期刊文献+
共找到31篇文章
< 1 2 >
每页显示 20 50 100
Effects of Ketamine on Basal Gamma Band Oscillation and Sensory Gating in Prefrontal Cortex of Awake Rats 被引量:1
1
作者 Renli Qi Jinghui Li +3 位作者 Xujun Wu Xin Geng Nanhui Chen Hualin Yu 《Neuroscience Bulletin》 SCIE CAS CSCD 2018年第3期457-464,共8页
Gamma band oscillation(GBO) and sensory gating(SG) are associated with many cognitive functions.Ketamine induces deficits of GBO and SG in the prefrontal cortex(PFC). However, the time-courses of the effects of ... Gamma band oscillation(GBO) and sensory gating(SG) are associated with many cognitive functions.Ketamine induces deficits of GBO and SG in the prefrontal cortex(PFC). However, the time-courses of the effects of different doses of ketamine on GBO power and SG are poorly understood. Studies have indicated that GBO power and SG have a common substrate for their generation and abnormalities. In this study, we found that(1) ketamine administration increased GBO power in the PFC in rats differently in the low-and high-dose groups;(2) auditory SG was significantly lower than baseline in the 30 mg/kg and 60 mg/kg groups, but not in the 15 mg/kg and 120 mg/kg groups; and(3) changes in SG and basal GBO power were significantly correlated in awake rats. These results indicate a relationship between mechanisms underlying auditory SG and GBO power. 展开更多
关键词 gamma band oscillation Sensory gating KETAMINE SCHIZOPHRENIA Parvalbumin-positive basket cell
原文传递
Morphological disruption and visual tuning alterations in the primary visual cortex in glaucoma(DBA/2J)mice 被引量:1
2
作者 Yin Yang Zhaoxi Yang +9 位作者 Maoxia Lv Ang Jia Junjun Li Baitao Liao Jing’an Chen Zhengzheng Wu Yi Shi Yang Xia Dezhong Yao Ke Chen 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第1期220-225,共6页
Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the pr... Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the primary visual cortex(V1)is altered in glaucoma.This study used DBA/2J mice as a model for spontaneous secondary glaucoma.The aim of the study was to compare the electrophysiological and histomorphological chara cteristics of neurons in the V1between 9-month-old DBA/2J mice and age-matched C57BL/6J mice.We conducted single-unit recordings in the V1 of light-anesthetized mice to measure the visually induced responses,including single-unit spiking and gamma band oscillations.The morphology of layerⅡ/Ⅲneurons was determined by neuronal nuclear antigen staining and Nissl staining of brain tissue sections.Eighty-seven neurons from eight DBA/2J mice and eighty-one neurons from eight C57BL/6J mice were examined.Compared with the C57BL/6J group,V1 neurons in the DBA/2J group exhibited weaker visual tuning and impaired spatial summation.Moreove r,fewer neuro ns were observed in the V1 of DBA/2J mice compared with C57BL/6J mice.These findings suggest that DBA/2J mice have fewer neurons in the VI compared with C57BL/6J mice,and that these neurons have impaired visual tuning.Our findings provide a better understanding of the pathological changes that occur in V1 neuron function and morphology in the DBA/2J mouse model.This study might offer some innovative perspectives regarding the treatment of glaucoma. 展开更多
关键词 DBA/2J DEGENERATION gamma band oscillations GLAUCOMA primary visual cortex(V1) RETINA single-unit recording tuning curve
下载PDF
Gamma神经振荡产生机制及其功能研究进展 被引量:12
3
作者 王静 李小俚 +1 位作者 邢国刚 万有 《生物化学与生物物理进展》 SCIE CAS CSCD 北大核心 2011年第8期688-693,共6页
Gamma神经振荡的频率在30~100 Hz之间,存在于动物和人类大脑的多个区域,如丘脑、体感皮层以及海马等部位,在各个尺度水平上都可被检测到.抑制性中间神经元组成的神经网络是产生此高频节律性活动的主要条件之一.皮层的gamma神经振荡与丘... Gamma神经振荡的频率在30~100 Hz之间,存在于动物和人类大脑的多个区域,如丘脑、体感皮层以及海马等部位,在各个尺度水平上都可被检测到.抑制性中间神经元组成的神经网络是产生此高频节律性活动的主要条件之一.皮层的gamma神经振荡与丘脑-皮层系统有关.Gamma神经振荡具有易化突触可塑性和调节神经网络的作用,主要参与感觉特征绑定、选择性注意以及记忆等高级功能. 展开更多
关键词 gamma神经振荡 抑制性中间神经元 特征绑定 记忆
下载PDF
精神分裂症中听觉M100的频率效应和瞬时gamma频带反应
4
作者 唐纳德 张艺卉(译) 《华南师范大学学报(社会科学版)》 CSSCI 北大核心 2019年第2期5-11,191,共8页
以往研究对精神分裂症患者基本听觉和生理上的缺陷进行了详尽的描述。在当前的实验中,我们研究了平均低频听觉诱发磁场(AEF) M100的听觉皮层调谐,以及它与精神分裂症患者瞬时听觉调谐频带反应的潜在关系。用脑磁图(MEG)记录20名精神分... 以往研究对精神分裂症患者基本听觉和生理上的缺陷进行了详尽的描述。在当前的实验中,我们研究了平均低频听觉诱发磁场(AEF) M100的听觉皮层调谐,以及它与精神分裂症患者瞬时听觉调谐频带反应的潜在关系。用脑磁图(MEG)记录20名精神分裂症患者(患者组)和20名健康被试(对照组)的听觉调谐,听觉调谐是通过检测1kHz中心频率邻近频率的影响得出的。在gamma频带范围内,利用平均诱发磁场和时频测量的方法来量化邻近频率的影响。被试还需要在单独的行为实验中进行频率的辨别。M100和gamma频带反应以1kHz为中心进行调谐,这些调谐曲线的形状在精神分裂患者组更宽。精神分裂患者组的M100振幅、瞬时gamma频带锁相因子(PLF)和诱发振幅源估计均显著降低,PLF与诱发gamma振幅和AEF振幅相关。行为实验中的频率辨别在精神分裂患者组明显较差,且与瞬时gamma频带的MEG测量相关。精神分裂症患者的瞬时gamma频带锁相降低与同一频带内诱发源测量强度降低以及由平均低频M100诱发反应的测量振幅高度相关。知觉障碍可能与听觉系统生理缺陷有部分关系。 展开更多
关键词 脑磁图 诱发电位 听觉皮层 N100 M100 gamma 频带 时频
下载PDF
Eye on the Sky: A UAP Research and Field Study off New York’s Long Island Coast
5
作者 John Joseph Tedesco Gerald Thomas Tedesco 《Open Journal of Applied Sciences》 2024年第8期2267-2295,共29页
A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a... A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a coastal location and to characterize their properties and behaviors. Primary and secondary field observation methods were utilized in this data-centric study. Forensic engineering principles and methodologies guided the study. The challenges set forward were object detection, observation, and characterization, where multispectral electro-optical devices and radar were employed due to limited visual acuity and intermittent presentation of the phenomena. The primary means of detection utilized a 3 cm X-band radar operating in two scan geometries, the X- and Y-axis. Multispectral electro-optical devices were utilized as a secondary means of detection and identification. Data was emphasized using HF and LF detectors and spectrum analyzers incorporating EM, ultrasonic, magnetic, and RF field transducers to record spectral data in these domains. Data collection concentrated on characterizing VIS, NIR, SWIR, LWIR, UVA, UVB, UVC, and the higher energy spectral range of ionizing radiation (alpha, beta, gamma, and X-ray) recorded by Geiger-Müller counters as well as special purpose semiconductor diode sensors. 展开更多
关键词 Unidentified Anomalous Phenomenon (UAP) Forensic Techno-Signatures Office of the Director of National Intelligence (ODNI) Multispectral Electro-Optical (MEO) Ultraviolet A Radiation (UVA) Ultraviolet B Radiation (UVB) Ultraviolet C Radiation (UVC) Visible (VIS) Near-Infrared (NIR) Short-Wave Infrared (SWIR) Long-Wave Infrared (LWIR) Low-Frequency (LF) High-Frequency (HF) Radio-Frequency (RF) Alpha Beta gamma Ultrasonic X-band Active Radar Kinematics Aerodynamics Luminous Spheroids Robert Moses State Park (RMSP)
下载PDF
Females with schizophrenia have abnormal functional cortical connectivity in the gamma frequency during an auditory oddball task using magnetoencephalography
6
作者 Toshiro Fujimoto Eiichi Okumura +8 位作者 Kouzou Takeuchi Atsushi Kodabashi Toshiaki Otsubo Katsumi Nakamura Masaki Sekine Shinichiro Kamiya Yuji Higashi Susumu Shimooki Toshiyo Tamura 《Open Journal of Psychiatry》 2014年第1期24-38,共15页
We studied differences in imaginary coherence (IC) of the gamma band between brain regions of female schizophrenia patients during the auditory oddball task using magnetoencephalography (MEG). Subjects were 12 right-h... We studied differences in imaginary coherence (IC) of the gamma band between brain regions of female schizophrenia patients during the auditory oddball task using magnetoencephalography (MEG). Subjects were 12 right-handed female schizophrenia patients, who were evaluated by the Positive and Negative Syndrome Scales (PANSS). Functional connectivity during an auditory oddball task was reconstructed in low gamma (30 - 50 Hz) and high gamma (50 - 100 Hz and 100 - 150 Hz) bands, and represented by IC using seeds determined by the significant oscillatory power changes obtained by event-related synchronization (ERS) and event-related desynchronization (ERD) power measurements. Gamma ERS (30 - 50 Hz) power was decreased in the left precuneus at 500 - 750 ms and in the right precuneus at 750 - 1000 ms. IC in the gamma band (50 - 100 Hz) was decreased between the right precuneus (seed) and right paracentral lobule (target) and between the right precuneus and right hypothalamus at 0 - 250 ms. IC in the gamma band (100 - 150 Hz) was increased between the left precuneus and right cuneus (Brodmann area 7) at 250 - 500 ms, between the left precuneus and right culmen at 500 - 750 ms, and between the left precuneus and right cuneus (Brodmann area 17), between the left precuneus and right posterior cingulate cortex, and between the left precuneus and right caudate nucleus at 750 - 1000 ms. In the high gamma band (50 - 100 Hz) at 0 - 250 ms, significant positive correlations were shown between IC and conceptual disorganization in PANSS scores, between IC and unusual thought content score, and between IC and positive scale score. IC within the high gamma band in female schizophrenia patients showed two types of functional disconnection, intrahemispheric and interhemispheric. IC between the right or left precuneus and other specific cortical areas showed dysfunction, suggesting that the parietal lobe plays an important role in dysfunction in connectivity in the gamma band during the oddball task. 展开更多
关键词 SCHIZOPHRENIA Female gamma band COHERENCE Functional Connectivity ODDBALL MAGNETOENCEPHALOGRAPHY
下载PDF
Gamma irradiation-induced effects on the properties of TiO_2 on fluorine-doped tin oxide prepared by atomic layer deposition
7
作者 Syed Mansoor Ali M.S.Algarawi +3 位作者 Turki S.ALKhuraiji S.S.Alghamdi Muhammad Hammad Aziz M.Isa 《Nuclear Science and Techniques》 SCIE CAS CSCD 2018年第7期191-197,共7页
The effect of gamma irradiation with different doses(25–75 kGy) on TiO_2 thin films deposited by atomic layer deposition has been studied and characterized by X-ray diffraction(XRD),photoluminescence measurements,ult... The effect of gamma irradiation with different doses(25–75 kGy) on TiO_2 thin films deposited by atomic layer deposition has been studied and characterized by X-ray diffraction(XRD),photoluminescence measurements,ultraviolet–visible(UV–Vis) spectroscopy,and impedance measurements.The XRD results for the TiO_2 films indicate an enhancement of crystallization after irradiation,which can be clearly observed from the increase in the peak intensities upon increasing the gamma irradiation doses.The UV–Vis spectra demonstrate a decrease in transmittance,and the band gap of the TiO_2 thin films decreases with an increase in the gamma irradiation doses.The Nyquist plots reveal that the overall charge-transfer resistance increases upon increasing the gamma irradiation doses.The equivalent circuit,series resistance,contact resistance,and interface capacitance are measured by simulation using Z-view software.The present work demonstrates that gamma irradiation-induced defects play a major role in the modification of thestructural,electrical,and optical properties of the TiO_2 thin films. 展开更多
关键词 TiO2 原子层 gamma 性质 氧化物 gamma NYQUIST 光致发光
下载PDF
Study the Effect of Gamma Radiation on the Optical Energy Gap of Poly(Vinyl Alcohol) Based Ferrotitanium Alloy Film: Its Possible Use in Radiation Dosimetry
8
作者 Sayeda Eid Seif Ebraheem Nehad M. Abdel-Kader 《Open Journal of Polymer Chemistry》 2014年第2期21-30,共10页
Ferrotitanium alloy polymer films, prepared by a simple technique of casting aqueous solutions of poly(vinyl alcohol) PVA containing ferrotitanium alloy on a horizontal glass plate, are useful as routine high-dose dos... Ferrotitanium alloy polymer films, prepared by a simple technique of casting aqueous solutions of poly(vinyl alcohol) PVA containing ferrotitanium alloy on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters have pale yellow color, are bleached when exposed to gamma rays. The chemical composition of alloy was determined by EDX, and structure of alloy was determined by XRD. The response of these dosimeters depends on the concentration of alloy. The energy band gap Eg was calculated and the effect of gamma radiation on its value was determined. The optical absorption spectra showed that the absorption mechanism is an indirect allowed transition which found that energy band gap Eg decreases after irradiation. The response of these films has negligible humidity effects on the range of relative humidity from 0 to 100%. And also, it exhibits good preand post-irradiation stability in dark and light. 展开更多
关键词 Polymer FERROTITANIUM Alloy gamma IRRADIATION Optical band GAP
下载PDF
认知过程中的捆绑问题——认知神经科学的研究 被引量:5
9
作者 陈彩琦 付桂芳 +1 位作者 金志成 李坚 《心理科学》 CSSCI CSCD 北大核心 2004年第3期590-594,共5页
捆绑问题是当前脑科学研究中的主要问题之一,近来已成为意识争论的焦点。该文结合国外对捆绑问题研究的最新成果,在概括介绍关于捆绑机制的主要理论的基础上,综述了捆绑问题与主要认知功能关系的研究,并指出不同认知过程中捆绑脑机制的... 捆绑问题是当前脑科学研究中的主要问题之一,近来已成为意识争论的焦点。该文结合国外对捆绑问题研究的最新成果,在概括介绍关于捆绑机制的主要理论的基础上,综述了捆绑问题与主要认知功能关系的研究,并指出不同认知过程中捆绑脑机制的精细化研究和一般性捆绑脑机制的系统化研究可能是今后这方面研究的重点。 展开更多
关键词 认知神经科学 脑科学 捆绑机制 神经同步激活理论 感知信息
下载PDF
肝癌特异性 GGT 的发生及其定量分析的临床价值 被引量:9
10
作者 姚登福 黄介飞 +2 位作者 陈澍周 黄中伟 孟宪镛 《胃肠病学和肝病学杂志》 CAS 1997年第1期78-81,共4页
目的探讨肝癌特异性GGT的动态变化及其定量分析的临床价值。方法以化学致癌剂2-FAA(005%)制备鼠肝癌模型,观察肝癌GGT的产生及其肝组织内分布,并对不同肝病患者血清肝癌特异性GGT区带(HSB)进行定量分析研... 目的探讨肝癌特异性GGT的动态变化及其定量分析的临床价值。方法以化学致癌剂2-FAA(005%)制备鼠肝癌模型,观察肝癌GGT的产生及其肝组织内分布,并对不同肝病患者血清肝癌特异性GGT区带(HSB)进行定量分析研究。结果在实验性鼠的诱癌过程中,鼠肝脏癌变组织中GGT大量表达,出现早并具有胎肝GGT的特点;人血清中HSB的定量检测发现:肝癌组明显高于其他肝病组,肝外肿瘤及正常对照组(P<0001);HSB在小肝癌中的阳性率为75%,在AFP阴性肝癌中为783%。结论研究资料提示HSB的定量检测其临床价值优于HSB的定性分析,且有助于小肝癌和AFP阴性肝癌的早期诊断。 展开更多
关键词 GGT 定量分析 肝肿瘤 谷氨酰移换酶
下载PDF
40 Hz Auditory Steady State Response to Linguistic Features of Stimuli during Auditory Hallucinations 被引量:1
11
作者 应俊 闫铮 高小榕 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2013年第5期748-753,共6页
The auditory steady state response (ASSR) may reflect activity from different regions of the brain, depending on the modulation frequency used. In general, responses induced by low rates (_〈40 Hz) emanate mostly ... The auditory steady state response (ASSR) may reflect activity from different regions of the brain, depending on the modulation frequency used. In general, responses induced by low rates (_〈40 Hz) emanate mostly from central structures of the brain, and responses from high rates (〉80 Hz) emanate mostly from the peripheral auditory nerve or brainstem structures. Besides, it was reported that the gamma band ASSR (30-90 Hz) played an important role in working memory, speech understanding and recognition. This paper investigated the 40 Hz ASSR evoked by modulated speech and reversed speech. The speech was Chinese phrase voice, and the noise-like reversed speech was obtained by temporally reversing the speech. Both auditory stimuli were modulated with a frequency of 40 Hz. Ten healthy subjects and 5 patients with hallucination symptom participated in the experiment. Results showed re- duction in left auditory cortex response when healthy subjects listened to the reversed speech compared with the speech. In contrast, when the patients who experienced auditory hallucinations listened to the reversed speech, the auditory cortex of left hemispheric responded more actively. The ASSR results were consistent with the behavior results of patients. Therefore, the gamma band ASSR is expected to be helpful for rapid and objective diagnosis of hallucination in clinic. 展开更多
关键词 auditory steady state response gamma band speech recognition auditory hallucination ELECTROENCEPHALOGRAPH
下载PDF
空间用特种光纤的辐射致衰减效应 被引量:13
12
作者 王学勤 张春熹 +2 位作者 金靖 宋凝芳 袁慧铮 《红外与激光工程》 EI CSCD 北大核心 2011年第12期2516-2520,共5页
为了评估掺铒光纤、保偏光纤、单模纯硅芯光纤和多模纯硅芯光纤等特种光纤在空间辐射环境下的适应性,采用60Coγ辐射源模拟空间电离辐射环境对4种光纤进行了辐射致衰减效应测试,得到了光纤辐射致衰减与辐射剂量间的关系曲线。引入能带... 为了评估掺铒光纤、保偏光纤、单模纯硅芯光纤和多模纯硅芯光纤等特种光纤在空间辐射环境下的适应性,采用60Coγ辐射源模拟空间电离辐射环境对4种光纤进行了辐射致衰减效应测试,得到了光纤辐射致衰减与辐射剂量间的关系曲线。引入能带理论分析光纤的辐射效应机理,结合速率方程理论推得了光纤的辐射致衰减与辐射剂量间的多成份饱和指数模型,并用该模型对实验数据进行了拟合。通过与传统的幂律模型进行比较,证明了该模型的有效性。通过多成分饱和指数模型参数隐含的物理意义对光纤的辐射致衰减效应机理进行了分析,评价了各种光纤在空间辐射环境下的适应性。 展开更多
关键词 特种光纤 Γ辐射 辐射致衰减 能带理论模型 多成分饱和指数模型
下载PDF
岩样自然γ能谱的测量与分析 被引量:2
13
作者 郭余峰 韩有信 《大庆石油学院学报》 CAS 北大核心 1989年第2期87-92,共6页
本文阐述了岩石自然γ能谱测量的物理基础,并且重点论述了γ能谱测量系统的调试以及自然γ能谱的分析方法,从而为自然γ能谱测井提供了必要的理论基础。
关键词 自然γ能谱 岩石 放射性核素 测井
下载PDF
Ti-48Al-2M^1-2M^2(M^1=Nb,V;M^2=Mn,Cr,V)合金电子结构
14
作者 黄尊行 郭鸿旭 +1 位作者 周立新 李俊■ 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2002年第3期331-335,共5页
用紧束缚能带计算方法(EHT)研究了标题多元合金的能带及电子结构。发现少量的多种元素在γ-TiAl中掺杂,对合金中电荷分布的影响,具有单种元素掺杂的叠加性;选择适当的合金元素就能达到多种掺杂的性能互补。多种元素掺杂能更有效地使成... 用紧束缚能带计算方法(EHT)研究了标题多元合金的能带及电子结构。发现少量的多种元素在γ-TiAl中掺杂,对合金中电荷分布的影响,具有单种元素掺杂的叠加性;选择适当的合金元素就能达到多种掺杂的性能互补。多种元素掺杂能更有效地使成键电子云趋势于球形化,Peierls力均称为化,有利于增加γ-TiAl合金的塑性和变形性。 展开更多
关键词 Γ-TIAL EHT 能带 电子结构 紧束缚能带计算方法 钛铝合金 掺杂 塑性
下载PDF
测量反应堆快中子注量率的电流型宽禁带半导体探测器设计 被引量:1
15
作者 苏春磊 欧阳晓平 +4 位作者 李达 刘洋 宋晓靓 余小任 欧阳潇 《原子能科学技术》 EI CAS CSCD 北大核心 2014年第12期2359-2363,共5页
为解决强流混合场快中子注量率实时测量的难题,本文基于反冲质子法,以耐辐照性能强、噪声低的半绝缘型(SI)GaN半导体材料为基础,采用带石墨平衡体及聚乙烯转换靶的并联结构,设计补偿式电流型探测器的方案,有效地降低了γ射线灵敏度。利... 为解决强流混合场快中子注量率实时测量的难题,本文基于反冲质子法,以耐辐照性能强、噪声低的半绝缘型(SI)GaN半导体材料为基础,采用带石墨平衡体及聚乙烯转换靶的并联结构,设计补偿式电流型探测器的方案,有效地降低了γ射线灵敏度。利用该探测器测量了西安脉冲堆1#径向孔道内混合场的快中子注量率,其结果与已有测量结果符合较好,验证了该方案的可行性。 展开更多
关键词 中子、γ混合场 反冲质子法 宽禁带半导体 快中子注量率 补偿电流并联结构
下载PDF
利用高频脑电的局灶性癫痫患者癫痫发作检测 被引量:1
16
作者 王栋 李扩 +2 位作者 刘晓芳 闫相国 王刚 《西安交通大学学报》 EI CAS CSCD 北大核心 2018年第2期148-154,共7页
针对现有的大多数癫痫发作自动检测方法都是在脑电的低频段进行而忽略高频成分这一现象,利用长时程头皮脑电的高频成分对局灶性癫痫患者进行癫痫发作检测。首先将19通道的脑电数据在一个滑动时间窗内利用小波分解提取出高频γ波段,再利... 针对现有的大多数癫痫发作自动检测方法都是在脑电的低频段进行而忽略高频成分这一现象,利用长时程头皮脑电的高频成分对局灶性癫痫患者进行癫痫发作检测。首先将19通道的脑电数据在一个滑动时间窗内利用小波分解提取出高频γ波段,再利用有向传递函数算法来提取信息流特征,求得流出信息强度特征用以降维,然后将此波段的特征通过支持向量机进行分类,通过五重交叉验证得到癫痫发作效果评价。结果表明:利用高频检测脑电癫痫发作的正确率为98.4%,平均选择性为60.7%,平均敏感性为93.4%,平均特异性为98.4%,平均检出率为95.9%;通过和使用其他子频带进行癫痫发作检测的结果对比发现,γ波段有着更高的分类效果;表明了对于局灶性癫痫患者,在癫痫发作时,其γ波段的流出信息强度显著性集中和增强在某些脑区。研究内容验证了癫痫发作与脑电中高频成分有关的观点。 展开更多
关键词 癫痫发作 有向传递函数 信息流差异 γ波段 支持向量机
下载PDF
基于微雨雷达的六盘山区地形云降水宏微观特征观测分析 被引量:12
17
作者 曹宁 张立新 +3 位作者 桑建人 姚展予 马宁 田磊 《气象科学》 北大核心 2019年第6期775-785,共11页
利用2017年6—11月宁夏六盘山区收集的微雨雷达和微波辐射计等探测资料,对比分析了六盘山区山脊和山谷对流云降水、层状云和浅积云降水过程中的云微物理特征及亮带,针对典型层状云降水事件山脊和山谷站的亮带及以下各层的雨滴谱分布特征... 利用2017年6—11月宁夏六盘山区收集的微雨雷达和微波辐射计等探测资料,对比分析了六盘山区山脊和山谷对流云降水、层状云和浅积云降水过程中的云微物理特征及亮带,针对典型层状云降水事件山脊和山谷站的亮带及以下各层的雨滴谱分布特征,探索了亮带以上几层水凝物的分类。结果发现:六盘山区三类降水云山脊的反射率及反射率衰减程度均高于山谷,表明地形强迫使得山脊降水云的物理和动力过程较山谷更剧烈,层状云降水过程中山脊0℃等温线以上的反射率明显高于山谷,表明山脊在0℃等温线以上有更多水凝物。分析一次典型层状云降水过程发现:六盘山区降水液滴自亮带下落的过程中,碰并过程占主导;亮带以下各层DSD符合Gamma分布,山脊站Gamma分布的相关性比山谷站强且拟合优度更优;降水开始的前3 min,推测-4~0℃等温线之间的水凝物主要是霰,此后水凝物主要是雪颗粒和霰,而山谷在降水开始的前5 min,-4~0℃等温线层之间的水凝物主要是雪颗粒和较大的霰,此后水凝物主要是霰。 展开更多
关键词 六盘山区 微雨雷达 亮带 DSD 伽马分布
下载PDF
孤独症谱系障碍儿童脑磁图静息态伽马频带脑功能网络探析 被引量:5
18
作者 王晨光 周正荣 +1 位作者 钟丽娟 林枫 《中国康复》 2021年第2期86-92,共7页
目的:研究孤独症谱系障碍(ASD)儿童静息态脑磁图伽马频带的脑功能网络特征。方法:ASD儿童6名,健康对照9名。采集静息态脑磁图信号和磁共振数据,在信号源水平进行伽马频带信号在大脑皮层的功率谱密度分析,并计算相位转移熵,构建脑网络,... 目的:研究孤独症谱系障碍(ASD)儿童静息态脑磁图伽马频带的脑功能网络特征。方法:ASD儿童6名,健康对照9名。采集静息态脑磁图信号和磁共振数据,在信号源水平进行伽马频带信号在大脑皮层的功率谱密度分析,并计算相位转移熵,构建脑网络,用于患儿组和对照组比较。结果:在脑网络节点激活程度方面,与对照组相比,患儿的伽马频带激活程度偏低(均P<0.05),受到显著抑制的脑区主要集中在双侧额叶、双侧颞叶和双侧岛叶,少量分布在右侧边缘叶及右侧顶叶。在脑网络节点间信息传递方面,信息汇集点存在组间差异(均P<0.05),患儿组为左侧角回中部,对照组为右侧枕中回腹部和左侧舌回后部。另外,信息发散点也有组间差异(均P<0.05),患儿组为右侧前眶额回和右侧岛盖部上部以及左侧梭状回前部,对照组则无显著的信息发放核心脑区。结论:ASD儿童大脑静息态伽马频带激活程度较低,提示患儿大脑存在兴奋-抑制失衡。ASD儿童伽马频带脑网络中,信息接收和发放的核心脑区分布模式与对照组存在差异,信息发放失衡。 展开更多
关键词 孤独症谱系障碍 静息态 伽马频带 脑磁图 脑网络
下载PDF
基于球不变过程的相关广义伽玛分布雷达杂波仿真 被引量:2
19
作者 谢灵巧 陈祝明 +1 位作者 江朝抒 周云 《信号处理》 CSCD 北大核心 2009年第2期199-203,共5页
本文推导了相关广义伽玛分布随机变量为球不变随机变量的条件;并在此基础上利用SIRP(球不变随机过程)法模拟仿真了相关广义伽玛分布序列;并给出了基于SIRP法的相关广义伽玛分布序列仿真的原理和方法流程图,利用此方法产生了三种常见分布... 本文推导了相关广义伽玛分布随机变量为球不变随机变量的条件;并在此基础上利用SIRP(球不变随机过程)法模拟仿真了相关广义伽玛分布序列;并给出了基于SIRP法的相关广义伽玛分布序列仿真的原理和方法流程图,利用此方法产生了三种常见分布(瑞利分布、韦布尔分布、伽玛分布)序列,证实了此方法的通用性。最后分析了实测宽带雷达树林杂波数据,证明了此方法的实用性。 展开更多
关键词 雷达杂波仿真 相关广义伽玛分布 SIRP ZMNL 宽带雷达
下载PDF
基于脑磁图的自闭症谱系障碍早期筛查和诊断指标 被引量:1
20
作者 谢点 孔令志 《中国听力语言康复科学杂志》 2021年第3期232-237,共6页
自闭症谱系障碍(autism spectrum disorder,ASD)是以社交障碍、重复刻板行为和狭隘的兴趣为主要特征的神经发育障碍性疾病,其患病率呈逐年上升趋势。大量关于ASD的研究仅凭行为特征进行诊断,而ASD的病因、临床症状及并发症等都具有高度... 自闭症谱系障碍(autism spectrum disorder,ASD)是以社交障碍、重复刻板行为和狭隘的兴趣为主要特征的神经发育障碍性疾病,其患病率呈逐年上升趋势。大量关于ASD的研究仅凭行为特征进行诊断,而ASD的病因、临床症状及并发症等都具有高度异质性,使得无法对ASD儿童进行早期的筛查和诊断,从而错过最佳治疗时机。基于生物学的标志物可以提供一种客观、容易量化的方式,不仅能够用于早期筛查诊断及预后,而且还可以用于药物开发和治疗疗效的反应指标。鉴于脑磁图(magnetoencephalography,MEG)相较于其他脑成像方法在ASD中的适用性及其优点,本文对ASD中MEG相关生物标志物的研究进行了综述,主要包括听觉诱发电位M50/M100、听觉失匹配磁场(magneticmis matchfiels,MMF)以及听觉gamma频段反应。 展开更多
关键词 孤独谱系障碍 脑磁图 M50/M100 失匹配磁场 gamma频段反应
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部