Results 21 to 30 of about 11,585 (166)

Optimization simulation and crushing experiment of anti-impact energy absorption component of hydraulic support column [PDF]

open access: yes
Hydraulic support, being the primary supporting equipment in coal mining operations, is frequently subjected to rock burst pressure. Hence, the anti-impact energy absorption components play a pivotal role in safeguarding the hydraulic support system ...
Liyong TIAN   +4 more
core   +1 more source

Comparing the Effects of Collaborative and Independent Writing on EFL Learners’ Individual Writing Performance: An Intervention Study

open access: yesInternational Journal of Applied Linguistics, EarlyView.
ABSTRACT Collaborative writing has attracted increasing attention in English as a Foreign Language (EFL) instruction due to its potential to enhance learners’ writing competence. However, few studies have examined the comparative effects of collaborative versus independent writing on EFL learners’ individual performance, especially in higher‐order ...
Ting Huang, Chenze Wu, Wenkang Zhang
wiley   +1 more source

动态冲击下泡沫能量吸收对头盔防护性能的影响 [PDF]

open access: yes, 2018
为摩托车头盔的安全性设计,需要研究在冲击载荷下内衬泡沫的能量吸收能力对摩托车头盔防护性能的影响。该文建立了有限元数值分析头盔模型,依据欧洲经济委员会(ECE)的法规ECE R22.05的动态测试方法,验证该模型的有效性。改变头盔不同测试点下的泡沫密度,进行了12个跌落的仿真试验。结果表明:在头盔的前部、冠部和后部测试点区泡沫密度由40 kg/m3增加到80 kg/m~3时,泡沫的能量吸收能力逐渐增大,头部冲击能量衰减得更快,导致3个测试点头部颅骨骨折的风险从25%、55%、39%分别增大至53%、96%、
何伟   +4 more
core  

Cs2SnI6: A Perovskite‐Based Electromagnetic Wave Absorbing Material

open access: yesRare Metals, Volume 45, Issue 4, April 2026.
ABSTRACT Lead halide perovskites and carbon‐based materials are interesting, high‐performing electromagnetic wave absorbing materials. However, only a few studies have been carried out to examine in detail the electromagnetic wave absorption properties of these materials.
Fei Han   +11 more
wiley   +1 more source

尿素与复合氮肥增效剂配施对水稻氮素利用的影响

open access: yesShuitu Baochi Xuebao, 2006
采用^15N-尿素进行盆栽和田间试验,研究了复合氮肥增效剂用量、尿素与复合氮肥增效剂配施对水稻生长、籽粒产量和氮素吸收利用的影响。结果表明,适宜用量(施氮量的20%)的复合氮肥增效剂能显著促进水稻幼苗生长发育;尿素全量配施复合氮肥增效剂不影响水稻生长,能显著提高水稻植株Ndff%、氮吸收总量,氮素利用率和^15N的吸收量,尿素减量5%~15%(即减少施氮7.8~23.7kg/hm^2)配施复合氮肥增效剂基本上不影响水稻生长、籽粒产量和吸氮总量,能显著提高氮素的农学效率、生理效率和氮素利用率;植株吸氮总量、
田秀英, 王正银
doaj   +2 more sources

Total gastrectomy vs subtotal gastrectomy for the Control of blood pressure on spontaneously hypertensive rats and the exploration of underlying mechanism [PDF]

open access: yes, 2015
背景:我们的临床研究发现胃癌合并原发性高血压的病人,进行全胃切除术及胃大部切除术后,降压效果有显著差异。也有文章提出,胃减容手术能够有效改善肥胖患者的血压。因而我们推论,单纯胃切除术即可对血压产生影响。胃减容手术在肥胖个体上改善血压的效果被主要归因于体重的降低;而水钠代谢的紊乱被认为是原发性高血压的重要发病原因之一,胃转流手术对于水钠代谢的改善作用也已被人所验证。那么胃切除手术改善血压的原因可能也是由于这两者的作用。因此,本实验的研究目的在于对比单纯胃大部切除及单纯全胃切除术对原发性高血压大鼠体血压 ...
金娜
core  

Impact resistance performance of rockbolt system with(out) rubber cushion energy absorbing and buffering components [PDF]

open access: yes
The practice of impact resistance support in dangerous roadways has shown that energy absorbing and buffering components can improve the impact resistance performance of rockbolt support systems. A rubber cushion layer was used as an energy absorbing and
Fuqiang GAO   +8 more
core   +1 more source

Synergistic Electron Density and Oxygen Defect Regulation in Fluorite High‐Entropy Oxides for Superior Ionizing Radiation Shielding

open access: yesRare Metals, Volume 45, Issue 4, April 2026.
ABSTRACT Lightweight and lead‐free radiation shielding materials remain urgently needed. This work designed a fluorite high‐entropy oxide (FHEO) system through a combined computational–experimental route. Density functional theory based on special quasi‐random structures was used to identify thermodynamically stable fluorites from a wide compositional ...
Xiangjie Duan   +9 more
wiley   +1 more source

直流换流站中性母线避雷器组故障仿真研究

open access: yesDianci bileiqi, 2022
直流换流站中性母线避雷器在限制过电压过程中需要吸收大量能量,因此采用大规模多柱并联结构。为了研究中性母线多柱并联避雷器组的故障暂态特性,基于宁东-青岛±660 kV特高压直流输电工程,利用PSCAD程序建立系统仿真模型,计算避雷器组参数并建立多柱并联避雷器组模型,仿真得到不同运行方式下典型故障时中性母线避雷器过电压、电流及吸收能量的波形,分析波形特征。研究避雷器组自身发生击穿故障时的特性以及对系统的影响。仿真结果显示,在发生单极阀顶接地故障时中性母线EM避雷器吸收能量21 MJ,当某一柱伏安特性降低10%
刘志远   +6 more
doaj  

Achieving Ambient‐Temperature Fast Hydrogenation Properties in Ga‐Doped Mg–Ni Alloy: Dual‐Phase Synergistic Catalysis and Stacking Fault Channels

open access: yesRare Metals, Volume 45, Issue 4, April 2026.
ABSTRACT The high operating temperatures and sluggish kinetics of Mg‐based hydrogen storage materials (HSMs) are urgently being addressed. In this work, a novel Mg–Ni–Ga HSM with dual‐phase synergistic catalysis is developed, including the fishbone‐like Mg3Ni2Ga1 catalytic phase and the Mg2Ni phase with stacking faults (SFs).
Shiyang Hu   +7 more
wiley   +1 more source

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