Results 31 to 40 of about 400,328 (142)

Rare Records of Tropical Spiders Preying on Vertebrates in Southwest China 热带地区罕见的蜘蛛捕食脊椎动物记录:来自中国西南部的四例观察

open access: yesIntegrative Conservation, Volume 4, Issue 3, Page 334-338, September 2025.
This study reports four rare events of spiders preying on vertebrates in the Xishuangbanna Tropical Botanical Garden, Southwest China. The predators included a giant golden orb‐weaver, huntsman spiders, and a wandering spider, while the prey consisted of a small bird, a blind snake, a gecko, and a tiny shrew.
Wanlu Liu   +6 more
wiley   +1 more source

连续饱和型磁控电抗器数学模型及谐波的数值计算

open access: yesGaoya dianqi, 2015
不同结构及尺寸的磁阀对磁控电抗器输出的谐波电流含量有不同的影响。通过对分级磁阀结构的分析,提出结构更为简单的新型磁阀——连续型磁阀。这种磁阀结构不存在分级面积及级数等问题,从而分析与设计得到简化。利用小斜率理想磁化模型及积分思想建立了连续型磁阀的等效磁化特性模型,进而得出该磁阀结构的磁控电抗器(连续饱和型磁阀式可控电抗器)的谐波特性模型。在此基础上,对连续饱和型磁控电抗器的控制特性和谐波特性进行了分析。理论研究表明:连续饱和型磁控电抗器对除3次外的5、7次谐波电流有较好的抑制效果,均不超过额定电流的0 ...
石鹏太, 田铭兴, 王兴龙
doaj  

Study on gas accumulation modes of Xujiahe Formation tight sand gas reservoirs, in the middle of Western Sichuan Depression, China(川西坳陷中段须家河组致密砂岩气藏成藏模式探讨)

open access: yesZhejiang Daxue xuebao. Lixue ban, 2016
通过分析流体包裹体均一温度和砂岩碳酸盐胶结物氧同位素数据,并结合沉积-埋藏史,研究须家河组流体活动特征,进行储层致密化分析.在此基础上,结合烃源岩演化、储层致密化、流体活动等研究,探讨川西坳陷须家河组致密砂岩气藏成藏模式.认为:须家河组具有形成“连续型”气藏的地质条件,砂岩持续致密化,自烃源岩沉积后持续生烃,流体包裹体的显微观测也表明油气充注在持续进行.据此认为,须家河组气藏成藏模式是“前期边致密边成藏,后期裂缝发育成藏”.
SHANGChangjian(尚长健)   +4 more
doaj   +1 more source

基于连续非连续质点法的冰的脆性破坏模拟

open access: yes, 2014
本文在基于连续介质力学的离散元方法基础上,引入可分裂物质点和子域的 概念,结合有限元法、离散元法和无网格法的优势发展了连续非连续质点法,并 在拉格朗日系统下给出了严格的数学表述。该算法不仅可以描述材料的静态变形, 更能准确计算材料内部的波传播特性、裂缝的产生和发展过程、破裂面的接触摩 擦以及块体的碰撞运动,实现了连续-非连续统一表述。 提出了一类可描述脆性材料渐进破坏行为的损伤本构模型——应变强度分 布本构模型,并给出了几种不同表述形式。该模型引入应变强度分布的概念,刻 画材料的非均匀性 ...
周东
core   +2 more sources

Trump, Personalism, and US Administrative Capacity

open access: yesPolitics &Policy, Volume 53, Issue 4, August 2025.
ABSTRACT Donald Trump represents an extraordinary degree of personalism in American politics, especially given the traditional power and capacity of the Republican Party and American democracy. A lesson Trump drew from his first term in office is that he needed to better institutionalize mechanisms of personal loyalty to deal with perceived betrayals ...
Donald Moynihan
wiley   +1 more source

一种连续流动超极化氙气体发生及样品原位处理装置

open access: yes, 2007
一种连续流动超极化氙气体发生及样品原位处理装置,其特征在于,由碱金属蒸发器和激光泵浦室组成;其中,碱金属蒸发器为一内部放置有碱金属的石英密封管,该石英密封管的一端连接样品处理气体阀,另一端连接一激光泵浦室;该激光泵浦室为一石英密封管,其一端通过一冷凝管连接至核磁共振仪的核磁探头;石英密封管外部套设一加热套,该加热套与温控仪连接;激光泵浦室与一激光器相连接。本实用新型提供的连续流动超极化氙气体发生及样品原位处理装置,适于催化材料孔结构与催化过程研究,利用激光泵浦超极化氙技术 ...
包信和   +4 more
core  

连续管钻井系统摩阻计算方法与试验研究

open access: yesShiyou jixie, 2015
连续管应用越来越广泛,但是由于连续管管径小、流阻大等特点,系统性地研究连续管钻井系统摩阻压降已迫在眉睫。基于理论研究,筛选相关计算模型,得到了符合连续管钻井实际的摩阻计算模型;筛选了4种数值模拟计算模型,并进行多盘管规格和多流量的数值模拟计算,通过分析计算结果与理论计算的误差,采用标准κepsilon模型作为数值模拟计算模型更为合适。开展了连续管钻井系统盘管摩阻压降试验,将理论计算、数值模拟计算与试验数据进行比较,在绝大多数试验流量测点处,它们的误差范围均在10%以下 ...
周博   +5 more
doaj  

Transformation of social‐ecological systems in the Songhua River Basin, Northeast China: Lessons for a more sustainable development

open access: yesPeople and Nature, Volume 7, Issue 7, Page 1749-1768, July 2025.
Abstract Social‐ecological systems (SES) are coupled systems formed by the intricate interactions between humans and nature. Our movement towards sustainable lifestyles requires a robust understanding of these interactions. Achieving a sustainable win‐win situation for both social and ecological systems, therefore, necessitates a sound scientific ...
Na Sa   +6 more
wiley   +1 more source

基于COMSOL Multiphysics的连续雷电流分量对OPGW断股分析

open access: yesDianci bileiqi, 2020
光纤复合架空地线(OPGW)的断股严重影响着电力系统的安全稳定性,为了研究雷电流对OPGW断股的影响,应用COMSOL Multiphysics对雷击点局部温度进行仿真,对雷电流C分量单独作用和连续雷电流A、C分量作用下的OPGW断股特性进行分析。结果表明:雷电流C分量对OPGW的破坏性较为严重,转移电荷量是产生断股的主要原因。连续雷电流A、C分量作用产生温度与断股程度均高于C分量单独作用,雷电流A分量对断股有明显影响。仿真结果为今后OPGW的抗雷击性能与机械性能研究提供参考。
孙伟   +6 more
doaj  

Amazonian conservation across archipelagos of Indigenous territories

open access: yesConservation Biology, Volume 39, Issue 2, April 2025.
Abstract Indigenous stewardship is essential to the conservation of biocultural diversity, yet conventional conservation models often treat Indigenous territories (ITs) as homogeneous or isolated units. We propose that archipelagos of Indigenous territories (AITs), clusters of ITs that span geographies but are connected through shared cultural or ...
Michael S. Esbach   +3 more
wiley   +1 more source

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