Results 41 to 50 of about 14,108 (165)
Shuitu Baochi Xuebao, 2008 采用室内模拟土柱淋洗方法研究了无机复合肥、有机复合肥、猪粪堆肥和花生麸4种肥料单施和两两混施条件下氮磷在赤红壤中的淋失特征。结果表明,各处理总氮淋失率在43.2%～74.8%之间,总磷淋失率在0.01%～0.08%之间,赤红壤中肥料氮淋失严重,肥料磷淋失有限。肥料单施处理的无机氮淋失量和有机氮基本相近,肥料混施处理的无机氮淋失量远高于有机氮;各施肥处理磷的淋失均以颗粒磷为主。肥料混施显著增加铵态氮和无机氮淋失,减少有机氮和总氮淋失。猪粪与复合肥混施减少颗粒磷和总磷淋失 ...
曾曙才 +3 more
doaj
Strength Calculation of Harmonic Gear Reducer in Assembly and Dynamic Operation Process [PDF]
, 2017 自从C.W.Musser发明了谐波齿轮减速器并运用到火箭上后，由于它的传动比大、重量轻、可靠度强、体积小、传动精度高等优点而倍受关注。我国从两弹一星开始，在大力发展航天事业的背景下，谐波齿轮减速器被广泛地运用到火箭及卫星的传动机构中。但国内对于谐波齿轮减速器的失效机理和结构优化及多样化等方面还需深入研究，尤其缺乏对其动态运转强度较为精确的计算和对其疲劳寿命的评估。 针对上述问题，本文研究谐波齿轮减速器的强度与失效机理，给出了一种基于应力-寿命法的疲劳预测过程，并对谐波减速器的结构进行了改进 ...
杨健
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Growing Demand and Uneven Supply: Eight Years of Nature Education in China 需求增长与供给不均:中国自然教育八年发展回顾
Integrative Conservation, Volume 5, Issue 1, Page 46-58, March 2026.ABSTRACT This study examines the role of nature education in advancing conservation and sustainability in China between 2014 and 2023. Drawing on national survey reports and historical–comparative methods, it analyses the dynamics of public demand, institutional supply, and practitioner capacity.
Qi Yunxi, Lyu Xiang, Huang Yu
wiley +1 more source
Shuitu Baochi Xuebao, 2007 利用土柱淋洗模拟试验,研究了酸雨影响下,不同施肥处理紫色土氮、磷淋失的动态变化特征。结果表明,在酸雨作用下,紫色土中硝态氮的淋失量远远大于磷元素;不同施肥处理下二者淋失量的大小不同,淋失量大小排序均为有机无机混合施用〉化肥〉有机肥〉对照处理;淋失量受施肥量和降雨量的影响明显,土壤中硝态氮、磷元素淋失量随施肥量的增加而增加,淋失过程主要集中在雨季。同一施肥处理下,土壤硝态氮淋失量随降雨pH值的升高而增加;pH值5.5是土壤磷元素淋失量的临界点,此时土壤有效磷含量最高,淋失量达到峰值。
张华, 杨永奎, 谢德体, 王定勇
doaj +2 more sources
Rare Metals, Volume 45, Issue 3, March 2026.ABSTRACT Expanding near‐infrared (NIR) spectral response and utilizing ultraviolet (UV) photons are effective strategies for enhancing the power conversion efficiency (PCE) of lead halide perovskite solar cells (PSCs). However, the range of NIR spectral response extension and the utilization of UV light for devices are not enough, and the loss of ...
Li He +9 more
wiley +1 more source
Multichannel Online Lifetime Accelerating and Testing System for Light-Emitting Diodes [PDF]
, 2017 LED寿命长达数万小时，具有高效、节能、环保、高可靠性的优点，是当前国家正在提倡和推广的照明光源。然而，LED长寿命的优点却成为寿命评估的短板，需要耗费大量时间。加速寿命可大大缩短实验时间，同时也是探索LED失效机理，进一步提升LED性能的有效手段。传统的LED加速寿命方法往往采用离线测试方法，将样品连同夹具置于高温箱中，通过高温箱控制样品的整体环境温度，但是在老化过程期间需要中断老化，将样品冷却取出对其各个参数进行测试。为了更加便捷地连续性测试，一些科研机构也提出了在线测试方法 ...
肖菁菁
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Experimental study on progressive failure of anchoring structure under high-frequency and low-energy impact disturbance [PDF]
High-frequency, low-energy impacts consistently inflict damage on the surrounding rock and anchoring structure in deep roadways, leading to ongoing instability. The construction of anchoring support system that can withstand these dynamic impact loads is
Jiaguang KAN +5 more
core +1 more source
Evolution of research on global amphibian declines
Conservation Biology, Volume 40, Issue 1, February 2026.Abstract In the late 1980s, the scientific community became aware of severe, enigmatic amphibian population declines. These declines triggered a wave of research focused on quantifying their extent and identifying key drivers. We used text‐analysis techniques, including topic modeling and geoparsing, to examine the evolution of research focused on ...
Jordann Crawford‐Ash +6 more
wiley +1 more source
Monte-Carlo simulation of lifetime distribution on array interconnection of LED module [PDF]
, 2011 利用蒙特卡洛方法对阵列化互连lEd模组的可靠寿命进行了模拟,假设分档后的大功率白光lEd的正向电压符合正态分布,额定电流下的寿命符合对数正态分布,且寿命和电流、温度的关系符合EyIng模型,研究了nxn(6≤n≤12)lEd阵列的寿命分布。模拟结果表明,对于nxnlEd阵列,寿命随lEd数目的增加没有下降反而略有增加,表明对多数目lEd模组采用阵列化互连电路较传统串并联电路具有优势,能提高阵列的可靠性;对系统采用电流降额使用,可靠寿命随着电流降额量的增大而增大,电流降额越大,寿命增大越多 ...
夏正浩, 李炳乾, 郑同场
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