Results 31 to 40 of about 13,777 (167)

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

open access: yesIntegrative 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

Research on Eddy Current Testing of Damages in Carbon Fiber Reinforced Polymers [PDF]

open access: yes, 2015
碳纤维增强树脂基复合材料因其优异的性能已被广泛应用于飞行器制造、汽车制造、化学工业、造船与电气设备等各个行业,尤其是在航空航天、船舰以及核能设备等领域受到高度重视。然而,复合材料结构件在制造和使用过程中不可避免的会因为冲击等原因产生各种类型的缺陷。此外,复合材料结构件在损坏之前几乎没有先兆,其破坏具有突然性,这一点往往造成严重的后果。因此对碳纤维增强树脂基复合材料损伤的无损检测研究具有极其重要的意义。 目前应用较多的检测碳纤维增强树脂基复合材料损伤的方法有红外检测、X射线检测以及超声检测等 ...
杜飞
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Risk of Secondary Extinction in the Asian Songbird Trade, as Exemplified by the Selling of Crested Jayshrikes as Master Birds

open access: yesIntegrative Conservation, Volume 5, Issue 1, Page 33-45, March 2026.
The Asian Songbird Crises negatively affects so‐called master birds, species that are used to increase the song complexity of competitive songbirds. We assessed the trade in a master bird, the crested jayshrike, in Indonesia before and after its legal protection.
Vincent Nijman   +11 more
wiley   +1 more source

Influence of Spatial Reinforcement Corrosion on Shear Performance of RC Beams---Based on a Numerical Investigation [PDF]

open access: yes, 2016
钢筋混凝土(以下简称RC)结构的耐久性近年来逐渐成为国内外广泛关注的问题。其中,钢筋锈蚀是影响RC结构耐久性的重要因素之一。然而,以往大部分研究多是针对受弯性能,而对于受剪性能的关注较少。但在海洋氯化物环境下,由于箍筋相对截面较小且易受氯离子侵蚀,箍筋的锈蚀程度较纵向受拉钢筋严重,有可能发生脆性的受剪破坏先于受弯破坏的预期外现象。再者,大部分的研究多是考虑钢筋整体均匀锈蚀对结构性能的影响,但这与实际结构中混凝土内部的钢筋锈蚀多呈非均匀、非对称的空间分布不符。 数值模拟是一种非常有效的研究方法 ...
张瀚引
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Automatic Grid Generation of CAD for Gear Reducer Housing

open access: yesJixie chuandong, 1994
本文针对齿轮减速机CAD过程中箱体类复杂板块组合结构有限元强度分析的特点,提出了基于等参数变换法的三维有限元组合网格自动生成方法,其特点是可将大型复杂结构自动离散为不同单元组成的网格,且可避免过渡单元,特别适用于复杂板块组合结构的有限元分析。
程燕青
doaj  

Ionic‐Liquid‐Assisted Synthesis of NiTe/CoTe Heterostructure With Te Vacancies in N, P, and F Co‐Doped Hollow Carbon Nanorods for Efficient Alkaline Hydrogen Evolution and High‐Performance Flexible Supercapacitors

open access: yesRare Metals, Volume 45, Issue 3, March 2026.
ABSTRACT Low conductivity, slow ion‐diffusion, and limited reactive sites are common problems in electrocatalysts and electrode materials. In this study, a complex NiTe–CoTe heterojunction with abundant Te vacancies embedded in N, P, and F co‐doped hollow carbon nanorods (NiTe1−x–CoTe1−x/NPFC) was fabricated via a simple ionic liquid‐assisted ...
Mingjie Yi   +7 more
wiley   +1 more source

Dispersive Behaviour of Dual-Petrov-Galerkin Methods for the One-way Wave Equation Comparing with High Order Finite Element Schemes [PDF]

open access: yes, 2016
MarkAinsworth(2014)曾针对单向流方程,利用高阶有限元方法构造离散波,考察它对于同速情况下的物理波的估计效果。文章不仅给出了详细的分析过程,更是得到了估计相应Floquet因子的相对误差的显性表达式,同时,将其与间断Galerkin方法下的相对误差结果进行了对比。然而,事实证明,无论是高阶有限元方法,还是间断Galerkin方法,它们的估计效果都是具有奇偶特性的。即是说,在多项式阶数为奇数和为偶数时,Floquet因子的相对误差具有不同的表达式,进一步来说,当多项式阶数不断增大时 ...
居文瑜
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蒙皮支撑两连跨连续檩条模拟风吸力作用的试验研究

open access: yesJianzhu Gangjiegou Jinzhan, 2010
为了更深入了解金属蒙皮支撑连续檩条在整体蒙皮结构中所起的作用,为今后我国对连续檩条以及蒙皮结构的设计、计算提供依据,通过足尺模型试验和有限元模型的分析,研究了蒙皮支撑冷弯薄壁连续型钢檩条模拟风吸力作用的承载力。利用有限元程序ANSYS建立了带有非线性弹簧单元模拟自攻螺钉这一符合实际连接状况的有限元模型,与足尺试验模型的失稳模式、荷载-位移曲线、连接强度以及连接刚度的规律等相对比,验证了有限元模型的合理性、有效性及适用性。
潘宇   +6 more
doaj  

Colorimetric and Photothermal Hollow Nanocomposite Based on Silver‐Seeded Prussian Blue Analog for Dopamine Monitoring and Photothermal Sterilization

open access: yesRare Metals, Volume 45, Issue 3, March 2026.
ABSTRACT Multi‐element Prussian blue analog (PBA) nanocomposites have attracted wide attention for their superior characteristics to single‐functional nanomaterials in extensive applications of diagnosis and therapy. In this study, a novel hollow nanocomposite was designed and fabricated by embedding S2− and Ag nanoparticles into a NiCuMnFe (PBA).
Tao Ji   +7 more
wiley   +1 more source

Research on Structural Design and Mechanical Behavior of Double Arc Tooth Profile Harmonic Drive [PDF]

open access: yes, 2015
谐波齿轮减速器是一种传动精度高、减速比大并能够在密闭空间传动的齿轮传动机构,应用领域广泛,尤其在航空航天领域有不可替代的优势。常用的渐开线齿廓齿根处会出现应力集中以及齿顶产生尖点啮合现象,影响其承载性能和啮合质量。双圆弧齿形谐波齿轮以其良好的承载能力与啮合性能逐渐成为研究热点,本文根据谐波齿轮设计理论设计了双圆弧谐波齿轮装置,并对其结构性能、接触特性以及动力学等方面的分析,探索相关规律,为后续在结构优化、增强啮合性能提供了一定的理论依据。 论文主要包括以下几方面内容: 1 ...
王萌萌
core  

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