Results 81 to 90 of about 164,546 (209)

嵌体修复下领第一磨牙残冠的三维有限元模型的建立

open access: yesZhongshan Daxue xuebao. Yixue kexue ban, 2005
【目的】建立带桩嵌体修复下颌第一磨牙残冠的三维有限元模型。【方法】制成第一磨牙残冠的制锁式带桩嵌体修复体的模型,将该模型置于水杯中,利用螺旋CT扫描,通过图像合成软件建立三维数字模型,结合大型有限元软件ANSYS进行建模。【结果】建成后三维有限元模型与实体组织具有良好的几何相似性。【结论】将牙体修复模型置于水中,经螺旋CT扫描并与有限元方法结合起来,可以建立复杂的牙模型,且能真实地模拟实际情况,使用性好。
连克乾   +4 more
doaj  

Biodiversity‐driven spatial conservation planning to delineate temporally stable regions

open access: yesConservation Biology, EarlyView.
Abstract The accelerating loss of biodiversity underscores the critical need for effective conservation strategies, particularly in the face of climate change and anthropogenic pressures. We devised a conservation planning framework that adopts a temporal stacking approach to species distribution models and landscape connectivity analyses. These models
Mattia Iannella   +5 more
wiley   +1 more source

冲击接地电阻模型对输电线路耐雷水平的比较研究

open access: yesDianci bileiqi, 2015
对规程法冲击接地电阻模型、火花效应接地电阻模型以及暂态接地电阻模型等三种不同的接地模型进行了分析。结合220 kV双回输电线路,在ATP/EMTP中建立了相应的输电线路耐雷水平模型。在该耐雷模型中,使用无损多波阻抗模拟输电线路杆塔,同时考虑了工频电压对耐雷水平的影响。分别在工频电压初相角为0°、60°、120°、180°、240°以及300°等6种情况下计算了模型的反击和绕击耐雷水平。仿真结果表明:在相同的条件下,反击耐雷水平从高到低依次为火花效应模型、规程法模型、暂态电阻特性模型 ...
刘杰   +4 more
doaj  

MSCT影像组学对Borrmann Ⅳ型胃癌与原发性胃淋巴瘤的鉴别诊断价值

open access: yesZhongshan Daxue xuebao. Yixue kexue ban, 2022
目的探讨CT影像组学模型鉴别Borrmann Ⅳ型胃癌与原发性胃淋巴瘤的价值。方法回顾性收集2008年6月至2018年4月经手术或内镜病理确诊的Borrmann Ⅳ型胃癌或原发性胃淋巴瘤的病例共186例,其中Borrmann Ⅳ型胃癌132例,原发性胃淋巴瘤54例。采用计算机软件对CT动脉期、静脉期图像提取放射组学特征,再选择Lasso Logistic回归方法进行特征筛选,并建立CT影像组学模型,此外亦筛选CT主观征象构建CT主观征象模型,并同时利用CT主观征象及组学特征构建联合模型 ...
陈钦贤   +7 more
doaj  

Defining and identifying relevant stakeholders to advance effective conservation

open access: yesConservation Biology, EarlyView.
The challenge of defining stakeholders in environmental science and an approach for refining existing definitions. Abstract Stakeholder is a contested term that has spawned a multitude of ad hoc definitions. The ambiguity of these definitions has oftentimes impeded transdisciplinary research in environmental governance and conservation science because ...
Milan Büscher   +5 more
wiley   +1 more source

Scenarios and strategies for future‐proofing ecosystem management under climatic novelty

open access: yesConservation Biology, EarlyView.
Abstract Climate change is driving unprecedented declines in dominant, habitat‐forming foundation species across marine and terrestrial ecosystems globally. As climatic novelty becomes the norm, ecosystem reassembly will become increasingly common. Predicting and understanding these transitions, and their implications for future ecosystem functioning ...
Lauren T. Toth   +14 more
wiley   +1 more source

Perceived costs as drivers of wildlife management preferences in rural Tanzanian communities

open access: yesConservation Biology, EarlyView.
Abstract Effectively managing human–wildlife interactions is crucial for fostering coexistence on shared landscapes. Management options are most effective when aligned with the preferences of people directly affected by wildlife, yet little is known about how socioecological factors influence these preferences.
Christian Kiffner   +10 more
wiley   +1 more source

平衡态和非平衡态等离子体的微观模型研究

open access: yesGaoya dianqi, 2005
总结和比较了当前主要的几种等离子体微观模型: Potapov模型、Eindhoven模型、基于动力学的模型和基于最小吉布斯自由焓原理的模型。前两种模型的理论依据都是道尔顿分压定律、质量作用定律、电荷准中性条件与化学计量平衡条件,但质量作用定律和配分函数的表达式不同:后两种一个是从化学反应动力学的角度,一个是从热力学和统计物理的基本定义出发,来描述等离子体的微观过程。分平衡态和非平衡态阐述了模型的变化:推荐了Eindhoven模型作为工程计算用的首选模型。
臧春艳, 何俊佳, 程礼椿
doaj  

Drivers of bat researchers’ intent to adopt field hygiene practices

open access: yesConservation Biology, EarlyView.
Abstract Infectious disease is a growing threat to wildlife, with zoonotic transmission most likely at the human–wildlife interface. One underappreciated activity at this interface is fieldwork with wild animals, but associated risks can be mitigated through field hygiene (FH) practices, such as using personal protective equipment and other appropriate
Joanna L. Coleman   +6 more
wiley   +1 more source

输电线路雷击闪络分析中杆塔模型的研究

open access: yesGaoya dianqi, 2015
为更方便地计算输电杆塔各横担的电位以评估多回高塔的耐雷性能,建立了改进单波阻抗模型。基于电磁暂态计算程序,将新杆塔模型与传统的集中电感模型、单一波阻抗模型和多波阻抗模型对比,分析4种模型下塔身垂直方向上电位分布。采用反推法,由Hara多波阻抗模型推导出110、220、500 k V 3种电压等级下常见双回同塔和四回同塔高塔改进单波阻抗的推荐取值。研究结果表明,改进单波阻抗模型下的杆塔塔身电位分布与多波阻抗模型最为接近,在进行整条输电线路或者多基杆塔的防雷特性评估工作时,用改进单波阻抗模型代替多波阻抗模型,
黄文武   +6 more
doaj  

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