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某微通道液冷板的性能分析与优化 被引量:1
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作者 李健 蒋宏邦 +1 位作者 王辉 马雷 《机械设计与制造》 北大核心 2023年第3期102-105,共4页
针对电子设备工作时局部温度过高问题,提出了翅柱与流道相结合的结构设计。分别将平行四边形翅柱、沙漏型翅柱、双层平行四边形翅柱内置于流道中,保证相同的流道截面积、冷却液进口流量与温度,借助仿真软件ICEPAK分别对这三种液冷板的... 针对电子设备工作时局部温度过高问题,提出了翅柱与流道相结合的结构设计。分别将平行四边形翅柱、沙漏型翅柱、双层平行四边形翅柱内置于流道中,保证相同的流道截面积、冷却液进口流量与温度,借助仿真软件ICEPAK分别对这三种液冷板的散热性能进行仿真分析,并利用试验来加以验证仿真结果的可靠性。结果表明:三种优化后的冷板散热性能都优于常规通道冷板。其中,平行四边形翅柱冷板散热性能最差;双层平行四边形翅柱冷板散热性能最好,但流阻较大;沙漏型翅柱冷板散热性能适中,流阻明显小于前两者。 展开更多
关键词 电子设备 结构设计 液冷板 翅柱 ICEPAK 散热性能
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激光增材制造WC_(p)钛基复合材料界面连接机理及力学性能
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作者 吴诚福 李新意 +3 位作者 陈洪胜 李健 聂慧慧 王文先 《焊接学报》 EI CAS CSCD 北大核心 2023年第3期44-53,I0005,I0006,共12页
颗粒增强金属基复合结构件在航空航天、机械制造以及电子电工等领域有着广泛的应有前景.文中选用激光增材选区熔化技术制备碳化钨(WC)颗粒增强TC4复合材料(WC/TC4),研究了WC颗粒含量和激光功率对复合材料微观组织和力学性能的影响.结果... 颗粒增强金属基复合结构件在航空航天、机械制造以及电子电工等领域有着广泛的应有前景.文中选用激光增材选区熔化技术制备碳化钨(WC)颗粒增强TC4复合材料(WC/TC4),研究了WC颗粒含量和激光功率对复合材料微观组织和力学性能的影响.结果表明,随着WC颗粒含量的增加,复合材料宏观试样成形能力降低,在WC颗粒含量为(0%~15%)时,WC颗粒分布较为均匀,未见微气孔、裂纹的出现,当颗粒含量为20%时,材料内部出现气孔和裂纹,难以成形;在WC/基体的界面处形成了一层TiC和W_(2)C界面层,界面结合性能良好;随着复合材料内部颗粒含量和激光功率的增加,材料的断裂强度和断后伸长率降低,断裂机理主要为WC颗粒的脆性断裂和沿WC-W2C界面的层状撕裂. 展开更多
关键词 激光选区熔化 WC/TC4复合材料 界面 断裂机理
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Ni离子注入聚四氟乙烯的表面结构与浸润性 被引量:2
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作者 但敏 李建 +3 位作者 王新超 董思成 王坤 金凡亚 《功能材料》 EI CAS CSCD 北大核心 2020年第2期2214-2220,共7页
为提高PTFE基材的表面活性及浸润性来增加后续涂层的结合强度,采用金属Ni离子注入方式对其进行了10、15、20、25、30 kV 5种不同能量的改性处理,并通过X射线光电子能谱、扫描电子显微镜和接触角测量,探究不同注入能量对其处理后的浸润... 为提高PTFE基材的表面活性及浸润性来增加后续涂层的结合强度,采用金属Ni离子注入方式对其进行了10、15、20、25、30 kV 5种不同能量的改性处理,并通过X射线光电子能谱、扫描电子显微镜和接触角测量,探究不同注入能量对其处理后的浸润性影响。研究结果表明,注入过程中PTFE表面发生脱氟反应,并形成C—O及C=O等自由基,所得表面与未经注入处理材料相比浸润性均得到显著提高,且随着注入能量的增加,润湿性呈递增趋势,当注入能量为30 kV时,表面润湿性最佳,与去离子水和二碘甲烷的接触角由处理前的110.5°和78.2°降至22.4°和49.8°;表面能由处理前的18.58 mJ·m^-2升至67.4 mJ·m^-2,极性分量所占比例由处理前的1.42%升至69.9%。 展开更多
关键词 聚四氟乙烯 离子注入 表面改性 浸润性 表面能
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四川高海拔地区生态扶贫策略研究 被引量:1
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作者 隋明 管永林 +3 位作者 李建 朱克永 张崇军 向月波 《现代农业研究》 2018年第8期11-12,共2页
我国的贫困区大多处于高海拔地区,针对不同地区的贫困案例,许多学者经过研究提出了生态扶贫的理念,对生态环境与当地农业产业化发展之间的关系,环境灾害对人民生活的影响,及高海拔地区生态功能建设等方面进行了分析和研究。本文将对此... 我国的贫困区大多处于高海拔地区,针对不同地区的贫困案例,许多学者经过研究提出了生态扶贫的理念,对生态环境与当地农业产业化发展之间的关系,环境灾害对人民生活的影响,及高海拔地区生态功能建设等方面进行了分析和研究。本文将对此进行深入分析,并提出高海拔地区生态扶贫的基本模式和政策建议。 展开更多
关键词 高海拔地区 生态扶贫 政治策略
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城市更新与产业转型研究
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作者 李健 陈晨 《全球城市研究(中英文)》 2020年第1期62-73,189,共13页
城市更新是城市发展到成熟阶段必须推动的工作任务,从世界主要城市的发展经验看,城市更新往往能够推动城市产业转型与功能升级的巨大跃升。本文采用比较和归纳的方法,分析迭代视角下全球城市在不同阶段城市更新的工作框架、重点和策略,... 城市更新是城市发展到成熟阶段必须推动的工作任务,从世界主要城市的发展经验看,城市更新往往能够推动城市产业转型与功能升级的巨大跃升。本文采用比较和归纳的方法,分析迭代视角下全球城市在不同阶段城市更新的工作框架、重点和策略,认为上海推进城市更新与产业转型,必须从自身“城市区域”空间特征和发展阶段出发,不能搞“一刀切”模式,同时也要尊重城市更新与产业转型内在运行规律,包括:(1)重视中央活力区、滨水地区的关键地位;(2)突出科技创新对城市更新工作的引领力;(3)提升城市更新中的历史保护和功能融合;(4)强化城市更新中对新技术、新文化的应用;(5)激发社会积极性引导“自下而上”力量发展。 展开更多
关键词 全球城市 城市更新 产业转型
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Distribution Characteristics of Effective Source Rocks and Their Control on Hydrocarbon Accumulation: A Case Study from the Dongying Sag, Eastern China 被引量:32
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作者 ZHUGuangyou JINQiang +3 位作者 ZHANGShuichang DAIJinxing ZHANGLinye lijian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第6期1275-1288,共14页
The exploration conducted in the Bohai Bay basin, eastern China has demonstrated that the abundant petroleum resources have close affinities to the hydrocarbon kitchen with rich organic matter. A number of oil-generat... The exploration conducted in the Bohai Bay basin, eastern China has demonstrated that the abundant petroleum resources have close affinities to the hydrocarbon kitchen with rich organic matter. A number of oil-generating associations with various characteristics of organic geochemistry and assemblages of multiple reservoir facies are developed due to the multi-center sedimentation, multi-source supply and multi-cycle evolution of filling, which have resulted in the formation of multiple oil and gas accumulation zones of various layers and trap styles. Among them the Paleogene Shahejie Formation is the most important hydrocarbon accumulation combination in the Dongying sag. Heretofore, its proved reserve has reached nearly 1.8×109t, which accounts for more than 90% of the total proved reserves of the Dongying sag. Based on previous studies, more than 600 source rock samples and 186 crude oil samples of the Shahejie Formation, collected from 30 oilfields, have been treated with organic geochemical testing. By combining the sedimentary sequence characteristics and geochemical analysis results, the source rocks of the Shahejie Formation can be divided into three genetic types, i.e. the saline lake facies (the upper ES4, brackish water deep lake facies (the lower ES3) and fresh-water lake facies (the middle ES3), which correspond to the under-filling, balanced-filling and over-filling lake types respectively and represent the three most essential genetic models for source rocks of non-marine fault basins in China. Based on a thorough oil-source correlation, the source rocks of the saline lake and brackish deep lake facies are determined to be the most contributive source rocks in the Dongying sag. Furthermore, by probing into the accumulation of organic matter and hydrocarbon migration pattern, it can be inferred that the hydrocarbons, generated from source rocks of the saline lake facies with relatively low maturity, have mainly accumulated in the uplifted parts of the basin's margin via lateral migration and the reservoirs are dominated by the buried hill and stratigraphic types, while hydrocarbons generated from source rocks of the brackish lake facies are mainly distributed in the basin's center via vertical migration and characterized by forming lithologic reservoirs. Also, the reservoirs located in the transitional belts have complex types and mostly controlled by faults, characterized by block (structural-lithologic) reservoirs, and the crude oils mainly come from source beds of Es31 and Es42 respectively. 展开更多
关键词 source rocks association characteristics fluctuation lacustrine facies sedimentation heterogeneity Dongyingsag
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IMPROVED SINGULAR VALUE DECOMPOSITION TECHNIQUE FOR DETECTING AND EXTRACTING PERIODIC IMPULSE COMPONENT IN A VIBRATION SIGNAL 被引量:15
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作者 LiuHongxing lijian +1 位作者 ZhaoYing QuLiangsheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2004年第3期340-345,共6页
Vibration acceleration signals are often measured from case surface of arunning machine to monitor its condition. If the measured vibration signals display to have periodicimpulse components with a certain frequency, ... Vibration acceleration signals are often measured from case surface of arunning machine to monitor its condition. If the measured vibration signals display to have periodicimpulse components with a certain frequency, there may exist a corresponding local fault in themachine, and if further extracting the periodic impulse components from the vibration signals, theseverity of the local fault can be estimated and tracked. However, the signal-to-noise ratios (SNRs)of the vibration acceleration signals are often so small that the periodic impulse components aresubmersed in much background noises and other components, and it is difficult or inconvenient for usto detect and extract the periodic impulse components with the current common analyzing methods forvibration signals. Therefore, another technique, called singular value decomposition (SVD), istried to be introduced to solve the problem. First, the principle of detecting and extracting thesignal periodic components using singular value decomposition is summarized and discussed. Second,the infeasibility of the direct use of the existing SVD based detecting and extracting approach ispointed out. Third, the approach to construct the matrix for SVD from the signal series is improvedlargely, which is the key program to improve the SVD technique; Other associated improvement is alsoproposed. Finally, a simulating application example and a real-life application example ondetecting and extracting the periodic impulse components are given, which showed that the introducedand improved SVD technique is feasible. 展开更多
关键词 Fault diagnosis VIBRATION Signal processing Singular value decomposition
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Partial Sequence Analysis of Mitochondrial COI Gene of the Chinese Shrimp,Fenneropenaeus Chinensis 被引量:6
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作者 GAOTianxiang lijian +1 位作者 WANGQingyin LIUJinxian 《Journal of Ocean University of Qingdao》 2003年第2期167-170,共4页
Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents ... Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents of the sequence were 235bp(28.0%), 307bp(36.6%), 138bp(16.5%) and 158bp(18.9%), respectively. Furthermore, 556bp fragment of the sequence was used to discuss the phylogenetic relationship among 14 Penaeidae species using Alpheus armillatus as the outgroup. From the molecular phylogenetic tree constructed by neighbor-joining method, we obtained three large shrimp groups:Farfantepenaeus, Litopenaeus and Fenneropenaeus group. The results also indicated that there were a closer genetic relationships between F. aztecus and F. paulensis, L. schmitti and L. setiferus, F. indicus and F. merguiensis, and the genus Farfantepenaeus was closer to Litopenaeus. 展开更多
关键词 遗传因子 DNA序列 起源
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医学人类学与血吸虫病防治 被引量:1
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作者 lijian 《中国血吸虫病防治杂志》 CAS CSCD 2006年第2期157-160,共4页
In this article, I analyze theoretical trends, ethnographic fieldwork, and case studies in medical anthropology related to schistosomiasis control worldwide, highlighting useful examples for anthropologists and socio-... In this article, I analyze theoretical trends, ethnographic fieldwork, and case studies in medical anthropology related to schistosomiasis control worldwide, highlighting useful examples for anthropologists and socio-behavioral scientists involved in schistosomiasis control in China. I begin by reviewing recent research developments and medical anthropological perspectives that have been applied in schistosomiasis control. Then, I dissect and examine three medical anthropological projects carried out in St. Lucia, Brazil, and Cameroon, with an emphasis on their methodology, fieldwork strategies, and theoretical implications for schistosomiasis control. I conclude that an integration of anthropology and related socio-behavioral sciences will consummate our broader understanding of schistosomiasis, and help to build community-centered, sustainable control of schistosomiasis. 展开更多
关键词 医学人类学 血吸虫病防治 健康问题 疾病相关 应用人类学 20世纪 人类社会
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Effect of Neoadjuvant Chemotherapy on Improvement of Surgical Resectibility and Survival of Patients with Stage ⅢA Non Small Cell Lung Cancer 被引量:1
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作者 lijian YULichao 《The Chinese-German Journal of Clinical Oncology》 CAS 2002年第3期135-138,共4页
Ojbective To assess the effect of neoadjuvant chemotherapy on surgical resectibility and survival in patients with stage ⅢA non small cell lung cancer(NSCLC).Methods 42 patients with stage ⅢA NSCLC were randomized... Ojbective To assess the effect of neoadjuvant chemotherapy on surgical resectibility and survival in patients with stage ⅢA non small cell lung cancer(NSCLC).Methods 42 patients with stage ⅢA NSCLC were randomized to receive either two cycles chemotherapy followed by surgery(neoadjuvant chemotherapy group)or surgery alone(surgery alone group).All patients received four cycles chemotherapy after surgery.Results The overall response to chemotherapy was 42.9%(38.1% partial response and 4.8% complete response).Toxicity of chemotherapy was minor and consisted mainly of gastroenterological side effects and myelosuppression.Patients treated with neoadjuvant chemotherapy had estimated surgical resection rate of 95.2%(n=20)and a complete resection rate in 52.4%(n=11) compared to 66.7%(n=14)and 28.6%(n=6)respectively,for patients with surgery alone(P<0.05).None of the patients died from the operation.The median survival was 24.6 months in the neoadjuvant chemotherapy group as compared to only 10.8 months in the surgery alone group(P<0.05).The 2-year survival rate was 57.1% in the chemotherapy group as compared to 28.6% in the surgery alone group(P<0.05).Conclusion Neoadjuvant chemotherapy improves the surgical resectibility and increases the median survival and 2-year survival rate of patients with stage ⅢA NSCLC. 展开更多
关键词 ⅢA期 非小细胞肺癌 外科手术切除 患者 生存期 新辅助化疗 作用
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紫砂陶艺的繁盛及其成因考 被引量:3
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作者 李健 《陶瓷》 CAS 2019年第10期68-71,共4页
紫砂陶艺在明清两代走向繁盛并产生巨大社会、文化影响,是包括茶饮文化、制陶工艺、文人知识分子深度参与在内的等多重因素共同促成的。紫砂陶艺的特殊制作工艺又使其形成一个区别于其他陶瓷制业、由名家茗壶建构的紫砂艺术史脉络。其... 紫砂陶艺在明清两代走向繁盛并产生巨大社会、文化影响,是包括茶饮文化、制陶工艺、文人知识分子深度参与在内的等多重因素共同促成的。紫砂陶艺的特殊制作工艺又使其形成一个区别于其他陶瓷制业、由名家茗壶建构的紫砂艺术史脉络。其兴衰沉浮本身,则成为中国社会历史语境深刻变迁的重要表征之一。 展开更多
关键词 紫砂陶艺 繁盛期 文人知识分子 艺术史 成因考
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基于电气特性分析的台区拓扑变化辨识方法 被引量:3
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作者 蔡永智 唐捷 +4 位作者 危阜胜 李健 郭文翀 杨银 刘斯亮 《机电工程技术》 2021年第11期227-230,共4页
低压台区拓扑关系识别是支撑配电网智能化、数字化的关键基础。当前台区相序识别多从静态识别角度研究,缺少拓扑变化识别方法,就此提出了基于电气特性分析的台区拓扑变化辨识方法。对台区每天的用电数据设置滑动窗口,首先判断每一帧滑... 低压台区拓扑关系识别是支撑配电网智能化、数字化的关键基础。当前台区相序识别多从静态识别角度研究,缺少拓扑变化识别方法,就此提出了基于电气特性分析的台区拓扑变化辨识方法。对台区每天的用电数据设置滑动窗口,首先判断每一帧滑动窗口的电流数据的拟合偏差是否超过阈值;然后在拓扑变动较大的情况下直接启动拓扑计算程序,对台区用户重新计算相序拓扑关系,而在拓扑发生小变动的场景下,启动拓扑变动辨识程序,进一步分析了拓扑变动的电气特性并提出辨识方法;最后通过算例表明所提方法可以有效发现并辨识出相序拓扑变化的用户。 展开更多
关键词 低压台区 相序识别 拓扑变化 滑动窗口
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Research on Wear Behavior of ATC Cermet Material
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作者 ZHULiu LINGGuo-ping +1 位作者 lijian WANGYou-wen 《材料热处理学报》 EI CAS CSCD 北大核心 2004年第05B期1080-1083,共4页
By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of A12O3 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.% Al2O3-Co+30wt.... By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of A12O3 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.% Al2O3-Co+30wt.%TiC-Co) was hot-pressed into ATC (A12O3—TiC—Co8wt%) cermet samples. The wear test was carried out under dry sliding wear condition by the pin-on-disk rig. The volume-loss of the samples in three sliding pairs, ATC/Steel, ATC/SiC and ATC/artificial diamond (AD) were investigated. The wear morphologies were examined by SEM. The wear-resistance between ATC cermet and Co-cemented WC were compared. The results show that the effect of fracture toughness is better than that of hardness to the wear resistance of high hardness materials. The wear mechanisms of ATC cermet samples were found that abrasion predominated in the wear process. The wear surface of ATC cermet samples became smoother with fine asperities spalling off and the volume loss was decreased. 展开更多
关键词 ATC金属陶瓷 无电化学淀积 干滑动磨损 钴薄膜
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Analysis of the SiO_(x) Film Microstructure on Al Substrate by APC VD Process
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作者 ZHANGJi-liang lijian +2 位作者 WOYin-hua WANGYou-wen GANZheng-hao 《材料热处理学报》 EI CAS CSCD 北大核心 2004年第05B期847-850,共4页
A new kind of SiOx film on Al substrate,prepared by Ambient Pressure Chemical Vapor Deposition (APCVD) is reported in this paper. It is proposed that the SiOx particles as products of SiH4 and O2 reaction deposited on... A new kind of SiOx film on Al substrate,prepared by Ambient Pressure Chemical Vapor Deposition (APCVD) is reported in this paper. It is proposed that the SiOx particles as products of SiH4 and O2 reaction deposited on the heated Al surface, followed by close packing and further growth to form the thin film. The morphology, composition and microstructure of the film are characterized by SEM, XPS, XRD and HRTEM. The results show that the SiO, film comprises a majority of uncrystalline structure with a fraction of dispersed ordered zones and the atomic ratio of Si/O in the film is 1:1.60-1:1.75. The tests show that the film is well-bonded with the substrate. 展开更多
关键词 SIOX薄膜 显微结构 APCVD 铝衬底
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Coercivity of fractal aggregates formed by single-domain particles
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作者 WangQian SunQiang lijian 《西南师范大学学报(自然科学版)》 CAS CSCD 1994年第4期390-395,共6页
Coercivityoffractalaggregatesformedbysingle-do-mainparticlesWangQian,SunQiang,LiJian(DepartmentofPhysics,Sou... Coercivityoffractalaggregatesformedbysingle-do-mainparticlesWangQian,SunQiang,LiJian(DepartmentofPhysics,SouthwestChinaNormal... 展开更多
关键词 磁性粒子 分形原体 顽力特征
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The fractal research of Ultrafine Fe particle aggregation
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作者 LiangYiping DengZhaojing +1 位作者 WangQian lijian 《西南师范大学学报(自然科学版)》 CAS CSCD 1994年第4期378-382,共5页
ThefractalresearchofUltrafineFeparticleaggregationLiangYiping,DengZhaojing,WangQian,LiJian(DepartmentofPhysi... ThefractalresearchofUltrafineFeparticleaggregationLiangYiping,DengZhaojing,WangQian,LiJian(DepartmentofPhysics,SouthwestChina... 展开更多
关键词 铁超微粒 凝聚体 分形
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The study of the law of the space density distribution of Ag-Ultrafine particles
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作者 DengZhaojing LiangYiping +1 位作者 lijian RenHongxiang 《西南师范大学学报(自然科学版)》 CAS CSCD 1994年第4期371-377,共7页
ThestudyonthespacedensitydistributionofAg-UltrafineparticlesDengZhaojing,LiangYiping,LiJian,RenHongxiang(Dep... ThestudyonthespacedensitydistributionofAg-UltrafineparticlesDengZhaojing,LiangYiping,LiJian,RenHongxiang(DepartmentofPhysics,... 展开更多
关键词 银超微粒 空间密度分布律
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奥密克戎感染相关难治性心律失常临床特点
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作者 时向民 李健 +3 位作者 李世兴 张闯 葛兰 刘琪 《临床心电学杂志》 2023年第5期333-339,共7页
目的探讨奥密克戎感染相关难治性心律失常的种类,临床特点,潜在机制,处理及转归。方法回顾分析2022年12月至2023年1月奥密克戎感染爆发期间,14例难治性心律失常患者,其中男性7例,女性7例,年龄15~92(70.1±19.8)岁。既往有致心律失... 目的探讨奥密克戎感染相关难治性心律失常的种类,临床特点,潜在机制,处理及转归。方法回顾分析2022年12月至2023年1月奥密克戎感染爆发期间,14例难治性心律失常患者,其中男性7例,女性7例,年龄15~92(70.1±19.8)岁。既往有致心律失常性右室发育不良及扩张型心肌病植入ICD患者各1例,肥厚型心肌病1例,分析心律失常出现时间,以及与血氧饱和度、炎症指标、心肌标志物、D-二聚体相关性,治疗方法及临床转归。结果心律失常出现于奥密克戎感染后1~7天,包括左后分支型室速2例;阵发性房颤8例,其中合并尖端扭转型室速2例;右室心尖起源室速电风暴1例;房室阻滞3例,其中完全性房室阻滞2例,一度房室阻滞1例。白介素-6、肌钙蛋白I、D-二聚体升高,低氧血症与房颤,尖端扭转型室速及完全性房室阻滞密切相关。死亡5例,均为高龄房颤患者;2例ICD植入后疑似电风暴经远程随访指导治疗后稳定,1例完全性房室阻滞恢复正常房室传导。两例尖端扭转型室速停用胺碘酮及左氧氟沙星后消失,2例左后分支型室速经口服维拉帕米后得到控制。结论奥密克戎感染急性期易出现顽固性心律失常,低氧、炎症风暴、心肌损伤是心律失常的可能原因,某些抗生素及抗心律失常药联合治疗可延长QTc间期,房颤在感染急性期建议控制心室率为主,ICD植入患者易发生电风暴,远程随访技术可及时指导治疗。 展开更多
关键词 奥密克戎感染 心房颤动 室性心动过速 完全性房室阻滞 远程随访
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BP神经网络和SARIMA模型在手足口病发病率预测中的比较
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作者 李剑 刘莉红 +2 位作者 何志勇 徐幼莉 叶珍珍 《安徽预防医学杂志》 2023年第6期454-458,496,共6页
目的 探讨BP神经网络和季节差分自回归移动平均模型(SARIMA)模型在手足口病(HFMD)发病率预测中的应用,建立HFMD发病的预警系统,为其有效防控提供参考依据。方法 收集2012-2020年南昌市东湖区HFMD的发病数据,用BP神经网络和SARIMA进行模... 目的 探讨BP神经网络和季节差分自回归移动平均模型(SARIMA)模型在手足口病(HFMD)发病率预测中的应用,建立HFMD发病的预警系统,为其有效防控提供参考依据。方法 收集2012-2020年南昌市东湖区HFMD的发病数据,用BP神经网络和SARIMA进行模型拟合,预测2021年1-12月HFMD的发病情况,并用MSE、MAE、MAPE来评估2种模型的预测效果。结果 2012-2021年东湖区累计报告HFMD例2 923例,年平均发病率为52.56/10万,不同年度HFMD发病率有所不同(χ2=286.066,P<0.001)。对于2021年1-12月东湖区HFMD发病率的预测,BP神经网络模型的MSE、MAE、MAPE分别为2.87、1.37、0.82%,SARIMA模型MSE、MAE、MAPE分别为11.47、2.85、6.24%。结论 BP神经网络和SARIMA模型均适用于预测HFMD发病率,且BP神经网络模型的预测效果优于SARIMA模型。 展开更多
关键词 BP神经网络模型 SARIMA模型 手足口病 预测
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“抖音”在短视频领域的异军突起及其优化研究 被引量:1
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作者 季丹 李剑 《传媒观察》 2018年第10期40-45,共6页
音乐短视频APP“抖音”已成为短视频领域的现象级产品。其走红的原因包括在视听内容上构建较为完善,以强大的智能技术支持内容的引导以及多维度、多层次的传播方式。然而,内容质量总体偏低、外部经营风险与自身定位的变化,是其在后... 音乐短视频APP“抖音”已成为短视频领域的现象级产品。其走红的原因包括在视听内容上构建较为完善,以强大的智能技术支持内容的引导以及多维度、多层次的传播方式。然而,内容质量总体偏低、外部经营风险与自身定位的变化,是其在后续发展中的隐忧与挑战。必须优化内容,顺应网络发展趋势并加快商业化运作,才能谋得更好的发展。 展开更多
关键词 抖音 短视频 内容生态 去中心化 多维运营
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