant or classical conditioning to determine hearing thresholds. A potential disadvantage of these methods is that any sound conditioning may in principle alter auditory perception and therefore auditory thresholds. To exclude this type of methodological bias a prepulse inhibition (PPI) paradigm can be used where an audiogram can be determined without any kind of pre-training. Here we compare the threshold estimates obtained by two different ABR and PPI measurements where stimuli are presented in different contexts, either randomly or non-randomly, to test for a possible effect of auditory sensitization. In addition we test the effect of a frequency specific acoustic trauma on the audiograms obtained with both methods. In general we find behaviorally determined audiograms to be significantly lower in absolute thresh- old compared to ABR measurements. Furthermore non-randomized presentation context of the stimuli generally results in audiograms with 10 to 15 dB lower thresholds than pseudo-randomized presentation. Finally, the amount of threshold loss induced by acoustic trauma is similar for all methods tested. 展开更多
关键词 Acoustic TRAUMA HEARING thresholds AUDITORY Processing STARTLE response
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Strain-threshold- and frequency-dependent seismic simulation of nonlinear soils 被引量:1
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作者 Duguo Wang Chenggang Zhao 《Earthquake Science》 2014年第6期615-626,共12页
A one-dimensional equivalent linear method (EQL) is widely used in estimating seismic ground response. For this method, the shear modulus and damping ratio of inelastic soil are supposed to be frequency independent.... A one-dimensional equivalent linear method (EQL) is widely used in estimating seismic ground response. For this method, the shear modulus and damping ratio of inelastic soil are supposed to be frequency independent. However, historical earthquake records and laboratory test results indicate that nonlinear soil behavior is frequency- dependent. Several frequency-dependent equivalent linear methods (FDEQL) related to the Fourier amplitude of shear strain time history have been developed to take into account the frequency-dependent soil behavior. Furthermore, the shear strain threshold plays an important role in soil behavior. For shear strains below the elastic shear strain threshold, soil behaves essentially as a linear elastic mate- rial. To consider the effect of elastic-shear-strain-threshold- and frequency-dependent soil behavior on wave propaga- tion, the shear-strain-threshold- and frequency-dependent equivalent linear method (TFDEQL) is proposed. A series of analyses is implemented for EQL, FDEQL, and TFDEQL methods. Results show that elastic-shear-strain-threshold- and frequency-dependent soil behavior plays a great influence on the computed site response, especially for the high- frequency band. Also, the effect of elastic-strain-threshold- and frequency-dependent soil behavior on the site response is analyzed from relatively weak to strong input motion, and results show that the effect is more pronounced as input motion goes from weak to strong. 展开更多
关键词 Nonlinear soil behavior Strain threshold Frequency-dependent Site response
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Behavioral and neural auditory thresholds in a frog 被引量:1
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作者 Ryan C.TAYLOR Karin AKRE +1 位作者 Walter WILCZYNSKI Michael J.RYAN 《Current Zoology》 SCIE CAS CSCD 2019年第3期333-341,共9页
Vocalizations play a critical role in mate recognition and mate choice in a number of taxa, especially, but not limited to, orthopterans, frogs, and birds. But receivers can only recognize and prefer sounds that they ... Vocalizations play a critical role in mate recognition and mate choice in a number of taxa, especially, but not limited to, orthopterans, frogs, and birds. But receivers can only recognize and prefer sounds that they can hear. Thus a fundamental question linking neurobiology and sexual selection asks-what is the threshold for detecting acoustic sexual displays? In this study, we use 3 methods to assess such thresholds in tdngara frogs: behavioral responses, auditory brainstem responsesz and multi unit electrophysiological recordi ngs from the midbrain.We show that thresholds are lowest for multiunit recordings (ca. 45 dB SPL), and then for behavioral responses (ca. 61 dB SPL), with auditory brainstem responses exhibiting the highest thresholds (ca. 71 dB SPL). We discuss why these estimates differ and why, as with other studies, it is unlikely that they should be the same. Although all of these studies estimate thresholds they are not measuring the same thresholds;behavioral thresholds are based on signal salienee whereas the 2 neural assays estimate physiological thresholds. All 3 estimates, however, make it clear that to have an appreciation for detection and salienee of acoustic signals we must listen to those signals through the ears of the receivers. 展开更多
关键词 ANURANS AUDITORY BRAINSTEM responses AUDITORY thresholds mate choice Physalaemus pustulosus signal recog nition thresholds sexual selection tungara FROGS VOCALIZATIONS
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干旱胁迫下植被生产力与冠层结构易损性的非一致性评估 被引量:1
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作者 张璐 畅建霞 +2 位作者 杨贵斌 郭爱军 王义民 《农业工程学报》 北大核心 2025年第6期145-153,共9页
频繁的干旱事件已对植被正常生长与生态系统稳定构成威胁。为解析干旱对植被影响的复杂性,该研究基于Copula模型,利用归一化植被指数、总初级生产力和标准化降水蒸散发指数,构建了气象干旱胁迫下植被生产力与冠层结构损失的条件概率模型... 频繁的干旱事件已对植被正常生长与生态系统稳定构成威胁。为解析干旱对植被影响的复杂性,该研究基于Copula模型,利用归一化植被指数、总初级生产力和标准化降水蒸散发指数,构建了气象干旱胁迫下植被生产力与冠层结构损失的条件概率模型,并运用偏最小二乘路径模型,探讨了植被对干旱响应的驱动因子。结果表明,1982—2018年长江流域植被生产力、冠层结构对气象干旱的滞后响应在时间维和空间维呈现出非一致性特征。时间上,植被生产力对气象干旱的响应时间较冠层结构更长;空间上,汉江流域和长江中下游干流区植被生产力易损性高,而金沙江流域和长江干流区间冠层结构易损性高。不同类型植被的易损性不同,水田和常绿阔叶林的生产力损失概率较高,分别为21.05%、17.26%,草地和常绿针叶林的冠层结构损失概率更大,分别为36.35%、35.73%。此外,植被生产力与冠层结构的关键环境影响因子不同,前者主要受控于冠层结构和土壤水分,后者则对海拔和气候因子更为敏感。研究成果有助于深入了解干旱对植被的影响,进而为生态系统管理与保护提供重要的科学依据。 展开更多
关键词 植被生产力 冠层结构 植被响应 触发阈值 长江流域
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露井联采台阶爆破对井下巷道振动的影响 被引量:1
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作者 徐杰 李祥龙 +3 位作者 王建国 胡涛 张彪 刘金保 《高压物理学报》 北大核心 2025年第5期85-102,共18页
在露井联采过程中,为了控制露天台阶爆破振动对井下邻近既有巷道衬砌的破坏,以拉拉铜矿露天转井下过渡开采阶段为背景,采用现场振动监测、理论计算、数值模拟方法,研究既有邻近巷道的动力响应规律。通过对监测数据进行回归分析,得出井... 在露井联采过程中,为了控制露天台阶爆破振动对井下邻近既有巷道衬砌的破坏,以拉拉铜矿露天转井下过渡开采阶段为背景,采用现场振动监测、理论计算、数值模拟方法,研究既有邻近巷道的动力响应规律。通过对监测数据进行回归分析,得出井下振动衰减规律,并对振动主频及瞬时能量进行了分析。采用LS-DYNA数值模拟软件,对露天台阶和井下巷道建立6种不同相对空间位置的模型,进而建立双孔延期爆炸模型,研究了爆破荷载作用下邻近井下既有巷道的动态响应规律。结果表明:露天台阶爆破过程中,爆源下方邻近既有巷道产生的最大振速主要出现在拱部和迎爆侧的边墙部;巷道与爆源的相对空间位置不同,峰值振速所在的方向和位置也不同;在巷道拱顶与炮孔底部竖直方向距离固定为10 m的情况下,巷道边墙与炮孔水平距离在15 m以内时,炸药起爆后巷道结构竖直方向振速较大,超过15 m后,巷道结构水平径向振速较大。通过拟合应力与振速之间的关系,利用巷道极限动态抗拉强度推导出振速阈值为19 cm/s。基于安全阈值调整爆破参数后,可以保证邻近既有巷道的安全。 展开更多
关键词 露井联采 露天台阶爆破 既有邻近巷道 振动响应 安全阈值
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峰前循环扰动下的深埋花岗岩特征参数演化规律与损伤变量研究 被引量:2
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作者 张胜 徐鼎平 +2 位作者 石汉明 吴小刚 易明尚 《岩土力学》 北大核心 2025年第1期73-87,共15页
深部地下厂房开挖过程中所产生的循环扰动会导致围岩损伤,从而降低围岩力学性质。为揭示叶巴滩水电站地下厂房中深埋花岗岩在循环扰动后的分级卸载破坏特性和损伤过程,首先进行了围压为30 MPa、循环应力分别为12.5%~17.5%(低应力)、10.0... 深部地下厂房开挖过程中所产生的循环扰动会导致围岩损伤,从而降低围岩力学性质。为揭示叶巴滩水电站地下厂房中深埋花岗岩在循环扰动后的分级卸载破坏特性和损伤过程,首先进行了围压为30 MPa、循环应力分别为12.5%~17.5%(低应力)、10.0%~37.5%(中应力)、62.5%~72.5%(高应力)峰值强度的峰前恒幅循环扰动,在此基础上进行了3种分级卸围压试验,进而开展了峰前循环扰动下的深埋花岗岩特征参数演化规律分析与损伤变量构建。研究结果显示:低、中应力循环扰动对花岗岩造成的损伤可忽略不计,但高应力恒幅循环扰动会导致轻微损伤。在不同分级卸围压路径下,岩样变形主要集中在最后3个阶段的围压降低过程中,其宏观破裂模式为压剪破坏;弹性模量呈下降趋势,泊松比呈上升趋势,最大剪胀角基本相同;高轴压恒幅循环扰动后的分级卸围压试验下的岩样累积应变能最高,表现出更强的脆性破坏倾向。此外,分级卸围压下的岩样应变能均高于常规三轴压缩下的岩样应变能,后者可作为分级卸围压岩样是否进入加速损伤破裂阶段的判别阈值。采用侧向应变响应法和裂纹体积应变法确定的深埋花岗岩闭合应力、起裂应力和损伤应力分别为其峰值强度的17.9%、42.7%和73.8%,并据此建立了基于裂纹体积应变的损伤变量,进而划分了深部硬岩损伤过程的4个阶段。研究成果可为分析高应力花岗岩的破坏过程提供试验和理论支撑。 展开更多
关键词 峰前循环扰动 分级卸载 特征阈值 侧向应变响应法 裂纹体积应变
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分泌性中耳炎婴幼儿气导短纯音听性脑干反应阈分析
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作者 汪玮 王璐 +6 位作者 沈佳丽 马孝宝 贺宽 宋佳玥 陈建勇 杨军 金玉莲 《临床儿科杂志》 北大核心 2025年第12期902-907,共6页
目的分析分泌性中耳炎(OME)婴幼儿气导短声(c-ABR)和短纯音听性脑干反应(Tb-ABR)阈结果,探讨气导Tb-ABR反应阈对OME婴幼儿分频听力评估的临床意义。方法回顾性分析2018年1月至2022年12月完成ABR反应阈测试的0~24月龄OME婴幼儿以及正常... 目的分析分泌性中耳炎(OME)婴幼儿气导短声(c-ABR)和短纯音听性脑干反应(Tb-ABR)阈结果,探讨气导Tb-ABR反应阈对OME婴幼儿分频听力评估的临床意义。方法回顾性分析2018年1月至2022年12月完成ABR反应阈测试的0~24月龄OME婴幼儿以及正常对照婴幼儿的测试结果。比较两组间气导c-ABR和Tb-ABR反应阈,分析OME组内气导c-ABR和Tb-ABR反应阈相关性。结果OME组43例,男28例、女15例,中位年龄为8(3~14)月龄;气导c-ABR完成检测43例(60耳)、Tb-500 Hz ABR完成检测32例(45耳)、Tb-1000 Hz ABR完成检测27例(39耳)、Tb-2000 Hz ABR完成检测11例(17耳)、Tb-4000 Hz ABR完成检测11例(17耳)。对照组21例,男10例、女11例,中位年龄为6(4~8.25)月龄;气导c-ABR和4个频率Tb-ARB完成检测21例(42耳)。OME组气导c-ABR和Tb-500 Hz、Tb-1000 Hz、Tb-2000 Hz、Tb-4000 Hz ABR反应阈均高于正常对照组(P<0.01)。OME组内气导Tb-ABR 4个频率反应阈均高于气导c-ABR反应阈(P<0.05)。各频率反应阈间呈正相关性(P<0.05),Tb-2000 Hz与Tb-4000 Hz ABR反应阈间相关系数为0.925。结论OME婴幼儿在低、中、高频均可能发生气导听力下降;与气导c-ABR相比,气导Tb-ABR反应阈可提供更多分频听力信息;测试时间有限时,Tb-2000 Hz和Tb-4000 Hz ABR或可选其一完成。 展开更多
关键词 分泌性中耳炎 听性脑干反应阈 婴幼儿
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