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皖西大别山地区无尾两栖类alpha和beta多样性格局及其影响因素
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作者 熊欢 刘雪艳 +7 位作者 吴燕芳 陈红州 马妍 胡星月 张静宜 夏瑨宇 吴伟泽 陈伟 《生物多样性》 北大核心 2025年第11期180-194,共15页
山地因独特的环境特征(地形地貌、气候和海拔等)和高度丰富的物种组成,被认为是研究生物多样性分布格局及群落构建的热点地区。截至目前,尚未有针对南北气候过渡带区域(如皖西大别山区)的山地两栖类物种多样性分布格局及其群落构建机制... 山地因独特的环境特征(地形地貌、气候和海拔等)和高度丰富的物种组成,被认为是研究生物多样性分布格局及群落构建的热点地区。截至目前,尚未有针对南北气候过渡带区域(如皖西大别山区)的山地两栖类物种多样性分布格局及其群落构建机制的报道。因此,本文于2024年采用标准样线调查法,在不同海拔梯度、生境类型和季节尺度上,对皖西大别山地区无尾两栖类展开调查,并对其alpha多样性与beta多样性进行分析,结合气候、地形、生境及人为干扰等环境因素,探讨其多样性格局及其影响因素。Alpha多样性的结果显示:该区域共有无尾两栖类6科12属18种,且物种丰富度与海拔呈显著负相关,而Pielou均匀度指数则显示了相反的海拔变异规律;此外,该区域内无尾两栖类的Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数在不同生境类型间表现出显著差异(农田生境高于其他生境),其中Shannon-Wiener多样性指数也呈现出显著的季节性差异(夏季高于春季),同时发现年降水量是影响物种丰富度、Shannon-Wiener多样性指数和Simpson优势度指数的主要因素。Beta多样性的研究表明,Bray-Curtis相异性指数和Sørensen相异性指数表现出周转组分高于嵌套组分且年均温是影响beta多样性指数及其周转组分的主要因素。本研究阐明了处于气候过渡带的皖西大别山地区无尾两栖类多样性格局及其影响因素,为该区域生物多样性保护提供了数据支撑和理论依据。 展开更多
关键词 alpha多样性 beta多样性 大别山地区 生物多样性 无尾两栖类
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基于Alpha-Beta剪枝的三维空间四子棋系统
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作者 陈昊天 刘晓彤 陈冰洋 《软件导刊》 2025年第8期137-144,共8页
棋类游戏研究已经从传统的二维空间扩展到三维空间,三维空间的引入增加了游戏的复杂性和策略深度。针对三维空间四子棋的立体结构和规则,应用Alpha-Beta剪枝算法可以开发一个高效的三维空间四子棋系统,使用遗传算法等方法优化棋形得分... 棋类游戏研究已经从传统的二维空间扩展到三维空间,三维空间的引入增加了游戏的复杂性和策略深度。针对三维空间四子棋的立体结构和规则,应用Alpha-Beta剪枝算法可以开发一个高效的三维空间四子棋系统,使用遗传算法等方法优化棋形得分进一步提高系统智能性,并通过KANs分析结果。该系统设计了具有良好交互性和游戏性的3D界面,使用户能够从不同角度观察棋盘。在系统构建过程中,设计了适应三维棋盘的数据结构和局面评估函数,以确保AI能够高效地进行决策和对战。该系统支持多种游戏模式,包括不同难度的AI对战和本地双人对战。此外,系统提供对局历史记录回放,用户可以通过该功能进行棋局复盘和数据分析。对局结果数据显示,AI在不同难度下的表现与计客智能四子棋系统的难度相对应,能够有效适应各类用户的对局需求。 展开更多
关键词 三维空间四子棋 alpha-beta剪枝 遗传算法 KANs
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Design and synthesis of KIT-5/Beta composites under varied hydrothermal temperatures and evaluation of their hydrodenitrogenation performance
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作者 LIU Xing GUO Shaoqing +7 位作者 CUI Haitao LI Zhenrong LI Xin WANG Lei WU Xingjie WANG Xiaoxiao YUAN Lijing ZHAO Liangfu 《燃料化学学报(中英文)》 北大核心 2026年第1期46-57,共12页
KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method,and NiW/KIT-5/Beta catalysts were prepared by impregnation.A series of characterization techniques were utilized to eva... KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method,and NiW/KIT-5/Beta catalysts were prepared by impregnation.A series of characterization techniques were utilized to evaluate the influence of varying hydrothermal synthesis temperatures on the physicochemical properties of both the KIT-5/Beta supports and the resulting catalysts.The catalytic performances of catalysts were evaluated under reaction conditions of 320℃,4 MPa H_(2)pressure,and a weight hourly space velocity(WHSV)of 4.8 h^(-1)for hydrodenitrogenation(HDN)of quinoline.The results indicated that the specific surface area and pore structure of the materials could be effectively regulated by adjusting the hydrothermal synthesis temperature,which in turn influenced the number of active sites on the catalyst.The NiW/KB-125 catalyst,synthesized at 125℃,presented the highest quinoline HDN efficiency(96.8%),which can be attributed to its favorable pore channel structure,greater Brønsted acid number,higher degree of metal sulfidation(80.12%)and appropriate metal-support interaction(MSI). 展开更多
关键词 mesoporous-microporous material KIT-5/beta composite NiWS QUINOLINE HYDRODENITROGENATION
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西门子NAEOTOM Alpha光子计数CT故障维修2例
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作者 殷旭 陈冠军 王觊玺 《医疗卫生装备》 2026年第2期109-114,共6页
阐述了西门子NAEOTOM Alpha光子计数CT的结构,介绍了机架无法正常启动、日常校准失败2例故障,分析了故障产生的原因,并给出了具体的排除方法,为工程技术人员维修此类故障提供了参考。
关键词 西门子NAEOTOM alpha光子计数CT 故障维修 故障排除
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人工晶状体Alpha角对连续视程人工晶状体眼视觉质量的影响
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作者 刘振 周维维 +3 位作者 刘涵婧 张艺 朱玉广 朱艳 《山东大学耳鼻喉眼学报》 2026年第1期47-53,共7页
目的探讨IOL Alpha角对连续视程人工晶体(extended depth-of-field intraocular lens,EDOF IOL)植入术后视觉质量的影响。方法选取行白内障超声乳化联合EDOF IOLs植入术的年龄相关性白内障患者50例(50只眼)。采用OPD-ScanⅢ像差分析仪的... 目的探讨IOL Alpha角对连续视程人工晶体(extended depth-of-field intraocular lens,EDOF IOL)植入术后视觉质量的影响。方法选取行白内障超声乳化联合EDOF IOLs植入术的年龄相关性白内障患者50例(50只眼)。采用OPD-ScanⅢ像差分析仪的日-夜瞳孔测量系统,得到人工晶状体(intraocular len,IOL)植入术后Alpha角,根据光学路径差扫描仪Ⅲ(Optical Path Difference ScanⅢ,OPD ScanⅢ)测量术后IOL Alpha角大小分为3组:A组19只眼(0 mm<Alpha角≤0.2 mm),B组19只眼(0.2 mm<Alpha角≤0.4 mm),C组12只眼(Alpha角>0.4 mm)。采用OPD-ScanⅢ像差分析仪检测术前Alpha角;术后3个月检测裸眼远视力(uncorrected distance visual acuity,UDVA),OPD-ScanⅢ测量EDOF IOLs植入眼的客观视觉质量,包括眼内高阶像差(higher-order aberrations,HOA)、斯特列尔比(strehl ratio,SR)、全眼HOA、彗差(Coma)、三叶草像差(Trefoil)并进行比较分析。采用视功能指数量表-14(visual function index,VF-14)评估患者的视功能。结果术前Alpha角与IOL Alpha角差异不具有统计学意义(t=0.11,P=0.915)。经Pearson相关性分析,术前Alpha角与IOL Alpha角之间呈正相关(r=0.983,P<0.001)。IOL Alpha角三组间UDVA、眼内HOA、SR、全眼HOA、Coma、Trefoil差异都具有统计学意义(P均<0.05)。眼内HOA、SR值及Coma值组间两两比较均有统计学差异(P均<0.05);Trefoil值及全眼HOA值仅在A组与C组之间差异具有统计学意义(P=0.030,P=0.001)。VF-14问卷调查显示A、B、C组眩光或光晕的发病率分别为47.4%(9/19)、68.4%(13/19)和100%(12/12),差异具有统计学意义(χ^(2)=9.365,P=0.009)。结论IOL Alpha角可反映IOL居中性及在眼内的实际状态,其不仅影响术后患者视觉质量、反映其术后实际视觉效果,较大的IOL Alpha角还会增加术后眩光、光晕发生率,进而影响患者生活质量。 展开更多
关键词 alpha 光学路径差扫描仪Ⅲ 连续视程人工晶体 视觉质量
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催化裂解催化剂Beta分子筛改性研究综述
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作者 王新宇 段宏昌 +3 位作者 宋文强 马永鹏 吕鹏刚 黄校亮 《炼油技术与工程》 2026年第1期1-5,共5页
催化裂解工艺技术升级的关键在于研发具备高活性、高选择性及长寿命的先进催化剂体系。文中聚焦Beta分子筛,综述了酸碱处理、元素掺杂、添加软硬模板剂及复合改性等手段对其微观结构的调控机制,以及水热稳定性的影响。通过精准调控酸类... 催化裂解工艺技术升级的关键在于研发具备高活性、高选择性及长寿命的先进催化剂体系。文中聚焦Beta分子筛,综述了酸碱处理、元素掺杂、添加软硬模板剂及复合改性等手段对其微观结构的调控机制,以及水热稳定性的影响。通过精准调控酸类型、酸量与酸强度,可为优化反应路径奠定基础;构筑多级孔道结构可显著改善催化剂扩散特性,提升大分子反应物在孔内的传质效率。孔道结构优化与酸性位点修饰相互协同,共同强化分子筛水热稳定性,保障其在高温水汽工况下的结构完整性。同时,探讨了改性Beta分子筛在催化裂解过程中对低碳烯烃选择性的影响规律。 展开更多
关键词 催化裂解 催化剂 beta分子筛 低碳烯烃 调控酸性 孔道结构 水热稳定性
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Alpha-synuclein-induced upregulation of SKI family transcriptional corepressor 1: A new player in aging and Parkinson's disease?
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作者 Lauren Barrett Rebekah Bevans +2 位作者 Aideen M.Sullivan Louise M.Collins Gerard W.O’Keeffe 《Neural Regeneration Research》 2026年第1期320-321,共2页
SKI family transcriptional corepressor 1(SKOR1also known as LbxCor1, Fussel15, or CORL1), is a member of the SKI family of proteins and is transcribed from a protein-coding gene located on chromosome 15 in humans, tha... SKI family transcriptional corepressor 1(SKOR1also known as LbxCor1, Fussel15, or CORL1), is a member of the SKI family of proteins and is transcribed from a protein-coding gene located on chromosome 15 in humans, that has a molecular weight of approximately 100 kDa. Skor1 is highly expressed in neurons in the central nervous system of both humans and rodents. 展开更多
关键词 alpha Cor AGING
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Identification of TMED10 as A Regulator for Neuronal Exocytosis of Amyloid Beta 42
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作者 Peixin Meng Longze Sha +6 位作者 Xiaolin Yu Yanbing Wang Erning Zhang Kexin Meng Bingnan Li Qin Zhao Qi Xu 《Neuroscience Bulletin》 2026年第2期403-418,共16页
Alzheimer’s disease(AD)is a neurodegenerative disorder characterized by neurotoxic amyloid beta(Aβ)deposition in the brain.Neurons can internalize and exocytose Aβ;however,the molecular pathways governing Aβreleas... Alzheimer’s disease(AD)is a neurodegenerative disorder characterized by neurotoxic amyloid beta(Aβ)deposition in the brain.Neurons can internalize and exocytose Aβ;however,the molecular pathways governing Aβrelease remain poorly understood.To identify key regulators of Aβ42 transport,we applied formaldehyde cross-linking of protein complexes combined with co-immunoprecipitation and mass spectrometry analysis to identify TMED10 as a novel Aβ42-interacting protein.In cultured neurons,TMED10 knockdown(KD)increased intracellular Aβ42 levels by preventing Aβ42 exocytosis.TMED10 expression was significantly reduced in the cortex of AD patients.Overexpression of TMED10 in primary neurons mitigated the toxic effects of exogenous Aβ42.In 5×FAD mice,overexpression of TMED10 via tail vein injection of a brain-penetrable adeno-associated virus improved cognitive function and reduced Aβ42 plaque accumulation.Together,these findings position TMED10 as a potential regulator of Aβ42 exocytosis and underscore the need for further studies to evaluate its therapeutic potential in AD. 展开更多
关键词 Alzheimer's disease Amyloid beta Neuron Exocytosis TMED10
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Patterns and drivers of beta diversity in bird communities associated with blue-green infrastructure in rapidly urbanizing landscapes
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作者 Fuqiang Zhao Yuan Wang +3 位作者 Dazhi Zhang Ying Yang Xuetao Li Ying Liang 《Avian Research》 2026年第1期10-21,共12页
Habitat loss driven by land-use change is a major factor shaping the dynamics of urban bird community structures.However,the potential mechanisms by which the spatial configuration and composition of blue-green infras... Habitat loss driven by land-use change is a major factor shaping the dynamics of urban bird community structures.However,the potential mechanisms by which the spatial configuration and composition of blue-green infrastructure,recognized as biodiversity hotspots in urban landscapes,influence urban bird beta diversity remain insufficiently understood.This study was conducted in the built-up area of Yinchuan,an internationally recognized wetland city in Northwest China.From December 2023 to June 2024,we systematically surveyed bird communities during both the breeding and wintering periods across 29 blue-green space mosaics.We quantified taxonomic,functional,and phylogenetic beta diversity,along with their turnover component and nestedness-resultant component,based on both pairwise beta diversity and multiple-site beta diversity.We further assessed the relative importance of landscape variables and spatial geographic distance in shaping beta diversity patterns and used hierarchical modeling of species communities(HMSC)to explore the responses of bird occurrence and functional traits to landscape variables.Our results revealed that species turnover was the dominant driver of taxonomic,functional,and phylogenetic beta diversity.Seasonal differences were observed in the effects of spatial geographic distance and landscape structure on beta diversity and its components,with landscape variables showing higher explanatory power than geographic isolation.In the breeding period,landscape diversity and waterbody area had positive effects on bird occurrence,whereas in the wintering period,most landscape features—except for landscape diversity—exerted neutral or negative influences.Regarding functional traits,we found that reproductive traits,flight ability,and foraging characteristics responded significantly to landscape structure,and that some small-bodied species active in aerial and canopy layers were more adaptable to habitat fragmentation.This study provides novel insights into the assembly processes and driving mechanisms of urban bird communities and offers scientific support for the notion that designing and maintaining blue-green infrastructure can contribute to urban biodiversity conservation. 展开更多
关键词 Blue-green infrastructure Bird beta diversity Community structure Functional HMSC PHYLOGENETIC URBANIZATION
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基于Alpha进化算法的关节型机器人时间最优轨迹规划研究
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作者 宋航 李鑫 张振顺 《南方农机》 2026年第7期133-135,156,共4页
针对飞机装配领域的关节型机器人在关节空间内的时间最优轨迹规划问题,文章提出了一种基于Alpha进化算法的3-5-3型混合多项式插值轨迹规划方法。该算法引入具备自适应基向量与随机步长特性的alpha算子,通过进化矩阵估计种群状态,并利用... 针对飞机装配领域的关节型机器人在关节空间内的时间最优轨迹规划问题,文章提出了一种基于Alpha进化算法的3-5-3型混合多项式插值轨迹规划方法。该算法引入具备自适应基向量与随机步长特性的alpha算子,通过进化矩阵估计种群状态,并利用双进化路径实现基向量的自适应更新。同时,结合复合微分运算构建自适应步长,以估计梯度并加快收敛速度。最后采用MATLAB对所提出的轨迹规划算法进行仿真验证。结果表明:Alpha进化算法能够高效地求解时间最优轨迹规划问题,算法在60代内趋向于收敛,所生成的关节空间轨迹平滑、无速度突变,验证了该方法在关节型机器人时间最优轨迹规划任务中的有效性。 展开更多
关键词 关节型机器人 关节空间 时间最优 轨迹规划 alpha进化算法
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Imaging alpha-synuclein pathology in Parkinson's disease
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作者 Ruiqing Ni 《Neural Regeneration Research》 2026年第4期1566-1567,共2页
Parkinson's disease(PD)is the second most common neurodegenerative disorder.The clinical manifestations of PD include motor symptoms,such as bradykinesia,resting tremor,rigidity,and nonmotor symptoms,which include... Parkinson's disease(PD)is the second most common neurodegenerative disorder.The clinical manifestations of PD include motor symptoms,such as bradykinesia,resting tremor,rigidity,and nonmotor symptoms,which include disturbances in sleep,gastrointestinal function,and olfaction.PD misdiagnosis rates have been reported to reach approximately 30%,partly owing to the heterogeneity of parkinsonism with non-PD pathologies,and the differential diagnosis of PD from neurodegenerative diseases such as multiple systemic atrophy(MSA)and progressive supranuclear palsy poses another unmet need. 展开更多
关键词 neurodegenerative diseases neurodegenerative disorder alpha synuclein pathology parkinsons disease pd Parkinsons disease resting tremor neurodegenerative disorderthe BRADYKINESIA
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Neonatal-onset multisystem inflammatory disease responsive to interleukin-1beta inhibition
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作者 Raphaela Goldbach-Mansky 《四川生理科学杂志》 2026年第2期277-277,共1页
Background:Neonatal-onset multisystem inflammatory disease is characterized by fever,urticarial rash,aseptic meningitis,deforming arthropathy,hearing loss,and mental retardation.Many patients have mutations in the col... Background:Neonatal-onset multisystem inflammatory disease is characterized by fever,urticarial rash,aseptic meningitis,deforming arthropathy,hearing loss,and mental retardation.Many patients have mutations in the cold-induced autoinflammatory syndrome 1(CIAS1)gene,encoding cryopyrin,a protein that regulates inflammation. 展开更多
关键词 interleukin beta inhibition CRYOPYRIN inflammation cold induced autoinflammatory syndrome neonatal onset multisystem inflammatory disease rashaseptic meningitisdeforming arthropathyhearing
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Secretase inhibition in Alzheimer's disease therapeutics reveals functional roles of amyloid-beta42
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作者 Timothy Daly Bruno P.Imbimbo 《Neural Regeneration Research》 2026年第5期2003-2004,共2页
In the words of the late Sir Colin Blakemore,neurologists have historically sought to infer brain functions in a manner akin to to king a hammer to a computeranalyzing localized anatomical lesions caused by trauma,tum... In the words of the late Sir Colin Blakemore,neurologists have historically sought to infer brain functions in a manner akin to to king a hammer to a computeranalyzing localized anatomical lesions caused by trauma,tumors,or strokes,noting deficits,and inferring what functions certain brain regions may be responsible for.This approach exemplifies a deletion heuristic,where the absence of a specific function reveals insights about the underlying structures or mechanisms responsible for it.By observing what is lost when a particular brain region is damaged,throughout the history of the field,neurologists have pieced together the intricate relationship between anatomy and function. 展开更多
关键词 infer brain functions secretase inhibition Alzheimers disease therapeutics king hammer deletion heuristic amyloid beta deletion heuristicwhere observing what l
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Role of peroxisome proliferator-activated receptor alpha in neurodegenerative diseases and other neurological disorders:Clinical application prospects
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作者 Zijun Wu Yuying Zhao +3 位作者 Shujing Hao Mengyao An Chengcheng Song Jing Li 《Neural Regeneration Research》 2026年第4期1468-1482,共15页
Peroxisome proliferator-activated receptor alpha is a member of the nuclear hormone receptor superfamily and functions as a transcription factor involved in regulating cellular metabolism.Previous studies have shown t... Peroxisome proliferator-activated receptor alpha is a member of the nuclear hormone receptor superfamily and functions as a transcription factor involved in regulating cellular metabolism.Previous studies have shown that PPARαplays a key role in the onset and progression of neurodegenerative diseases.Consequently,peroxisome proliferator-activated receptor alpha agonists have garnered increasing attention as potential treatments for neurological disorders.This review aims to clarify the research progress regarding peroxisome proliferator-activated receptor alpha in nervous system diseases.Peroxisome proliferator-activated receptor alpha is present in all cell types within adult mouse and adult neural tissues.Although it is conventionally believed to be primarily localized in the nucleus,its function may be regulated by a dynamic balance between cytoplasmic and nuclear shuttling.Both endogenous and exogenous peroxisome proliferator-activated receptor alpha agonists bind to the peroxisome proliferator-activated response element to exert their biological effects.Peroxisome proliferator-activated receptor alpha plays a significant therapeutic role in neurodegenerative diseases.For instance,peroxisome proliferator-activated receptor alpha agonist gemfibrozil has been shown to reduce levels of soluble and insoluble amyloid-beta in the hippocampus of Alzheimer's disease mouse models through the autophagy-lysosomal pathway.Additionally,peroxisome proliferator-activated receptor alpha is essential for the normal development and functional maintenance of the substantia nigra,and it can mitigate motor dysfunction in Parkinson's disease mouse models.Furthermore,peroxisome proliferator-activated receptor alpha has been found to reduce neuroinflammation and oxidative stress in various neurological diseases.In summary,peroxisome proliferator-activated receptor alpha plays a crucial role in the onset and progression of multiple nervous system diseases,and peroxisome proliferator-activated receptor alpha agonists hold promise as new therapeutic agents for the treatment of neurodegenerative diseases,providing new options for patient care. 展开更多
关键词 AGONISTS Alzheimer's disease gut microbiota multiple sclerosis nervous system disease NEURODEGENERATION neurodegenerative disease NEUROINFLAMMATION Parkinson's disease peroxisome proliferator-activated receptor alpha
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Determinants of alpha-synuclein pathogenesis in Parkinson's disease
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作者 Oriol Barcenas Marc Estivill-Alonso Salvador Ventura 《Neural Regeneration Research》 2026年第4期1568-1569,共2页
Alpha-synuclein and Parkinson's disease:Neuronal damage and inflammation caused by the aggregation of alpha-synuclein(α-syn)are central to a group of disorders known as synucleopathies,which includes Parkinson... Alpha-synuclein and Parkinson's disease:Neuronal damage and inflammation caused by the aggregation of alpha-synuclein(α-syn)are central to a group of disorders known as synucleopathies,which includes Parkinson's disease(PD),dementia with Lewy bodies,and multiple system atrophy,among others.PD,the most common synucleinopathy,is the second most prevalent neurodegenerative disease after Alzheimer's disease,and it is the fastest growing.Its primary hallmark is the degeneration of dopaminergic neurons in the substantia nigra pars compacta,disrupting the communication with the striatum. 展开更多
关键词 parkinsons disease pd dementia parkinsons disease neuronal neurodegenerative disease multiple system atrophyamong alzheimers diseaseand Parkinsons disease alpha synuclein degeneration dopaminergic neurons
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优化全身PET仪^(18)F-Florbetapir PET脑显像采集时间
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作者 程文悦 赵晓雯 +7 位作者 夏梓豪 柴雷英 荆玉东 高琳 崔晓 李坤 程召平 段艳华 《中国医学影像技术》 北大核心 2026年第2期280-284,共5页
目的优化全身PET仪^(18)F-Florbetapir PET脑显像采集时间。方法前瞻性对63例疑诊AD患者以全身PET仪行采集时间为20 min的^(18)F-Florbetapir PET脑显像;之后分别将采集时间设为10 min、5 min、3 min及1 min进一步进行重建,并对所获5组... 目的优化全身PET仪^(18)F-Florbetapir PET脑显像采集时间。方法前瞻性对63例疑诊AD患者以全身PET仪行采集时间为20 min的^(18)F-Florbetapir PET脑显像;之后分别将采集时间设为10 min、5 min、3 min及1 min进一步进行重建,并对所获5组图像进行主观视觉评分及客观半定量分析。利用受试者工作特征(ROC)曲线评估各组诊断效能。结果17例20 min图像,以及其中的13例10 min图像、6例5 min图像中存在显著运动伪影而无法诊断,故予以剔除;最终针对46例进行图像质量分析,包括β-淀粉样蛋白(Aβ)阳性28例、Aβ-阴性18例。主观视觉评分显示,除1 min组9例(Aβ-阳性6例、阴性3例)图像噪声明显、得分为2,2例(Aβ-阳性、阴性各1例)诊断信心低于3分外,其余35例各组主观图像质量评分均≥3分;客观半定量评估结果显示,随采集时间缩短,信噪比均逐渐降低而噪声均小幅升高(P均<0.001)。各组评估Aβ脑显像诊断准确率差异无统计学意义(χ^(2)=1.590、P=0.207),未加权平均标准摄取值比值的曲线下面积差异亦无统计学意义(P均>0.05)。结论利用全身PET仪行^(18)F-Florbetapir PET脑显像时,推荐以3 min作为常规采集时间;对无法配合者,选择1 min采集时间亦可获得满意效能。 展开更多
关键词 淀粉样β肽 正电子发射断层显像 前瞻性研究 短时扫描 图像质量
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自适应Alpha-beta修正的线谱检测后置处理方法 被引量:5
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作者 戴文舒 陈新华 +1 位作者 孙长瑜 余华兵 《电子与信息学报》 EI CSCD 北大核心 2014年第10期2419-2424,共6页
矩形包络的单频信号时域频率方差等于频域有效带宽,且频率方差为信噪比的函数,在信噪比下降时,线谱方位权值计算误差变大,频率方差线谱检测器丢失目标。传统Alpha-beta滤波的增益恒定,不能有效修正频率估计。该文提出后置处理方法,将每... 矩形包络的单频信号时域频率方差等于频域有效带宽,且频率方差为信噪比的函数,在信噪比下降时,线谱方位权值计算误差变大,频率方差线谱检测器丢失目标。传统Alpha-beta滤波的增益恒定,不能有效修正频率估计。该文提出后置处理方法,将每个方位下多次求得的功率谱叠加后得到功率谱-频率曲线作为该方位下各频率对应的增益。当频率观测值对应的增益大时,新息在递推过程中占的比重大,当频率观测值对应的增益小时,预测值在递推过程中起的作用大,对滤波后频率估计值计算方差来修正方位谱输出。仿真和实验处理结果证明在低信噪比情况下,修正后的线谱检测后置处理算法抗干扰性强,能够实现弱线谱的提取,同时压低了干扰背景。 展开更多
关键词 水声信号处理 线谱检测 频率方差 alpha-beta滤波 后置处理
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中国象棋Alpha-Beta搜索算法的研究与改进 被引量:11
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作者 岳金朋 冯速 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第2期156-160,共5页
针对中国象棋机器博弈中较为高效的Alpha-Beta搜索算法进行研究,以提升其效率.依据Alpha-Beta搜索算法的效率与子节点扩展的排列顺序高度相关的事实及中国象棋自身的特点,本研究从优化着法的排列顺序入手,设计出了启发能力较强的着法排... 针对中国象棋机器博弈中较为高效的Alpha-Beta搜索算法进行研究,以提升其效率.依据Alpha-Beta搜索算法的效率与子节点扩展的排列顺序高度相关的事实及中国象棋自身的特点,本研究从优化着法的排列顺序入手,设计出了启发能力较强的着法排列方案,并进一步提出了扩大窗口的内部迭代加深算法对上述着法排列方案进行修正,从而使着法顺序得到了进一步的优化.实验数据证明,本研究明显提升了Alpha-Beta算法的效率. 展开更多
关键词 中国象棋 alpha-beta剪枝 着法顺序 内部迭代加深 扩大窗口
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HYPOSENSITIVE TO LIGHT, an Alpha/Beta Fold Protein, Acts Downstream of ELONGATED HYPOCOTYL 5 to Regulate Seedling De-Etiolation 被引量:5
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作者 Xiao-Dong Sun Min Ni 《Molecular Plant》 SCIE CAS CSCD 2011年第1期116-126,共11页
Ambient light has profound effects on early seedling de-etiolation through red and far-red light-absorbing phytochromes and blue and UV-A light-absorbing cryptochromes. Subsequent integration of various light signal t... Ambient light has profound effects on early seedling de-etiolation through red and far-red light-absorbing phytochromes and blue and UV-A light-absorbing cryptochromes. Subsequent integration of various light signal trans- duction pathways leads to changes in gene expression and morphogenic responses. Here, we report the isolation of a new Arabidopsis light-signaling component, HYPOSENSITIVE TO LIGHT or HTL. Both htl-1 and htl-2 alleles displayed a long hypocotyl phenotype under red, far-red, and blue light, whereas overexpression of HTL caused a short hypocotyl pheno- type under similar light conditions. The mutants also showed other photomorphogenic defects such as elongated petioles, retarded cotyledon and leaf expansion, reduced accumulation of chlorophyll and anthocyanin pigments, and attenuated expression of light-responsive CHLOROPHYLL A/B BINDING PROTEIN 3 and CHALCONE SYNTHASE genes. HTL belongs to an alpha/beta fold protein family and is localized strongly in the nucleus and weakly in the cytosol. The expression of HTL was strongly induced by light of various wavelengths and this light induction was impaired in elongated hypocotyl 5. HY5 directly bound to both a C/G-box and a G-box in the HTL promoter but with a greater affinity toward the C/G-box. HTL, therefore, represents a new signaling step downstream of HY5 in phy- and cry-mediated de-etiolation responses. 展开更多
关键词 HTL DE-ETIOLATION alpha/beta fold protein HY5.
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