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S Zorb装置反应器接收器脱气线和再生器取热盘管改造
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作者 张伟 《炼油技术与工程》 CAS 2024年第5期29-32,共4页
某公司对S Zorb装置首个运行周期内出现的反应器接收器脱气线泄漏、再生器取热盘管泄漏等运行问题开展了技术攻关,提出了工艺优化调整、工程技术改造建议。2019年大检修时对反应器脱气线进行扩径,由DN100扩径为DN150,控制气提量小于670 ... 某公司对S Zorb装置首个运行周期内出现的反应器接收器脱气线泄漏、再生器取热盘管泄漏等运行问题开展了技术攻关,提出了工艺优化调整、工程技术改造建议。2019年大检修时对反应器脱气线进行扩径,由DN100扩径为DN150,控制气提量小于670 m^(3)/h,对再生系统取热蒸汽和再生风流控阀等进行了工程技术改造。第二运行周期未出现脱气线减薄泄漏和再生器取热盘管泄漏问题。2023年6月大检修时对上次大检修改造部位进行检查以验证工程改造的有效性,经全面检查,确认脱气线内部未发现冲刷痕迹,再生器取热盘管打压合格,外观正常,证明改造措施有效,可以满足“四年一修”目标要求。 展开更多
关键词 s Zorb装置 反应器接收器 脱气线 再生器 取热盘管 泄漏 冲刷腐蚀 高频振荡
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Numerical Modeling and Computer Simulation of a Meander Line Antenna for Alzheimer’s Disease Treatment, a Feasibility Study
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作者 Felipe P. Perez Maryam Rahmani +8 位作者 Jorge Morisaki Farhan Amran Syazwani Bakri Akmal Halim Alston Dsouza Nurafifi Mohd Yusuff Amran Farhan James Maulucci Maher Rizkalla 《Journal of Biosciences and Medicines》 CAS 2023年第2期177-185,共9页
Alzheimer’s disease (AD) is a brain disorder that eventually causes memory loss and the ability to perform simple cognitive functions;research efforts within pharmaceuticals and other medical treatments have minimal ... Alzheimer’s disease (AD) is a brain disorder that eventually causes memory loss and the ability to perform simple cognitive functions;research efforts within pharmaceuticals and other medical treatments have minimal impact on the disease. Our preliminary biological studies showed that Repeated Electromagnetic Field Stimulation (REFMS) applying an EM frequency of 64 MHz and a specific absorption rate (SAR) of 0.4 - 0.9 W/kg decrease the level of amyloid-β peptides (Aβ), which is the most likely etiology of AD. This study emphasizes uniform E/H field and SAR distribution with adequate penetration depth penetration through multiple human head layers driven with low input power for safety treatments. In this work, we performed numerical modeling and computer simulations of a portable Meander Line antenna (MLA) to achieve the required EMF parameters to treat AD. The MLA device features a low cost, small size, wide bandwidth, and the ability to integrate into a portable system. This study utilized a High-Frequency Simulation System (HFSS) in the design of the MLA with the desired characteristics suited for AD treatment in humans. The team designed a 24-turn antenna with a 60 cm length and 25 cm width and achieved the required resonant frequency of 64 MHz. Here we used two numerical human head phantoms to test the antenna, the MIDA and spherical head phantom with six and seven tissue layers, respectively. The antenna was fed from a 50-Watt input source to obtain the SAR of 0.6 W/kg requirement in the center of the simulated brain tissue layer. We found that the E/H field and SAR distribution produced was not homogeneous;there were areas of high SAR values close to the antenna transmitter, also areas of low SAR value far away from the antenna. This paper details the antenna parameters, the scattering parameters response, the efficiency response, and the E and H field distribution;we presented the computer simulation results and discussed future work for a practical model. 展开更多
关键词 Alzheimer’s Disease Meander line Antenna HFss EMF linearity sAR Field Distribution
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基于YOLOv5s的轻量化架空输电线路鸟巢检测网络
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作者 徐业东 蔡亚恒 +2 位作者 李严 刘学雷 曹英丽 《电子测量技术》 北大核心 2024年第7期138-148,共11页
架空输电线路上的鸟巢侵占会对铁塔上的电力设备造成安全隐患,间接可能影响整个电力系统的稳定运行。针对目前架空输电线路鸟巢检测模型在复杂场景以及小目标场景下检测精度不高,检测效率低,模型复杂等问题。本研究提出一种基于YOLOv5s... 架空输电线路上的鸟巢侵占会对铁塔上的电力设备造成安全隐患,间接可能影响整个电力系统的稳定运行。针对目前架空输电线路鸟巢检测模型在复杂场景以及小目标场景下检测精度不高,检测效率低,模型复杂等问题。本研究提出一种基于YOLOv5s框架的轻量化架空输电线路鸟巢检测网络。首先在主干部分采用Fasternet重构YOLOv5s特征提取网络,降低模型复杂度,提高运行速度;然后在特征融合网络部分嵌入ConvMixer层,ConvMixer层的结构设计有助于在特征信息中更好的捕捉空间和通道的关系,提升模型对于小目标的检测能力;最后在特征融合网络部分引入ODConv模块,令送入检测头的特征图包含更多有效特征,提高模型对复杂场景和小目标的检测性能。实验结果表明,本文与基线模型YOLOv5s相比,计算量和模型体积分别减少了86%和72%,平均精度均值达到96.4%,检测速度达到104.2帧/s,验证了本文改进模型的有效性和可行性。 展开更多
关键词 轻量化 架空输电线路 YOLOv5s 鸟巢 目标检测
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基于TDLAS的H_(2)S高温反应特性实验研究
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作者 王嘉琦 田思迪 +3 位作者 高东波 田志伟 彭志敏 杜艳君 《热力发电》 CAS CSCD 北大核心 2024年第2期162-169,共8页
电站锅炉在低NO_(x)燃烧过程中因锅炉内还原性气氛浓度较高,会产生较多H_(2)S气体。针对H_(2)S因具有易燃、强腐蚀性、剧毒性而可能对火电厂造成多种危害的问题,采用可调谐二极管激光吸收光谱(tunable diode laser absorption spectrosc... 电站锅炉在低NO_(x)燃烧过程中因锅炉内还原性气氛浓度较高,会产生较多H_(2)S气体。针对H_(2)S因具有易燃、强腐蚀性、剧毒性而可能对火电厂造成多种危害的问题,采用可调谐二极管激光吸收光谱(tunable diode laser absorption spectroscopy,TDLAS)方法结合多通池和计算机搭建低气体摩尔分数在线测量系统,实现了对混合气体中摩尔分数在10–6量级H_(2)S的精确在线测量,并利用该测量系统进行了H_(2)S高温反应实验,探究实验温度和混合气体中O_(2)摩尔分数对该反应的影响。实验结果展示了压力为80 kPa、O_(2)摩尔分数为0~5%的条件下,H_(2)S开始发生化学反应的温度随O_(2)摩尔分数变化的变化规律,整体而言,混合气体中O_(2)摩尔分数越高,H_(2)S开始发生化学反应的温度越低。实验结果可以为锅炉烟气中H_(2)S的生成、转化和危害控制提供一定数据基础。 展开更多
关键词 TDLAs H_(2)s 在线测量 高温反应 O_(2)摩尔分数
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城市轨道交通S型曲线夹直线与长直线地段振动对比试验研究
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作者 张明凯 赵炎南 +2 位作者 许以凯 赵才友 易强 《噪声与振动控制》 CSCD 北大核心 2024年第2期178-184,共7页
夹直线在一定程度上可以保证线型连续和行车平顺,但过短的夹直线长度会导致振动叠加,影响旅客舒适度和列车运行的稳定性,增加运营维护成本。本文通过对城市轨道交通S型曲线夹直线与长直线地段振动对比试验研究,从时域、时频域、振动加... 夹直线在一定程度上可以保证线型连续和行车平顺,但过短的夹直线长度会导致振动叠加,影响旅客舒适度和列车运行的稳定性,增加运营维护成本。本文通过对城市轨道交通S型曲线夹直线与长直线地段振动对比试验研究,从时域、时频域、振动加速度级及地面Z振级等方面对获得的数据进行分析,解释了夹直线段振动叠加的产生机理,验证了车体垂向加速度峰值在缓直点处会出现峰值提前现象,并阐述了夹直线段的振动叠加现象对地面环境振动的影响。结论如下:车辆在通过S型曲线线形变化点时产生的冲击振动会通过钢轨以弹性波的形式向前传播,与车辆在夹直线段行驶产生的振动叠加;由于弹性波的形式传播的速度远高于车辆行驶速度,因此会导致夹直线段出现振动加速度峰值提前现象;S型曲线夹直线的垂向振动加速度的优势频率要高于长直线段,且更向高频分散;S型曲线夹直线产生的振动叠加现象不会对地面环境振动产生影响。 展开更多
关键词 振动与波 地铁 s型曲线夹直线 试验研究 环境振动 弹性波
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Analysis and Simulation of the Influence of Electromagnetic Fields on Living Beings near HV Power Lines Using the FDTD Method
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作者 Anthony Bassesuka Sandoka Nzao 《Open Journal of Applied Sciences》 2023年第12期2343-2359,共17页
Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-freque... Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-frequency electromagnetic fields on the environment and which are capable of modifying and destroying our ecosystem. Particular interest was given in this article due to a massive influx of population living near high voltage lines. The analysis and simulation of the influence of low frequency electromagnetic fields on living beings in the vicinity of high voltage sources 132 kV and 220 kV in urban areas in DR Congo is the subject of our research with a view to estimating the level of exposure of humans to low frequency electromagnetic fields. To carry out our research, we used the classic method of analyzing the field produced near a high voltage line based on Maxwell’s image theory, the Maxwell-Gauss theorem and Maxwell-Ampère theorem to model and quantify low-frequency electromagnetic fields in the vicinity of high-voltage lines. The 2D FDTD numerical formulation was developed from telegraphers’ equations and allowed us to obtain models of current and voltage induced by electromagnetic fields on living beings below and near HV lines. The different simulations carried out on the proposed models illustrate the effects of the electrical and geometric parameters of the pylons on the distribution of the electromagnetic field in the vicinity of the HV lines. The results obtained were compared to the safety limits recommended by the standards. 展开更多
关键词 Low Frequency Electromagnetic Field Modeling Field and Health Maxwell’s Equations FDTD Method Electromagnetic Compatibility High Voltage line
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Unilateral lichen planus with Blaschko line distribution: A case report
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作者 Shuai Dong Wen-Jing Zhu +2 位作者 Meng Xu Xue-Qi Zhao Yan Mou 《World Journal of Clinical Cases》 SCIE 2022年第24期8679-8685,共7页
BACKGROUND Lichen planus(LP)with distribution of lesions along Blaschko’s lines is a rare entity,accounting for 0.24%-0.62%of all patients.Unilateral distribution of lesions in arm,leg,trunk,and waist is even less co... BACKGROUND Lichen planus(LP)with distribution of lesions along Blaschko’s lines is a rare entity,accounting for 0.24%-0.62%of all patients.Unilateral distribution of lesions in arm,leg,trunk,and waist is even less common.Approximately 10%of patients with LP manifest nail lesions.CASE SUMMARY A 20-year-old woman presented to our department with polygonal,purpuric,flattopped papules over the right arm,right leg,and right side of trunk and waist for the last 5 mo.The patient initially developed nail deformation in the left middle finger with no obvious cause,followed by development of blue-purple and red maculopapular rash with pruritus.During the disease course,the skin lesions aggravated and spread to several segments due to scratching.The lesions showed unilateral distribution along the Blaschko’s lines.The diagnosis of LP along Blaschko’s lines was established based on dermoscopy and skin biopsy.Her cutaneous lesions considerably improved after 4-wk treatment with intramuscular glucocorticoid,oral acitretin,topical glucocorticoid,and retinoids.CONCLUSION Cases of LP involving multiple segments of the body along the Blaschko’s lines with nail damage are rare. 展开更多
关键词 Lichen planus blaschkolines Lichen planus involving nails Case report
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优质籼型光温敏核不育系荃时S的选育与应用
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作者 丁友奇 《园艺与种苗》 CAS 2024年第8期94-95,98,共3页
介绍了荃时S的选育过程、特征特性、配组应用及繁殖技术要点。荃时S是以银312S为母本,与配合力好的优良恢复系YR0822杂交,采用系谱法选育而成的籼型光温敏核不育系,具有育性转换起点温度较低、不育性稳定、异交率高、抗倒伏、米质优等特... 介绍了荃时S的选育过程、特征特性、配组应用及繁殖技术要点。荃时S是以银312S为母本,与配合力好的优良恢复系YR0822杂交,采用系谱法选育而成的籼型光温敏核不育系,具有育性转换起点温度较低、不育性稳定、异交率高、抗倒伏、米质优等特点,2021年通过安徽省农作物品种审定委员会组织的专家技术鉴定。该不育系与恢复系银泰香占配制的籼型两系杂交水稻品种时两优泰香具有中抗稻瘟病、米质达部标优1级、丰产等特点,并获得2022年(第四届)安徽省优质稻品种食味品质籼稻金奖,2022年通过国家农作物品种审定委员会审定。 展开更多
关键词 杂交水稻 光温敏核不育系 荃时s 选育
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大跨度S形舞台升降台设计
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作者 丁守红 张凤宝 《现代制造技术与装备》 2024年第6期28-31,共4页
针对大跨度S形舞台升降台设计中的难点进行分析,优选多组多点钢丝绳卷扬提升方式,采用双驱动系统同步驱动,并阐述多分段刚性传动轴的折线布置方法。结合工程实例提出经济、合理的设计方案,为此类设备的设计提供参考。
关键词 s形升降台 大跨度 钢丝绳卷扬 双驱动 传动轴折线布置
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Comparative Studies on the Changes of Microtubule Distribution and Reorganization During the Meiotic Stages of Development in Normal (IR36) and a Temperature/photoperiod Sensitive Male Sterile Line (Peiai 64S) of Rice ( Oryza sativa ) 被引量:3
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作者 徐是雄 刘向东 +1 位作者 冯九焕 卢永根 《Acta Botanica Sinica》 CSCD 2001年第3期221-226,共6页
Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sen... Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sensitive male sterile line (Peiai 64S) of rice were studied using immunofluorescence confocal microscopy. In IR36, from pre-meiotic interphase to metaphase I, the pattern of microtubule distribution in the meiocytes underwent a series of changes. Some new organizational patterns of microtubules (that have not been described before) were observed during microsporogenesis, including the existence of a broad band of perinuclear microtubules at the diakinesis stage of development. The pattern of microtubule distribution in the meiocytes of the male sterile line, Peiai 64S, was quite different front that seen in IR36. In Peiai 64S, the microtubules showed abnormal patterns of distribution from pre-meiotic interphase to metaphase I. For example the broad band of perinuclear microtubules seen at diakinesis in IR36 was much disorganized and loosened in Peiai 64S. The spindles formed were also very abnormal and different from the normal spindle. The appearance of abnormal microtubule distribution in the early stages of microsporogenesis may contribute to the malformation and ultimate abortion of pollen in Peiai 64S. 展开更多
关键词 Oryza sativa temperature/photoperiod sensitive male sterile rice line microtubules Peiai 64s IR36 microsporocyte meiosis microsporogenesis
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Breeding and Application of Indica PTGMS Line Yan 161S and Its Hybrid Yanliangyou 1618 in Rice
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作者 孙明法 严国红 +12 位作者 唐红生 王爱民 朱国永 何冲霄 任仲玲 刘凯 张桂云 施伟 万林生 孙红芹 倪正斌 单忠德 姚立生 《Agricultural Science & Technology》 CAS 2015年第6期1140-1143,共4页
In 2006, the indica photoperiod- and thermo-sensitive genic male sterile (PTGMS) line Yan 161S was successful y bred by crossing the Guangzhan 63S (♀) and the medium indica breeding material Yan 229 (♂), which... In 2006, the indica photoperiod- and thermo-sensitive genic male sterile (PTGMS) line Yan 161S was successful y bred by crossing the Guangzhan 63S (♀) and the medium indica breeding material Yan 229 (♂), which was bred by the Institute of Agricultural Sciences in Coastal Region of Jiangsu Province, after years' and generations’ selection in different areas. It passed the identification by Jiangsu Provincial Crop Variety Appraisal Committee in 2013. Crossing the Yan 161S with Yanhui 888, a new high-yielding and high-quality two-line hybrid rice combination Yanliangyou 1618 was developed, and it passed the variety identification in 2014. This paper introduced the breeding processes and characteristics of Yan 161S and Yanliangyou 1618 and the cultivation and seed production techniques of Yanliangyou 1618. 展开更多
关键词 盐161s Two-line hybrid rice PTGMs line Yan 161s BREEDING
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Breeding and Application of Indica PTGMS Line Yan 220S in Rice
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作者 孙明法 严国红 +10 位作者 唐红生 王爱民 朱国永 何冲霄 任仲玲 刘凯 张桂云 施伟 赵绍路 孙一标 姚立生 《Agricultural Science & Technology》 CAS 2017年第8期1410-1412,共3页
Yan 220S, which is derived from a natural variant plant discovered among the population of Guangzhan 63S and developed by Jiangsu Agricultural Research Institute for Coastal Regions through pedigree selection over yea... Yan 220S, which is derived from a natural variant plant discovered among the population of Guangzhan 63S and developed by Jiangsu Agricultural Research Institute for Coastal Regions through pedigree selection over years, is an indica photo- and thermo-sensitive genic male sterile (PTGMS) line in rice. In 2013, it was technically identified by Jiangsu Crop Variety Appraisal Committee. Its hybrid Yan-liangyou 2208 (Yan 220S/Yanhui 888), a new two-line hybrid rice combination with high yield and good grain quality, was subsequently developed and released for commercial production by the National Crop Variety Appraisal Committee in 2013. 展开更多
关键词 Hybrid rice PTGMs line Yan 220s BREEDING
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Characterization of Reverse Thermo-sensitive Genic Male Sterile Lines in Cold Regions of China
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作者 高扬 谭炎宁 +2 位作者 孟昭河 段美娟 徐秋生 《Agricultural Science & Technology》 CAS 2017年第7期1183-1186,1201,共5页
Yannong S, a reverse thermo-sensitive genic male sterile (TGMS) line, is sterile at high temperature and fertile at low temperature. In the present study, the fertility of Yannong S and the japonica reverse TGMS lin... Yannong S, a reverse thermo-sensitive genic male sterile (TGMS) line, is sterile at high temperature and fertile at low temperature. In the present study, the fertility of Yannong S and the japonica reverse TGMS lines derived from it was in- vestigated in Harbin, Heilongjiang from 2013 to 2015. The results showed that Yan- nong S was completely male sterile in July and August (the hottest months of the year in Harbin), and the seed setting rate of bagged panicles was 0. We also in- ferred that the critical temperature for inducing the sterility of Yannong S was higher than 28 ℃. Most of the japonica reverse TGMS lines derived from Yannong S were completely aborted in July and August, with a seed setting rate of 0. It can be con- cluded that the reverse TGMS lines derived from Yannong S are genetically stable lines that have a long period of sterility in cold regions, so they may be the ideal genetic materials for the development and in-situ seed production of japonica hybrid rice. 展开更多
关键词 Japonica hybrid rice Reverse thermo-sensitive genic male sterile lines Cold regions Yannong s FERTILITY
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沿Blaschko线分布雀斑样痣一例
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作者 王晨 李振鲁 《实用皮肤病学杂志》 2019年第2期125-126,共2页
11岁女性患儿,下腹中部、右侧会阴、臀部及右下肢淡褐色斑疹8年。下腹中部、右侧会阴、臀部及右下肢至足踝处可见沿Blaschko线分布的针尖至米粒大小密集、不融合淡褐色斑疹。皮损组织病理示轻度角化过度,棘层轻度肥厚,表皮突下延,个别... 11岁女性患儿,下腹中部、右侧会阴、臀部及右下肢淡褐色斑疹8年。下腹中部、右侧会阴、臀部及右下肢至足踝处可见沿Blaschko线分布的针尖至米粒大小密集、不融合淡褐色斑疹。皮损组织病理示轻度角化过度,棘层轻度肥厚,表皮突下延,个别表皮突基底层色素明显增多,真皮浅层血管周围少量淋巴细胞浸润。诊断:沿Blaschko线分布雀斑样痣。 展开更多
关键词 雀斑样痣 blaschko线
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基于Pearson相关系数与广义S变换的低压直流微电网的故障选线方法 被引量:3
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作者 高淑萍 李晓芳 +2 位作者 宋国兵 郑瀚 郭芳宾 《电力系统保护与控制》 EI CSCD 北大核心 2023年第15期120-129,共10页
针对低压直流微电网线路的故障选线方法的研究有限,提出一种基于Pearson相关系数与广义S变换的故障选线方法。首先,介绍了低压直流微电网的一般组成。在此基础上,研究了低压直流微电网的单极故障以及极间故障的故障特征,提出选线方法,... 针对低压直流微电网线路的故障选线方法的研究有限,提出一种基于Pearson相关系数与广义S变换的故障选线方法。首先,介绍了低压直流微电网的一般组成。在此基础上,研究了低压直流微电网的单极故障以及极间故障的故障特征,提出选线方法,对各线路正负极首末端电流差进行Pearson相关系数计算来确定故障线路。然后对所选故障线路正负线路首端的电流量进行广义S变换,计算出其能量和的比值判别故障极性或者极间故障。最后,在PSCAD/EMTDC中搭建出低压直流微电网模型以输出各线路电流数据,并利用Matlab对数据进行仿真。结果表明,所提选线方法直接有效,且耐受过渡电阻的能力较强。 展开更多
关键词 低压直流微电网 广义s变换 Pearson相关系数 单极故障 故障选线
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沿Blaschko线分布的硬化性萎缩性苔藓合并局限性硬皮病1例 被引量:2
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作者 曾雪 谢勇 +1 位作者 渠涛 方凯 《中国皮肤性病学杂志》 CAS 北大核心 2011年第8期623-624,628,共3页
患者女,57岁。右颈部及腰部出现沿Blaschko线分布的条状硬化性白斑8月。皮损与Blaschko线分布区域相吻合。皮损组织病理示:基底细胞灶状液化变性,真皮乳头层均一化变性,真皮中深层胶原纤维增粗融合,皮肤附属器数目减少。诊断:硬化性萎... 患者女,57岁。右颈部及腰部出现沿Blaschko线分布的条状硬化性白斑8月。皮损与Blaschko线分布区域相吻合。皮损组织病理示:基底细胞灶状液化变性,真皮乳头层均一化变性,真皮中深层胶原纤维增粗融合,皮肤附属器数目减少。诊断:硬化性萎缩性苔藓;局限性硬皮病。 展开更多
关键词 硬化性萎缩性苔藓 局限性硬皮病 blaschko线
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沿Blaschko线分布的四例炎症性疾病临床病理分析
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作者 于越乾 付希安 +4 位作者 暴芳芳 周桂芝 陈声利 陈学超 刘红 《中国麻风皮肤病杂志》 2021年第10期650-652,共3页
Blaschko线是分布于人体皮肤黏膜上的一种特殊的线条排列,被认为是皮肤嵌合体的表现形式。既往文献已报道多种沿B线分布的皮肤病,分为先天性及后天性。现报道4例沿B线分布的炎症性疾病,分别为线状皮肤型红斑狼疮、线状硬化性萎缩性苔藓... Blaschko线是分布于人体皮肤黏膜上的一种特殊的线条排列,被认为是皮肤嵌合体的表现形式。既往文献已报道多种沿B线分布的皮肤病,分为先天性及后天性。现报道4例沿B线分布的炎症性疾病,分别为线状皮肤型红斑狼疮、线状硬化性萎缩性苔藓、线状苔藓、线状扁平苔藓。 展开更多
关键词 blaschko线 线状皮肤型红斑狼疮 线状苔藓
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Relationships of climate change and tree ring of Betula ermanii tree line forest in Changbai Mountain 被引量:34
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作者 YU Da-pao GU Hui-yan +2 位作者 WANG Jian-dong WANG Qing-li DAI Li-min 《Journal of Forestry Research》 SCIE CAS CSCD 2005年第3期187-192,共6页
Based on the tree-ring growth characteristics of Erman's birch (Betula ermanii charm.) and the relationships between it and climatic )'actors at elevation of 1950m, the sensitivity of tree lines in Changbai Mount... Based on the tree-ring growth characteristics of Erman's birch (Betula ermanii charm.) and the relationships between it and climatic )'actors at elevation of 1950m, the sensitivity of tree lines in Changbai Mountain to climatic factors was assessed. The results indicated tree line forest in Changbai Mountain had an obvious sensitivity to climate factors. However, difference from other study sits is that the main climatic control factor on tree-ring growth was not current growth season temperatures, as might be expected, but previous winter and current March temperature. Although the precipitation in the region was quite abundant, the tree-ring growth was still significantly correlated with the precipitation during previous winter and current spring. Additionally, climatic factors which influenced the Erman's birch growth were not the yearly variables, but seasonal and monthly variables. Therefore, the reported increase in yearly mean temperature and total yearly precipitation since 1980s was not responded by sustained increase in ring widths in recent decades. 展开更多
关键词 Climatic change dendrochronology Erman's birch Tree line in Changbai Mountain
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Establishment of an artificial β-cell line expressing insulin under the control of doxycycline 被引量:15
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作者 Xin-Yu Qin Kun-Tang Shen,Department of General Surgery,Zhongshan Hospital,Fudan University,Shanghai 200032,China Xin Zhang Zhi-Hong Cheng Xiang-Ru Xu Ze-Guang Han,Functional Genomics Division,Chinese National Human Genome Center At Shanghai,Shanghai 201203,China 《World Journal of Gastroenterology》 SCIE CAS CSCD 2002年第2期367-370,共4页
AIM: Artificial beta-cell lines may offer an abundant source of cells for the treatment of type I diabetes, but insulin secretion in beta-cells is tightly regulated in physiological conditions. The Tet-On system is a ... AIM: Artificial beta-cell lines may offer an abundant source of cells for the treatment of type I diabetes, but insulin secretion in beta-cells is tightly regulated in physiological conditions. The Tet-On system is a &quot;gene switch&quot; system, which can induce gene expression by administration of tetracycline (Tet) derivatives such as doxcycline (Dox). Using this system, we established 293 cells to an artificial cell line secreting insulin in response to stimulation by Dox. METHODS: The mutated proinsulin cDNA was obtained from plasmid pcDNA3.1/C-mINS by the polymerase chain reaction (PCR), and was inserted downstream from the promoter on the expression vector pTRE2, to construct a recombined expression vector pTRE2mINS. The promoter on pTRE2 consists of the tetracycline-response element and the CMV minimal promoter and is thus activated by the reverse tetracycline-controlled transactivator (rtTA) when Dox is administrated. pTRE2mINS and plasmid pTK-Hyg encoding hygromycin were co-transfected in the tet293 cells, which express rtTA stably. Following hygromycin screening, the survived cells expressing insulin were selected and enriched. Dox was used to control the expression of insulin in these cells. At the levels of mRNA and protein, the regulating effect of Dox in culture medium on the expression of proinsulin gene was estimated respectively with Northern blot, RT-PCR, and radioimmunoassay. RESULTS: From the 28 hygromycin-resistant cell strains, we selected one cell strain (tet293/Ins6) secreting insulin not only automatically, but in response to stimulation by Dox. The amount on insulin secretion was dependent on the Dox dose (0,10,100,200,400,800 and 1000 microg.L(-1)), the level of insulin secreted by the cells treated with Dox (1000 microg.L(-1)) was 241.0pU.d(-1).cell(-1) , which was 25-fold that of 9.7pU.d(-1).cell(-1) without Dox treatment. Northern blot analyses and RT-PCR further confirmed that the transcription of insulin gene had already been up-regulated after exposing tet293/Ins6 cells to Dox for 15 minutes, and was also induced in a dose-dependent manner. However, the concentration of insulin in the media did not increase significantly until 5 hours following the addition of Dox. CONCLUSION: Human proinsulin gene was transfected successfully and expressed efficiently in 293 cells, and the expression was modulated by tetracycline and its derivatives, improving the accuracy, safety, and reliability of gene therapy, suggesting that conditional establishment of artificial beta-cells may be a useful approach to develop cellular therapy for diabetes mellitus. 展开更多
关键词 Cell line Gene Expression Regulation Islets of Langerhans Diabetes Mellitus Type 2 DOXYCYCline Humans INsULIN Research support Non-U.s. Gov't TRANsFECTION
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沿Blaschko线分布的儿童汗孔角化症一例
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作者 张春阳 李雪莉 +1 位作者 李振鲁 张帅 《实用皮肤病学杂志》 2019年第6期371-372,共2页
13岁男性患儿,右侧腰腹部褐色丘疹10年、增多伴瘙痒6个月。皮肤科情况:右侧腰腹部密集绿豆大小、暗褐色、疣状增生性丘疹,丘疹中央轻度萎缩,边缘堤状隆起,无鳞屑,皮损整体呈S形沿Blaschko线分布。组织病理示:表皮凹窝处角化不全柱,其下... 13岁男性患儿,右侧腰腹部褐色丘疹10年、增多伴瘙痒6个月。皮肤科情况:右侧腰腹部密集绿豆大小、暗褐色、疣状增生性丘疹,丘疹中央轻度萎缩,边缘堤状隆起,无鳞屑,皮损整体呈S形沿Blaschko线分布。组织病理示:表皮凹窝处角化不全柱,其下方颗粒层消失,真皮浅层中等量淋巴细胞浸润。诊断:汗孔角化症(沿Blaschko线分布)。 展开更多
关键词 汗孔角化症 blaschko线
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