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基于Focal Loss^(IM)-Transformer的电网虚假数据注入攻击检测
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作者 席磊 和昀 +3 位作者 李子豪 曹利锋 李宗泽 石雨凡 《南方电网技术》 北大核心 2025年第6期26-38,共13页
虚假数据注入攻击对电力信息物理系统造成严重安全威胁。由于受到攻击样本与正常样本之间存在类别不平衡特性,导致机器学习检测方法偏向于多数类的预测,影响其对攻击的检测精度。为此,提出了基于Focal Loss^(IM)-Transformer的虚假数据... 虚假数据注入攻击对电力信息物理系统造成严重安全威胁。由于受到攻击样本与正常样本之间存在类别不平衡特性,导致机器学习检测方法偏向于多数类的预测,影响其对攻击的检测精度。为此,提出了基于Focal Loss^(IM)-Transformer的虚假数据注入攻击检测。Transformer利用其自注意力机制能够捕捉数据中的长期依赖性,进而识别不平衡的虚假数据注入攻击数据。Focal Loss^(IM)通过引入调制因子来更好地匹配虚假数据注入攻击样本的分布和特性,来增强检测方法对不平衡数据的识别能力,以提高检测方法对攻击的检测精度。通过在IEEE 14节点系统、IEEE 30节点系统和IEEE 57节点系统进行仿真,验证了所提方法的有效性。且相较于传统损失函数和其他检测方法,所提方法显示出更好的泛化能力和对少数类的识别能力,且辨识精度高、误报率低。 展开更多
关键词 电力信息物理系统 虚假数据注入攻击 不平衡数据 TRANSFORMER focal loss
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基于边界自适应SMOTE和Focal Loss函数改进LightGBM的信用风险预测模型 被引量:13
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作者 陈海龙 杨畅 +1 位作者 杜梅 张颖宇 《计算机应用》 CSCD 北大核心 2022年第7期2256-2264,共9页
针对信用风险评估中数据集不平衡影响模型预测效果的问题,提出一种基于边界自适应合成少数类过采样方法(BA-SMOTE)和利用FocalLoss函数改进LightGBM损失函数的算法(FLLightGBM)相结合的信用风险预测模型。首先,在边界合成少数类过采样(B... 针对信用风险评估中数据集不平衡影响模型预测效果的问题,提出一种基于边界自适应合成少数类过采样方法(BA-SMOTE)和利用FocalLoss函数改进LightGBM损失函数的算法(FLLightGBM)相结合的信用风险预测模型。首先,在边界合成少数类过采样(Borderline-SMOTE)的基础上,引入自适应思想和新的插值方式,使每个处于边界的少数类样本生成不同数量的新样本,并且新样本的位置更靠近原少数类样本,以此来平衡数据集;其次,利用FocalLoss函数来改进LightGBM算法的损失函数,并以改进的算法训练新的数据集以得到最终结合BA-SMOTE方法和FLLightGBM算法建立的BA-SMOTE-FLLightGBM模型;最后,在LendingClub数据集上进行信用风险预测。实验结果表明,与其他不平衡分类算法RUSBoost、CUSBoost、KSMOTE-AdaBoost和AK-SMOTE-Catboost相比,所建立的模型在G-mean和AUC两个指标上都有明显的提升,提升了9.0%~31.3%和5.0%~14.1%。以上结果验证了所提出的模型在信用风险评估中具有更好的违约预测效果。 展开更多
关键词 信用风险 不平衡数据 过采样 LightGBM focalLoss
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结合改进VGGNet和Focal Loss的人脸表情识别 被引量:32
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作者 崔子越 皮家甜 +6 位作者 陈勇 杨杰之 鲜焱 吴至友 赵立军 曾绍华 吕佳 《计算机工程与应用》 CSCD 北大核心 2021年第19期171-178,共8页
针对目前表情识别准确率偏低,表情数据集中类别样本类间差异小、类内差异大以及误标注样本产生的误分类等问题,提出了一种结合改进VGGNet和Focal Loss的人脸表情识别算法。在迁移学习的基础上,通过设计新的输出模块对VGGNet模型进行改进... 针对目前表情识别准确率偏低,表情数据集中类别样本类间差异小、类内差异大以及误标注样本产生的误分类等问题,提出了一种结合改进VGGNet和Focal Loss的人脸表情识别算法。在迁移学习的基础上,通过设计新的输出模块对VGGNet模型进行改进,提升了模型的特征提取能力,能够较好地避免过拟合现象;通过设置概率阈值对Focal Loss进行改进,避免误标注样本对模型分类性能产生影响。实验结果表明,该模型在CK+、JAFFE以及FER2013数据集上的识别准确率分别达到了99.68%、97.61%和72.49%,在实际应用中泛化能力突出。 展开更多
关键词 表情识别 深度学习 迁移学习 focalLoss 卷积神经网络
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基于Focal损失SSDAE的变压器故障诊断方法 被引量:14
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作者 武天府 刘征 +2 位作者 王志强 李劲松 李国锋 《电力工程技术》 北大核心 2021年第6期18-24,共7页
研究变压器的故障诊断对电力系统安全稳定运行具有重大现实意义。以油中溶解气体特征为输入的传统变压器故障诊断方法在处理样本不平衡数据时具有较大的局限性。针对这一问题,文中提出一种基于Focal损失栈式稀疏降噪自编码器(SSDAE)的... 研究变压器的故障诊断对电力系统安全稳定运行具有重大现实意义。以油中溶解气体特征为输入的传统变压器故障诊断方法在处理样本不平衡数据时具有较大的局限性。针对这一问题,文中提出一种基于Focal损失栈式稀疏降噪自编码器(SSDAE)的变压器故障诊断方法。该方法通过类别权重确定超参数,并在原始输入中加入高斯白噪声,有利于自编码器充分提取有效特征,进而得到有效的深度特征提取模型;采用Focal损失函数对模型进行优化,并利用Softmax分类器输出诊断结果。案例分析结果表明,与传统三比值法、反向传播神经网络(BPNN)和支持向量机(SVM)法等变压器故障诊断方法相比,文中方法可进一步提升诊断准确率。 展开更多
关键词 变压器 故障诊断 栈式稀疏降噪自编码器(SSDAE) Softmax分类器 focal损失 类别权重
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融合GIoU和Focal loss的YOLOv3目标检测算法 被引量:29
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作者 邹承明 薛榕刚 《计算机工程与应用》 CSCD 北大核心 2020年第24期214-222,共9页
YOLOv3目标检测算法检测速度快且精度较高,但存在对小目标检测能力不足、边界框定位不准确等问题。提出了一种基于YOLOv3改进的目标检测算法,该算法在YOLOv3的基础上,对网络中的残差块增加旁路连接,进一步进行特征重用,以提取更多的特... YOLOv3目标检测算法检测速度快且精度较高,但存在对小目标检测能力不足、边界框定位不准确等问题。提出了一种基于YOLOv3改进的目标检测算法,该算法在YOLOv3的基础上,对网络中的残差块增加旁路连接,进一步进行特征重用,以提取更多的特征信息。同时,采用GIoUloss作为边界框的损失,使网络朝着预测框与真实框重叠度较高的方向去优化。在损失函数中加入Focal loss,减小正负样本不平衡带来的误差。在PASCAL VOC和COCO数据集上的实验结果表明,该算法能够在不影响YOLOv3算法实时性的前提下,提高目标检测的mAP。该算法在PASCAL VOC 2007测试集上达到83.7mAP(IoU=0.5),在COCO测试集上比YOLOv3算法提升2.27mAP(IoU[0.5,0.95])。 展开更多
关键词 YOLOv3算法 目标检测 GIou loss focal loss
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基于空洞卷积和Focal Loss的改进YOLOv3算法 被引量:16
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作者 许腾 唐贵进 +1 位作者 刘清萍 鲍秉坤 《南京邮电大学学报(自然科学版)》 北大核心 2020年第6期100-108,共9页
为了进一步提升YOLOv3的小目标检测能力,文中提出将Darknet-53中的第2个残差块输出的特征图用混合空洞卷积处理后,与YOLOv3的8倍下采样特征图相融合,建立新的检测特征;同时,使用Focal Loss改进损失函数中的负样本置信度公式,缓解YOLOv3... 为了进一步提升YOLOv3的小目标检测能力,文中提出将Darknet-53中的第2个残差块输出的特征图用混合空洞卷积处理后,与YOLOv3的8倍下采样特征图相融合,建立新的检测特征;同时,使用Focal Loss改进损失函数中的负样本置信度公式,缓解YOLOv3的正负样本比例失衡问题。实验结果表明,在小目标数量占比为47.7%的特定测试集上,改进YOLOv3的平均准确率和召回率分别比原YOLOv3提高了8.8%和16%;在VOC测试集上,改进YOLOv3的平均精度均值比原YOLOv3提升了3.4%。 展开更多
关键词 小目标检测 样本不平衡 混合空洞卷积 focal Loss
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Focal损失在图像情感分析上的应用研究 被引量:12
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作者 傅博文 唐向宏 肖涛 《计算机工程与应用》 CSCD 北大核心 2020年第10期179-184,共6页
充分利用Focal损失函数具有挖掘困难样本和调节样本不平衡问题的特性,将其应用在基于神经网络的图像情感分析模型中。为了缓解训练数据集的类别样本不平衡问题,提升情感分类模型的训练效率,对Focal损失函数中参数设置进行了改进。该方... 充分利用Focal损失函数具有挖掘困难样本和调节样本不平衡问题的特性,将其应用在基于神经网络的图像情感分析模型中。为了缓解训练数据集的类别样本不平衡问题,提升情感分类模型的训练效率,对Focal损失函数中参数设置进行了改进。该方法通过类别权重大小来确定平衡参数α,并在神经网络模型训练的不同阶段,采用渐增方式对聚焦因子γ进行调节,然后将改进的Focal损失函数应用于图像情感分析模型的神经网络训练中。仿真实验表明,相比于交叉熵损失函数,改进的Focal损失函数能够提升神经网络对图像情感分析的性能。实验结果表明,所采用方法的准确率、宏召回率、宏精准率分别提升了0.5~2.3个百分点、0.4~3.9个百分点、0.5~3.3个百分点。 展开更多
关键词 图像情感分析 情感图像数据集 卷积神经网络 样本不平衡 focal损失函数
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基于Focal Loss改进的GBDT模型对天津强对流灾害的预报 被引量:4
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作者 路志英 汪永清 +1 位作者 孙晓磊 贾惠珍 《灾害学》 CSCD 北大核心 2020年第3期34-37,50,共5页
强对流灾害是气象研究的重点,不准确的强对流灾害天气预报往往给人们的安全以及社会经济造成影响。该文利用天津2006-2018年的地面气象观测站点的地面物理场数据,筛选出强对流灾害性天气过程,对天津强对流灾害天气进行研究。首先对地面... 强对流灾害是气象研究的重点,不准确的强对流灾害天气预报往往给人们的安全以及社会经济造成影响。该文利用天津2006-2018年的地面气象观测站点的地面物理场数据,筛选出强对流灾害性天气过程,对天津强对流灾害天气进行研究。首先对地面站点获取的数据通过主成分分析方法进行降维,然后构建基于Focal Loss改进的GBDT模型,最后通过五折交叉验证的方式进行训练与测试。结果表明,该模型对强对流灾害天气预报的命中率、误警率和临界成功指数上都有较好的表现,可为天津强对流天气的预报提供有效的依据。 展开更多
关键词 强对流灾害 主成分分析 focal Loss GBDT模型 交叉验证
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基于Focal Loss的多特征融合地物小目标检测 被引量:6
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作者 宋建辉 饶威 +1 位作者 于洋 刘砚菊 《火力与指挥控制》 CSCD 北大核心 2021年第1期20-24,31,共6页
针对无人机影像中地物车辆目标占整体像素不超过0.4%的小目标检测效果差的问题,在融合FPN结构的Faster R-CNN(FFRCNN)网络基础上,提出一种改进算法——FM-FFRCNN。利用Resnet-50网络进行特征提取,并联多个卷积核进行卷积操作实现多特征... 针对无人机影像中地物车辆目标占整体像素不超过0.4%的小目标检测效果差的问题,在融合FPN结构的Faster R-CNN(FFRCNN)网络基础上,提出一种改进算法——FM-FFRCNN。利用Resnet-50网络进行特征提取,并联多个卷积核进行卷积操作实现多特征融合,达到扩大感受野的效果,并通过检测模块进行回归与分类。同时,为解决模型中正负样本不平衡问题,采用Focal Loss损失函数抑制背景样本对损失的贡献值。实验结果表明:FM-FFRCNN模型在平均精度(Average Precision,AP)上较原先模型提升了19.7%。 展开更多
关键词 小目标检测 多特征融合 focal LOSS 信息融合
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融合Focal Loss与典型卷积神经网络结构的水稻病害图像分类 被引量:7
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作者 杨非凡 徐伟诚 +1 位作者 陈盛德 兰玉彬 《江苏农业科学》 北大核心 2023年第14期198-204,共7页
快速高效地识别水稻病害的种类并及时采取有效的防治措施对避免水稻减产具有重要意义,为解决人工识别水稻病害效率低、识别精度不高、深度学习样本不平衡导致识别准确率不高等问题,融合Focal Loss与4种典型卷积神经网络结构对7种水稻病... 快速高效地识别水稻病害的种类并及时采取有效的防治措施对避免水稻减产具有重要意义,为解决人工识别水稻病害效率低、识别精度不高、深度学习样本不平衡导致识别准确率不高等问题,融合Focal Loss与4种典型卷积神经网络结构对7种水稻病害进行分类识别。利用TensorFlow的Keras深度学习框架搭建卷积神经网络的图像识别分类系统,使用Focal Loss损失函数解决数据集不平衡导致识别准确率低的问题,采用ResNet50、ResNet101、MobileNetV2、VGG16作为特征提取骨干,对7种水稻病害进行识别。通过imgaug库增强数据,将13543张水稻病害图像按照9∶1的比例划分为训练集和验证集并参与训练模型,将1404张水稻病害图像作为测试集来验证模型的准确性。结果表明,所搭建的数据集中ResNet50、ResNet101、MobileNetV2、VGG16的识别准确率分别为98.06%、94.26%、92.47%、97.83%。可见,在融合Focal Loss损失函数的情况下,ResNet50作为特征提取骨干训练出的模型在水稻病害图像分类中拥有最高的准确率,该成果可在实际生产中实现水稻病害的自动分类识别,有助于水稻病害的防治工作。 展开更多
关键词 水稻病害识别 卷积神经网络 focal Loss ResNet MobileNetV2 VGG16
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Design of ultra-low-power readout circuit for 1 024×1 024 UV AlGaN focal plane arrays 被引量:2
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作者 Xie Jing Li Xiaojuan +1 位作者 Zhang Yan Li Xiangyang 《红外与激光工程》 EI CSCD 北大核心 2020年第5期163-169,共7页
A novel ultra-low-power readout integrated circuit(ROIC) for 1 024×1 024 ultraviolet(UV) AlGaN focal plane arrays(FPA) with 18 μm-pitch was presented. In order to optimize power consumption for UVFPA readout cir... A novel ultra-low-power readout integrated circuit(ROIC) for 1 024×1 024 ultraviolet(UV) AlGaN focal plane arrays(FPA) with 18 μm-pitch was presented. In order to optimize power consumption for UVFPA readout circuit these methods were adopted, which including single-terminal amplifier under subthreshold region as CTIA amplifier, common current source load for source follow(SF) buffer in column pixels and level shift circuits, and time-sharing tail current source for column buffer. The smallest operational current of CTIA in pixel unit is only 8.5 nA with 3.3 V power supply by using single-terminal amplifier. The ROIC has been fabricated in SMIC 0.18 μm 1P6M mixed signal process and also achieved better performances with the novel design of bias current adjustable. Furthermore, the overall power consumption of the chip is 67.3 mW at 2 MHz in 8-outputs mode by the above methods according to the experimental results. 展开更多
关键词 readout integrated circuit(ROIC) ultraviolet focal plane arrays(UVFPA) ultra-low-power CTIA
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IMM-H004 therapy for permanent focal ischemic cerebral injury and cardiopulmonary complications via CKLF1/CCR4-mediated inflammation pathway
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作者 AI Qi-di CHEN Chen +7 位作者 CHU Shi-feng ZHANG Zhao LUO Yun GUAN Fei-fei ZHANG Shuai WANG Sha-sha YAN Xu CHEN Nai-hong 《中国药理学与毒理学杂志》 CAS CSCD 北大核心 2018年第9期675-676,共2页
OBJECTIVE To investigate the effects of IMM-H004 on permanent focal cerebral ischemia injury and associated cardiopulmonary complications,further elucidating the molecular mechanisms.METHODS The effects of IMM-H004 we... OBJECTIVE To investigate the effects of IMM-H004 on permanent focal cerebral ischemia injury and associated cardiopulmonary complications,further elucidating the molecular mechanisms.METHODS The effects of IMM-H004 were investigated in wild-type(WT) and CKLF1-/-rats.The effects of IMM-H004 on ischemic stroke injury and its cardiopulmonary complications were determined using 2,3,5-triphenyltetrazolium chloride(TTC) staining,behavior tests,magnetic resonance imaging(MRI)scans,enzyme-linked immunosorbent assay(ELISA),Nissl staining,and histo-pathological examination.Multiple molecular experiments including immunohistological staining,immunofluorescence staining,quantitative RT-PCR,Western blotting,and co-immunoprecipitation assays were used to elucidate the underlying mechanisms.RESULTS IMM-H004 treatment provided significant protection against ischemic stroke-induced brain injury and associated cardiopulmonary complications,through CKLF1-depedent-anti-inflammation pathway in rats.IMM-H004 downregulated the amount of CKLF1 and disturbed the combination between CKLF1 and C-C chemokine receptor type 4,suppressing the inflammatory response and protecting the damaged organs in ischemic setting.CONCLUSION This preclinical study established efficacy of IMM-H004 as a potential therapeutic medicine for ischemic stroke and associated cardiopulmonary complications.The protective effects of IMM-H004 may due to its specific mechanism through CKLF1.These results support further efforts to develop IMM-H004 for human clinical trials in acute cerebral ischemia,especially for patients who are not suitable for reperfusion therapy. 展开更多
关键词 IMM-H004 PERMANENT focal cere-bral ischemia injury COMPLICATION INFLAMMATION CKLF1/CCR4
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Effects of reduction of Sheng-Nao-Kang decoction in focal cerebral ischemia/reperfusion model rats
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《中国药理学通报》 CAS CSCD 北大核心 2015年第B11期151-151,共1页
Aim Reduction of Sheng-Nao-Kang decoction (RSNK), is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which is protective in rats against focal cerebral ischemia/reperfusion (I/R... Aim Reduction of Sheng-Nao-Kang decoction (RSNK), is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which is protective in rats against focal cerebral ischemia/reperfusion (I/R) injury. In the current study, we investigate the protective effect of RSNK against apoptosis and oxidative damage induced by cerebral I/R and explore the underlying mechanisms. Cerebral I/R injury was induced by in- traluminal middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion for 24 h in adult male Sprague- Dawley rats. Rats were randomized into seven groups (n- 8): Sham group, I/R group, RSNK-treated groups ( 0.7 g · kg ^- 1, 1 . 4 g · kg ^- 1 and 2. 8 g · kg^ - 1 ) , nimodipine (NMP) -treated group and Whitmania pigra Whitman (WW)-treated group. Neurological deficit scores, cerebral humidity content and cerebral infarction volume were measured after the 24 h reperfusion. Malondialdehyde ( MDA), superoxide dismutase ( SOD), catalase ( CAT), inducible nitric oxide synthase (iNOS) and total nitric oxide synthase (TNOS) in serum were measured by assay kits for biochemical analysis. Histological structures of the cortex of the ipsilateral ischemic cerebral hemisphere in rats were observed by Nissl staining. The caspase-3 protein content in the hippocampus and cortex was detected by immunohistochemistry. Additionally, Bax and Bcl-2 protein expressions in the injured brain were evaluated by Western blot. RSNK administration not only markedly improved neurological deficit scores, but also reduced cere- bral humidity content and cerebral infarction volume, lowered MDA content, up-regulated SOD and CAT levels, down-regulated iNOS and TNOS levels, restrained the expression of caspase-3 positive protein and alleviated the Bax and Bcl-2 protein expressions. 展开更多
关键词 reduction of Sheng-Nao-Kang DECOCTION (RSNK) middle CEREBRAL artery occlusion focal CEREBRAL is-chemia/reperfusion injury anti-apoptosis anti-oxidation protect effect.
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Normal mouse serum alleviates radiation pneumonitis in mice by inhibiting the focal adhesion signaling pathway
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作者 YUAN Tong GUO Yuying +1 位作者 ZHANG Junling FAN Saijun 《南方医科大学学报》 CAS CSCD 北大核心 2024年第5期801-809,共9页
Objective To evaluate the therapeutic effect of normal mouse serum on radiation pneumonitis in mice and explore the possible mechanism.Methods Mouse models of radiation pneumonitis induced by thoracic radiation exposu... Objective To evaluate the therapeutic effect of normal mouse serum on radiation pneumonitis in mice and explore the possible mechanism.Methods Mouse models of radiation pneumonitis induced by thoracic radiation exposure were given intravenous injections of 100μL normal mouse serum or normal saline immediately after the exposure followed by injections once every other day for a total of 8 injections.On the 15th day after irradiation,histopathological changes of the lungs of the mice were examined using HE staining,the levels of TNF-α,TGF-β,IL-1αand IL-6 in the lung tissue and serum were detected using ELISA,and the percentages of lymphocytes in the lung tissue were analyzed with flow cytometry.High-throughput sequencing of exosome miRNA was carried out to explore the changes in the signaling pathways.The mRNA expression levels of the immune-related genes were detected by qRT-PCR,and the protein expressions of talin-1,tensin2,FAK,vinculin,α-actinin and paxillin in the focal adhesion signaling pathway were detected with Western blotting.Results In the mouse models of radiation pneumonitis,injections of normal mouse serum significantly decreased the lung organ coefficient,lowered the levels of TNF-α,TGF-β,IL-1αand IL-6 in the serum and lung tissues,and ameliorated infiltration of CD45^(+),CD4^(+)and Treg lymphocytes in the lung tissue(all P<0.05).The expression levels of Egfr and Pik3cd genes at both the mRNA and protein levels and the protein expressions of talin-1,tensin2,FAK,vinculin,α‑actinin and paxillin were all significantly down‑regulated in the mouse models after normal mouse serum treatment.Conclusion Normal mouse serum ameliorates radiation pneumonitis in mice by inhibiting the expressions of key proteins in the Focal adhesion signaling pathway. 展开更多
关键词 normal mouse serum radiation pneumonitis EXOSOMES focal adhesion pathway
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A monolithic integrated medium wave Mercury Cadmium Telluride polarimetric focal plane array
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作者 CHEN Ze-Ji HUANG You-Wen +4 位作者 PU En-Xiang XIAO Hui-Shan XU Shi-Chun QIN Qiang KONG Jin-Cheng 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第4期479-489,共11页
A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure opt... A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure optimization and crosstalk suppression.A monolithic fabrication process with low damage was explored,which was verified to be compatible well with HgCdTe devices.After monolithic integration of MPA,NETD<9.5 mK was still maintained.Furthermore,to figure out the underlying mechanism that dominat⁃ed the extinction ratio(ER),specialized MPA layouts were designed,and the crosstalk was experimentally vali⁃dated as the major source that impacted ER.By expanding opaque regions at pixel edges to 4μm,crosstalk rates from adjacent pixels could be effectively reduced to approximately 2%,and promising ERs ranging from 17.32 to 27.41 were implemented. 展开更多
关键词 infrared physics infrared polarimetric focal plane array monolithic integration Mercury Cadmium Telluride extinction ratio
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Focal nodular hyperplasia with concomitant hepatocellular carcinoma: a case report and clonal analysis
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作者 ZhangSH CongWM WuMC 《第二军医大学学报》 CAS CSCD 北大核心 2005年第7期763-763,共1页
This report describes a hepatocellular carcinoma (HCC) with concomitant focal nodular hyperplasia (FNH) in a 56 years old Chinese man. There were two well circumscribed tumours measuring 3×2.5×2 cm and 2... This report describes a hepatocellular carcinoma (HCC) with concomitant focal nodular hyperplasia (FNH) in a 56 years old Chinese man. There were two well circumscribed tumours measuring 3×2.5×2 cm and 2×1.5×1.5 cm. The larger mass was grey and soft with a small area of bleeding and necrosis and an intact capsule. The smaller mass was yellow and had no capsule. Clonal analysis was carried out to clarify the relation between the HCC and the adjacent FNH. The clonal analysis was based on the methylation pattern of the polymorphic X chromosome linked androgen receptor gene (HUMARA). In FNH, after Hpa Ⅱ digestion, the allelic bands showed two well defined peaks. The intensity of the two peaks in the DNA from cirrhotic tissue did not differ significantly, consistent with a random pattern of X chromosome inactivation. However, in HCC, after Hpa Ⅱ digestion, the allelic bands differed significantly in intensity. Therefore, there was a typical polyclonal pattern of inactivation in FNH but the HCC was interpreted as being monoclonal. 展开更多
关键词 CASE focal nodular hyperplasia with concomitant hepatocellular carcinoma a case report and clonal analysis
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Focalizations and Their Functions in Heart of Darkness
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作者 Dong Xiaohua (Foreign Languages Department, Northwest Normal University, Lanzhou, 730070, China) 《兰州大学学报(社会科学版)》 CSSCI 北大核心 2000年第S1期109-113,共5页
As an important technique involved in the novel writing,the focalization is studied in detail in Narratology.The paper is an attempt to analyze the arrangement of focalizations and their functions in Heart of Dartness... As an important technique involved in the novel writing,the focalization is studied in detail in Narratology.The paper is an attempt to analyze the arrangement of focalizations and their functions in Heart of Dartness according to Narratology. 展开更多
关键词 focalizations narratology functions
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Focal mechanism study of north Potwar dformed zone, Pakistan 被引量:1
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作者 MonaLisa ShahidA.Khan +1 位作者 AzamA.Khwaja 许忠淮 《地震学报》 CSCD 北大核心 2004年第3期231-237,共7页
Northern Potwar Deformed Zone (NPDZ) is a part of the foreland zone of NW Himalayan folds and thrust belt. Seismicity map has been prepared for this region, which appears to be less active as compared with adjacent re... Northern Potwar Deformed Zone (NPDZ) is a part of the foreland zone of NW Himalayan folds and thrust belt. Seismicity map has been prepared for this region, which appears to be less active as compared with adjacent re-gions with apparently no distinct pattern or relationship with surface structures. Focal mechanism solutions of 4 events, for which required parameters are available, indicate left-lateral strike- slip faulting for 3 events and thrust-ing for one event. P-axes orientations are in NW-SE and NE-SW. Basement is most likely involved in the ongoing deformation. 展开更多
关键词 震源机制 地震活动性 巴基斯坦北部
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RIGHT FOCAL BOUNDARY VALUE PROBLEM WITH SINGULARITY
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作者 田玉 葛渭高 《数学物理学报(A辑)》 CSCD 北大核心 2006年第B12期1064-1076,共13页
This article proves existence results for singular problem ( - 1)n-px(n)(t) = f(t,x(t),…,x(n-1)(t)), for 0 < t < l,x(i)(0) = 0,i = 1,2.…,p - l,x(i)(1) = 0,i = p,p + 1,…, n - 1. Here the positive Carathedory f... This article proves existence results for singular problem ( - 1)n-px(n)(t) = f(t,x(t),…,x(n-1)(t)), for 0 < t < l,x(i)(0) = 0,i = 1,2.…,p - l,x(i)(1) = 0,i = p,p + 1,…, n - 1. Here the positive Carathedory function f may be singular at the zero value of all its phase variables. The interesting point is that the degrees of some variables in the nonlinear term f(t,x0,x1,…,xn-1) are allowable to be greater than 1. Proofs are based on the Leray-Schauder degree theory and Vitali's convergence theorem. The emphasis in this article is that f depends on all higher-order derivatives. Examples are given to illustrate the main results of this article. 展开更多
关键词 高阶微分方程 边值问题 集中收敛定理 规则化
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Effects of Electroacupuncture Combined with Repetitive Transcranial Magnetic Stimulation on the Expression of Nestin in Neural Stem Cell after Focal Cerebral Ischemia in Adult Rats
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作者 HUANG Guofu HUANG Xiaolin +1 位作者 CHEN Hong HAN Xiaohua 《中国康复医学杂志》 CAS CSCD 北大核心 2009年第5期390-393,共4页
Objective:To investigate the influence of electroacupuncture(EA) combined with repetitive transcranial magnetic stimulation(rTMS) on the temporal profile of nestin expression after induction of focal cerebral ischemia... Objective:To investigate the influence of electroacupuncture(EA) combined with repetitive transcranial magnetic stimulation(rTMS) on the temporal profile of nestin expression after induction of focal cerebral ischemia in adult rats and to explore the mechanism of EA combined with rTMS in treating ischemic brain injury.Method:The model of transient focal ischemia was produced by occlusion of middle cerebral artery.Seventy-five Wistar rats were randomly divided into normal group,model group,EA group,rTMS group and EA +rTMS group.The neurologic impairment rating and ability of learning and memory were observed at the 7th、14th and 28th d after infarction respectively.Meanwhile,Western blotting was used to observe the number of nestin expression positive cells.Result:Nestin-positive cells were found in cortex,subgranular zone(SGZ),subventricular zone(SVZ) of the ipsilateral side at different time points after cerebral ischemia.The number of nestin-positive cells peaked at the 7th d,began to decrease at the 14th d and was significantly higher in EA+rTMS group than that in model group(P< 0.05),then almost reached normal at the 28th d.The improvement of neural motor function deficits as well as the indexes of learning and memory were more obvious in EA+rTMS group compared with model group(P<0.01,P<0.05).These effects were most obvious in EA +rTMS group compared with the EA and rTMS group(P<0.05).Conclusion:EA and rTMS possess the potency of building up and can increase the number of nestin-positive cells in some brain regions after focal cerebral ischemia,which might be one of the important mechanisms of EA combined with rTMS in treating ischemia brain injury. 展开更多
关键词 神经系统 神经细胞 康复医学 研究 RTMS
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