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1.
磁共振弥散张量成像动态观察脑梗死后继发锥体束损害   总被引:7,自引:4,他引:3  
目的动态观察脑梗死后,远离梗死灶的锥体束纤维继发性损害的过程,并探讨其对神经功能恢复的影响。方法选择具单侧大脑中动脉(middle cerebral artery,MCA)供血区、累及内囊的单一病灶的脑梗死患者18例,选择年龄性别相匹配的健康志愿者18人作对照组。分别在发病的第1周、4周和第12周进行磁共振弥散张量成像(diffusion tensor imanging,DTI)检测,并行美国国立卫生研究院卒中评分(National Institutes of Health Stroke Scale,NIHSS)、简式Fugl-Meyer运动功能评分(FM)和Barthel生活指数(Barthel index,BI)评定。结果患者远离梗死灶的脑干(大脑脚、脑桥和延髓等部位的均数)部分弥散各向异性(fractional anisotropy,FA)值在第1周、4周和第12周各时间点逐渐减少(P<0.01),而平均弥散量(mean diffusivity,MD)却无明显变化(P>0.05)。脑干FA值减少的百分数与NIHSS减少的百分数(r=-0.46,P<0.05)及FM增加的百分数(r=-0.61,P<0.05)相关,与BI变化的百分数无明显相关(P>0.05)。结论局灶性脑梗死后,锥体束纤维继发性损害会随时间延长而逐渐加重,并可能会阻碍患者神经功能的恢复。  相似文献
2.
Bilateral white matter diffusion changes persist after epilepsy surgery   总被引:5,自引:0,他引:5  
PURPOSE: Bilateral white matter diffusion tensor imaging (DTI) abnormalities have been reported in patients with temporal lobe epilepsy (TLE) and unilateral mesial temporal sclerosis (MTS), but it is unknown whether these are functional or structural changes. We performed a longitudinal study in patients with unilateral MTS who were seizure-free for 1 year after surgery to determine whether the observed presurgical white matter diffusion abnormalities were reversible. METHODS: Eight TLE patients with unilateral MTS who were seizure-free after anterior temporal resection and 22 healthy subjects were recruited. DTI was performed before surgery and at 1-year follow-up. Tractography and region-of-interest (ROI) analyses were performed in the fornix, cingulum, genu, and splenium of the corpus callosum and external capsules. Diffusion tensor parameters were compared between groups and before and after surgery in the patient group. RESULTS: The fornix, cingulum, and external capsules showed preoperative bilateral abnormal diffusion parameters (i.e., decreased diffusion anisotropy and increased mean and perpendicular diffusivities). The fornix and cingulum ipsilateral to the resected mesial temporal structures showed signs of wallerian degeneration at 1-year follow-up. The contralateral tracts of the fornix, cingulum, and external capsules, as well as the genu of the corpus callosum, failed to show a normalization of their diffusion parameters. CONCLUSIONS: The irreversibility of the white matter DTI abnormalities on seizure freedom suggests underlying structural abnormalities (e.g., axonal/myelin degradation) as opposed to functional changes (e.g., fluid shifts due to seizures) in the white matter.  相似文献
3.
Few themes have been more central to neurological models of aphasia than the disconnection paradigm and the role of the arcuate fasciculus. Introduced by luminaries of 19th Century neurology and resurrected by the charismatic work of Norman Geschwind, the disconnection theme has triggered spectacular advances of modern understanding of language and aphasia. But the disconnection paradigm had alternate fortunes, ranging from irrational exuberance to benign neglect, and its followers have not always shared the same view on its functional consequences and anatomical correlates. Our goal in this paper is, first, to survey the 19th Century roots of the connectionist approach to aphasia and, second, to describe emerging imaging technologies based on diffusion tensor imaging (DTI) that promise to consolidate and expand the disconnection approach to language and its disorders.  相似文献
4.
局灶性脑梗死继发逆行性神经纤维变性及其临床意义   总被引:4,自引:3,他引:1  
目的应用磁共振弥散张量成像(diffusion tensorimaging,DTI)技术前瞻性动态观察皮质下或脑干局灶性脑梗死后,病灶上方继发的神经纤维逆行性变性的过程,探讨其对神经功能恢复的影响。方法选择具有单侧内囊区或脑干的独立病灶的脑梗死患者16例,选择年龄及性别相匹配的健康志愿者16名作为对照组。患者分别在发病的第1周(W1)、第4周(W4)、第12周(W12)进行DTI检测和美国国立卫生研究院卒中评分(national institutes of health stroke scale,NIHSS)、简式Fugl-Meyer运动功能评分法(FM)和Barthel生活指数(Barthel Index,BI)评分。计算半卵园中心的DTI参数和各临床评分在观察期内变化的百分数绝对值,分析两者之间的相关关系。结果与对照组比较,病灶上方半卵园中心的部分弥散各向异性(fractional anisotropy,FA)值在各个时间点均明显减少(患者组W1:(0.43±0.02),W4:(0.39±0.01),W12:(0.33±0.02),分别与对照组比较:(0.46±0.01),P<0.01),而平均弥散量(mean diffusivity,MD)无统计学差异(P>0.05)。患者从W1至W12,半卵园中心FA值减少的百分数的绝对值与NIHSS评分减少百分数的绝对值之间(r=-0.49,P<0.05)及与FM增加百分数的绝对值之间(r=-0.56,P<0.05)呈负相关,与BI变化的百分数的绝对值之间无明显相关(P>0.05)。结论局灶性皮质下脑梗死可引起神经纤维逆行性的继发性变性,而且这种逆行性的神经纤维继发性变性会持续存在并可能阻碍患者神经功能的恢复。  相似文献
5.
6.
弥散张量成像(DTI)对肿瘤脑浸润的量化和应用   总被引:3,自引:2,他引:1  
目的研究磁共振弥散张量成像对颅内肿瘤脑浸润程度的量化和临床应用。方法颅内肿瘤40例,其中脑胶质瘤20例,脑膜瘤12例,脑转移瘤8例,均经病理证实;建立不同颅内肿瘤的脑浸润病理标准,并以此标准分入各亚组;利用MRI常规成像和弥散张量成像(Diffusion Tensor Imaging,DTI)比较,确定并测量5个兴趣区(肿瘤实体区、瘤周水肿区、水肿外区、相对正常白质区和对侧白质区)的分量各向异性值(fractional anisotropy,FA);比较分析不同肿瘤FA值的差异及其与肿瘤脑浸润程度的相关性。结果脑胶质瘤中有10例的DTI图像超出常规MRI范围,脑膜瘤和脑转移瘤中未见;FA值由瘤体区向外呈递增趋势,其中胶质瘤组内最大增幅出现在瘤周水肿区和水肿外区之间,而脑膜瘤和脑转移瘤亚组出现在肿瘤实体区和瘤周水肿区之间;胶质瘤瘤周水肿区FA值与肿瘤脑浸润程度显著相关;在脑胶质瘤中有脑浸润者的瘤周水肿区FA值显著低于无脑浸润胶质瘤和非胶质来源肿瘤。结论DTI可用于量化比较不同脑肿瘤的脑浸润程度,其瘤周水肿区的FA值可用于指导脑胶质瘤的手术切除范围,对延缓复发、改善预后有较大意义。  相似文献
7.
Gold BT  Powell DK  Xuan L  Jiang Y  Hardy PA 《Neuropsychologia》2007,45(11):2439-2446
Speed of visual word recognition is an important variable affecting linguistic competence. Although speed of visual word recognition varies widely between individuals, the neural basis of reaction time (RT) differences is poorly understood. Recently, a magnetic resonance technique called diffusion tensor imaging (DTI) has been shown to provide information about white matter (WM) microstructure in vivo. Here, we used DTI to explore whether visual word recognition RT correlates with regional fractional anisotropy (FA) values in the WM of healthy young adults. Participants completed a speeded lexical decision task that involved visual input, linguistic processes, and a motor response output. Results indicated that lexical decision RT was correlated negatively with FA in WM of inferior parietal and frontal language regions rather than in WM of visual or motor regions. Voxels within the inferior parietal and frontal correlation clusters were composed primarily of DTI-based tracts oriented in the anterior-posterior orientation at or near the superior longitudinal fasciculus (SLF) and likely including other smaller association fibers. These results provide new microstructural evidence demonstrating that speed of lexical decision is associated with the degree to which portions of frontal and parietal WM are directionally oriented.  相似文献
8.
目的:应用MR弥散张量成像(DTI)观察阿尔茨海默病(AD)患者脑白质纤维束完整性。方法:健康老年志愿者为对照组(NC)组、遗忘型轻度认知障碍(aMCI)组、AD组和皮质下缺血性血管性痴呆(SIVD)组各20例,行常规MRI和DTI扫描后,测定相同感兴趣区(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值进行比较。结果:与NC组比较, AD组前额叶、颞叶、海马等部位FA值降低,颞叶、海马等部位ADC值升高(P〈0.05);aMCI组仅扣带束FA值降低,与AD组比差异有统计学意义(P〈0.05);SIVD组下额枕束等部位FA值下降,ADC值升高,与AD组比较差异有统计学意义(P〈0.05)。结论:DTI可以用来评估白质纤维束完整性,AD组白质损害甚于aMCI患者;扣带束FA值可以作为aMCI患者筛查的指标;根据受累部位不同可对SIVD与AD进行鉴别。  相似文献
9.
胶质瘤脑浸润程度与病理级别的相关性研究   总被引:2,自引:0,他引:2  
目的运用病理和影像学的方法研究胶质瘤脑浸润程度与其病理级别的关系。方法选择需作内减压的脑胶质瘤患者30例,通过手术获取肿瘤区和瘤周水肿区组织标本;肿瘤区组织通过病理检查确定肿瘤分级,瘤周水肿区通过病理检查作肿瘤细胞计数和细胞密度分析,确定肿瘤脑浸润程度,将两者作相关分析;利用磁共振弥散张量成像(DTI)测量5个兴趣区(肿瘤实体区、瘤周水肿区、水肿外区、相对正常白质区和对侧白质区)的分量各向异性(FA)值,将瘤周水肿区的FA值与肿瘤的病理脑浸润程度和病理级别分别作相关分析。结果胶质瘤脑浸润程度和病理级别间无显著相关性;瘤周水肿区的FA值与胶质瘤病理脑浸润程度呈负相关性;瘤周水肿区的FA值与胶质瘤病理级别间无显著相关性。结论从病理和影像学分析的角度来看,传统脑胶质瘤病理分级与肿瘤脑浸润程度无显著相关性,高级别的胶质瘤并不一定具有更高的侵袭性。  相似文献
10.
Visualization of disconnection syndromes in humans   总被引:2,自引:2,他引:0  
Knowledge of the relationship between structure and function is essential to the exploration of the architecture of cognition. Cognitive processes require the coordinated activity of large-scale brain networks consisting of distant cortical regions, connected by long-range white matter tracts. Despite decades of connectional tracing studies in monkeys, the backwardness of human anatomy makes it difficult to draw conclusions from lesion studies and functional neuroimaging when brain connectivity is at issue. We propose an approach to clinico-anatomical correlation, based on a standardized atlas of white matter tracts derived from diffusion tensor imaging tractography. Using OVER-TRACK, a method based on tracking and overlapping white matter tracts, we mapped the course of three rostro-caudal association pathways in the Montreal Neurological Institute space. For each voxel we defined the probability of finding fibers belonging to individual tracts. This method is defined to localize in the white matter the overlapping lesion derived from a group of patients with brain damage. Our study provides a general approach for establishing anatomo-functional correlations by estimating the cortical areas connected in normal subjects, or disconnected by white matter lesions. This method will help researchers and clinicians to identify the neural bases of cognitive abilities and the behavioral consequences of brain lesions.  相似文献
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