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WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION 被引量:6
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作者 YU Ming XU Qiang 《Chinese Journal of Reactive Polymers》 2006年第1期23-28,共6页
Water-blown polyurethane rigid foams are getting more and more attention,because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction.However,the polyurethane r... Water-blown polyurethane rigid foams are getting more and more attention,because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction.However,the polyurethane rigid foams blown by water have serious defects,i.e.friability and resulting lower adhesion strength.Thus,the purpose of this study is to resolve the problems by chemical plastication.The maleate was added to polyol-premix containing water or to polyisocyanate,with both of which maleate does not react.To prove the reaction when polyol-premix and polyisocyanate were mixed,the model composite was synthesized and analyzed by IR,NMR and ESI(MS).Furthermore,a series of water-blown polyurethane rigid foams added different amount maleate were successfully prepared.By testing impact strength and adhesion strength of the foams,the actual effect of adding maleate was obtained. 展开更多
关键词 WATER-BLOWN Rigid foams Chemical plastication.
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Hippocampal damage through foreign body placement in organotypic cultures leads to plastic responses in newly born granule cells
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作者 Tassilo Jungenitz Lukas Frey +2 位作者 Sophia Kirscht Stephan W.Schwarzacher Angélica Zepeda 《Neural Regeneration Research》 2026年第3期1142-1150,共9页
The dentate gyrus of the hippocampus is a plastic structure that displays modifications at different levels in response to positive stimuli as well as to negative conditions such as brain damage.The latter involves gl... The dentate gyrus of the hippocampus is a plastic structure that displays modifications at different levels in response to positive stimuli as well as to negative conditions such as brain damage.The latter involves global alterations,making understanding plastic responses triggered by local damage difficult.One key feature of the dentate gyrus is that it contains a well-defined neurogenic niche,the subgranular zone,and beyond neurogenesis,newly born granule cells may maintain a“young”phenotype throughout life,adding to the plastic nature of the structure.Here,we present a novel experimental model of local brain damage in organotypic entorhino-hippocampal cultures that results in the activation of adjacent newly born granule cells.A small piece of filter paper was placed on the surface of the granule cell layer of the dentate gyrus,which evoked a foreign body reaction of astrocytes,along with the activation of local young neurons expressing doublecortin.Forty-eight hours after foreign body placement,the number of doublecortin-immunoreactive cells increased in the subgranular zone in the direct vicinity of the foreign body,whereas overall increased doublecortin immunoreactivity was observed in the granule cell layer and molecular layer of the dentate gyrus.Foreign body placement in the pyramidal layer of the CA1 region evoked a comparable local astroglial reaction but did not lead to an increase in doublecortin-immunoreactive in either the CA1 region or the adjacent dentate gyrus.Seven days after foreign body placement in the dentate gyrus,the increase in doublecortin-immunoreactivity was no longer observed,indicating the transient activation of young cells.However,7 days after foreign body placement,the number of doublecortin-immunoreactive granule cells coimmunoreactive for calbindin was lower than that under the control conditions.As calbindin is a marker for mature granule cells,this result suggests that activated young cells remain at a more immature stage following foreign body placement.Live imaging of retrovirally green fluorescent protein-labeled newly born granule cells revealed the orientation and growth of their dendrites toward the foreign body placement.This novel experimental model of foreign body placement in organotypic entorhino-hippocampal cultures could serve as a valuable tool for studying both glial reactivity and neuronal plasticity,specifically of newly born neurons under controlled in vitro conditions. 展开更多
关键词 ASTROCYTE brain plasticity dendritic plasticity dentate gyrus focal brain injury hippocampus NEUROPLASTICITY NEUROREPAIR newborn granule cells regeneration REORGANIZATION
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Neuronal plasticity and its role in Alzheimer's disease and Parkinson's disease
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作者 Israt Jahan Mohammad Harun-Ur-Rashid +4 位作者 MdAminul Islam Farhana Sharmin Soad K.Al Jaouni Abdullah M.Kaki Samy Selim 《Neural Regeneration Research》 2026年第1期107-125,共19页
Neuronal plasticity,the brain's ability to adapt structurally and functionally,is essential for learning,memory,and recovery from injuries.In neurodegenerative diseases such as Alzheimer's disease and Parkinso... Neuronal plasticity,the brain's ability to adapt structurally and functionally,is essential for learning,memory,and recovery from injuries.In neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease,this plasticity is disrupted,leading to cognitive and motor deficits.This review explores the mechanisms of neuronal plasticity and its effect on Alzheimer's disease and Parkinson's disease.Alzheimer's disease features amyloid-beta plaques and tau tangles that impair synaptic function,while Parkinson's disease involves the loss of dopaminergic neurons affecting motor control.Enhancing neuronal plasticity offers therapeutic potential for these diseases.A systematic literature review was conducted using databases such as PubMed,Scopus,and Google Scholar,focusing on studies of neuronal plasticity in Alzheimer's disease and Parkinson's disease.Data synthesis identified key themes such as synaptic mechanisms,neurogenesis,and therapeutic strategies,linking molecular insights to clinical applications.Results highlight that targeting synaptic plasticity mechanisms,such as long-term potentiation and long-term depression,shows promise.Neurotrophic factors,advanced imaging techniques,and molecular tools(e.g.,clustered regularly interspaced short palindromic repeats and optogenetics)are crucial in understanding and enhancing plasticity.Current therapies,including dopamine replacement,deep brain stimulation,and lifestyle interventions,demonstrate the potential to alleviate symptoms and improve outcomes.In conclusion,enhancing neuronal plasticity through targeted therapies holds significant promise for treating neurodegenerative diseases.Future research should integrate multidisciplinary approaches to fully harness the therapeutic potential of neuronal plasticity in Alzheimer's disease and Parkinson's disease. 展开更多
关键词 Alzheimer's disease long-term depression long-term potentiation NEUROINFLAMMATION neuronal plasticity Parkinson's disease synaptic plasticity
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Metabolic reprogramming of astrocytes:Emerging roles of lactate
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作者 Zeyu Liu Yijian Guo +2 位作者 Ying Zhang Yulei Gao Bin Ning 《Neural Regeneration Research》 2026年第2期421-432,共12页
Lactate serves as a key energy metabolite in the central nervous system,facilitating essential brain functions,including energy supply,signaling,and epigenetic modulation.Moreover,it links epigenetic modifications wit... Lactate serves as a key energy metabolite in the central nervous system,facilitating essential brain functions,including energy supply,signaling,and epigenetic modulation.Moreover,it links epigenetic modifications with metabolic reprogramming.Nonetheless,the specific mechanisms and roles of this connection in astrocytes remain unclear.Therefore,this review aims to explore the role and specific mechanisms of lactate in the metabolic reprogramming of astrocytes in the central nervous system.The close relationship between epigenetic modifications and metabolic reprogramming was discussed.Therapeutic strategies for targeting metabolic reprogramming in astrocytes in the central nervous system were also outlined to guide future research in central nervous system diseases.In the nervous system,lactate plays an essential role.However,its mechanism of action as a bridge between metabolic reprogramming and epigenetic modifications in the nervous system requires future investigation.The involvement of lactate in epigenetic modifications is currently a hot research topic,especially in lactylation modification,a key determinant in this process.Lactate also indirectly regulates various epigenetic modifications,such as N6-methyladenosine,acetylation,ubiquitination,and phosphorylation modifications,which are closely linked to several neurological disorders.In addition,exploring the clinical applications and potential therapeutic strategies of lactic acid provides new insights for future neurological disease treatments. 展开更多
关键词 ASTROCYTE epigenetic modifications inflammation LACTATE lactylation METABOLIC PLASTICITY regeneration treatment
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Brain structural plasticity in large-brained mammals:Not only narrowing roads
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作者 Marco Ghibaudi Alessandro Zanone Luca Bonfanti 《Neural Regeneration Research》 2026年第5期1669-1680,共12页
The capacity of the central nervous system for structural plasticity and regeneration is commonly believed to show a decreasing progression from“small and simple”brains to the larger,more complex brains of mammals.H... The capacity of the central nervous system for structural plasticity and regeneration is commonly believed to show a decreasing progression from“small and simple”brains to the larger,more complex brains of mammals.However,recent findings revealed that some forms of neural plasticity can show a reverse trend.Although plasticity is a well-preserved,transversal feature across the animal world,a variety of cell populations and mechanisms seem to have evolved to enable structural modifications to take place in widely different brains,likely as adaptations to selective pressures.Increasing evidence now indicates that a trade-off has occurred between regenerative(mostly stem cell–driven)plasticity and developmental(mostly juvenile)remodeling,with the latter primarily aimed not at brain repair but rather at“sculpting”the neural circuits based on experience.In particular,an evolutionary trade-off has occurred between neurogenic processes intended to support the possibility of recruiting new neurons throughout life and the different ways of obtaining new neurons,and between the different brain locations in which plasticity occurs.This review first briefly surveys the different types of plasticity and the complexity of their possible outcomes and then focuses on recent findings showing that the mammalian brain has a stem cell–independent integration of new neurons into pre-existing(mature)neural circuits.This process is still largely unknown but involves neuronal cells that have been blocked in arrested maturation since their embryonic origin(also termed“immature”or“dormant”neurons).These cells can then restart maturation throughout the animal's lifespan to become functional neurons in brain regions,such as the cerebral cortex and amygdala,that are relevant to high-order cognition and emotions.Unlike stem cell–driven postnatal/adult neurogenesis,which significantly decreases from small-brained,short-living species to large-brained ones,immature neurons are particularly abundant in large-brained,long-living mammals,including humans.The immature neural cell populations hosted in these complex brains are an interesting example of an“enlarged road”in the phylogenetic trend of plastic potential decreases commonly observed in the animal world.The topic of dormant neurons that covary with brain size and gyrencephaly represents a prospective turning point in the field of neuroplasticity,with important translational outcomes.These cells can represent a reservoir of undifferentiated neurons,potentially granting plasticity within the high-order circuits subserving the most sophisticated cognitive skills that are important in the growing brains of young,healthy individuals and are frequently affected by debilitating neurodevelopmental and degenerative disorders. 展开更多
关键词 adult neurogenesis AMYGDALA brain plasticity cerebral cortex comparative approach evolution immature neurons
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Plasticity meets regeneration during innate spinal cord repair
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作者 Amruta Tendolkar Mayssa H.Mokalled 《Neural Regeneration Research》 2026年第3期1136-1137,共2页
Regenerative capacity of the central nervous system(CNS)is unevenly distributed among vertebrates.While most mammalian species including humans elicit limited repair following CNS injury or disease,highly regenerative... Regenerative capacity of the central nervous system(CNS)is unevenly distributed among vertebrates.While most mammalian species including humans elicit limited repair following CNS injury or disease,highly regenerative vertebrates including urodele amphibians and teleost fish spontaneously reverse CNS damage.Teletost zebrafish(danio rerio)are tropical freshwater fish that proved to be an excellent vertebrate model of successful CNS regeneration.Differential neuronal,glial,and immune injury responses underlie disparate injury outcomes between highly regenerative zebrafish and poorly regenerative mammals.This article describes complications associated with neuronal repair following spinal cord injury(SCI)in poorly regenerative mammals and highlights intersecting modes of plasticity and regeneration in highly regenerative zebrafish(Figures 1 and 2).Comparative approaches evaluating immunoglial SCI responses were recently reviewed elsewhere(Reyes and Mokalled,2024). 展开更多
关键词 urodele amphibians central nervous system central nervous system cns REGENERATION vertebrate model PLASTICITY vertebrates teleost fish
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Synapses and dendritic spines are eliminated in the primary visual cortex of mice subjected to chronic intraocular pressure elevation
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作者 Xinyi Zhang Deling Li +6 位作者 Weiting Zeng Yiru Huang Zongyi Zhan Yuning Zhang Qinyuan Hu Lianyan Huang Minbin Yu 《Neural Regeneration Research》 2026年第3期1236-1248,共13页
Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglio... Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglion cells and their axons,leading to axonal transport dysfuntion,subsequently causing secondary damage to anterior or posterior ends of the visual system.Accordingly,recent evidence indicates that glaucoma is a degenerative disease of the central nervous system that causes damage throughout the visual pathway.However,the effects of glaucoma on synaptic plasticity in the primary visual cortex remain unclear.In this study,we established a mouse model of unilateral chronic ocular hypertension by injecting magnetic microbeads into the anterior chamber of one eye.We found that,after 4 weeks of chronic ocular hypertension,the neuronal somas were smaller in the superior colliculus and lateral geniculate body regions of the brain contralateral to the affected eye.This was accompanied by glial cell activation and increased expression of inflammatory factors.After 8 weeks of ocular hypertension,we observed a reduction in the number of excitatory and inhibitory synapses,dendritic spines,and activation of glial cells in the primary visual cortex contralateral to the affected eye.These findings suggest that glaucoma not only directly damages the retina but also induces alterations in synapses and dendritic spines in the primary visual cortex,providing new insights into the pathogenesis of glaucoma. 展开更多
关键词 chronic ocular hypertension dendritic spines GLAUCOMA glial cells NEUROINFLAMMATION NEURON retinal ganglion cells synaptic plasticity visual cortex visual pathway
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Differential plasticity of excitatory and inhibitory reticulospinal fibers after spinal cord injury:Implication for recovery
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作者 Rozaria Jeleva Carmen Denecke Muhr +1 位作者 Alina P.Liebisch Florence M.Bareyre 《Neural Regeneration Research》 2026年第5期2011-2020,共10页
The remodeling of axonal connections following injury is an important feature driving functional recovery.The reticulospinal tract is an interesting descending motor tract that contains both excitatory and inhibitory ... The remodeling of axonal connections following injury is an important feature driving functional recovery.The reticulospinal tract is an interesting descending motor tract that contains both excitatory and inhibitory fibers.While the reticulospinal tract has been shown to be particularly prone to axonal growth and plasticity following injuries of the spinal cord,the differential capacities of excitatory and inhibitory fibers for plasticity remain unclear.As adaptive axonal plasticity involves a sophisticated interplay between excitatory and inhibitory input,we investigated in this study the plastic potential of glutamatergic(vGlut2)and GABAergic(vGat)fibers originating from the gigantocellular nucleus and the lateral paragigantocellular nucleus,two nuclei important for locomotor function.Using a combination of viral tracing,chemogenetic silencing,and AI-based kinematic analysis,we investigated plasticity and its impact on functional recovery within the first 3 weeks following injury,a period prone to neuronal remodeling.We demonstrate that,in this time frame,while vGlut2-positive fibers within the gigantocellular and lateral paragigantocellular nuclei rewire significantly following cervical spinal cord injury,vGat-positive fibers are rather unresponsive to injury.We also show that the acute silencing of excitatory axonal fibers which rewire in response to lesions of the spinal cord triggers a worsening of the functional recovery.Using kinematic analysis,we also pinpoint the locomotion features associated with the gigantocellular nucleus or lateral paragigantocellular nucleus during functional recovery.Overall,our study increases the understanding of the role of the gigantocellular and lateral paragigantocellular nuclei during functional recovery following spinal cord injury. 展开更多
关键词 GABAergic(vGat)fibers gait features glutamatergic(vGlut2)fibers PLASTICITY recovery of function reticulospinal tract spinal cord injury
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两相流条件下微纳塑料颗粒迁移及滞留机理研究
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作者 刘启明 杨志兵 吴婷 《地学前缘》 北大核心 2026年第1期222-235,共14页
微纳塑料(micro/nano-plastics,M/NPs)在多孔介质中的迁移与滞留机制是土壤与地下水污染领域的重要问题,然而受当前可视化技术的限制,两相流条件下M/NPs迁移与滞留过程的细观机理尚不明确。本研究基于三维可视化实验平台,直接观测并量... 微纳塑料(micro/nano-plastics,M/NPs)在多孔介质中的迁移与滞留机制是土壤与地下水污染领域的重要问题,然而受当前可视化技术的限制,两相流条件下M/NPs迁移与滞留过程的细观机理尚不明确。本研究基于三维可视化实验平台,直接观测并量化了渗吸条件下M/NPs在孔隙空间中的分布特征,重点分析了驱替结束后其在多孔介质骨架颗粒接触区、固相表面及液液界面的滞留规律,探究了M/NPs粒径与驱替流量对其空间分布的控制机制。结果表明:M/NPs粒径通过改变M/NPs-固相表面与M/NPs-流体界面间的相互作用能来主导其滞留位点的选择;而M/NPs间的相互作用能大小是决定其能否聚集成团簇并滞留在孔隙空间的关键因素;驱替流量则通过改变固相湿润相界面面积影响其滞留总量。此外,M/NPs滞留在多孔介质中不同点位的主导机制不同,其在多孔介质骨架颗粒接触区的滞留主要受筛分作用控制,而在固相表面与液液界面处的滞留则主要依赖于界面吸附作用。在高剪切条件下滞留在固相表面的M/NPs可能会脱落,而骨架颗粒接触区作为低速区,其聚集团簇数量随流速增大而增加。本研究揭示并量化了M/NPs粒径与流速对其迁移滞留的作用机制,可为预测土壤和地下水等多相流体环境中污染物的迁移与归宿提供重要的理论依据。 展开更多
关键词 微纳塑料 多孔介质 两相流 滞留机理 分布特性
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有氧和抗阻运动改善肥胖相关认知障碍的作用机制
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作者 刘煜 雷森林 +2 位作者 周锦涛 刘辉 李先辉 《中国组织工程研究》 北大核心 2026年第5期1171-1183,共13页
背景:肥胖不仅与糖尿病、心血管疾病等代谢性疾病有关,还与认知功能下降、痴呆等神经退行性疾病的风险增加密切相关。研究发现,有氧运动和抗阻运动有助于改善肥胖相关认知障碍,然而治疗效果和相关作用机制尚不明确。目的:探究有氧运动... 背景:肥胖不仅与糖尿病、心血管疾病等代谢性疾病有关,还与认知功能下降、痴呆等神经退行性疾病的风险增加密切相关。研究发现,有氧运动和抗阻运动有助于改善肥胖相关认知障碍,然而治疗效果和相关作用机制尚不明确。目的:探究有氧运动、抗阻运动对肥胖相关认知障碍小鼠神经中枢的保护作用及机制。方法:48只8周龄C57BL/6J野生型雄性小鼠随机分为4组:对照组正常饲养20周;高脂组用高脂饲料(60%脂肪供能)饲养20周;有氧运动组高脂饲养12周后,有氧运动干预8周;抗阻运动组高脂饲养12周后,抗阻运动干预8周。运动干预结束后分别称量体质量,进行胰岛素耐量测试、葡萄糖耐量测试、新物体识别实验和Y迷宫实验;苏木精-伊红染色观察各组小鼠海马和皮质组织细胞形态;实时荧光定量PCR检测肿瘤坏死因子α和白细胞介素6 mRNA表达;Western blot检测Bax、Bcl-2、核因子κB、Cleaved Caspase-1、Caspase-3、突触蛋白1、脑源性神经营养因子蛋白表达。结果与结论:①与对照组相比,高脂组小鼠体质量增加(P<0.05),并伴随胰岛素抵抗以及认知功能障碍发生,海马组织中核因子κB、Bax、Caspase-3、Cleaved Caspase-1蛋白表达显著增加(P<0.05),脑源性神经营养因子、突触蛋白1、Bcl-2蛋白表达显著降低(P<0.05),Bcl-2/Bax比值显著降低(P<0.05),炎症因子肿瘤坏死因子α和白细胞介素6 mRNA表达显著增加(P<0.05)。②与高脂组相比,有氧运动组小鼠上述指标均得到显著改善(P<0.05),而抗阻运动组小鼠体质量减轻、炎症因子肿瘤坏死因子α、白细胞介素6 mRNA表达显著降低(P<0.05)、Caspase-3蛋白表达显著降低(P<0.05)以及脑源性神经营养因子蛋白表达显著增加(P<0.05),其他指标无显著变化(P>0.05)。综合以上结果发现,长期运动可通过降低肥胖小鼠胰岛素抵抗、下调核因子κB通路表达、减轻炎症反应、抑制神经元凋亡和改善突触可塑性产生神经保护作用,有效缓解肥胖相关认知功能障碍,其中有氧运动的治疗效果优于抗阻运动。 展开更多
关键词 肥胖相关认知障碍 核因子ΚB 有氧运动 抗阻运动 神经炎症 突触可塑性 凋亡 工程化组织构建
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轴向冲击载荷下深沟球轴承的损伤及响应研究
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作者 金峰 蔡振清 +3 位作者 谢志浩 刘璐璐 赵振华 陈伟 《航空动力学报》 北大核心 2025年第4期182-191,共10页
针对轴向冲击载荷下转子轴承的损伤和响应问题开展了研究,设计了一种试验室用模拟航空发动机轴承损伤试验台,并建立了基于plastic kinematic(PK)本构模型的轴承冲击有限元模型,研究了低、中、高这3种冲击速度下深沟球轴承的损伤和响应... 针对轴向冲击载荷下转子轴承的损伤和响应问题开展了研究,设计了一种试验室用模拟航空发动机轴承损伤试验台,并建立了基于plastic kinematic(PK)本构模型的轴承冲击有限元模型,研究了低、中、高这3种冲击速度下深沟球轴承的损伤和响应。结果表明:有限元仿真计算结果与试验误差在10%以内,随着冲击速度增大,轴承滚珠的损伤形式由细长的凹痕增大为区域型的凹坑,损伤产生的原因为由于变形引起的滚珠与轴承内外圈之间的挤压;不同速度的冲击过程中,最大应力总是出现在轴承滚珠上,且滚珠与轴承内外圈之间接触力及变化规律基本一致;保持架接合处和与滚珠接触的内圈位置为轴向载荷冲击下的塑性变形较大位置处。 展开更多
关键词 轴向冲击载荷 深沟球轴承 plastic kinematic(PK)本构模型 宏观损伤 动态响应
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西北绿洲灌区玉米叶片衰老特征对不同地膜覆盖利用方式的响应 被引量:4
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作者 王丽萍 李盼 +6 位作者 赵连豪 樊志龙 胡发龙 范虹 何蔚 柴强 殷文 《作物学报》 CAS 北大核心 2025年第1期233-246,共14页
西北绿洲灌区玉米传统生产模式中大量使用地膜伴随着生态环境污染严重,且在极端高温下玉米出现叶片早衰。针对该现象,通过免耕一膜2年覆盖利用技术探讨延缓玉米叶片衰老并增加玉米产量的可行性,以期为构建西北绿洲灌区地膜减量玉米高效... 西北绿洲灌区玉米传统生产模式中大量使用地膜伴随着生态环境污染严重,且在极端高温下玉米出现叶片早衰。针对该现象,通过免耕一膜2年覆盖利用技术探讨延缓玉米叶片衰老并增加玉米产量的可行性,以期为构建西北绿洲灌区地膜减量玉米高效生产技术提供理论支撑。2013年在西北绿洲灌区设置免耕一膜2年覆盖利用(NTP)、秋免耕春覆膜(RTP)和传统每年覆新膜(对照, CTP) 3种处理(本文采用2021-2023数据),探究玉米叶片光合源、持绿特性、细胞抗氧化酶活性和渗透调节物质含量对不同地膜覆盖利用方式的响应。结果表明,NTP和RTP可有效调节玉米生育期内光合源和叶片持绿性能的动态关系,维持生育后期较大的叶面积指数(LAI)、光合势(LAD)、叶片持绿性(SG)和叶绿素相对含量(SPAD),有利于延缓叶片衰老。与CTP相比, NTP玉米出苗后75~120 d的LAI、LAD、SG和SPAD分别提高15.1%~16.1%、14.8%~15.5%、7.2%~9.2%和11.3%~11.7%,RTP分别提高12.4%~13.0%、11.5%~12.4%、10.0%~17.6%和6.0%~6.7%。同时,通过单株绿色叶面积的拟合,发现NTP和RTP较CTP叶片衰老时间平均推迟了5.8~7.0d和6.2~7.7d,这可能是由于NTP和RTP有助于增强玉米大喇叭口期-灌浆期叶片的抗氧化能力和细胞渗透调节作用。玉米出苗后60~105 d, NTP较CTP叶片抗氧化酶(SOD、POD、CAT和APX)活性分别提高17.6%~20.0%、28.4%~34.4%、6.7%~8.4%和8.3%~10.9%, RTP较CTP分别提高11.3%~11.7%、16.9%~18.2%、4.4%~6.1%和5.8%~7.7%。此外,与CTP相比,NTP与RTP可溶性蛋白和脯氨酸含量分别提高35.9%~43.9%和29.5%~31.8%,20.7%~31.7%和17.4%~20.4%,丙二醛含量分别降低26.0%~27.8%和17.5%~25.9%。NTP对抗氧化酶和渗透调节物质的影响更大,NTP较CTP增产5.2%~6.0%。免耕一膜2年覆盖利用技术是西北灌区在实现资源减投条件下,有效延缓玉米叶片衰老且增加产量的适宜措施。 展开更多
关键词 地膜覆盖 光合源 抗氧化酶活性 细胞渗透调节能力 籽粒产量
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“以竹代塑”发展理念、面临挑战与发展模式研究 被引量:2
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作者 张亚慧 姜伯言 +3 位作者 周昌平 赖相燕 黄宇翔 于文吉 《林业工程学报》 北大核心 2025年第4期10-18,共9页
针对全球每年产生约3亿t塑料垃圾引发的生态环境危机,我国创新性提出“以竹代塑”可持续发展倡议。“以竹代塑”倡议是基于自然解决因塑料废物造成污染的全球性环境可持续发展的中国治理方案,这一绿色发展战略也将成为我国竹产业在2035... 针对全球每年产生约3亿t塑料垃圾引发的生态环境危机,我国创新性提出“以竹代塑”可持续发展倡议。“以竹代塑”倡议是基于自然解决因塑料废物造成污染的全球性环境可持续发展的中国治理方案,这一绿色发展战略也将成为我国竹产业在2035年实现万亿级产业规模战略目标的重要窗口期。首先,深入剖析了“以竹代塑”发展理念的构成要素、价值体现及内涵特性,对引领性、创新性、绿色性、和谐性以及可持续性这五大核心要素的具体内涵予以详尽阐释;其次,从自然属性、社会属性、经济属性和科技属性4个层面出发,针对性地提出了“以竹代塑”理念下“以竹代塑+”多元应用场景的实践策略;然后,围绕产业创新、产业生态和产业价值链3个维度系统梳理了“以竹代塑”产业在发展进程中的现状与所面临的挑战,并深入分析了这些挑战产生的深层次成因。基于上述研究基础,提出了我国“以竹代塑”产业的4种发展模式:(1)以第二产业为主导,第一、三产业融合发展的模式;(2)以有组织的新质生产力为驱动,推动科技创新和产业创新深度融合的国家创新领导模式;(3)基于“链式思维”构建全要素政策支持的产业扶持增强模式;(4)以多元化、多层次为特征,健康且安全的竹产品供给市场需求驱动模式。最后,希望按照“战略引领-核心突破-市场转化-保障支撑”的逻辑层次,重点突出国家创新领导模式的核心引擎作用,强化产业融合与市场需求驱动的双轮驱动效应,完善产业扶持增强模式的保障功能,形成层次分明、有机协同的发展体系,以期为我国竹产业高质量发展提供新思路。 展开更多
关键词 以竹代塑 发展理念 挑战 发展模式
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钨材料中缺陷的形成及演化规律 被引量:1
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作者 罗来马 魏国庆 +2 位作者 刘祯 朱晓勇 吴玉程 《金属学报》 北大核心 2025年第4期526-540,共15页
钨材料作为一种重要的工业材料,以其高密度、高熔点和卓越的硬度及耐磨性能而闻名。晶体缺陷在钨材料的晶体结构中是常见的,调控钨材料中的缺陷是改善其性能的重要手段,深入理解钨材料中缺陷的形成与演化是实现其调控的理论基础。本文... 钨材料作为一种重要的工业材料,以其高密度、高熔点和卓越的硬度及耐磨性能而闻名。晶体缺陷在钨材料的晶体结构中是常见的,调控钨材料中的缺陷是改善其性能的重要手段,深入理解钨材料中缺陷的形成与演化是实现其调控的理论基础。本文从烧结过程引入缺陷、应力效应引入缺陷2个关键方面,综述了钨材料缺陷的形成机制及其研究进展,对应地从制备、加工等角度来理解钨材料中的缺陷,并对相关领域近年来的研究进展进行了评述和展望,旨在为钨材料的研究提供参考。 展开更多
关键词 钨材料 缺陷 烧结 塑性变形 晶体缺陷
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植物纤维复合塑料健身器械结构件综合力学性能分析研究 被引量:2
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作者 杨改红 杨建设 +1 位作者 赵丽华 赵冬 《造纸科学与技术》 2025年第7期67-70,共4页
植物纤维如竹纤维、麻纤维等被认为是非常理想的复合材料增强纤维。为分析植物纤维在健身器械生产领域的应用价值,以竹纤维、聚丙烯、改性剂等材料制备了一种植物纤维复合塑料健身器械工字型结构件,以试验方式对该结构件的力学性能进行... 植物纤维如竹纤维、麻纤维等被认为是非常理想的复合材料增强纤维。为分析植物纤维在健身器械生产领域的应用价值,以竹纤维、聚丙烯、改性剂等材料制备了一种植物纤维复合塑料健身器械工字型结构件,以试验方式对该结构件的力学性能进行分析。结果表明,与传统的聚丙烯塑料、金属材料相比,植物纤维复合塑料在拉伸强度等方面优于传统聚丙烯塑料,但劣于金属材料,但植物纤维复合塑料健身器械结构件的动态疲劳性能全面优于另外两种材料。 展开更多
关键词 植物纤维复合塑料 聚丙烯塑料 健身器械 工字型结构件
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植塑复合类食品接触制品中化学污染物迁移的检测和评估 被引量:2
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作者 倪永标 孙姗姗 +3 位作者 许力 朱昱臻 唐敏敏 邹洁 《塑料科技》 北大核心 2025年第7期131-136,共6页
研究市售植塑复合类食品接触制品与不同食品模拟物接触(体积分数4%的乙酸、10%的乙醇和95%的乙醇)时多种化学污染物的迁移情况。采用液相色谱质谱联用仪、电感耦合等离子体质谱仪对食品模拟液中的重金属、三聚氰胺、抗氧化剂、双酚A、... 研究市售植塑复合类食品接触制品与不同食品模拟物接触(体积分数4%的乙酸、10%的乙醇和95%的乙醇)时多种化学污染物的迁移情况。采用液相色谱质谱联用仪、电感耦合等离子体质谱仪对食品模拟液中的重金属、三聚氰胺、抗氧化剂、双酚A、芳香族伯胺、三乙醇胺及磷酸三乙酯迁移物进行定量检测,采用扫描电子显微镜对浸泡前后的食品接触材料进行形貌分析,以深入剖析迁移原因。结果显示,在特定条件下,部分植塑复合类样品存在迁移风险,其中重金属、双酚A和三乙醇胺的迁移量超过相关标准限值。经迁移实验后的竹纤维餐具表面结构不密实,其他辅料更易填充于密胺树脂分子间隙,在高温、酸性实验条件下,在表面形成较多微孔,使有害物质更易迁出。研究结果可为相关职能部门制定监管政策、保障消费者健康提供依据。 展开更多
关键词 化学污染物 迁移量 植塑复合材料 食品接触制品
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汽车用先进高强度中锰钢研究进展 被引量:4
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作者 李倩 陈晨 +3 位作者 李艳国 杨志南 吕博 张福成 《燕山大学学报》 北大核心 2025年第1期1-9,共9页
中锰钢属于第三代汽车用先进高强钢的范畴,其很好地平衡了汽车工业对强塑性和生产成本的要求,十多年来吸引了众多材料研究学者开展相关研究工作。本文介绍了汽车用先进高强度中锰钢的起源、化学成分及力学性能特点,分析讨论了高强度中... 中锰钢属于第三代汽车用先进高强钢的范畴,其很好地平衡了汽车工业对强塑性和生产成本的要求,十多年来吸引了众多材料研究学者开展相关研究工作。本文介绍了汽车用先进高强度中锰钢的起源、化学成分及力学性能特点,分析讨论了高强度中锰钢的强塑化机制,总结了合金化和奥氏体逆转变退火工艺对高强度中锰钢微观组织和力学性能调控的研究现状,并论述了中锰钢焊接性和氢脆敏感性问题。最后,对今后一段时间内中锰钢的基础理论和应用研究方向进行了讨论。 展开更多
关键词 汽车用钢 中锰钢 强塑性 焊接性 氢脆敏感性
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材料成型专业塑性力学教学的思考与探讨 被引量:1
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作者 李洪洋 李红 +1 位作者 许兴燕 刘颖 《机械设计》 北大核心 2025年第2期155-158,共4页
塑性力学是一门专注于探究材料在受力作用下产生永久变形的物理现象及其相关力学特性的科学,对于深入理解并预测材料在各种工程应用环境中的表现具有举足轻重的意义。然而,随着社会的持续进步和工程技术的日新月异,当前的教学方法在培... 塑性力学是一门专注于探究材料在受力作用下产生永久变形的物理现象及其相关力学特性的科学,对于深入理解并预测材料在各种工程应用环境中的表现具有举足轻重的意义。然而,随着社会的持续进步和工程技术的日新月异,当前的教学方法在培养学生应对实际工程问题的能力上显示出明显的局限性,这使得塑性力学的教学改革变得愈发迫切。文中致力于通过革新教学理念、丰富教学内容、优化教学方法及完善评价体系等多维度策略,探讨提升塑性力学教学质量的有效途径,并着重增强学生分析问题及解决实际问题的能力。 展开更多
关键词 材料成型 塑性力学 人才培养 教学方法
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“以竹代塑”背景下四川竹富产区乡村规划设计策略研究 被引量:1
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作者 温耀龙 杨凌云 杨亚 《林产工业》 北大核心 2025年第6期95-100,共6页
四川竹资源丰富,竹文化历史悠久,底蕴深厚,内涵丰富,应用范围广,涵盖了生产、生活、艺术、文学等方面。借助竹元素和乡村规划设计相结合,自然环境与人文景观结合,有助于继承与发展我国悠久的传统竹文化,也有助于打造富有地方特色和竹文... 四川竹资源丰富,竹文化历史悠久,底蕴深厚,内涵丰富,应用范围广,涵盖了生产、生活、艺术、文学等方面。借助竹元素和乡村规划设计相结合,自然环境与人文景观结合,有助于继承与发展我国悠久的传统竹文化,也有助于打造富有地方特色和竹文化特征的美丽乡村。分析了四川竹富产区乡村规划建设的现状及背后原因,提出了以竹元素为主题进行美丽乡村规划设计的策略研究,从竹林景观观赏、竹文创体验、竹博园游览、竹林康养等方面分析探索了竹元素在美丽乡村规划设计的应用,以期为其他竹富产区的乡村规划设计提供参考和示范。 展开更多
关键词 以竹代塑 竹元素 乡村 规划设计 策略
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血管化骨瓣在下颌骨缺损修复重建中存活率的网状Meta分析 被引量:1
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作者 王丽 李晨曦 +4 位作者 王正业 龚忠诚 丁明超 刘慧 孙家琳 《中国循证医学杂志》 北大核心 2025年第1期74-80,共7页
目的基于贝叶斯网状Meta分析系统评价不同血管化骨瓣在下颌骨缺损修复重建中的存活率。方法计算机检索PubMed、EBSCO、Scopus、Web of Science、Cochrane Library、WanFang Data和CNKI数据库,搜集与研究目的相关的临床研究,检索时限均... 目的基于贝叶斯网状Meta分析系统评价不同血管化骨瓣在下颌骨缺损修复重建中的存活率。方法计算机检索PubMed、EBSCO、Scopus、Web of Science、Cochrane Library、WanFang Data和CNKI数据库,搜集与研究目的相关的临床研究,检索时限均从建库至2024年2月。由2名研究者独立筛选文献、提取资料并评价纳入研究的偏倚风险后,采用R软件进行贝叶斯网状Meta分析。结果共纳入24项研究,包括1615名患者。Meta分析结果显示腓骨游离瓣、旋髂深动脉髂骨瓣、肩胛骨瓣及携带桡骨的前臂桡侧皮瓣用于下颌骨重建的术后存活率分别为95.62%、94.09%、98.16%和93.75%。网状Meta分析结果显示各组织瓣术后存活率之间的差异均无统计学意义。结论当前证据表明,不同血管化骨瓣在下颌骨缺损修复重建中的存活率相似。受纳入研究数量和质量的限制,上述结论尚待更多高质量研究予以验证。 展开更多
关键词 下颌骨 整形外科和重建技术 网状Meta分析 临床预后
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