Results 21 to 30 of about 1,112,601 (164)
Shuitu Baochi Xuebao, 2007 通过对沙坡头地区不同植被类型沙地土壤表层水分时空变化特征的研究表明，该区不同植被类型沙地土壤表层水分的分布均符合正态分布，降雨使表层土壤水分的空间变异性减小，空间自相关性减弱，分维数减小，空间自相关范围由干旱时的5m左右内变化扩大到几十米，土壤表层水分的空间依赖性增强；在土壤表层水分含量极低的情况下，土壤表层水分的空间变异性规律与土壤水分含量的变化规律一致；在土壤水分含量不是很低的情况下，其空间变异性与土壤表层水分含量变化趋势相反，流沙地、柠条地A、柠条地B、油蒿地 ...
潘颜霞 +3 more
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International Journal of Applied Linguistics, EarlyView.ABSTRACT This study examines how foreign language teachers’ beliefs about the medium of instruction and translanguaging evolve over time by revisiting three in‐service teachers twelve years after their initial interviews. Using a qualitative longitudinal design, the study traces how translanguaging was initially framed as pedagogically deficient but ...
Danping Wang
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Facets of Crises: How Problem Indicators and Public Perceptions Affect Policy Change
Policy Studies Journal, EarlyView.ABSTRACT Crises are widely acknowledged as catalysts for policy change. Yet, our understanding of the policy effects of crises remains limited. Why do only some crises lead to major changes, while significant policy changes also occur during seemingly non‐crisis periods?
Constantin Kaplaner +6 more
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Shuitu Baochi Xuebao, 2004 通过野外调查和对2000年TM影像的解译，分析了研究区土地沙漠化的分布格局与发展态势，以及土地沙漠化造成的负面影响。从气候因子的时空分布与变化和人地关系两大方面，探讨了研究区土地沙漠化发生、发展的原因。结果表明，沙漠化土地在空间分布上，与春季风蚀气候因子分布范围不一致；沙漠化在发展的速率上，与三大气候因子的动态变化不一致。结论指出：近50年来，气候因子的时空变化不是研究区土地沙漠化的主要原因；人畜压力与环境容量严重失衡，研究区人地关系的管理上屡有失误，落后的生产、生活方式转变缓慢 ...
刘树林 王涛
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New Phytologist, Volume 251, Issue 3, Page 1267-1282, August 2026.Biosynthesis and accumulation of tanshinones in the periderm of Salvia miltiorrhiza during secondary root growth. Summary Perennial herbs develop long‐lived roots that undergo repeated cycles of secondary growth, during which the periderm functions as a protective barrier and a major site of specialized metabolite accumulation.
Licheng Liu +19 more
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Shuitu Baochi Xuebao, 2008 土壤含水率在水平和垂直方向上均具有高度的时空异质性,关于水平方向变异的研究取得了很大进展,而对垂直方向变异的研究较为缺乏。为掌握土壤含水率在剖面上的垂直变异特征,采用经典统计、地统计及分形分析相结合的方法,研究了黄土高原典型坡地剖面土壤含水率的时空变异性。结果表明:不同测定时间下的剖面土壤含水率均服从自然对数正态分布,在空间上均表现为中等变异性,沿土层深度方向的变化趋势均为增长型,且这种变化规律具有时间稳定性;剖面土壤含水率在整个研究区域尺度、微尺度上的半方差函数均可用指数模型进行很好地拟合 ...
王云强, 张兴昌
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Enhanced Magnetocaloric Effect in Tb‐Co‐Ni Magnets via Chemical Pressure
Rare Metals, Volume 45, Issue 7, July 2026.ABSTRACT Magnetic refrigeration materials are significantly needed in versatile modern industries, including scientific research, aerospace, and health care, due to their potential applications in gas liquefaction and storage. Herein, a significantly enhanced magnetocaloric effect with a suitable operation temperature range of 53–114 K and a giant ...
Lei Xi +11 more
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Gaoya dianqi, 2014 提出了一种计算投入空载变压器时引起的励磁涌流最大值的方法。基于对空投变压器励磁涌流机理的分析,提出根据变压器的铭牌基本参数,并通过磁通饱和点的定位,确定变压器的磁化特性曲线大致形状,利用磁化曲线饱和区段近似于线性的特性跟踪磁通变化,估算励磁涌流的最大值,并计算最大励磁涌流引起电压暂降的深度及持续时间。通过对一个配电变压器及电力变压器进行空载合闸操作仿真,对比仿真结果和计算结果,结果验证了所提方法的有效性和准确性。
刘晓华, 黄静, 阮绵晖, 曾庆辉
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Mechanoluminescent Mixed‐Anion Borate Sr2B5O9Cl:Eu for Dynamic Anticounterfeiting
Rare Metals, Volume 45, Issue 7, July 2026.ABSTRACT Mechanoluminescence (ML)—the emission of light in response to mechanical stimuli—offers a direct and visually intuitive route for transducing mechanical information into optical signals. Herein, we report a mixed‐anion strategy to prepare mixed‐anion borate Sr2B5O9Cl:Eu phosphors through a facile, low‐temperature, and ambient‐atmosphere solid ...
Yuhong Han +7 more
wiley +1 more source
Shuitu Baochi Xuebao, 2020 基于1968年、2004年和2018年3期高分遥感影像，以王茂沟流域为典型研究区，提取了3个时间点的沟沿线、土地利用、水土保持措施、植被覆盖度和LS因子，对近50年侵蚀沟时空变化特征及其影响因素进行了分析。结果表明：（1）用遥感方法采集的信息，可基本满足侵蚀沟中长期变化分析；（2）50年来王茂沟流域侵蚀沟一直处于变化中，时间上变化速度逐渐减缓，前期和后期沟头年均前进速率分别为0.30，0.27 m/a，沟壁年均扩张速率分别为0.009，0.004 m/a；空间上2个时期年均侵蚀沟变化密度大于200 m/（
杨力华 +6 more
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