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Seasonal Variation in a Hymenopterous Parasitoid, Holcotetrastichus rhosaces (Walker) (Hymenoptera: Tetrastichinae), on Its Hosts, Cassida nebulosa L. and C. piperata Hope (Coleoptera: Chrysomelidae), in Sendai, Northeastern Area of Japan
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作者 Atsuhiko Nagasawa 《Advances in Entomology》 2014年第4期176-179,共4页
To investigate the seasonal variation of parasitism on Cassida nebulosa L. and C. piperata Hope, this research was conducted at the experimental field of Tohoku University in Sendai, Japan, where these tortoise beetle... To investigate the seasonal variation of parasitism on Cassida nebulosa L. and C. piperata Hope, this research was conducted at the experimental field of Tohoku University in Sendai, Japan, where these tortoise beetles were parasitized by hymenopterous parasitoid Holcotetrastichus rhosaces (Walker). Percentage parasitism started to increase from the middle of July and reached nearly 100% in August. Adults of H. rhosaces emerged from the pre-pupae of the tortoise beetles, with 6 to 30 adults emerging per pre-pupae. The second generation of C. nebulosa and C. piperata was heavily parasitized by H. rhosaces. The adults of these tortoise beetles were rarely found in the field during late summer due to the high rates of parasitism. 展开更多
关键词 TORTOISE BEETLE WASP Percentage PARASITISM
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Reflections on a Science and Technology Agenda for 21st Century Disaster Risk Reduction Based on the Scientific Content of the 2016 UNISDR Science and Technology Conference on the Implementation of the Sendai Framework for Disaster Risk Reduction 2015–203 被引量:17
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作者 Amina Aitsi-Selmi Virginia Murray +5 位作者 Chadia Wannous Chloe Dickinson David Johnston Akiyuki Kawasaki Anne-Sophie Stevance Tiffany Yeung 《International Journal of Disaster Risk Science》 SCIE CSCD 2016年第1期1-29,共29页
The first international conference for the post-2015 United Nations landmark agreements(Sendai Framework for Disaster Risk Reduction 2015–2030, Sustainable Development Goals, and Paris Agreement on Climate Change) wa... The first international conference for the post-2015 United Nations landmark agreements(Sendai Framework for Disaster Risk Reduction 2015–2030, Sustainable Development Goals, and Paris Agreement on Climate Change) was held in January 2016 to discuss the role of science and technology in implementing the Sendai Framework for Disaster Risk Reduction 2015–2030. The UNISDR Science and Technology Conference on the Implementation of the Sendai Framework for Disaster Risk Reduction 2015–2030 aimed to discuss and endorse plans that maximize science's contribution to reducing disaster risks and losses in the coming 15 years and bring together the diversity of stakeholders producing and using disaster risk reduction(DRR) science and technology. This article describes the evolution of the role of science and technology in the policy process building up to the Sendai Framework adoption that resulted in an unprecedented emphasis on science in the text agreed on by 187 United Nations member states in March 2015 and endorsed by the United Nations General Assembly in June 2015. Contributions assembled by the Conference Organizing Committee and teams including the conference concept notes and the conference discussions that involved a broad range of scientists and decision makers are summarized in this article. The conference emphasized how partnerships and networks can advance multidisciplinary research and bring together science, policy, and practice; how disaster risk is understood, and how risks are assessed and early warning systems are designed; what data, standards, and innovative practices would be needed to measure and report on risk reduction; what research and capacity gaps exist and how difficulties in creating and using science for effective DRR can be overcome. The Science and Technology Conference achieved two main outcomes:(1) initiating the UNISDR Science and Technology Partnership for the implementation of the Sendai Framework; and(2) generating discussion and agreement regarding the content and endorsement process of the UNISDR Science and Technology Road Map to 2030. 展开更多
关键词 Disaster risk reduction Sendai Framework implementation Science and Technology Conference Science-policy interface
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Global Community of Disaster Risk Reduction Scientists and Decision Makers Endorse a Science and Technology Partnership to Support the Implementation of the Sendai Framework for Disaster Risk Reduction 2015–2030 被引量:5
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作者 Chloe Dickinson Amina Aitsi-Selmi +2 位作者 Pedro Basabe Chadia Wannous Virginia Murray 《International Journal of Disaster Risk Science》 SCIE CSCD 2016年第1期108-109,共2页
At the first gathering of its kind on the role of science in implementing the Sendai Framework for Disaster Risk Reduction 2015–2030,over 750 scientists,policymakers,business people,and practitioners met in Geneva fr... At the first gathering of its kind on the role of science in implementing the Sendai Framework for Disaster Risk Reduction 2015–2030,over 750 scientists,policymakers,business people,and practitioners met in Geneva from January 27–29,2016.The UNISDR Science and Technology Conference on the Implementation of the Sendai Framework for Disaster Risk Reduction 2015–2030 fea- 展开更多
关键词 work Global Community of Disaster Risk Reduction Scientists and Decision Makers Endorse a Science and Technology Partnership to Support the Implementation of the Sendai Framework for Disaster Risk Reduction 2015
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Aging-induced memory loss due to decreased N1-acetyl-5-methoxykynuramine,a melatonin metabolite,in the hippocampus:a potential prophylactic agent for dementia
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作者 Kazuki Watanabe Atsuhiko Hattori 《Neural Regeneration Research》 SCIE CAS 2025年第6期1705-1706,共2页
Melatonin(N-acetyl-5-methoxytryptamine)is known as the hormone of darkness because it is synthesized at night and involved in regulating the circadian clock.The hormone is primarily synthesized by the vertebrate pinea... Melatonin(N-acetyl-5-methoxytryptamine)is known as the hormone of darkness because it is synthesized at night and involved in regulating the circadian clock.The hormone is primarily synthesized by the vertebrate pineal gland,but is ubiquitous among invertebrates,unicellular organisms,plants,and even cyanobacteria(Hattori and Suzuki,2024).Melatonin is well-conserved evolutionarily and possesses several physiological functions,such as immune response,bone and glucose metabolism,and memory formation besides regulating the circadian rhythm. 展开更多
关键词 metabolism primarily AGENT
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The Sendai Framework for Disaster Risk Reduction at Five:Lessons from the 2011 Great East Japan Earthquake and Tsunami
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作者 Elizabeth Maly Anawat Suppasri 《International Journal of Disaster Risk Science》 SCIE CSCD 2020年第2期167-178,共12页
The Sendai Framework for Disaster Risk Reduction 2015–2030(SFDRR) represents an inclusive approach to disaster risk reduction, linked to development and recovery. Building on previous international guidelines, the SF... The Sendai Framework for Disaster Risk Reduction 2015–2030(SFDRR) represents an inclusive approach to disaster risk reduction, linked to development and recovery. Building on previous international guidelines, the SFDRR promotes practical and measurable outcomes for reducing disaster losses, including indicators to measure progress towards seven specific global targets.Evaluated in the context of the priorities and global targets of the SFDRR, the article considers the case of the Great East Japan Earthquake and Tsunami of 2011 to illustrate advances and limitations in pre-disaster tsunami hazard engineering and post-disaster recovery. With respect to the targets set out in the Sendai Framework related to risk reduction and tsunami engineering, especially Priority 1,understanding disaster risk, there have been significant advances in hazard assessment and systems for tsunami detection and warning. Although the SFDRR emphasizes actions in the recovery phase through Priority 4, enhancing disaster preparedness with an emphasis on the concept of build back better, on its own this does not function as a clear directive for guiding recovery. However, the overall people-centered and inclusive approach of the SFDRR, as well as the global targets and several sub-priorities, can be a useful way to shape good practices in recovery and evaluate recovery progress. 展开更多
关键词 Build back better Disaster recovery Great East Japan Earthquake Sendai Framework Tsunami risk
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X形软钢阻尼器延性断裂的试验研究与数值模拟
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作者 谢丽宇 仝运佳 +2 位作者 薛松涛 李林 王兵 《建筑结构》 北大核心 2024年第7期59-63,71,共6页
为了研究X形软钢阻尼器在大变形状态下的耗能性能和损伤演化规律,设计了6组试件进行单向和循环荷载作用下延性断裂的试验研究,分析了软钢阻尼器的破坏过程和滞回曲线。采用Lemaitre-Chaboche混合强化模型,分别对各工况下包含与不包含基... 为了研究X形软钢阻尼器在大变形状态下的耗能性能和损伤演化规律,设计了6组试件进行单向和循环荷载作用下延性断裂的试验研究,分析了软钢阻尼器的破坏过程和滞回曲线。采用Lemaitre-Chaboche混合强化模型,分别对各工况下包含与不包含基于应力三轴度的钢材微观损伤模型的软钢阻尼器进行了精细的有限元模拟。对比有限元模拟结果和试验结果,分析结果表明,颈部为X形耗能软钢阻尼器的薄弱位置,最容易发生集中损伤甚至破坏。考虑钢材损伤准则的有限元模拟的荷载-位移曲线与试验结果更加吻合,能够表征软钢阻尼器的承载力与刚度退化现象,并能较为准确地预测软钢阻尼器的损伤演化过程和断裂破坏位置。 展开更多
关键词 X形软钢阻尼器 应力三轴度 损伤模型 延性断裂 承载力退化
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Fe含量对粉末冶金Cu-Fe合金显微组织与性能的影响
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作者 张平 袁晓波 +4 位作者 曾梓名 滕剑威 周芸合 杨标标 李云平 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第5期1571-1587,共17页
研究Fe含量对粉末冶金Cu-Fe合金显微组织及性能的影响。采用电火花等离子烧结、冷轧以及时效处理工艺制备4种不同铁含量(5%、10%、20%和40%,质量分数)的Cu-Fe合金。研究结果表明,随着Fe含量从5%(质量分数)增加到40%(质量分数),Fe相由离... 研究Fe含量对粉末冶金Cu-Fe合金显微组织及性能的影响。采用电火花等离子烧结、冷轧以及时效处理工艺制备4种不同铁含量(5%、10%、20%和40%,质量分数)的Cu-Fe合金。研究结果表明,随着Fe含量从5%(质量分数)增加到40%(质量分数),Fe相由离散球形分布演变为连续交错分布,Fe相尺寸从0.29μm增加到1.20μm;时效态的Cu-Fe合金的屈服强度从411.5 MPa提高到788.8 MPa,电导率从62.5%(IACS)降低到42.0%(IACS)。在以上结果的基础上,提出一种混合法则计算Cu基体、初级Fe相和次级Fe相对屈服强度的贡献,可较好地预测Fe含量高于10%(质量分数)合金的力学性能。 展开更多
关键词 铜铁合金 粉末冶金 快速凝固 力学性能 强度计算
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附加不同形式调谐质量惯容系统的高耸烟囱轻量化减震控制
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作者 张力 张瑞甫 +1 位作者 薛松涛 谢丽宇 《振动工程学报》 EI CSCD 北大核心 2024年第3期464-475,共12页
附加调谐质量阻尼器是烟囱结构的一种传统减震控制方法,然而其通常需要较大的附加质量及额外的安装空间,这为施工安装带来不便。本文提出附加调谐质量惯容系统(TMIS)控制高耸烟囱的地震响应,以利用惯容元件的表观质量效果实现轻量化减... 附加调谐质量阻尼器是烟囱结构的一种传统减震控制方法,然而其通常需要较大的附加质量及额外的安装空间,这为施工安装带来不便。本文提出附加调谐质量惯容系统(TMIS)控制高耸烟囱的地震响应,以利用惯容元件的表观质量效果实现轻量化减震目标。同时,考虑烟囱高阶模态对其地震响应不容忽视的影响,提出沿烟囱高度布置的分布式TMIS以实现多模态控制效果。建立了基于两种不同惯容子系统的TMIS力学模型及相应的附加分布式TMIS烟囱运动方程。以金井清谱为随机地震激励输入,并基于改进的定点理论提出了分布式TMIS的部分设计参数简化假设,提出了基于需求的分布式TMIS烟囱结构多模态优化设计方法。通过实例验证了所建议设计方法的有效性,并对比检验了分布式TMIS的轻量化及多模态控制效果,通过参数分析检验了所采用的改进定点理论简化的合理性。结果表明:所建议的设计方法可以按照预定目标发挥两种分布式TMIS的减震性能,两种分布式TMIS均显示了明显的轻量化减震效果。 展开更多
关键词 减震 惯容 烟囱 多模态控制 调谐
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中国黄酒和白酒中生物胺的研究进展 被引量:1
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作者 李书婷 尹礼国 +2 位作者 吴正云 张文学 五味胜也 《食品与发酵工业》 CAS CSCD 北大核心 2024年第10期327-334,共8页
生物胺是发酵食品中常见的一类健康风险因子。生物胺与乙醇有协同作用,会加剧饮酒后带来的不利影响。该文对不同类型黄酒和白酒中的生物胺含量、生物胺在酿酒过程中生成规律和影响因素进行了综述,以期为黄酒和白酒中生物胺的控制提供参考。
关键词 酿酒 生物胺 微生物 影响因素
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西北太平洋板块边缘俯冲特征:来自堪察加壳幔速度成像的约束 被引量:1
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作者 刘晏廷 钟成城 +1 位作者 江国明 赵大鹏 《CT理论与应用研究(中英文)》 2024年第2期135-148,共14页
堪察加半岛位于太平洋板块的西北边缘处。太平洋板块沿堪察加海沟俯冲进入地幔,而在板块边缘处,其俯冲特征是否有不同?本研究从IRIS网站下载76个固定台站记录到的来自2239个近震事件和75个远震事件的77141条P波到时数据,利用近震-远震... 堪察加半岛位于太平洋板块的西北边缘处。太平洋板块沿堪察加海沟俯冲进入地幔,而在板块边缘处,其俯冲特征是否有不同?本研究从IRIS网站下载76个固定台站记录到的来自2239个近震事件和75个远震事件的77141条P波到时数据,利用近震-远震联合层析成像方法(TOMOG3D)获得堪察加地区壳幔内的三维P波速度结构。成像结果显示,研究区域下方上地幔内存在非常明显的高速异常块体,且与深源地震的空间分布高度一致。分析认为,该高速异常体为俯冲的西太平洋板块,俯冲角度和深度沿堪察加海沟由北向南均逐渐增加。地幔过渡带和下地幔顶部存在明显的高速异常块体,可能是因为堪察加半岛下方的太平洋俯冲板块在边缘或深部发生岩石圈熔融或拆沉现象,该高速异常块体即为拆沉的岩石圈。本文的成像结果中还可清晰地观察到2个板块窗口。堪察加地区浅部火山前线下方出现大范围的低速异常,可能是由于俯冲板块脱水或流经板块窗口的地幔流热物质导致。 展开更多
关键词 天然地震层析成像 堪察加半岛 壳幔速度结构 西北太平洋俯冲板块
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Fourteen Actions and Six Proposals for Science and Technology-Based Disaster Risk Reduction in Asia Second Asian Science and Technology Conference for Disaster Risk Reduction:SciencePolicy Dialogue for Implementation of the Sendai Framework,April 2018
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作者 Peijun Shi Rajib Shaw +22 位作者 Ali Ardalan Emily Ying Yang Chan Jamilur Reza Choudhury Peng Cui Bojie Fu Guoyi Han Qunli Han Takako Izumi Fumiko Kasuga Antonia Yulo Loyzaga Joy Jacqueline PereiraShirish Kumar Ravan David Sanderson Vinod Kumar Sharma Frank Thomalla Sugeng Triutomo Siquan Yang Qian Ye Ming Wang Yaqiao Wu Renhe Zhang Wenjian Zhang Ying Li Saini Yang 《International Journal of Disaster Risk Science》 SCIE CSCD 2018年第2期275-279,共5页
1 Introduction The Sendai Framework for Disaster Risk Reduction 2015–2030 shifts the focus from managing disasters to reducing risks.Such a shift requires a better understanding of risk in all its dimensions of envir... 1 Introduction The Sendai Framework for Disaster Risk Reduction 2015–2030 shifts the focus from managing disasters to reducing risks.Such a shift requires a better understanding of risk in all its dimensions of environment,hazards,exposure,and vulnerability;a disaster risk governance that 展开更多
关键词 disaster ACTIONS Reduction governance dimensions managing VULNERABILITY technological innovative URGENT
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基于U形谐振器的无源裂缝传感器
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作者 姜康 薛松涛 +1 位作者 谢丽宇 万国春 《哈尔滨工程大学学报》 EI CAS CSCD 北大核心 2024年第8期1421-1426,共6页
针对传统裂缝传感器需要电源供应才能正常工作的缺陷,本文提出了一种基于无应力组合式贴片天线的无源裂缝传感器设计。利用U形谐振器实现裂缝传感,改变传感器内部谐振单元的谐振频率。通过观测回波信号的幅度和相位提取传感器的谐振频率... 针对传统裂缝传感器需要电源供应才能正常工作的缺陷,本文提出了一种基于无应力组合式贴片天线的无源裂缝传感器设计。利用U形谐振器实现裂缝传感,改变传感器内部谐振单元的谐振频率。通过观测回波信号的幅度和相位提取传感器的谐振频率,进而实现对裂缝的监测。基于天线理论建立了传感器的等效电路模型并推导谐振频率,研究裂缝宽度对传感器谐振频率的影响规律。进一步在三维电磁仿真软件CST中对传感器进行了数值模拟,并且通过试验研究了裂缝拓展对谐振频率的影响。研究表明:随着裂缝的扩展,传感器的谐振频率增加,且裂缝宽度与谐振频率之间具有较好的线性关系。 展开更多
关键词 结构健康监测 裂缝传感器 谐振频率 多维电磁特征参数 组合式贴片天线 无源 U形谐振器 电长度
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生物质和塑料加氢脱氧制备燃料和化学品的双金属催化剂研究进展
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作者 刘露杰 刘奔 +4 位作者 中川善直 刘斯宝 王亮 藪下瑞帆 冨重圭一 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第7期1-31,共31页
在全球致力于实现碳中和的大背景下,生物质和废弃塑料的高值化利用已成为科研领域的研究热点.加氢脱氧反应(HDO),作为实现这一目标的重要途径之一,通过精准解离C-O/C-C键,为生产燃料和化学品提供了有效方法.在HDO过程中,C-O键的氢解及... 在全球致力于实现碳中和的大背景下,生物质和废弃塑料的高值化利用已成为科研领域的研究热点.加氢脱氧反应(HDO),作为实现这一目标的重要途径之一,通过精准解离C-O/C-C键,为生产燃料和化学品提供了有效方法.在HDO过程中,C-O键的氢解及不饱和键的氢化是主要步骤,而C-C键的氢解则是需要避免的副反应.与简单的氢化反应相比,HDO过程需要具有双功能特性的催化剂,特别是当目标产物为含氧化合物时,催化剂的区域选择性至关重要.近年来,双金属催化剂在生物质及其衍生物以及含氧塑料废弃物和聚合物的HDO过程中的应用受到广泛关注.通过深入理解金属纳米颗粒与金属氧化物之间的协同作用和强相互作用,双金属催化剂的理性设计取得了显著进展.特别是,部分金属氧化物(如ReO_(x),WO_(x),MoO_(x),FeO_(x))与贵金属(如Ir,Pt,Ru)之间存在的强相互作用,不仅促进了C-O键的断裂,还有效保留了C-C键,为催化剂的高活性和高选择性奠定了基础.通过调整催化剂组成、使用小比表面积的载体等方法,可以进一步优化催化剂性能.本综述聚焦于金属氧化物改性的贵金属催化剂在HDO反应中的最新研究进展,特别是总结了Ir、Pt和Ru基催化剂在HDO反应中的应用.由于这类催化剂的结构和性能能够精确控制,并且每种催化剂都具备独特的选择性,因此被广泛应用于生物质衍生物和塑料废弃物的HDO过程中.本文总结了双金属催化剂的结构特点、HDO反应机制、催化剂结构与催化性能之间的关联,以及这些催化剂在高附加值化学品生产中的实际应用.我们以甘油和1,2-丙二醇的氢解为模型反应,深入探讨了基于Ir、Pt和Ru的双金属催化剂的催化性能、结构特点和催化机理.这些催化剂在温和条件下实现了高效的氢脱氧反应,有效抑制了C-C键的断裂,并优化了化学选择性和区域选择性.双金属催化剂在生物质精炼和塑料/聚合物转化方面展现出广泛的适用性.本文还介绍了其在木质纤维素衍生原料、羰基化合物以及聚碳酸酯等塑料中的应用.然而,双金属催化剂的稳定性在实际应用中仍面临挑战,如金属烧结、浸出、积碳及金属-金属氧化物界面的重构等问题.因此,未来的研究重点是开发高效的再生方法和高度稳定的催化剂.综上所述,金属氧化物改性的贵金属催化剂在HDO反应中展现出巨大潜力.通过深入研究和优化,有望为生物质和塑料的高值化利用提供有效解决方案.本文旨在为双金属催化剂的理性设计和优化提供参考,以期推动生物质和塑料的高值化利用技术的进一步发展和应用. 展开更多
关键词 加氢脱氧 氢解 双金属催化剂 生物质衍生物 塑料废弃物
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A dynamic database of solid-state electrolyte(DDSE)picturing all-solid-state batteries 被引量:1
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作者 Fangling Yang Egon Campos dos Santos +5 位作者 Xue Jia Ryuhei Sato Kazuaki Kisu Yusuke Hashimoto Shin-ichi Orimo Hao Li 《Nano Materials Science》 EI CAS CSCD 2024年第2期256-262,共7页
All-solid-state batteries(ASSBs)are a class of safer and higher-energy-density materials compared to conventional devices,from which solid-state electrolytes(SSEs)are their essential components.To date,investigations ... All-solid-state batteries(ASSBs)are a class of safer and higher-energy-density materials compared to conventional devices,from which solid-state electrolytes(SSEs)are their essential components.To date,investigations to search for high ion-conducting solid-state electrolytes have attracted broad concern.However,obtaining SSEs with high ionic conductivity is challenging due to the complex structural information and the less-explored structure-performance relationship.To provide a solution to these challenges,developing a database containing typical SSEs from available experimental reports would be a new avenue to understand the structureperformance relationships and find out new design guidelines for reasonable SSEs.Herein,a dynamic experimental database containing>600 materials was developed in a wide range of temperatures(132.40–1261.60 K),including mono-and divalent cations(e.g.,Li^(+),Na^(+),K^(+),Ag^(+),Ca^(2+),Mg^(2+),and Zn^(2+))and various types of anions(e.g.,halide,hydride,sulfide,and oxide).Data-mining was conducted to explore the relationships among different variates(e.g.,transport ion,composition,activation energy,and conductivity).Overall,we expect that this database can provide essential guidelines for the design and development of high-performance SSEs in ASSB applications.This database is dynamically updated,which can be accessed via our open-source online system. 展开更多
关键词 Solid-state electrolyte(SSE) All-solid-state battery(ASSB) Ionic conductivity Dynamic database Machine learning
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Anti-aquaporin-4 antibody(AQP4-IgG)and anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)in the cerebrospinal fluid 被引量:1
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作者 Tetsuya Akaishi Tatsuro Misu 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第5期949-950,共2页
In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in... In the last decade,a new neurological disease concept known as anti-myelin oligodendrocyte glycoprotein antibody(MOG-IgG)-associated disease(MOGAD)has emerged and is currently one of the most focused research areas in the field of neuroimmunology.MOG is a membrane protein mainly expressed on the surface of oligodendrocytes(Zhou et al.,2006).The exact pathogenic role of MOG-IgG in patients with MOGAD remains unclear;however,MOG-IgG has been suggested to cause tissue alterations and damage MOG-expressing cells(Zhou et al.,2006).The pathogenicity of MOG-IgG is further supported by the observation that only a few patients with acquired central nervous system(CNS)demyelinating syndromes exhibit both anti-aquaporin-4 antibody(AQP4-IgG)and MOG-IgG simultaneously,particularly with clear positivity levels of these antibodies as indicated by a cell-based assay result with a titer≥1:100(Sechi et al.,2021;Banwell et al.,2023). 展开更多
关键词 AQP4 MYELIN
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R134a制冷机组中压缩机和回热器性能的试验研究
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作者 司化 申道明 +2 位作者 夏锦红 桂超 薛松涛 《流体机械》 CSCD 北大核心 2024年第7期8-14,97,共8页
为研究R134a制冷机组中压缩机和回热器运转性能,以制冷机组运行压比为调节变量,使用压缩机排气温度、功耗、等熵效率、机组制冷量及系统能效比COP为评价指标,采用单一变量法对两元件运转性能进行测试。试验运行中,主要通过控制制冷机组... 为研究R134a制冷机组中压缩机和回热器运转性能,以制冷机组运行压比为调节变量,使用压缩机排气温度、功耗、等熵效率、机组制冷量及系统能效比COP为评价指标,采用单一变量法对两元件运转性能进行测试。试验运行中,主要通过控制制冷机组蒸发温度、冷凝温度实现压缩机压比的调节。结果表明:压缩机排气温度、功耗随压缩机压比的增加而增大,机组制冷量、COP及压缩机等熵效率随压缩机压比的增加而减小;压缩机功耗与蒸发温度呈负相关,而其他性能指标与蒸发温度呈正相关。根据试验数据揭示压缩机等熵效率与压缩机压比之间的内在联系,所获取模型可实现压缩机等熵效率的高精度预测,预测平均误差约为0.45%。基于试验数据对比分析了回热器应用前后压缩机功耗、机组性能的变化趋势,除回热器在低压比工况下可明显提升机组制冷量外,在大部分工况下回热器可通过降低压缩机功耗提升机组整体性能。 展开更多
关键词 压缩机 回热器 压比 排气温度 等熵效率 理论模型
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倾斜微肋管内两相流动冷凝换热特性研究
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作者 司化 申道明 +2 位作者 夏锦红 桂超 薛松涛 《低温工程》 CAS CSCD 北大核心 2024年第4期32-39,共8页
用实验方法对倾斜微肋管内两相流动冷凝换热特性进行实验研究,主要分析管内传热系数在不同实验工况、微肋管中的变化趋势,以揭示各实验变量对管内换热特性的影响机理,获取管内传热系数理论模型。实验结果显示:微肋管内传热系数随质流密... 用实验方法对倾斜微肋管内两相流动冷凝换热特性进行实验研究,主要分析管内传热系数在不同实验工况、微肋管中的变化趋势,以揭示各实验变量对管内换热特性的影响机理,获取管内传热系数理论模型。实验结果显示:微肋管内传热系数随质流密度和干度的增加而增大,随管倾斜角的增大呈现先升高后减小的变化趋势;相比于光滑管,40°微肋管和25°微肋管换热强化倍率随干度的增加而增大、随倾斜角的增加而减小。此外,现有关联式低估了大部分实验数据,其预测误差均随干度、肋片螺旋角等的升高而增大。基于实验数据所获取新关联式可对40°微肋管和25°微肋管表现出较好的预测效果,其平均预测误差小于7%。 展开更多
关键词 微肋管 倾斜角 流动冷凝 传热系数 关联式
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霍山震群区三维地壳速度结构与孕震环境
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作者 冀国强 雷建设 赵大鹏 《地震地质》 EI CSCD 北大核心 2024年第3期665-685,共21页
霍山震群可能是反映华东地区乃至青藏高原地震活动的重要窗口,其孕震环境与发震机制备受关注。文中手动拾取获得了1987个地震的7706条P波、394条PmP波、9263条S波和557条SmS波共计17920条震相到时数据,采用多震相体波层析成像方法反演... 霍山震群可能是反映华东地区乃至青藏高原地震活动的重要窗口,其孕震环境与发震机制备受关注。文中手动拾取获得了1987个地震的7706条P波、394条PmP波、9263条S波和557条SmS波共计17920条震相到时数据,采用多震相体波层析成像方法反演获得了霍山震群区下方深至30km的地壳三维P波速度(V_(P))、S波速度(V_(S))及纵横波速度比(V_(P)/V_(S))模型。结果显示,霍山震群区附近存在弱高V_(P)/V_(S)结构特征,但在震群区下方存在强高V_(P)/V_(S)结构特征,且该结构特征沿晓天-磨子潭断裂向深延伸至30km深度,推测霍山震群区下方存在流体作用。该流体作用可能降低断层面有效正应力,从而导致在晓天-磨子潭断裂与落儿岭-土地岭断裂交会的薄弱区发生霍山震群活动。这些流体的来源与太平洋板块在地幔转换带滞留脱水所形成的“大地幔楔”结构中的地幔热物质上涌有关,但还可能与青藏高原壳幔物质沿大别山造山带E向挤出有关,共同影响了霍山震群活动特征。文中成果也为深入理解霍山震群区的构造活动与华东地区及青藏高原构造活动的关联性提供了地震学证据。 展开更多
关键词 霍山震群区 多震相 地壳速度成像 深部流体
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Hydrogel loaded with bone marrow stromal cell-derived exosomes promotes bone regeneration by inhibiting inflammatory responses and angiogenesis 被引量:1
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作者 Shuai Zhang Chuan Lu +1 位作者 Sheng Zheng Guang Hong 《World Journal of Stem Cells》 SCIE 2024年第5期499-511,共13页
BACKGROUND Bone healing is a complex process involving early inflammatory immune regu-lation,angiogenesis,osteogenic differentiation,and biomineralization.Fracture repair poses challenges for orthopedic surgeons,neces... BACKGROUND Bone healing is a complex process involving early inflammatory immune regu-lation,angiogenesis,osteogenic differentiation,and biomineralization.Fracture repair poses challenges for orthopedic surgeons,necessitating the search for efficient healing methods.AIM To investigate the underlying mechanism by which hydrogel-loaded exosomes derived from bone marrow mesenchymal stem cells(BMSCs)facilitate the process of fracture healing.METHODS Hydrogels and loaded BMSC-derived exosome(BMSC-exo)gels were charac-terized to validate their properties.In vitro evaluations were conducted to assess the impact of hydrogels on various stages of the healing process.Hydrogels could recruit macrophages and inhibit inflammatory responses,enhance of human umbilical vein endothelial cell angiogenesis,and promote the osteogenic differen-tiation of primary cranial osteoblasts.Furthermore,the effect of hydrogel on fracture healing was confirmed using a mouse fracture model.RESULTS The hydrogel effectively attenuated the inflammatory response during the initial repair stage and subsequently facilitated vascular migration,promoted the formation of large vessels,and enabled functional vascularization during bone repair.These effects were further validated in fracture models.CONCLUSION We successfully fabricated a hydrogel loaded with BMSC-exo that modulates macrophage polarization and angiogenesis to influence bone regeneration. 展开更多
关键词 HYDROGEL Bone marrow mesenchymal stem cells Macrophage polarization ANGIOGENESIS Bone regeneration
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日本推进农村绿色旅游的案例分析与经验借鉴
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作者 贾磊 赵心童 +1 位作者 刘增金 覃梦妮 《上海农业学报》 2024年第1期133-139,共7页
日本在经历城乡差距扩大、农业农村衰退后,制定了农村振兴战略,并将绿色旅游作为激发地域活力的主要手段。立足于城乡共构的基本理念,日本绿色旅游经历了发展、扩大、转变和成熟4个阶段,在完备的政策支持下,发展水平不断提高,形成了多... 日本在经历城乡差距扩大、农业农村衰退后,制定了农村振兴战略,并将绿色旅游作为激发地域活力的主要手段。立足于城乡共构的基本理念,日本绿色旅游经历了发展、扩大、转变和成熟4个阶段,在完备的政策支持下,发展水平不断提高,形成了多种独具特色的发展模式和精品旅游项目。群马县的文化交流型绿色旅游将文化艺术与旅游融合,岩手县的观光教育型绿色旅游借旅游观光为学生创造体验农业的机会,宫城县的休闲体验型绿色旅游将高品质农产品和三产融合作为绿色旅游的核心动力,以上三种模式均促进农村经济和社会良性发展。为促进我国乡村旅游特色化发展,参考日本绿色旅游发展经验,在宏观上,应分区域制定旅游主题,分时段出台扶持政策,激发农民建设农村的热情。在微观上,应重视乡村文化建设,推动乡村旅游与教育相融合,做强区域农业品牌。 展开更多
关键词 绿色旅游 特色化发展 日本经验 乡村振兴
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