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MRI相位导航技术下2D T2-TSE与3D T2-SPACE序列在疑似隐匿性脊髓栓系综合征俯卧位扫描中的应用价值对比
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作者 李鹏 杨立棋 +5 位作者 徐守军 张艳慧 林飞飞 熊海芮 孙金磊 向葵 《磁共振成像》 北大核心 2025年第1期158-164,共7页
目的对比MRI相位导航技术下二维T2加权快速自旋回波(two dimensional T2 weighted imaging turbo spin echo,2D T2-TSE)序列与三维T2加权可变翻转角快速自旋回波(three dimensional T2 weighted imaging sampling perfection with appli... 目的对比MRI相位导航技术下二维T2加权快速自旋回波(two dimensional T2 weighted imaging turbo spin echo,2D T2-TSE)序列与三维T2加权可变翻转角快速自旋回波(three dimensional T2 weighted imaging sampling perfection with application optimized contrast using different flip angle evolution,3D T2-SPACE)序列在疑似隐匿性脊髓栓系综合征(occult tethered cord syndrome,OTCS)俯卧位扫描中的图像质量和临床应用价值。材料与方法回顾性分析2023年1月至2023年10月在我院接受MRI检查的疑似OTCS的6岁以下患者30例,均采用相位导航技术下俯卧位2D T2-TSE和3D T2-SPACE序列进行检查。根据所得图像整体质量、脊髓圆锥显示、马尾神经及终丝显示、蛛网膜下腔脑脊液信号显示、背景噪声显示情况进行主观评分,记录扫描时间,计算椎管内的图像信噪比(signal-to-noise ratio,SNR)和对比噪声比(contrast-to-noise ratio,CNR)。比较两种序列的图像质量的主观评分、扫描时间、椎管内SNR与CNR的客观分析。分别采用配对t检验、Mann-Whitney U检验,将两种检查方法的评估结果进行对比分析。通过Kappa检验分别评估两名医师主观评分的一致性,以及两名技师客观定量分析的一致性。结果图像质量的主观评分中,两名医师的评分一致性较强(Kappa=0.794,P<0.001),3D T2-SPACE序列图像整体质量、马尾神经及终丝显示、蛛网膜下腔脑脊液信号显示以及背景噪声显示评分均高于2D T2-TSE序列(Z=-2.305、-4.242、-3.453、-2.201,P均<0.05),在脊髓圆锥显示上,2D T2-TSE与3D T2-SPACE序列一致(Z=-0.948,P>0.05)。客观定量分析中,两名技师对椎管内SNR与CNR测量结果的一致性很强(Kappa=0.851、0.734,P均<0.001),2D T2-TSE对比3D T2-SPACE序列,两次测量的数据分析结果中3D T2-SPACE序列椎管内SNR和CNR均优于2D T2-TSE序列(第一次测量SNR与CNR:t=-3.058、-3.703;第二次测量SNR与CNR:t=-2.981、-2.965,P均<0.05)。3D T2-SPACE序列扫描时间较2D T2-TSE序列扫描时间长[(183.67±34.89)s vs.(120.53±27.93)s,t=-10.087,P<0.001]。结论在疑似OTCS患者的俯卧位MRI检查中,相位导航技术下的3D T2-SPACE序列相比2D T2-TSE序列可以提供更优良的椎管内图像质量、更小的FOV与体素,为临床诊治提供更多可靠信息。 展开更多
关键词 脊髓栓系综合征 隐匿性 三维T2加权可变翻转角快速自旋回波 俯卧位 相位导航技术 儿童 磁共振成像
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Analyzing Female-Oriented Games From the Perspective of Uses and Gratifications Theory--A Case Study of Love and Deep Space
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作者 Shuangkun Fu 《Journalism and Mass Communication》 2025年第2期84-88,共5页
With the expansion of the female player base and the increase in their purchasing power,the female-oriented game market has gradually risen.This paper employs the Uses and Gratifications Theory as a framework,using th... With the expansion of the female player base and the increase in their purchasing power,the female-oriented game market has gradually risen.This paper employs the Uses and Gratifications Theory as a framework,using the successful case of Love and Deep Space to explore how female players satisfy their specific social and psychological needs through gaming.The study finds that female-oriented games effectively meet the diverse needs of female players in terms of content design,interactive experiences,and community building,further promoting the prosperity and development of the female-oriented game market. 展开更多
关键词 Uses and Gratifications Theory female-oriented games Love and Deep space
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Investigation and Evaluation on Suitability of Afforestation Space in Henan Province: A Case Study of Nanyang City, Henan, China
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作者 WAN Meng 《Journal of Landscape Research》 2025年第3期23-26,共4页
Analysis on the investigation and evaluation data of afforestation space suitability in Nanyang City reveals that there are a total of 47,394 issued land parcels,covering an area of 102,400 hm^(2).Among these,20,834 p... Analysis on the investigation and evaluation data of afforestation space suitability in Nanyang City reveals that there are a total of 47,394 issued land parcels,covering an area of 102,400 hm^(2).Among these,20,834 parcels are suitable for afforestation with an area of 35,300 hm^(2),while 7,220 parcels are planned for afforestation but not yet implemented,covering an area of 19,900 hm^(2).Additionally,there are 26,560 parcels classified as unsuitable for afforestation with an area of 67,100 hm^(2).There are also 13,614 parcels,with an area of 15,400 hm^(2),that meet the criteria for afforestation space but have not been included in the planning.In view of discrepancies in land type classification or being outside the original evaluation scope in the investigation of afforestation space suitability evaluation,corresponding recommendations have been proposed to provide valuable references for scientifically formulating territorial greening plans and reasonably reserving afforestation space. 展开更多
关键词 Afforestation space Investigation and evaluation indicators Indicators of land use assessment scope Henan Province
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RESEARCH ACTIVITIES ON LAND USE/COVER CHANGE IN THE PAST TEN YEARS IN CHINA USING SPACE TECHNOLOGY 被引量:10
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作者 庄大方 刘纪远 刘明亮 《Chinese Geographical Science》 SCIE CSCD 1999年第4期43-47,共5页
Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapi... Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapid economic development in the last years. All of the above changes will affect sustainable development in the next century. The Chinese Academy of Sciences is conducting a study of land use/cover change over the last ten years based on the integration of remote sensing and GIS technology to establish a multitemporal database covering all of China. Fundamental data for land use/cover for the year 1996 has already been developed by the Chinese Academy of Sciences. In order to reconstruct fundamental land use/cover data for the year 1986, a central data processing and analyzing system and a regional data acquisition, processing and analyzing system have been established and are joined together as a network. After the 1986 database is established, the comparative research on the reduction in arable land, urbanization, desertification, changes in forest and grassland, and lake and wetland land use/cover change will be carried out. In addition, a transect for a key regional comparative study was selected along the Changjiang (Yangtze) River. The driving forces of these changes also will be extracted. The result of this study will be not only make a contribution to global land use/cover change research, but will also support decision making for sustainable national development. 展开更多
关键词 LAND use and LAND COVER change reconstruction space technology
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Investigation and Analysis of Urban Spatial Structure around the Train Stations in Kitakyushu by Using Space Syntax and GIS 被引量:3
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作者 Jianan Liu Danhua Wu +1 位作者 Fukahori Hidetosi Weijun Gao 《Open Journal of Civil Engineering》 2015年第1期97-108,共12页
Although many methods of spatial analysis have been developed for a better understanding and modelling of urban space analysis, there is still a need for exploration of new analytical techniques for modelling urban sp... Although many methods of spatial analysis have been developed for a better understanding and modelling of urban space analysis, there is still a need for exploration of new analytical techniques for modelling urban spaces. Space Syntax models the spatial configurations of urban spaces by using a connectivity graph representation. Such a configuration of space identifies patterns that can be used to study urban structures and human behaviors. This paper tries to present a new methodology to investigate the urban spatial structure by using Space Syntax with the GIS information including land use, buildings’ characteristics and practical evaluations of the potential of the Space Syntax approach with GIS and multivariate analysis technique. Finally we try to offer some recommendations that attempt to improve the identified problems faced in Kitakyushu, Japan. 展开更多
关键词 SPATIAL Structure space SYNTAX LAND Use GIS
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MR Visualization of Spinal Dural Arterio-Venous Fistula Using T2-Weighted 3D SPACE—A Spin-Echo Technique 被引量:1
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作者 Franz A. Fellner Christine M. Fellner +1 位作者 Rene Chapot Kaveh Akbari 《Journal of Biomedical Science and Engineering》 2015年第5期327-332,共6页
Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spin... Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spine, including contrast-enhanced MR angiography was done on a 1.5 T MR scanner. In addition a special (pre-contrast) 3D turbo-spin-echo sequence with variable flip angle evolution (SPACE) was performed providing a slice thickness of 0.9 mm. T2-weighted images showed extensive widened and tortuous vascular structures with typical flow voids intradurally due to dilated pial veins. The origin of the spinal dural arteriovenous fistula was found to be the radiculomeningeal artery at level D10/11 on the left side, visualized by the T2-weighted 3D SPACE sequence and CE MRA. After imaging the patient was referred to an interventional neuroradiology department for therapy. With the detailed information from MR imaging concerning the fistula level the interventional radiologist was able to find the fistula immediately and consequently treated it successfully by endovascular therapy. Interpreting the MR images of this obvious case of a SDAVF, SPACE sequence after post processing with 3D MPR software directly led to the location of the AV shunt at D10/11 on the left side, better than 3D contrast-enhanced MR angiography did. Therefore, SPACE can be a useful adjunct in further evaluation of spinal dural arteriovenous fistula and especially in defining fistula level. 展开更多
关键词 Contrast Enhanced Magnetic Resonance ANGIOGRAPHY (CE MRA) 3D Pulse Sequences 3D space SPINAL DURAL Arterio-Venous FISTULA (SDAVF)
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Space-to-Ground Quantum Key Distribution Using a Small-Sized Payload on Tiangong-2 Space Lab 被引量:1
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作者 Sheng-Kai Liao Jin Lin +33 位作者 Ji-Gang Ren Wei-Yue Liu Jia Qiang Juan Yin Yang Li Qi Shen Liang Zhang Xue-Feng Liang Hai-Lin Yong Feng-Zhi Li Ya-Yun Yin Yuan Cao Wen-Qi Cai Wen-Zhuo Zhang Jian-Jun Jia Jin-Cai Wu Xiao-Wen Chen Shan-Cong Zhang Xiao-Jun Jiang Jian-Feng Wang Yong-Mei Huang Qiang Wang Lu Ma Li Li Ge-Sheng Pan Qiang Zhang Yu-Ao Chen Chao-Yang Lu Nai-Le Liu Xiongfeng Ma Rong Shu Cheng-Zhi Peng Jian-Yu Wang Jian-Wei Pan 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第9期18-23,共6页
Quantum technology establishes a foundation for secure communication via quantum key distribution (QKD). In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. I... Quantum technology establishes a foundation for secure communication via quantum key distribution (QKD). In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum+weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads. 展开更多
关键词 QKD space-to-Ground Quantum Key Distribution using a Small-Sized Payload on Tiangong-2 space Lab
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Space moving target detection using time domain feature
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作者 王敏 陈金勇 +1 位作者 高峰 赵金宇 《Optoelectronics Letters》 EI 2018年第1期67-70,共4页
The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space ... The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects(target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10^(-5), which outperforms those of compared algorithms. 展开更多
关键词 AS space moving target detection using time domain feature
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Impact of Rapid Urbanization and Changing Housing Patterns on Urban Open Public Spaces of Amman, Jordan: A GIS and RS Perspective
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作者 Yahya Farhan Sireen Al-Shawamreh 《Journal of Environmental Protection》 2019年第1期57-79,共23页
Rapid urbanization and population growth of the Amman Area were combined with land resource degradation when the city was heading for mounting urbanization from the early 1950s. The deterioration of natural resources ... Rapid urbanization and population growth of the Amman Area were combined with land resource degradation when the city was heading for mounting urbanization from the early 1950s. The deterioration of natural resources and green areas, was coupled with the creation of different urban public open spaces in the city. The transformation from large single-family houses to dense residential apartments was associated with social and behavioral changes among the inhabitants living in the dense apartments. Consequently, a large private sector has been developed to provide public and social spaces. Photo-interpretation and satellite images were used to map and characterize land use/cover changes have been occurred in the Amman area between 1953 and 2017. Maximum Likelihood Classification method was employed to identify land use/cover changes between 1986 and 20017, and GIS was utilized also to map examples of the recently emerged socio-economic open spaces. Excessive urban development in the last two decades, and the adoption of neo-liberal privatization policies by the government, enhanced social stratification and residential segregation. So, instead of encouraging outdoor activity and social interaction among all groups of Amman residents, the freedom of accessibility to major open spaces has been restricted within the same urban fabric, thus, the “two Ammans” paradigm, a “tale of two cities”, has been recently acknowledged. 展开更多
关键词 URBAN Public space PRIVATE space Landsat Images Air PHOTOS Land Use/Cover Amman
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Construction of PBIB Desings by Using Subspace of Vector Space over Finite Fields
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作者 Wei Wandi (Dept. of Math. Sichuan University, Chengdu 610014)Yang Benfu ( Dept.of Math. Chengdu Teachers College, Pengzhou 611930) 《西华大学学报(哲学社会科学版)》 1998年第3期1-4,共4页
A new transitivity theorem of the general linear group GLn(Fq)is proved. A kind of new PBIB desings is constructed.
关键词 OVER Construction of PBIB Desings by using Subspace of Vector space over Finite Fields
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Ecological function transitions of land use in the Beibu Gulf Economic Zone from the perspective of production-living-ecological space
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作者 ZHOU Guipeng LONG Hualou +1 位作者 JIANG Yanfeng TU Shuangshuang 《Journal of Geographical Sciences》 SCIE CSCD 2024年第11期2212-2238,共27页
The ecological function of land use is the basis for developing an ecological civilization and realizing sustainable development.This paper may help guide the coordination of economic development and ecological develo... The ecological function of land use is the basis for developing an ecological civilization and realizing sustainable development.This paper may help guide the coordination of economic development and ecological development in China’s coastal border areas.Based on theoretical analysis,this paper studies the spatiotemporal evolution of the functional spaces and the ecological function transitions of land use in the Beibu Gulf Economic Zone(BGEZ)by analyzing patterns,processes,and factors by applying eco-environmental quality index,grid subdivision,kriging interpolation,barycenter model,and Geodetector.This paper constructs a theoretical framework of ecological function transitions of land use based on the research idea of“system-pattern-process-factor”,and carries out empirical research.Some conclusions can be drawn as follows:(1)The ecological space in the BGEZ has continuously decreased,converting mainly into agricultural production space and industrial-mining production space.The production space has expanded slowly.The area of living space in the BGEZ has increased rapidly.(2)The ecological function of land use in the BGEZ has continued to weaken,especially in the southern part of the BGEZ.The“high-sub-high”quality zones of ecological function are retreating to the north.(3)There were more deterioration transition areas than optimization transition areas of ecological function in the BGEZ.The former were mostly located in the central and southern urbanized areas of the BGEZ,whereas the latter were mostly located in the edge zones of district and county units.(4)As for the driving factors of the deterioration transitions of land use ecological function in the BGEZ,the significant trend of“de-ecologization”of the land cover/land use structure was the dominant driving factor;the interactions among the“natural-socioeconomic-managerial”systems were the main recessive factor.The natural system played a fundamental role,and the driving force of natural factors was the strongest.The industrialization,urbanization,and GDP increment in the socioeconomic system and the policy positioning of development intensity in the managerial system played a significant role.The interactions among natural factors,road construction,and industrial non-agricultural transformation had a“fuze”effect on stimulating driving forces. 展开更多
关键词 land use transitions ecological function eco-environmental quality production-living-ecological spaces dominant and recessive factors Beibu Gulf
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“时空同态”与“时空分立”——与刘正光教授面对面
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作者 王义娜 刘正光 《英语研究》 2025年第1期1-13,共13页
时空性与句法语义关系是当今学术界关心的核心话题。刘正光教授从汉英时空概念化方式出发,追问“现实—认知—语言”三者之间的关系,提出汉语“时空同态”而英语“时空分立”的观点,受到学界高度关注并荣获第四届许国璋外国语言研究奖(... 时空性与句法语义关系是当今学术界关心的核心话题。刘正光教授从汉英时空概念化方式出发,追问“现实—认知—语言”三者之间的关系,提出汉语“时空同态”而英语“时空分立”的观点,受到学界高度关注并荣获第四届许国璋外国语言研究奖(外国语言研究最高奖)。笔者就时空同态观的理论建构、与当今其他时空观的异同,以及如何开展认知对比研究三个话题与刘教授深度访谈,希冀刘教授对“时空同态”与“时空分立”的答疑解惑可为青年学者开展语言研究提供更广阔的理论视野。 展开更多
关键词 时空同态与时空分立 时空定位 名动包含 时空性差异 认知对比研究
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结合双重对比嵌入学习的生成式零样本图像识别
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作者 张桂梅 闫文尚 黄军阳 《中国图象图形学报》 北大核心 2025年第5期1389-1403,共15页
目的零样本学习(zero-shot learning,ZSL)是解决样本数据缺失情况下目标识别的有效方法。传统的零样本识别是通过对带标签的可见类数据训练,实现对无标签的未见类新数据的识别。根据任务设置的不同,分为传统零样本学习(conventional zer... 目的零样本学习(zero-shot learning,ZSL)是解决样本数据缺失情况下目标识别的有效方法。传统的零样本识别是通过对带标签的可见类数据训练,实现对无标签的未见类新数据的识别。根据任务设置的不同,分为传统零样本学习(conventional zero-shot learning,CZSL)和广义零样本学习(generalized zero-shot learning,GZSL)。生成式零样本识别方法由于可以生成未见类的视觉特征,从而将零样本学习问题转换为常规监督学习问题。但是生成式零样本识别存在特征判别性信息不足、伪视觉特征与语义信息不一致以及域偏移等问题。针对上述问题,提出结合双重对比嵌入学习的生成式零样本图像识别方法。方法首先,针对生成的特征判别性不足问题,基于VAE-GAN(variational autoencoder-generative adversarial network)生成框架,集成对比嵌入模块,多个网络协同训练,提高零样本图像识别精度;其次,以条件VAE-GAN为生成网络,提出双重对比学习策略。一方面,在现有可见类对比学习的基础上,引入未见类伪样本实例—原型域内对比学习,使生成的伪视觉特征与语义信息对齐,缓解可见类和未见类的语义混淆;另一方面,提出跨域中心—原型对比学习,缓解模型过于偏向于可见类,一定程度上减轻域偏移。结果在AWA1(animals with attributes1)、AWA2、CUB(Caltech-UCSD birds-200-2011)和SUN(SUNattribute)数据集上进行零样本和广义零样本识别实验,并与最新相关方法进行比较。在零样本识别任务中,提出的方法在AWA1和CUB数据集取得最优值,相比性能次优的模型,T1值分别提高2.2%和2.7%;在AWA2和SUN数据集均取得次优值。在广义零样本识别中,在AWA1、AWA2和CUB数据集H值均取得最优,相比次优值分别提升0.6%、0.8%和2.8%;在SUN数据集取得次优值。消融实验验证了提出算法的有效性。结论实验结果表明,提出的方法可提高零样本和广义零样本图像识别的精度,并具有较好的泛化性能。 展开更多
关键词 零样本学习(ZSL) 广义零样本学习(GZSL) 生成对抗网络(GAN) 嵌入空间 对比学习
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虚实时空的反衬化效应——夏目漱石文学中近代“多余人”的梦境叙事
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作者 陈雪 《牡丹江师范学院学报(社会科学版)》 2025年第2期46-53,共8页
夏目漱石在小说《三四郎》《从此以后》中通过梦境叙事表现近代“多余人”沉浸于非现实精神世界的状态,梦境的“自我”可谓是其心理现实的映照。梦境叙事中通过心理时空的构筑,展现人物对于绝对境界的向往。两部小说通过梦与现实的交错... 夏目漱石在小说《三四郎》《从此以后》中通过梦境叙事表现近代“多余人”沉浸于非现实精神世界的状态,梦境的“自我”可谓是其心理现实的映照。梦境叙事中通过心理时空的构筑,展现人物对于绝对境界的向往。两部小说通过梦与现实的交错叙事,生成虚实时空之间的反衬化效应。由于作品蕴含虚实时空的矛盾冲突,从而完整地展示出近代“多余人”的内涵,即面对现实时难以将理想付诸于行动的“妥协性”气质,且对应于“近代性”的文化语境,对时代性主题构建具有重要的叙事效果。 展开更多
关键词 梦境叙事 “多余人” 夏目漱石 虚实时空 反衬化效应
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高架桥下体育空间环境满意度的影响不对称分析——以合肥市为例
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作者 刘阳 丁文艳 邹友菡 《住区》 2025年第4期32-39,共8页
随着城市建设步入存量发展时期,高架桥构建起城市交通的重要脉络,其桥下空间的资源配置问题愈发受到各界关注。当前国内对高架桥下空间使用者满意度形成机制的研究尚不充分,本文以合肥市三所高架桥下体育空间为例,应用影响不对称分析方... 随着城市建设步入存量发展时期,高架桥构建起城市交通的重要脉络,其桥下空间的资源配置问题愈发受到各界关注。当前国内对高架桥下空间使用者满意度形成机制的研究尚不充分,本文以合肥市三所高架桥下体育空间为例,应用影响不对称分析方法,结合机器学习梯度提升决策树算法,识别高架桥下体育空间环境满意度关键影响因子。研究表明:合肥市高架桥下体育空间环境各属性满意度与总体环境满意度之间呈现非线性不对称关系;周边绿化景观、夜间可见度、照明设施、防护设施位于所有高架桥下体育空间的最优先提升等级,本文研究结果为相关部门制定高架桥下体育空间设计策略,规划空间环境提升的时序提供重要参考依据。 展开更多
关键词 高架桥下体育空间 环境满意度 影响不对称分析 存量发展 存量更新 奖惩对比分析模型 合肥市
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对比增强3D STIR SPACE序列对子宫内膜异位症患者骶丛神经异常的显示 被引量:7
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作者 毛丽娟 何绍富 +4 位作者 王朝阳 李美芝 胡仰玲 王梦意 张小玲 《中山大学学报(医学科学版)》 CAS CSCD 北大核心 2021年第1期66-72,共7页
【目的】探讨增强3D STIR SPACE序列对盆腔子宫内膜异位症患者骶丛神经异常的显示价值,并与增强3D VIBE序列进行对比。【方法】病例组包括30名子宫内膜异位症患者,对照组包括20名健康女性,均接受盆腔MRI检查,包括对比增强3D STIR SPACE... 【目的】探讨增强3D STIR SPACE序列对盆腔子宫内膜异位症患者骶丛神经异常的显示价值,并与增强3D VIBE序列进行对比。【方法】病例组包括30名子宫内膜异位症患者,对照组包括20名健康女性,均接受盆腔MRI检查,包括对比增强3D STIR SPACE序列和增强3D VIBE序列。评估骶丛神经显示的图像质量以及子宫内膜异位症患者中的骶丛神经侵犯。【结果】对照组和病例组中,3D STIR SPACE序列和3D VIBE序列均能很好地显示骶丛神经纤维(P<0.001)。阅片者应用3D-STIR-SPACE序列对病变的诊断信心分数一致性较强(Kappa=0.684,P<0.001),应用3D-VIBE序列的诊断信心分数一致性一般(Kappa=0.130,P=0.386)。【结论】对比增强T2-SPACE序列和3D VIBE序列能够清晰显示骶丛神经,前者对盆腔子宫内膜异位症患者骶丛神经异常的显示更有优势。 展开更多
关键词 对比增强 3D STIR space序列 子宫内膜异位症 骶丛神经
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基于关键语义驱动和对比学习的文本聚类方法
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作者 张士举 郭朝阳 +2 位作者 吴承亮 吴凌俊 杨丰玉 《计算机科学》 北大核心 2025年第8期171-179,共9页
文本聚类是指将大量文本数据按照它们的相似性进行分组的过程,其可以帮助理解文本数据的结构和内容,发现其中的模式和趋势,通常用于信息检索、文档管理等。现有文本聚类模型在信息抽取过程中存在过度依赖原始数据质量和容易造成关键信... 文本聚类是指将大量文本数据按照它们的相似性进行分组的过程,其可以帮助理解文本数据的结构和内容,发现其中的模式和趋势,通常用于信息检索、文档管理等。现有文本聚类模型在信息抽取过程中存在过度依赖原始数据质量和容易造成关键信息提取不充分的问题,而且不同类别的数据在表示空间中会相互重叠。针对以上问题,提出了一种基于关键语义驱动和对比学习的文本聚类方法(KSD-CLTC)。该方法在数据处理环节通过数据增强模块丰富原始数据来提高泛化性,并设计了一个关键语义驱动模块提取文本中的关键词,补足关键语义信息的丢失;在特征提取环节借助预训练模型和自动编码器对数据进行高质量表征;然后,在聚类学习环节借助聚类模块将聚类损失与关键语义驱动模块的重构损失相结合,进一步学习更适用于聚类的特征表示,并利用对比学习模块来实现更好的类别划分效果。实验结果表明,KSD-CLTC在公共数据集和工业数据集上的聚类效果优于对比的聚类算法,相比先进的SCCL方法,其在所有数据集上的ACC平均提高了2.92%,NMI平均提高了1.99%。聚类结果也证明了关键语义驱动模块对文本聚类的重要性。 展开更多
关键词 信息抽取 表示空间 文本聚类 关键语义驱动 对比学习
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高分辨率与低分辨率3D-SPACE序列在磁共振胰岛管水成像中的应用对比 被引量:5
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作者 肖建明 彭涛 +1 位作者 王宗勇 王娜 《中国医疗设备》 2017年第3期77-79,102,共4页
目的对比高分辨率与低分辨率三维快速自转回波成像技术(3D-Sampling Perfection with Application-Optimized Contrasts by using Different Flip Angle Evolutions,3D-SPACE)序列在磁共振胰胆管水成像(Magnetic Resonance Cholangiopan... 目的对比高分辨率与低分辨率三维快速自转回波成像技术(3D-Sampling Perfection with Application-Optimized Contrasts by using Different Flip Angle Evolutions,3D-SPACE)序列在磁共振胰胆管水成像(Magnetic Resonance Cholangiopancreatography,MRCP)中的应用效果。方法使用Siemens Avanto 1.5T磁共振扫描仪对44名受检者行胰胆管水成像,同时采用3D-SPACE的高分辨率与低分辨率序列扫描,两名高年资医师对成像效果进行评价和评分,评分的结果采用秩和校验进行统计学分析。结果高分辨率3D-SPACE原始图像对微小病变显示更清晰;低分辨率3D-SPACE成像时间更快;最大密度投影(Maximum Intensity Projection,MIP)重建图像质量无统计学差异(胆总管显示评分差异:P=0.899,左、右肝内胆管、主胰管显示评分差异:P=0.623)。结论对于配合程度较差的受检者应用低分辨率3D-SPACE更易获得较理想图像。 展开更多
关键词 磁共振胰胆管水成像 可变翻转角快速自旋回波 最大密度投影 分辨率 3Dspace
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肝脏实性占位性病变超声造影声像学特征及其诊断价值分析
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作者 李晶晶 范智慧 +3 位作者 梅冬雪 张丽 郝玉静 张冬艳 《实用肝脏病杂志》 2025年第2期274-277,共4页
目的分析肝脏实性占位性病变超声造影声像学特征及其诊断价值。方法2021年3月~2024年3月我院收治的肝脏实性占位性病变患者118例,行常规超声和超声造影(CEUS)检查。所有患者接受外科手术切除肝脏实性占位性病变,以术后组织病理学检查结... 目的分析肝脏实性占位性病变超声造影声像学特征及其诊断价值。方法2021年3月~2024年3月我院收治的肝脏实性占位性病变患者118例,行常规超声和超声造影(CEUS)检查。所有患者接受外科手术切除肝脏实性占位性病变,以术后组织病理学检查结果为金标准,应用Kappa分析超声造影定性评估肝脏实性占位性病变良恶性与金标准诊断的一致性,构建受试者工作特征(ROC)曲线分析诊断效能。结果在118例肝脏实性占位性病变患者中,术后组织病理学诊断为恶性病变72例,良性病变46例;良性病变造影剂到达时间为(2.5±0.6)s,显著短于恶性病变【(3.6±0.8)s,P<0.05】,达峰时间为(9.5±1.6)s,显著长于恶性病变【(7.3±1.2)s,P<0.05】,峰值强度为(9.4±2.1)dB,显著大于恶性病变【(5.8±0.9)dB,P<0.05】,拟合曲线尖度为(0.4±0.1)l/s,显著小于恶性病变【(1.2±0.3)l/s,P<0.05】;CEUS定性评估与金标准诊断的Kappa值为0.754(P<0.05),一致性较好;CEUS诊断的敏感度、特异度、准确率、阳性预测值和阴性预测值分别为87.5%、89.1%、88.1%、92.7%和82.0%,提示超声造影定性评估的效能较高(P<0.05)。结论超声造影定性评估肝脏实性占位性病变性质具有较高的临床应用价值。 展开更多
关键词 肝脏实性占位性病变 超声造影 声像学特征 诊断
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