Results 31 to 40 of about 1,112,601 (164)
Read the free Plain Language Summary for this article on the Journal blog. Abstract Grasslands worldwide are experiencing severe degradation due to overgrazing, climate change and anthropogenic disturbances, resulting in substantial declines in biodiversity and ecosystem functioning.
Xiaoqi Wang +5 more
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The underappreciated roles of fog and dew on vegetation and biocrusts
Summary Fog and dew represent minor components of ecosystem water budgets in most ecosystems. However, fog and dew can play an essential role in ecosystem dynamics and are particularly important for water‐limited systems. In addition to serving as direct water inputs, fog and dew can influence microclimate and water redistribution, thereby promoting ...
Lixin Wang, Yue Li, Mengyun Sun, Na Qiao
wiley +1 more source
Auto-focus technology and its application based on image processing
Auto-focusing technique is an important method to improve the precision,intelligentization,automatization for the indentation diameter measurement.The paper introduces an auto-focus method of indentation diameter measurement based on image processing ...
Chen, Xiaomei, Yang, Tao, Zuo, Yong
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用数值模拟的方法研究了真空开关开断含谐波的电流时可能出现的截流问题。发现由于谐波的存在,含谐波的电弧电流过零点处的电流变化率可能比基波的相应值增大或减小很多,增大的电流变化率可能使截流值减小,而减小的电流变化率可能使截流值增大,因此系统含谐波时就有可能更容易导致真空开关出现截流,从而可能导致危险的过电压,对被保护的设备造成危害,影响真空开关的应用。
淡淑恒, 唐新龙, 王季梅
doaj
A survey of IUCN Bear Specialist Group (BSG) members revealed that habitat loss, degradation and fragmentation is the greatest threat to each of the 7 species of terrestrial bears. Poaching and human–bear conflicts are also high threats for some of these species.
David L. Garshelis +3 more
wiley +1 more source
天山北坡是西北干旱区重要的绿洲基地,天山北坡的发展影响着新疆的稳定性和区域经济的发展,是新疆最具发展潜力的地区,近几十年以来,天山北坡绿洲人口的增加、社会经济的发展和水土资源的大规模开发利用以及长期农耕活动,促进了绿洲的发展,同时也出现了一系列的生态环境问题。因此,研究绿洲时空变化过程,准确把握绿洲化与荒漠化发展变化的特征与规律,探讨绿洲时空变化的驱动机制,了解天山北坡绿洲化、荒漠化过程及其对人类活动、自然因素变化的响应机制,对于解决绿洲化过程中出现的一些问题和绿洲的可持续发展具有重大现实意义 ...
宋洋
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为探索地磁长期变化中地磁急变事件的识别方法,分析地磁急变的特征,本文基于多个地磁台站子夜均值数据,利用线性拟合方法计算了地磁场X,Y和Z三个分量的年变率,对近年来发生的地磁急变事件进行了识别和分析。结果显示:Y分量能对分析时段内已报道的地磁急变事件进行很好的识别,其中1999年的地磁急变事件,在我国区域内发生的时间可能为1998年,此外2017年可能存在一个新的地磁急变事件;Z分量年变率整体变化平缓,2001年和2013年前后发生两次显著的地磁年变率变化 ...
Yufei He +4 more
doaj +1 more source
Kinetic‐Controlled Growth of Iron Chalcogenide Nanosheets Featuring Besnus Transition
ABSTRACT Two‐dimensional (2D) Fe‐based nanosheets have sparked wide attention owing to exotic magnetism, superconductivity and topological phases. However, the synthesis of 2D FemXn (X = Te/Se/S, m, n: integer), typically in a non‐stoichiometric ratio, remains challenging because of narrow thermodynamic windows.
Hongmei Zhang +11 more
wiley +1 more source
降水是水循环过程中最基本的环节,是地表径流的本源,也是地下水的主要补给来源,降水在时空分布上的不均匀是引起洪涝和旱灾的直接原因。降水的过程伴随着能量的转换过程,雨滴的凝结是吸热过程,而地表降水的蒸发又是散热过程。总之,降水是连接天气、气候和水循环等方面的关键物理过程,也是生态系统清洁水的最终来源,是关系到国计民生的重要气象要素之一。中国降水量的分布极不均匀,且洪涝干旱灾害频发。IPCC 第五次评估报告指出,近百年来全球气候变暖毋庸置疑,气温升高使得大气中水汽增多,水循环加快,极端降水事件增加,在此背景下,
宋世凯
core
ABSTRACT The intricate corrosion environment necessitates the polymeric coating's adaptability to the surroundings. In this work, the integration of rare‐earth Ce(III) ions and ethylene diamine tetramethylene phosphonic acid (EDTMP) in a layered double hydroxide (LDH) material is developed to enhance the corrosion protection and anti‐wear properties of
Yangu Liu +9 more
wiley +1 more source

