Results 31 to 40 of about 1,261,710 (147)

Life Stage‐Specific Genetic Diversity and Landscape Characteristics Collectively Influence Genetic Recovery in Pometia pinnata Population 生活史阶段特异的遗传多样性与景观特征对番龙眼种群遗传恢复的协同影响

open access: yesIntegrative Conservation, Volume 5, Issue 1, Page 137-149, March 2026.
Pometia pinnata demonstrated life‐stage‐specific genetic responses to landscape features, with asymmetric gene flow patterns and population recovery following historical bottlenecks, revealing complex topographic and demographic influences on forest genetic structure.
Madhuparna Chatterjee   +5 more
wiley   +1 more source

复合绝缘子芯棒湿热老化特性研究

open access: yesDianci bileiqi, 2020
由于长期运行在湿热的气候环境下,近年来我国南方地区复合绝缘子异常发热、击穿断裂等故障时有发生,严重威胁了电网的安全稳定运行。为了研究复合绝缘子芯棒的湿热老化特性,首先对芯棒材料进行湿热老化实验,然后利用扫描电镜、红外光谱、热重分析和介电分析等手段对湿热老化和酥朽断裂芯棒进行分析,结果表明:湿热的联合作用能够显著加速芯棒的老化进程,随着湿热老化时间的增加,样品的表面微观形貌、化学基团、热解性能和介电性能均逐渐劣化,其中环氧树脂的碳链和碳氧链的吸收峰、热解剩余质量、介电参数可作为芯棒材料的老化特征参量 ...
曾磊磊   +10 more
doaj  

Risk of Secondary Extinction in the Asian Songbird Trade, as Exemplified by the Selling of Crested Jayshrikes as Master Birds

open access: yesIntegrative Conservation, Volume 5, Issue 1, Page 33-45, March 2026.
The Asian Songbird Crises negatively affects so‐called master birds, species that are used to increase the song complexity of competitive songbirds. We assessed the trade in a master bird, the crested jayshrike, in Indonesia before and after its legal protection.
Vincent Nijman   +11 more
wiley   +1 more source

基于时域介电法和动态贝叶斯网络的变压器油纸绝缘老化状态评估

open access: yesGaoya dianqi, 2019
为了能够实现对变压器油纸绝缘老化状态的准确评估,文中在极化/去极化电流方法的基础上,提出6种表征油纸老化的特征量,并将动态贝叶斯网络引入到油纸绝缘老化状态评估问题中,建立了相应的老化阶段预测模型,针对该模型进行了实例验证。结果表明:从PDC及拓展Debye模型提取的绝缘纸电量Qpaper、稳定平均电导电流■以及平均极化时间常数■对油纸老化状态反映敏感,且与聚合度有良好的拟合关系,可作为表征绝缘纸老化的特征量;油纸绝缘老化状态评估问题符合动态贝叶斯网络的应用条件,通过划分特征量状态及老化阶段 ...
吴晋媛   +4 more
doaj  

Investigating Drivers of Tiger Bone Glue Consumption in Vietnam 调查越南虎骨胶消费的驱动因素 Điều Tra Nguyên Nhân Dẫn Đến Tình Trạng Tiêu Thụ Cao Hổ Cốt Tại Việt Nam

open access: yesIntegrative Conservation, Volume 5, Issue 1, Page 115-124, March 2026.
We found the estimated use of tiger bone glue within the last 12 months to be 6.9%. We found a stated motivation of taking TBG to improve health, and by the suggestion of one's social group. We suggest reducing the acceptability of TBG as medicine and encouraging non‐animal‐based medicinal alternatives.
Elizabeth Oneita Davis   +5 more
wiley   +1 more source

总糖作为油浸变压器纸绝缘热老化新特征量的可行性研究

open access: yesGaoya dianqi, 2020
对油中纸绝缘材料在不同温度条件下进行加速热老化试验,以绝缘纸聚合度作为诊断纸绝缘老化程度的标准,采用蒽酮比色法测量了老化油样中的总糖含量,探究油中总糖、糠醛与聚合度的相关性关系。研究表明:聚合度在1 000~600范围内对应的油样中的总糖含量均随着聚合度降低而逐渐增大且总糖含量比糠醛含量变化更显著,故在老化前中期阶段,油中总糖可作为新的特征量来表征油纸绝缘老化程度;聚合度在600~200范围内对应的油样中总糖含量未呈现出统一的变化规律,故在老化中后期阶段,总糖无法用来表征油纸绝缘老化程度 ...
付强   +4 more
doaj  

THE Role of Law in Structuring Sustainable Finance for Infrastructure Projects in Sub‐Saharan Africa: A Comparative Study of Nigeria, South Africa, and Kenya

open access: yesJournal of Critical Infrastructure Policy, Volume 7, Issue 2, Fall/Winter 2026.
ABSTRACT Sub‐Saharan Africa (SSA)'s infrastructure deficit is not fundamentally a consequence of insufficient capital but rather of legal and institutional failure. This article argues that law is a decisive factor in determining whether infrastructure finance becomes possible, functioning not merely as a background condition but as a mechanism through
Augustine Edobor Arimoro
wiley   +1 more source

基于频域介电谱和多输出支持向量回归的变压器油纸绝缘状态评估

open access: yesGaoya dianqi, 2018
为分别评估变压器油纸绝缘的老化程度和水分含量,文中通过加速热老化试验和吸潮实验制备了不同老化程度下含水量不同的油浸绝缘纸试品,测试了试品的介损因数频谱和阻抗相位频谱,分析了老化、水分对油纸绝缘频域介电谱特性的影响。采用多输出支持向量回归算法(multi-output support vectorregression,M-SVR)逼近频域介电谱曲线与油纸绝缘老化和水分之间的非线性映射关系,据此预测油纸绝缘试品的老化程度和水分含量。研究表明,对于含水量在0.5~5.6%范围内、具有不同老化程度的试品,M ...
杨飞豹   +5 more
doaj  

一种不溶性硫磺制备过程中老化进度检测方法

open access: yes, 2004
本发明涉及检测不溶性硫磺制备过程中老化是否完全的中间产品检验技术,具体地说是一种利用差热分析技术不溶性硫磺制备过程中老化进度检测方法,利用差热分析方法,以空气为检测气氛,检测温度为20℃~200℃,通过测定老化样品差热分析曲线,观测其在30℃~160℃内有无出现明显的放热峰,判断老化是否完全。其实用性好,能快速、准确确定老化程度;在制备不溶性硫磺过程中,本发明使用差热技术,利用老化产品差热峰型变化,适时监空老化进度,达到控制产品质量的目的 ...
徐杰, 孙志强
core  

计及电缆绝缘不均匀老化的接地电流相位角特性研究

open access: yesGaoya dianqi
交联聚乙烯(XLPE)电力电缆广泛应用于配电网和输电网,但它们在持续的电应力下遭受长期的老化退化,电缆老化容易造成绝缘击穿事故。为了提升电缆绝缘老化状态的在线评估技术,基于PSCAD建立了计及电缆绝缘不均匀老化的三芯管型电缆接地电流相位角计算模型,通过快速傅里叶变换FFT变化得到单相不均匀老化、双相不均匀老化、三相均匀老化3类情况的接电线电流相位角特性。结果表明:相比于钢铠接地线电流,屏蔽线电流相角对于老化特性的反应更为灵敏;对于单相老化,介电常数由2增加为5,屏蔽线电流相位角从-51.01°递增为 ...
刘刚   +5 more
doaj  

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