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Influence of Soft Segment Length on the Dielectric Polarization Behavior of Ketal-containing Polyurethane Elastomer
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作者 Xue Mei Wan Lu +6 位作者 Jian-Rong Dong Ke-Heng Pan Jun-Jie Tan Hong-Ye Yan Jun Wu yu zhou Hong-Xiang Chen 《Chinese Journal of Polymer Science》 2026年第1期189-197,I0015,共10页
Polyurethane elastomers exhibit high dielectric constants owing to their polar groups,and can be used as energy storage capacitors.Energy storage depends not only on the dielectric constant but also on the dielectric ... Polyurethane elastomers exhibit high dielectric constants owing to their polar groups,and can be used as energy storage capacitors.Energy storage depends not only on the dielectric constant but also on the dielectric loss.However,the relationship between chain structure and dielectric properties is not yet clear.Ketal-containing crosslinked polyurethane elastomers were prepared using cyclic ketal diol as a chain extender.The effect of the soft segment length on the dielectric properties and energy storage was investigated.The cause of the change in the dipolar polarization with the soft segment length was analyzed.As the soft segment length increased,the hard-soft hydrogen bonding decreased,whereas the hard-hard hydrogen bonding increased.Under the action of an electric field,the polar bonds in the ketal-containing polyurethane elastomer overcome the hydrogen bonding between hard-soft segments to produce polarization;meanwhile,they also experience crankshaft motions to generate polarization.The former has a relatively high relaxation activation energy of approximately 10-20 k J·mol^(-1),resulting in a large dielectric loss.The latter has a relatively low relaxation activation energy,approximately 0.7-1.7 kJ·mol^(-1),leading to low dielectric loss.As a result,the dielectric constant showed a decreasing trend,and the dielectric loss gradually decreased.This study provides a theoretical foundation for improving the dielectric properties of polyurethane elastomers. 展开更多
关键词 Dielectric polarization Polyurethane elastomer Soft segment length Intermolecular interaction
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职业院校产教融合效益评价指标体系构建研究
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作者 喻宙 刘娅 杨小琨 《中国职业技术教育》 北大核心 2026年第6期87-94,102,共9页
产教融合是职业教育高质量发展的核心路径,当前相关研究缺乏在具体评价实践中针对不同主体差异的深入拓展。采用质性研究与量化分析相结合的混合研究范式,以协同治理理论和需求导向理论为指导,系统阐释产教融合的内涵特征与核心要素。... 产教融合是职业教育高质量发展的核心路径,当前相关研究缺乏在具体评价实践中针对不同主体差异的深入拓展。采用质性研究与量化分析相结合的混合研究范式,以协同治理理论和需求导向理论为指导,系统阐释产教融合的内涵特征与核心要素。通过“理论奠基—要素提取—指标初构—专家优化—权重确权—实证验证”的科学流程构建评价体系,经德尔菲法优化指标、层次分析法确定权重,最终形成包含6个一级指标、25个二级指标的评价指标体系。选取职业本科、高职专科、中职三类代表性院校开展实证分析,从科学性与有效性双重维度验证体系价值,结果表明该体系具备良好的适配性与指导性,可为职业院校深化产教融合、推进校企合作提供理论支撑与实践参考。 展开更多
关键词 职业教育 产教融合 效益评价 指标体系 德尔菲法
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Ir调控中间体生成类型抑制光催化甲烷转化中产物过氧化
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作者 张宇航 李意 +3 位作者 曹玥晗 帅英杰 周宇 周莹 《物理化学学报》 北大核心 2026年第2期133-144,共12页
储量丰富的甲烷不仅是优质化石燃料,而且是合成高附加值化工产品的核心原料。太阳能推动的甲烷转化过程,为温和环境下直接制取甲醇(CH_(3)OH)、甲醛(HCHO)等高价值化学品提供了前景十分广阔的途径。然而,该转化过程的核心挑战在于目标... 储量丰富的甲烷不仅是优质化石燃料,而且是合成高附加值化工产品的核心原料。太阳能推动的甲烷转化过程,为温和环境下直接制取甲醇(CH_(3)OH)、甲醛(HCHO)等高价值化学品提供了前景十分广阔的途径。然而,该转化过程的核心挑战在于目标产物很容易发生过氧化反应,使得目标产物的选择性处于较低水平,这成为该领域迫切需要突破的关键瓶颈。在此,我们构建了Ir修饰的CdS(Ir_(x)/CdS)光催化体系,提出通过金属Ir调控关键核心反应中间体的生成种类,是提高目标产物选择性并遏制过氧化的有效策略。通过原位漫反射傅里叶变换红外光谱(in situ DRIFTS)证实,在甲烷活化过程里,关键中间体的生成种类存在差异,这对产物分布发挥决定性影响。在纯CdS表面CH4活化生成*CH_(3)O关键中间体倾向于通过其O原子参与到后续深度氧化反应中,最终生成CO_(2)等过氧化产物;而负载Ir后,关键反应中间体转变为*CH_(3),Ir位点通过局域电子转移促进*CH_(3)向‧CH_(3)自由基的转化,生成的‧CH_(3)自由基与‧OH自由基快速结合定向生成CH_(3)OH。光催化CH4转化性能评价结果显示,在60℃、0.1 MPa及分子氧为氧化剂作用下,0.50 wt%Ir负载的Ir_(0.50)/CdS时表现出最佳性能:其含氧液相产物(CH_(3)OH和HCHO)产率达509.2μmol g^(−1)h^(−1),总选择性提升至88%。结合X射线衍射(XRD)、X射线光电子能谱(XPS)及透射电子显微镜(TEM)等表征技术用于催化材料的表征测试,发现Ir在催化剂表面有两种价态共存(金属态Ir^(0)和氧化态Ir^(4+)),且以金属态为主导。本工作提出的金属修饰调控中间体生成类型以抑制过氧化的策略,为高效转化甲烷制备高值含氧化学品提供了新思路。 展开更多
关键词 甲烷转化 光催化 金属负载 关键中间体生成
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水蛭素通过调节Nrf2/HO-1信号通路改善小鼠结核性胸膜纤维化的研究
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作者 余洲 陈丽娜 +4 位作者 杨荣静 尚旋 肖国素 张先明 黄妮雯 《中国防痨杂志》 北大核心 2026年第1期131-138,共8页
目的:探讨水蛭素通过调控核因子E2相关因子2(Nrf2)/血红素加氧酶-1(HO-1)信号通路对小鼠结核性胸膜纤维化的影响。方法:60只体质量在20~25 g的C57雄性小鼠随机分为对照组、模型组、低剂量水蛭素组(L组)、中剂量水蛭素组(M组)、高剂量水... 目的:探讨水蛭素通过调控核因子E2相关因子2(Nrf2)/血红素加氧酶-1(HO-1)信号通路对小鼠结核性胸膜纤维化的影响。方法:60只体质量在20~25 g的C57雄性小鼠随机分为对照组、模型组、低剂量水蛭素组(L组)、中剂量水蛭素组(M组)、高剂量水蛭素组(H组)、高剂量水蛭素+ML385(Nrf2转录抑制剂)组(H+ML385组)。除对照组外,其余各组均注射卡介苗(BCG)的悬液造模。28 d后观察各组小鼠胸腔积液的分布情况,收集、记录胸腔积液量;并观察胸膜粘连情况,采用胸腔积液中纤维蛋白原(FBG)水平和胸腔粘连带数量评分评估小鼠胸腔积液粘连性,测量胸膜厚度,通过苏木精-伊红(HE)染色观察各组小鼠胸膜组织病理学改变情况,采用Western blot法检测各组小鼠胸膜组织中Nrf2和HO-1蛋白表达,采用酶联免疫吸附试验法检测各组小鼠胸膜组织中基质金属蛋白酶(MMP-1、MMP-9)、基质金属蛋白酶抑制剂-1(TIMP-1)、丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽(GSH)的含量。结果:28 d后,H组胸腔积液量为(666.00±87.62)μl,胸膜厚度为(16.50±1.17)μm,胸腔粘连带评分为(2.60±0.51)分,FBG为(0.30±0.07)g/L,MDA为(74.51±6.53)mmol/mg,MMP-1为(14.08±0.85)μg/L,MMP-9为(4.84±0.38)μg/L,TIMP-1为(2.63±0.13)μg/L,均明显低于模型组[分别为(1144.00±15.00)μl、(21.11±2.98)μm、(3.90±0.31)分、(0.48±0.07)g/L、(102.70±14.06)mmol/mg、(18.54±1.20)μg/L、(7.65±1.02)μg/L、(3.62±0.36)μg/L];SOD及GSH分别为(134.00±8.07)U/mg和(350.80±15.73)nmol/g,均明显高于模型组的(90.79±4.68)U/mg和(247.30±22.28)nmol/g,差异均有统计学意义(t=8.48,P<0.001;t=4.54,P<0.001;t=6.79,P<0.001;t=5.53,P<0.001;t=5.73,P<0.001;t=9.57,P<0.001;t=8.16,P<0.001;t=8.10,P<0.001;t=14.64,P<0.001;t=12.00,P<0.001)。HE染色显示,与模型组相比,水蛭素干预组(特别是高剂量组)小鼠的胸膜纤维化病理改变明显减轻。Western blot结果显示,H组Nrf2蛋白表达为0.83±0.07,明显高于模型组的0.57±0.06,也明显高于H+ML385组的0.67±0.50,差异均有统计学意义(t=8.36,P<0.001;t=4.09,P=0.017);H组HO-1蛋白表达为0.72±0.03,明显高于模型组的0.31±0.02,差异有统计学意义(t=8.36,P<0.001)。结论:水蛭素可以通过调节Nrf2/HO-1信号通路来抑制氧化应激,从而改善结核性胸膜纤维化。 展开更多
关键词 水蛭素类 结核 胸膜 纤维化 小鼠
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Multi-Label Classification Model Using Graph Convolutional Neural Network for Social Network Nodes
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作者 Junmin Lyu Guangyu Xu +4 位作者 Feng Bao yu zhou yuxin Liu Siyu Lu Wenfeng Zheng 《Computer Modeling in Engineering & Sciences》 2026年第2期1235-1256,共22页
Graph neural networks(GNN)have shown strong performance in node classification tasks,yet most existing models rely on uniform or shared weight aggregation,lacking flexibility in modeling the varying strength of relati... Graph neural networks(GNN)have shown strong performance in node classification tasks,yet most existing models rely on uniform or shared weight aggregation,lacking flexibility in modeling the varying strength of relationships among nodes.This paper proposes a novel graph coupling convolutional model that introduces an adaptive weighting mechanism to assign distinct importance to neighboring nodes based on their similarity to the central node.Unlike traditional methods,the proposed coupling strategy enhances the interpretability of node interactions while maintaining competitive classification performance.The model operates in the spatial domain,utilizing adjacency list structures for efficient convolution and addressing the limitations of weight sharing through a coupling-based similarity computation.Extensive experiments are conducted on five graph-structured datasets,including Cora,Citeseer,PubMed,Reddit,and BlogCatalog,as well as a custom topology dataset constructed from the Open University Learning Analytics Dataset(OULAD)educational platform.Results demonstrate that the proposed model achieves good classification accuracy,while significantly reducing training time through direct second-order neighbor fusion and data preprocessing.Moreover,analysis of neighborhood order reveals that considering third-order neighbors offers limited accuracy gains but introduces considerable computational overhead,confirming the efficiency of first-and second-order convolution in practical applications.Overall,the proposed graph coupling model offers a lightweight,interpretable,and effective framework for multi-label node classification in complex networks. 展开更多
关键词 GNN social networks nodes multi-label classification model graphic convolution neural network coupling principle
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Effective detection of chloramphenicol residues by self-assembled DNA tetrahedral structure-based electrochemical aptasensor
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作者 Zihan Gao yu zhou +2 位作者 Li Lin Changyuan yu Hao Li 《Food Science and Human Wellness》 2026年第2期601-607,共7页
Abuse of chloramphenicol(CAP)could cause serious side effects to human health.Therefore,it is necessary to detect CAP residues in animal sourced food effectively.Here,the superiority(better stability,higher Apt-CAP lo... Abuse of chloramphenicol(CAP)could cause serious side effects to human health.Therefore,it is necessary to detect CAP residues in animal sourced food effectively.Here,the superiority(better stability,higher Apt-CAP loading efficiency,and higher CAP binding associated conformational change,etc.)of tetrahedral structure to double-chained structure for developing aptasensor was evaluated.Then,a self-assembled DNA tetrahedral structure-based electrochemical aptasensor targeting CAP was developed.Under the optimized conditions,the aptasensor exhibited high sensitivity toward CAP with a limit of detection(LOD)of 0.0676 ng/m L(linear range 0.19-387.76 ng/m L),and high selectivity against the structural analogs of CAP.Moreover,the recovery rate of CAP from spiked milk samples ranged from 100.57%to 101.69%,and only USD 1.34 is needed for detecting CAP in 1 sample.These results suggested the application potential of this aptasesor for detecting CAP in animal sourced foods. 展开更多
关键词 Tetrahedral structure CHLORAMPHENICOL Electrochemical aptasensor MILK
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Multimodal Signal Processing of ECG Signals with Time-Frequency Representations for Arrhythmia Classification
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作者 yu zhou Jiawei Tian Kyungtae Kang 《Computer Modeling in Engineering & Sciences》 2026年第2期990-1017,共28页
Arrhythmias are a frequently occurring phenomenon in clinical practice,but how to accurately dis-tinguish subtle rhythm abnormalities remains an ongoing difficulty faced by the entire research community when conductin... Arrhythmias are a frequently occurring phenomenon in clinical practice,but how to accurately dis-tinguish subtle rhythm abnormalities remains an ongoing difficulty faced by the entire research community when conducting ECG-based studies.From a review of existing studies,two main factors appear to contribute to this problem:the uneven distribution of arrhythmia classes and the limited expressiveness of features learned by current models.To overcome these limitations,this study proposes a dual-path multimodal framework,termed DM-EHC(Dual-Path Multimodal ECG Heartbeat Classifier),for ECG-based heartbeat classification.The proposed framework links 1D ECG temporal features with 2D time–frequency features.By setting up the dual paths described above,the model can process more dimensions of feature information.The MIT-BIH arrhythmia database was selected as the baseline dataset for the experiments.Experimental results show that the proposed method outperforms single modalities and performs better for certain specific types of arrhythmias.The model achieved mean precision,recall,and F1 score of 95.14%,92.26%,and 93.65%,respectively.These results indicate that the framework is robust and has potential value in automated arrhythmia classification. 展开更多
关键词 ELECTROCARDIOGRAM arrhythmia classification MULTIMODAL time-frequency representation
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Strongly modifiable decay and angle-dependent light intensity for an atom near active plasmonic structures:A macroscopic QED study
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作者 Ji-yue Dai Meng-Dan Zhao +1 位作者 yu zhou Jun Xin 《Chinese Physics B》 2026年第2期555-562,共8页
Tunable plasmonic structures provide the possibility to actively modify the radiation from atoms through electromagnetic coupling.In this paper,we investigate the decay and radiation behavior of an atom near a dielect... Tunable plasmonic structures provide the possibility to actively modify the radiation from atoms through electromagnetic coupling.In this paper,we investigate the decay and radiation behavior of an atom near a dielectric nanosphere with conductive surface within the framework of macroscopic quantum electrodynamics.The electromagnetic fields including the losses in the materials can be taken as fundamental excitations which interact with the atom through a transition dipole.Both weak and strong coupling regimes have been investigated.The decay rate and the angle-dependent light intensities indeed strongly depend on the parameters of the system,i.e.,the position and orientation of the dipole,the geometric size,and the surface conductivity,providing the opportunity of artificial control over these quantities.Generalizing the formalism in this paper to other systems,like metamaterials,is straightforward,which we believe may pave a way for future active quantum nanophotonic devices. 展开更多
关键词 PLASMONICS quantum electrodynamics light–matter interaction
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纹层状页岩微观储层特征研究--以鄂尔多斯盆地西缘乌拉力克组为例 被引量:1
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作者 黄正良 曹斌风 +7 位作者 刘洋 罗晓容 闫伟 马占荣 程明 俞雨溪 于洲 王璐 《沉积学报》 北大核心 2025年第4期1251-1263,共13页
【目的】对鄂尔多斯盆地西缘中奥陶统乌拉力克组乌三段纹层状页岩的微观储层特征进行研究,深化认识纹层状页岩储层的有效性。【方法】通过岩性物理分离,综合X射线衍射全岩矿物,扫描电镜和矿物扫描,有机地球化学,二氧化碳、氮气吸附及压... 【目的】对鄂尔多斯盆地西缘中奥陶统乌拉力克组乌三段纹层状页岩的微观储层特征进行研究,深化认识纹层状页岩储层的有效性。【方法】通过岩性物理分离,综合X射线衍射全岩矿物,扫描电镜和矿物扫描,有机地球化学,二氧化碳、氮气吸附及压汞测试等技术方法,对比分析纹层状页岩不同组构之间矿物学、有机地球化学及孔隙结构等特征的差异性。【结果】乌三段纹层状页岩由灰岩纹层、凝灰岩纹层及富硅质层频繁互层形成,灰岩纹层、凝灰岩纹层密度介于60~180条/m,有机碳含量远低于富硅质层。纹层状页岩孔缝并存,其中富硅质层主要发育黏土矿物有关的粒间孔、粒内孔,有机孔发育很局限;灰岩纹层主要发育方解石、白云石粒内溶孔;凝灰岩纹层中主要发育黄铁矿晶间孔、黏土矿物粒间和粒内孔及白云石粒内溶孔。灰岩纹层、凝灰岩纹层中碳酸盐矿物溶孔的形成与毗邻富硅质层中有机质演化产生的酸性流体溶蚀相关。沿着这些纹层边界近水平裂缝发育丰富,裂缝密度介于63~130条/m,裂缝宽度介于0.2~4.9 mm。灰岩纹层、凝灰岩纹层的微孔发育程度较富硅质层低,但大孔发育程度高。灰岩纹层中大孔的孔体积是毗邻富硅质层的2.5~4.3倍,大孔对总孔体积的贡献率约是毗邻富硅质层的1.9~2.1倍;凝灰岩纹层中大孔的孔体积是毗邻富硅质层的1.5~2.3倍。【结论】在纹层状页岩中,富硅质层中有机质生成油气,沿孔缝发生微运移,优先运移至相邻灰岩纹层、凝灰岩纹层中。灰岩纹层和凝灰岩纹层大孔较多,游离气贡献多。乌拉力克组纹层状页岩游离气占比大,与灰岩纹层和凝灰岩纹层发育丰富密切相关。 展开更多
关键词 鄂尔多斯盆地 乌拉力克组 页岩气 纹层状页岩 孔隙类型 孔隙结构
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Discussion on the medication rule of Professor Ba Yuanming in the treatment of chronic glonerulonephritis based on data mining technology
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作者 Zi-Lin Wang yuan-Ming Ba +3 位作者 Cheng-Yin Li Qi Xu yu zhou Liang Li 《Journal of Hainan Medical University》 2021年第14期53-60,共8页
Objective:To explore the medication rule of Professor Ba Yuanming in the treatment of chronic glonerulonephritis by data mining technology,so as to provide certain reference for clinical and scientific research in the... Objective:To explore the medication rule of Professor Ba Yuanming in the treatment of chronic glonerulonephritis by data mining technology,so as to provide certain reference for clinical and scientific research in the treatment of Chronic glonerulonephritis with traditional Chinese medicine.Methods:collect,sort out and screen the cases of chronic nephritis diagnosed and treated by Professor Ba Yuanming in the outpatient department of Hubei Hospital of traditional Chinese medicine from 2018 to 2019,establish the database on the cloud platform of ancient and modern medical cases(v2.2.1),and use frequency statistics,association rules,hierarchical clustering and other analysis methods to study and analyze the drugs used.Results:1630 cases were included in the prescription,involving 212 traditional Chinese medicines.The high-frequency drugs are Poria cocos,astragalus,dangshen,yam,Chuanshanlong,Cornus,distracted wood,etc;the drugs are mainly warm,cold and calm;the five tastes are sweet and light,spicy and bitter;the meridian tropism is mostly found in the kidney,lung and spleen channels;the effects are calming the mind and the nerves,strengthening the spleen and stomach,promoting water and swelling,etc.The core Chinese medicine combinations of Astragalus and poria were obtained.Conclusion:Professor Ba Yuanming pays attention to comprehensive consideration,attack and supplement in the treatment of CGN,pays attention to the care of the healthy qi of Sanjiao,at the same time clearing away heat and dampness,removing blood stasis and firmness,and is good at using the sweet and gentle products. 展开更多
关键词 Chronic glomerulonephritis BA Yuan-ming Data mining Traditional Chinese medicine Medication experience
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猪舍智能清洁机器人研究与应用进展 被引量:5
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作者 于洲 王浩 +4 位作者 齐仁立 胡彬 潘学民 曾雅琼 刘作华 《农业工程学报》 北大核心 2025年第2期1-11,共11页
猪舍清洁卫生的管理是影响猪群健康状态、猪场用工成本和粪污处理的关键工作环节,具有劳动强度高、工作环境差等特点,是智能养猪机器人的重点发展方向。该研究针对猪舍空圈冲洗、带猪地面清粪和地下粪沟清理3种作业场景,梳理了国内外相... 猪舍清洁卫生的管理是影响猪群健康状态、猪场用工成本和粪污处理的关键工作环节,具有劳动强度高、工作环境差等特点,是智能养猪机器人的重点发展方向。该研究针对猪舍空圈冲洗、带猪地面清粪和地下粪沟清理3种作业场景,梳理了国内外相关机器人的研究与应用案例,从机器人的应用场景特征、底盘类型、驱动方式、导航避障、作业方式、粪污识别等方面分析了猪舍清洁机器人的关键技术研究进展。猪舍空圈冲洗机器人用于规模化猪场“全进全出”模式下,每批猪出栏后的猪舍地面及圈栏设施的清洁,主要以轮式底盘搭配机械臂和高压水枪在猪圈过道进行冲洗作业;带猪地面清粪机器人用于日常清理圈内地板或限位栏过道上的残留粪便,以刮板推铲和粪污收集2种方式为主进行作业,同时具备粪污识别、导航与路径规划和自主作业能力;地下粪沟清理机器人主要用于代替刮粪板等传统方式,以履带式底盘配合高压水冲洗、推铲作业方式,定期清除粪沟内残余粪便,确保舍内空气环境良好。该研究结合中国生猪养殖特点和清洁机器人研究现状提出未来研究建议,旨在推动生猪工厂化、无人化和福利化智能养殖。 展开更多
关键词 清粪 机器人 生猪 自主作业 自主导航
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SOFIA远端通路导管联合Aperio支架在急性脑卒中机械取栓中应用
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作者 于周 冯强龙 +1 位作者 马旭东 谌萌刚 《四川医学》 2025年第9期1041-1045,共5页
目的探讨对比分析SOFIA导管抽吸技术以及改良SWIM技术(SOFIA导管联合Aperio支架技术)在治疗前循环急性大血管闭塞性脑卒中(AIS-LVO)患者的有效性及安全性。方法收集2021年12月至2024年3月在我院采用机械取栓治疗的前循环AIS-LVO患者90例... 目的探讨对比分析SOFIA导管抽吸技术以及改良SWIM技术(SOFIA导管联合Aperio支架技术)在治疗前循环急性大血管闭塞性脑卒中(AIS-LVO)患者的有效性及安全性。方法收集2021年12月至2024年3月在我院采用机械取栓治疗的前循环AIS-LVO患者90例,随机分配为ADAPT组(n=47,给予单纯SOFIA导管抽吸技术),改良SWIM组(n=43,给予SOFIA导管联合Aperio支架技术)。对比观察两组患者穿刺至血管再通时间和围手术期、术后并发症发生情况。根据脑梗死溶栓(TICI)治疗后血流分级标准评价术后即刻血管再通率,根据美国国立卫生研究院卒中量表(NIHSS)评分评价术前和术后24 h神经功能情况,根据改良Rankin量表(mRS)评分评价术后90 d预后。结果两组患者在一次再通率、取栓次数方面组间比较,改良SWIM组有着较高一次再通率比例以及较低的取栓次数,两组间差异有统计学意义(P<0.05);术中改良SWIM组mTICI达到2b~3级比例高于对照组,术后24 h小时NIHSS评分低于对照组;两组症状性颅内出血比例比较差异无统计学意义(P>0.05);随访两组90 d mRS≤2分比例,改良组高于对照组,3~6分比例改良组明显低于对照组,两组间差异有统计学意义(P<0.05)。结论SOFIA远端通路导管联合Aperio支架SWIM技术治疗不确定病因机制的AIS-LVO安全有效,与ADAPT取栓技术相比,或能使此类患者获得更好的临床预后。 展开更多
关键词 SOFIA远端通路导管 Aperio支架 ADAPT SWIM 急性大血管闭塞性缺血性卒中
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聚醚多元醇型聚丁二酸丁二醇的合成与性能研究
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作者 黄继涛 余洲 +3 位作者 徐艺贞 蔡诗琪 张夜 李耀斌 《广东化工》 2025年第4期1-3,42,共4页
本实验采用熔融缩聚法制备聚丁二酸丁二醇酯(PBS)。利用聚醚多元醇具有分子高度旋转性的特点,对PBS进行化学改性,合成了聚醚多元醇型PBS。通过X射线衍射仪(XRD)、傅立叶红外变换光谱仪(FTIR)、热失重分析仪(TG)、差示扫描量热仪(DSC)和... 本实验采用熔融缩聚法制备聚丁二酸丁二醇酯(PBS)。利用聚醚多元醇具有分子高度旋转性的特点,对PBS进行化学改性,合成了聚醚多元醇型PBS。通过X射线衍射仪(XRD)、傅立叶红外变换光谱仪(FTIR)、热失重分析仪(TG)、差示扫描量热仪(DSC)和特性黏度测试手段对实验产物进行结构表征以及性能分析。结果表明:成功合成了具有较高分子量的聚醚多元醇型PBS;改性后PBS热稳定性升高,柔韧性好,更有利于加工制造。 展开更多
关键词 聚丁二酸丁二醇酯 熔融缩聚 聚醚多元醇 改性
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嵌入式SMA-CFRP复合板材加固RC梁有限元模拟及理论分析 被引量:1
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作者 余洁 陈星宇 +3 位作者 王宇航 余周 沈琪雯 薛尚铃 《建筑科学与工程学报》 北大核心 2025年第3期92-102,共11页
为研究碳纤维复合材料(CFRP)与形状记忆合金(SMA)采用内嵌(NSM)和外贴(EB)等不同加固方式组合加固钢筋混凝土(RC)梁后的抗弯性能,通过有限元软件ABAQUS创建有效的SMA以及CFRP加固RC梁模型,对其加固性能进行分析,研究了不同SMA直径与数... 为研究碳纤维复合材料(CFRP)与形状记忆合金(SMA)采用内嵌(NSM)和外贴(EB)等不同加固方式组合加固钢筋混凝土(RC)梁后的抗弯性能,通过有限元软件ABAQUS创建有效的SMA以及CFRP加固RC梁模型,对其加固性能进行分析,研究了不同SMA直径与数量对钢筋混凝土梁加固效果的响应;建立了嵌入式SMA加固RC梁的有限元模型,并基于有限元模拟结果推导加固梁的抗弯承载力计算公式。结果表明:提升SMA直径对试验梁加固效果有积极影响,加固梁开裂荷载提升了33%~133%,极限承载力提升了8%~31%;嵌入式SMA-CFRP复合板材加固梁能很大程度提升加固效果,极限承载力提升了92.7%,开裂荷载增长31.9%,屈服荷载增长33.3%;与外贴加固相比,嵌入式复合板材可以有效延缓端部剥离破坏,使加固材料充分发挥强度;提出的组合加固梁抗弯承载力计算公式的理论计算结果与有限元模型结果吻合良好,可为后续相关研究提供参考。 展开更多
关键词 结构加固 形状记忆合金 有限元分析 碳纤维板材 抗弯性能 钢筋混凝土梁
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一种JESD204B总线型D/A转换器单粒子功能中断评估方法研究 被引量:1
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作者 李静 蒋伟 +6 位作者 刘军 俞宙 温显超 王健安 郭刚 孙毅 王天琦 《微电子学》 北大核心 2025年第1期34-39,共6页
超高速数/模转换器(DAC)是微波回程系统和雷达干扰机信号处理单元的核心单元,在宇航环境中易受射线辐照影响导致功能异常,由于其接口数据速率极高,评估其单粒子功能中断具有很大的挑战。本文研究并分析高速DAC在重离子环境存在的四种单... 超高速数/模转换器(DAC)是微波回程系统和雷达干扰机信号处理单元的核心单元,在宇航环境中易受射线辐照影响导致功能异常,由于其接口数据速率极高,评估其单粒子功能中断具有很大的挑战。本文研究并分析高速DAC在重离子环境存在的四种单粒子功能中断类型,提出一种针对JESD204B接口DAC(≥12 GS/s)的单粒子功能中断地面模拟测试方法,结合电流舵数/模转换器结构设计实现JESD204B接口数/模转换器的单粒子功能中断在线测试系统。在中国原子能院串列加速器(HI-13)与空间环境地面模拟装置(SESRI)上进行试验验证,成功监测与器件结构机理分析一致的单粒子功能中断现象,对后续加固设计具有一定的指导意义。 展开更多
关键词 单粒子效应 DAC SESRI 单粒子功能中断 JESD204B
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牛活检胚胎细胞微量扩增体系效果评估
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作者 牛一凡 李崇阳 +8 位作者 张培培 张航 冯肖艺 余洲 曹建华 杜卫华 万鹏程 马友记 赵学明 《畜牧兽医学报》 北大核心 2025年第1期246-258,共13页
旨在通过二代测序技术评估不同单细胞全基因组扩增体系对不同数量胚胎细胞的扩增效率。本研究选择同一饲养管理条件下、体况良好的华西牛母牛为供体,采用FSH法超数排卵后进行人工授收集第7天胚胎,通过活检技术获得含1细胞(cell, 1C)、5C... 旨在通过二代测序技术评估不同单细胞全基因组扩增体系对不同数量胚胎细胞的扩增效率。本研究选择同一饲养管理条件下、体况良好的华西牛母牛为供体,采用FSH法超数排卵后进行人工授收集第7天胚胎,通过活检技术获得含1细胞(cell, 1C)、5C、10C胚胎细胞样本用于全基因组扩增(whole genome amplification),随后通过全基因组重测序(whole genome sequencing)技术评估单细胞基因组扩增体系扩增效率的差异。结果显示,在1C和5C样本中多重置换扩增(multiple displacement amplification, MDA)体系的扩增成功率优于多次退火环状循环扩增(multiple annealing and looping-based amplification cycles, MALBAC)体系(100%vs. 60%,100%vs. 80%,P<0.05),此外MDA体系的扩增产物总量极显著高于MALBAC体系(P<0.01),基于测序分析指标:正确比对率、重复率、分型一致率、等位基因缺失率、假阳性率等,MALBAC体系优于MDA体系;全同胞样品的分型一致率大于半同胞样品的分型一致率,但不同全同胞、半同胞胚胎样本之间的分型一致率有很大差异。综上所述,MDA和MALBAC体系各具特点,结合两者优势可能是改进扩增效率的途径之一,本研究为牛早期胚胎全基因组选择研究和促进牛育种发展提供一定理论基础。 展开更多
关键词 华西牛 活检胚胎 扩增体系 效果比较
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一种超高速A/D转换器单粒子效应试验系统设计
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作者 温显超 魏亚峰 +5 位作者 李婷 俞宙 付东兵 刘杰 郭刚 孙毅 《微电子学》 北大核心 2025年第1期27-33,共7页
超高速模/数转换器(ADC)是相控阵雷达和数字多模接收机等信号处理单元的关键元器件,其随系统在宇宙空间中容易受宇宙射线辐照发生单粒子效应,导致器件性能退化,严重的将导致功能消失。对流水线型ADC单粒子效应机理进行分析研究,提出了... 超高速模/数转换器(ADC)是相控阵雷达和数字多模接收机等信号处理单元的关键元器件,其随系统在宇宙空间中容易受宇宙射线辐照发生单粒子效应,导致器件性能退化,严重的将导致功能消失。对流水线型ADC单粒子效应机理进行分析研究,提出了一种针对超高速模数转换器(≥3 GS/s)的单粒子锁定、翻转和瞬态地面模拟测试方法,利用CER检测原理和高速码值异常处理方法等实现超高速模/数转换器的单粒子效应在线测试系统。在中国原子能研究院串列静电加速器(HI-13)与兰州重离子加速器(HIRFL)上进行试验验证,成功监测到单粒子锁定、翻转以及单粒子瞬态等典型单粒子试效应。最后根据试验数据结合电路结构进行了电路单粒子效应分析,对高速模数转换器集成电路的评估与应用阶段的系统验证具有重要意义。 展开更多
关键词 单粒子效应 HI-13 HIRFL 单粒子锁定 单粒子翻转 单粒子瞬态
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环境温度对列车制动界面摩擦磨损及振动噪声的影响
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作者 冯双喜 余洲 +4 位作者 张棋翔 唐斌 莫继良 金文伟 朱松 《表面技术》 北大核心 2025年第7期68-78,共11页
目的探究环境温度对列车制动界面摩擦磨损及振动噪声的影响及其机理。方法在环境温度可控的列车制动性能模拟试验台上,以环境温度为变量(20、0、-20、-40℃),开展停车制动试验,采集试验过程中的振动加速度、噪声、温度、制动力和制动扭... 目的探究环境温度对列车制动界面摩擦磨损及振动噪声的影响及其机理。方法在环境温度可控的列车制动性能模拟试验台上,以环境温度为变量(20、0、-20、-40℃),开展停车制动试验,采集试验过程中的振动加速度、噪声、温度、制动力和制动扭矩信号并进行分析。采用扫描电子显微镜(SEM)和光学显微镜(OM)对摩擦块表面形貌和磨屑进行表征,并对试验前后摩擦块进行称量评估其磨损率。结果在本试验条件下,随着环境温度降低,制动界面的切向振动加速度和噪声声压的RMS(均方根值)分别从20℃时的578.6 m/s^(2)和24.4 Pa增加至-40℃时的937.0 m/s^(2)和34.0 Pa;摩擦因数从20℃时的0.50降低至-40℃时的0.44;同时,磨损率从20℃时的111.0μg/s减少至-40℃时的54.8μg/s。结论在停车制动过程中,随着环境温度降低,制动盘和摩擦块的材料脆性增加,在摩擦作用下更容易破碎产生大颗粒磨屑,从而影响摩擦界面第三体的形成和分布,最终通过接触平台的大小和分布影响制动界面的摩擦磨损和振动噪声特性。 展开更多
关键词 环境温度 制动系统 停车制动 摩擦磨损 摩擦振动噪声
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Integration of Electrical Properties and Polarization Loss Modulation on Atomic Fe–N‑RGO for Boosting Electromagnetic Wave Absorption 被引量:1
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作者 Kaili Zhang yuefeng Yan +4 位作者 Zhen Wang Guansheng Ma Dechang Jia Xiaoxiao Huang yu zhou 《Nano-Micro Letters》 SCIE EI CAS 2025年第2期517-532,共16页
Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band ... Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism. 展开更多
关键词 Electromagnetic wave absorption Fe-N-RGO Dipole polarization Conduction loss Impedance matching
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A Novel Self-Supervised Learning Network for Binocular Disparity Estimation 被引量:1
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作者 Jiawei Tian yu zhou +5 位作者 Xiaobing Chen Salman A.AlQahtani Hongrong Chen Bo Yang Siyu Lu Wenfeng Zheng 《Computer Modeling in Engineering & Sciences》 SCIE EI 2025年第1期209-229,共21页
Two-dimensional endoscopic images are susceptible to interferences such as specular reflections and monotonous texture illumination,hindering accurate three-dimensional lesion reconstruction by surgical robots.This st... Two-dimensional endoscopic images are susceptible to interferences such as specular reflections and monotonous texture illumination,hindering accurate three-dimensional lesion reconstruction by surgical robots.This study proposes a novel end-to-end disparity estimation model to address these challenges.Our approach combines a Pseudo-Siamese neural network architecture with pyramid dilated convolutions,integrating multi-scale image information to enhance robustness against lighting interferences.This study introduces a Pseudo-Siamese structure-based disparity regression model that simplifies left-right image comparison,improving accuracy and efficiency.The model was evaluated using a dataset of stereo endoscopic videos captured by the Da Vinci surgical robot,comprising simulated silicone heart sequences and real heart video data.Experimental results demonstrate significant improvement in the network’s resistance to lighting interference without substantially increasing parameters.Moreover,the model exhibited faster convergence during training,contributing to overall performance enhancement.This study advances endoscopic image processing accuracy and has potential implications for surgical robot applications in complex environments. 展开更多
关键词 Parallax estimation parallax regression model self-supervised learning Pseudo-Siamese neural network pyramid dilated convolution binocular disparity estimation
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