Results 31 to 40 of about 560,483 (151)
Shuitu Baochi Xuebao, 2021 为探究春季解冻期覆沙黄土坡面能量参数动态响应时空演化过程，在相同放水流量（1 L/min）条件下，采用2个土壤处理（未冻坡面，冻结坡面）和4个覆沙厚度（0，1，2，3 cm）进行室内模拟冷冻和放水冲刷试验，系统分析了径流流速（V）、径流功率（W）、单位径流功率（P）和径流动能（E）在不同土壤处理和不同覆沙厚度条件下的时空演化过程。结果表明：（1）不同处理下的径流流速随产流时间的延长总体呈下降趋势，随着距坡顶距离的增大总体呈增大趋势。未冻坡面和冻结坡面径流流速的均值在0.23~0.35，0.18~0.35
王伟 +6 more
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Politics &Policy, Volume 54, Issue 2, April 2026.ABSTRACT This study employs advocacy coalition framework (ACF) theory to analyze debates over U.S. space policies designed to avoid dangerous collisions between objects in Earth orbit. For decades, the Department of Defense prioritized national security in its development of space traffic coordination (STC) systems like the Space Surveillance Network ...
Jeffrey S. Lantis
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, 2016 本文是中国科学院科技服务网络计划（STS计划）“城市综合评价技术研发与应用”（KFJ-EW-STS-088）、科技基础性工作专项资助项目“国民重要心理特征调查”（2009FY110100）、中国科学院心理所应急项目“中国人集体主义的心理地图”（Y4CX157009）的阶段性成果.董夏微对本文也有贡献,在此表示感谢! 基于从10个城市3173个样本与全国97543369个样本中获得的常见名字百分比，本研究分析了人名演变的时代变迁。
苏红, 陆柯雯, 任孝鹏, 张慧
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Journal of Critical Infrastructure Policy, Volume 7, Issue 2, Fall/Winter 2026.ABSTRACT Climate disasters are currently changing territory around the world by showing large inequalities that exist in infrastructure systems, governance arrangements, and development pathways. In many cases, climate risk response strategies like managed retreat have been framed as practical approaches to respond to increasing climate disasters ...
Chick Edmond
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Gaoya dianqi, 2015 基于新型永磁斥力混合高速操动机构和转移回路强迫过零开断的方法,在合成回路系统中进行了真空电弧直流开断实验。利用CMOS高速摄像机观测直流开断过程中不同转移电流频率下真空电弧的燃烧及转移过程,采用图像处理技术提取了电弧图像特征,得到了不同转移电流频率下强迫过零阶段电弧的形态变化,不同燃弧时间下的电弧形态变化以及不同预充电电压下的电弧形态变化,并对电弧形态变化的原因进行了分析。分析结果表明,注入同等的电弧能量,转移电流频率较低时,电弧形态演化过程长,有利于熄弧后电极间隙介质绝缘强度的恢复 ...
秦涛涛 +4 more
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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
, 2016 2016年2月11日，从大洋彼岸传来了振奋人心的好消息，科学家经过近百年的努力，终于直接探测到了来自宇宙深处的引力波信号。一百年前，爱因斯坦在创立他的广义相对论时，就预言了这种引力波的存在。长期以来，科学家虽然经历了几代人的努力，想尽了各种办法，使用了异常精密的科学装置，但是始终没有结果。如今，几十年的付出终于得到了回报。显然，这次所取得的非凡成果，在世界科学史上也具有十分重要的意义。这里将继续《话说时空（上）》的话题。 在高维时空中探索万物之理 2015年1月28日，在美国的科学新闻网站上 ...
林烈
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Rare Metals, Volume 45, Issue 1, January 2026.ABSTRACT High‐entropy alloys (HEAs) have emerged as a transformative class of materials distinguished by their complex chemical compositions, unique microstructures, and remarkable mechanical and functional properties. Traditionally, the discovery and optimization of HEAs have relied on conventional methods, including trial‐and‐error experimentation ...
Chrispin Ouko Zamzu +2 more
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The Rhetoric of Disenchantment: Ghost Belief and Secular Critique in Early Twentieth‐Century China
Cognitive Science, Volume 50, Issue 1, January 2026.Abstract This study presents the first large‐scale empirical analysis of how ghosts and spirits were debated during China's early twentieth‐century secular transformation. Using a novel dataset of over 2000 digitized texts—including newspapers, periodicals, and essays from 1890 to 1949—we combine close reading, AI‐assisted annotation, and statistical ...
Ze Hong, Yuqi Chen
wiley +1 more source
Shuitu Baochi Xuebao, 2023 不透水表面扩张对城市生态系统的过程、功能、服务有显著影响,研究其演变规律对城市发展有重要意义。以南京市为研究区,基于2000—2020年土地利用数据,采用空间梯度分析与景观格局分析相结合的方法,沿城市中心向外设置等距辐射状梯度带,分析不透水表面时空分布和梯度变化特征,同时建立沿江、跨江样带,研究不透水表面扩张规模与方向演变背后的驱动机制,最终为南京市景观格局优化提供政策依据。结果表明:(1)不透水表面景观优势度沿梯度带逐渐降低,城市中心不透水表面高度集聚,外围城区是扩张的重点区域,耕地、林地 ...
吴宇哲, 谷晨焯
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