Results 21 to 30 of about 4,146,338 (166)

坡面侵蚀产沙与水力学特征参数关系模拟

open access: yesShuitu Baochi Xuebao, 2017
坡面侵蚀产沙主要受坡面径流动态过程的影响,表征坡面径流过程特征是水力学特征参数。为了研究坡面侵蚀产沙与主要水力学特征参数的关系,揭示坡面侵蚀产沙的水动力学机理。采用人工模拟降雨的方式,通过不同坡长和雨强的组合试验,基于跨雨强和跨坡长的综合性分析的思路,应用经典水力学计算和统计拟合相结合的方法,对特定坡度(20°)下,5个坡长(1,2,3,4,5 m)13个降雨强度的试验监测数据进行了分析。结果表明:(1)在设计雨强(0.65~2.0 mm/min)和坡度范围内,坡面径流都属于缓流 ...
张锐波, 张丽萍, 付兴涛
doaj  

Global drivers of the conservation–invasion paradox

open access: yesConservation Biology, Volume 39, Issue 5, October 2025.
Abstract The conservation–invasion paradox (CIP) refers to a long‐term phenomenon wherein species threatened in their native range can sustain viable populations when introduced to other regions. Understanding the drivers of CIP is helpful for conserving threatened species and managing invasive species, which is unfortunately still lacking. We compiled
Yanhua Hong, Zhiyong Yuan, Xuan Liu
wiley   +1 more source

不同坡度坡面径流输沙能力对集中流流量变化的响应

open access: yesShuitu Baochi Xuebao, 2018
坡面水流的输沙能力是影响土壤侵蚀过程的重要参数之一,加强坡面集中水流输沙能力的研究有助于深入理解集中流发生机理,并为防治集中流侵蚀发生提供科学依据。采用室内集中流放水冲刷试验,以黄土高原典型黄绵土为研究对象,研究了集中流输沙能力与放水流量和坡度以及与单宽流量和坡度之间的关系,同时对集中流水力参数和输沙能力的相应关系进行了研究。结果表明:集中流输沙能力随着坡度和放水流量的增加而增加。多元统计分析建立输沙能力与坡度和放水流量之间的幂函数关系发现坡度指标对输沙能力相对放水流量影响更大,而在坡度和单宽流量作用下,
师宏强, 谷
doaj  

Seasonality of temperature dependence of methane fluxes from natural wetlands

open access: yesFunctional Ecology, Volume 39, Issue 9, Page 2383-2397, September 2025.
Read the free Plain Language Summary for this article on the Journal blog. Abstract Temperature dependence is a crucial parameter in estimating methane (CH4) fluxes from natural wetlands, yet our understanding of this parameter remains inadequate. Seasonal fluctuations in water levels and ecosystem productivity lead to seasonal differences in CH4 ...
Jinshuai Li   +6 more
wiley   +1 more source

高速弓网系统动力学参数敏度分析及优化

open access: yes, 2021
随着高速列车运行速度的提升,弓网关系这一基础力学问题备受关注.良好的弓网关系是确保列车安全高效运行、稳定可靠受流、降低接触线与受电弓滑板磨耗等的基本前提.其中,受电弓和接触网的动力学参数对弓网耦合作用起至关重要的作用.本文采用弓网接触力随机统计特征作为优化目标函数,进行受电弓动力学参数的敏度分析和优化设计.首先,建立了二维弹性链悬挂接触网-三质量块受电弓动力学模型,根据EN50318:2018标准验证了动力学建模和分析结果的正确性.然后,基于高速弓网系统的动力学仿真 ...
吴孟臻, 刘洋, 许向红
core  

三乙醇胺-Ce(Ⅲ)金属配合物催化水解双(对硝基苯酚)磷酸酯研究

open access: yes四川大学学报. 自然科学版, 2005
在30℃和pH8.0的条件下,研究了三乙醇胺与Ce(Ⅲ)形成的金属配合物对双(对硝基苯酚)磷酸酯(BNPP)的催化水解作用,实验发现,该金属配合物对BNPP有高效快速的催化水解作用,在pH8.0时,其水解的表观一级速率常数为1.42×10-2s-1,为BNPP自发水解的1.27×109倍,接近于天然酶的活性水平.提出了催化反应的机理,建立了催化反应的动力学数学模型,获得了相关的热力学和动力学参数.
聂丽, 张元勤
doaj  

Uncovering the Nanozostera japonica species complex suggests cryptic speciation and underestimated seagrass diversity

open access: yesNew Phytologist, Volume 247, Issue 5, Page 2086-2097, September 2025.
Summary The importance of marine angiosperms, or seagrasses, as foundation species for marine coastal ecosystems is in marked contrast to their low species number of only 70 described taxa. Seagrass species tend to have very similar overall morphologies dictated by hydrodynamic forces of the ocean environment.
Xiaomei Zhang   +14 more
wiley   +1 more source

脑动静脉畸形出血因素中的血液动力学分析 [PDF]

open access: yes, 2001
脑动静脉畸形(Arteriovenous Malformation,AVM)是一种先天性的动静脉间短路血管组织,其所导致的异常脑血液动力学状态是造成脑AVM血管破裂出血和产生某些神经功能障碍的重要原因之一。本文结合脑血管内血液动力学参数的临床测量数据,通过建立脑AVM血液动力学模型的方法,对脑AVM出血的血液动力学因素进行了系统的分析 ...
严宗毅, 凌锋, 孙树津, 王大明
core  

坡面产流产沙过程对植被过滤带响应的试验研究

open access: yesShuitu Baochi Xuebao, 2017
为探讨植被过滤带在坡面产流产沙过程中对水沙的拦截效果及其水动力学机理,通过在室内土槽上设置模拟植被过滤带并进行浑水冲刷试验,得到有无模拟植被过滤带情况下的产流产沙情况及相关水动力学参数,定量分析了植被过滤带对径流、泥沙的拦截效果并探讨了坡面产沙率与水动力学参数之间的关系。结果表明,植被过滤带在放水冲刷试验中能有效拦截径流和泥沙,且在较小流量下,径流和泥沙的拦截效果更好,在200 L/h流量下,拦截率分别可达33.2%和96.9%;在冲刷过程中,有无模拟植被过滤带产沙率与水流剪切力 ...
  +4 more
doaj  

Integrating local ecological knowledge into systematic conservation planning for seahorse conservation

open access: yesConservation Biology, Volume 39, Issue 3, June 2025.
Abstract Successful long‐term conservation relies on strategic planning for pragmatic actions to mitigate threats. Prioritizing actions and areas to support conservation goals in the most cost‐effective scenario becomes crucial in resource‐limited environments. However, planning and management can be challenging in data‐limited contexts.
Anna Karolina Martins Borges   +3 more
wiley   +1 more source

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