Results 41 to 50 of about 64,092 (179)
Functional Ecology, EarlyView.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
wiley +1 more source
Comprehensive Error Model and Experimental Research of Large Aperture Optics Measurement Platform [PDF]
, 2015 大口径高精度光学元件，特别是非球面光学元件，已经广泛应用于航空航天、天文及惯性约束聚变(ICF)激光装置等国家重大工程中，特殊的工作环境对光学元件的面形精度和表面质量均提出了很高的要求。在制造过程中，为了达到各项技术参数的要求，非球面光学元件必须经过反复检测，并将检测得到的面形精度信息反馈到加工系统中，以指导下一步加工工序的修正和补偿。为了使大口径光学元件检测平台的测量信息能够准确地指导加工，对大口径光学元件检测平台的精度提出了更高的要求。 本文以所在课题组自行研发设计的“大口径光学元件检测平台 ...
王詹帅
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Methods in Ecology and Evolution, EarlyView.Abstract Molecular identification of insect food webs can accurately reveal complex trophic interactions and serve as a foundation for understanding ecosystem functioning and advancing biodiversity conservation. This process typically involves DNA library construction, high‐throughput sequencing and subsequent steps, including data assembly, annotation,
Xiao‐man Zhang +9 more
wiley +1 more source
The experimental design and analysis for wavefront characterizing of an expended laser beam [PDF]
, 2015 激光波面分析与检测是精密测量技术的一个研究方向，它是建立在干涉测量技术的基础上而发展起来的。在经典物理学中，杨氏双缝干涉是最经典的干涉现象，这种干涉是基于等倾干涉原理通过条纹的变化来检测相干光束的波面特性。另外，基于等厚干涉技术发展起来的准直光检验器，在高效方便化的准直技术检验方面展现出了巨大的发展潜力。本文以由一块平行平晶组成的准直光检验器为核心，利用扩束镜改变633nmHe-Ne激光器的波面特性，在扩束镜光路轴后方，利用准直光检验器检验扩束激光波面特性 ...
林坤生
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Conservation Biology, EarlyView.Abstract Prioritization in conservation is crucial for the development of efficient and effective decision‐making policies. For many decades, the importance of some species and their habitats has been assessed and applied in conservation legislation, but bats and their diurnal roosts have ofbeen overlooked.
David López‐Bosch +6 more
wiley +1 more source
He jishu国际原子能机构（International Atomic Energy Agency，IAEA）与美国医学物理学家协会（American Association of Physicists in Medicine，AAPM）联合制定的外照射光子束小野静态射野剂量学操作规程（TRS-483）中提供的小野射野输出修正因子（kQclin,Qreffclin,fref）未考虑均整模式（Flattening Filter，FF）、非均整模式（Flattening Filter Free，FFF）束流间差异 ...
张 国龙 +8 more
doaj +1 more source
Research of Total Alkalinity Online Monitoring and Control System [PDF]
, 2016 总碱度是锅炉水处理过程中的一项重要指标，为保证锅炉的安全运行，需要对锅炉水总碱度进行精确测量并随时了解锅炉水中碱度的情况。目前，锅炉水总碱度的监测一般采用传统滴定的方法，即人工移取水样后再进行滴定的方式，但该方法不仅劳动强度大，还具有错误率较高、效率低下、管理混乱等问题，对安全生产也会产生一定的影响。针对以上问题，本文研究了一种对锅炉水总碱度进行自动测算、数据传输以及监控的总碱度在线监测和控制系统。 为了满足锅炉水总碱度自动测算和远程监测的需求，本文建立了锅炉水总碱度在线监测和控制系统 ...
陈宜飞
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A link between increased temperature and avian body condition in a logged tropical forest
Conservation Biology, EarlyView.Abstract The combined effects of anthropogenic disturbances, such as logging and climate change, remain poorly understood; yet, they are the main threats to tropical biodiversity. Most tropical African countries lack long‐term climate data, so climate impacts on biodiversity cannot be assessed.
Moreen Uwimbabazi +7 more
wiley +1 more source
Development of New Ultrasonic Flow Meter [PDF]
, 2015 过去，机械流量计和电磁流量计占据了国内流量计市场的绝大多数份额。但是，二者都存在着致命的缺陷，比如寿命短、流体质量要求高等，这些缺陷阻碍了流量计性能的进一步提升。近些年，超声波流量计在流量测量仪器领域所发挥的作用越发重要。相比于其它流量计，超声波流量计维护方便、寿命长等特点使其更能满足市场需求。最重要的是，它更容易获得高精度的测量结果。 随着超声波流量计在工业和商业领域得到越来越广泛的应用，也就越来越迫切地需要提高其测量性能。为了改进超声波流量计的测量稳定性，本文设计了一种圆管和方管相结合的新型流量管 ...
康凌
core
The collective application of shorebird tracking data to conservation
Conservation Biology, EarlyView.Abstract Addressing urgent conservation issues, such as the drastic declines of North American migratory birds, requires creative, evidence‐based, efficient, and collaborative approaches. The abundance of over 50% of monitored North American shorebird populations has declined by over 50% since 1980. To address these declines, we developed a partnership
Autumn‐Lynn Harrison +71 more
wiley +1 more source