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1.
OBJECTIVES: To develop age-adjusted norms for white matter lesions (WML) and to differentiate dementia from mild cognitive impairment and normal aging. MATERIALS AND METHODS: 240 patients underwent a comprehensive clinical, neuropsychological and MRI examination. A scale was developed quantify WML in anatomically defined regions by rating size and frequency. FLAIR sequences were used to determine a global and a frontal score. The scores were correlated with the psychometric test results and the final clinical diagnosis: cognitively normal (CN), mild cognitive impairment (MCI), Alzheimer's Disease (AD), vascular dementia (VD). Age-adjusted curves for WML scores were calculated by means of a non-parametic smoothing method. RESULTS: WML scores of the whole cerebrum and the frontal lobe were significantly increased in vascular dementia as compared to CN, MCI and AD. Individual WML scores correlated significantly with age and neuropsychological test results. For the age range 55-72, the WML scores of VD were significantly different from those of CN, MCI and AD. CONCLUSIONS: Age-corrected WML load was significantly higher in vascular dementia as compared to MCI, AD and cognitively normals over a wide age range.  相似文献   
2.
Objectives –  The aim of the study was to visualize cortical function in Parkinson's patients with various degrees of cognitive impairment.
Materials and methods –  Thirty-seven patients with Parkinson's disease and three with Parkinson plus syndromes underwent cognitive assessment and rCBF using 99mTC-HMPAO-SPECT.
Results –  Almost no regional reductions in cerebral blood flow were seen in patients without cognitive impairment ( n  = 16). Limited, mainly posterior, blood flow reductions were seen in patients with mild cognitive impairment ( n  = 14), whereas the reductions were extensive and bilaterally symmetric, involving both anterior and posterior brain regions in patients with dementia ( n  = 10).
Conclusions –  The findings suggest a widespread cortical, mainly posterior type of dysfunction and a relationship between the degree of cognitive impairment and the magnitude of the dysfunction.  相似文献   
3.
A temporal lobe factor in verb fluency   总被引:1,自引:0,他引:1  
Verb fluency requires self-sustained verb retrieval. The brain correlates of this task are virtually unknown. We investigated the relations between verb and noun (semantic) fluency and regional brain perfusion in subjects with varying degrees of cognitive decline, ranging from very mild subjective impairment to Alzheimer's disease (AD). Data consisted of single-photon emission computed tomography (SPECT) data and temporally resolved verb and noun fluency scores from 93 participants. Impaired verb fluency was predicted by a temporal lobe hypoperfusion factor and low education, whereas high age and low perfusion in the parietotemporal-occipital region predicted impaired noun fluency. Analysis of perfusion within the temporal region indicated primary involvement of the temporal pole and medial temporal lobe in AD. This might reflect pathology of the anterior parahippocampal region, which appears early in neurodegenerative disease. Although temporal lobe structures have not usually been implicated in verb processing, early temporal pathology thus appears to contribute to impaired verb fluency in cognitive decline.  相似文献   
4.
Cognitive phenotypes in Alzheimer's disease and genetic risk   总被引:2,自引:0,他引:2  
Variation in the clinical characteristics of patients with Alzheimer's disease (AD) is increasingly recognised, although the factors underlying variation are not fully understood. The study examined the cognitive characteristics of 523 AD patients at the time of their presentation to a neurological dementia clinic and explored the relationship to family history and apolipoprotein E (APOE) genotype. Distinct profiles were identified, which were mirrored by topographical differences on neuroimaging. Clinical distinctions were maintained over time. Two-thirds of patients showed a constellation of deficits at presentation which included memory, language, visuospatial and constructional difficulties. However, a quarter had circumscribed presentations of amnesia, aphasia, perceptuospatial disorder or apraxia. The rare presence of frontal lobe characteristics was associated with a younger age of onset, an increased incidence of myoclonus at presentation, a positive family history but not with possession of APOE epsilon4 allele. An amnestic presentation (severe, yet circumscribed amnesia) was strongly associated with an older age of onset, a positive family history and the presence of APOE epsilon4 allele. Posterior cortical presentations showed a female bias, were typically sporadic, and showed no association with APOE epsilon4. The findings support the notion of phenotypic variation in AD, and show that genetic risk factors can influence clinical presentation. The findings draw attention to the specific association between APOE epsilon4 allele and memory but challenge the commonly held notion that the presence of the epsilon4 allele inevitably reduces onset age. The findings indicate that risk factors other than APOE epsilon4 allele underlie the non-familial, early onset posterior hemisphere presentations of AD.  相似文献   
5.
Two decades of research examining repetition priming in aging and Alzheimer's disease (AD) has yielded a large body of contradictory findings due to differences between studies in participant and task characteristics. Recent research that has employed methodological advances indicates that this form of implicit memory is preserved in healthy aging. When a priming deficit does occur in studies of aging, it is likely a very early signal of neurological disease. Future directions for research in this area include linking priming ability to known risk factors for development of AD, integrating priming measures into clinical neuropsychological assessment batteries, and implementing programs of cognitive retraining that enhance memory using stimulus repetition techniques.  相似文献   
6.
BACKGROUND: Hippocampal atrophy is an early feature of Alzheimer's disease (AD) but it has also been reported in vascular dementia (VaD). It is uncertain whether hippocampal size can help differentiate the two disorders. METHODS: We assessed 90 stroke/TIA patients 3-6 months after the event, and 75 control subjects, with neuropsychological tests, medical and psychiatric examination and brain MRI scans. A diagnosis of VaD, vascular mild cognitive impairment (VaMCI) or no cognitive impairment (NCI) was reached by consensus on agreed criteria. T1-weighted MRI was used to obtain total intracranial volume (TICV), gray and white matter volume, CSF volume, hippocampus and amygdala volumes, and T2-weighted scans for white matter hyperintensity (WMH) ratings. RESULTS: Stroke/TIA patients had more white matter hyperintensities (WMHs), larger ventricle-to-brain ratios and smaller amygdalae than controls, but hippocampus size and gray and white matter volumes were not different. WMHs and amygdala but not hippocampal volume distinguished stroke/TIA patients with VaD and VaMCI and without NCI and amygdala volumes. Right hippocampus volume significantly correlated with new visual learning. CONCLUSIONS: Stroke/TIA patients and patients with post-stroke VaMCI or mild VaD do not have hippocampal atrophy. The amygdala is smaller in stroke/TIA patients, especially in those with cognitive impairment, and this may be accounted for by white matter lesions. The hippocampus volume relates to episodic memory, especially right hippocampus and new visual learning. A longitudinal study of these subjects will determine whether hippocampal atrophy is a late development in VaD.  相似文献   
7.
BACKGROUND AND PURPOSE: The cognitive decline in Alzheimer's disease (AD) patients has been reported to involve alterations in the medial temporal lobe and the posterior cingulate gyrus. On the other hand, the neurochemical pathologies of the behavioral and psychological symptoms of dementia (BPSD) have not been sufficiently discussed. The aim of this study was to clarify the pathologies of BPSD in AD patients. METHODS: Thirty patients with probable AD were included and underwent the following assessments: Mini Mental State Examination (MMSE), Clock Drawing Test (CDT), Story Recall Test (SRT), Behavioral pathology in Alzheimer's disease (BEHAVE-AD) and proton MRS ((1)H-MRS). None of them had been medicated for BPSD. RESULTS: The MRS study revealed that MMSE, CDT, and SRT scores were positively related to N-acetyl-aspartate (NAA)/creatine(Cr) and negatively related to myoinositol (mI)/Cr in the posterior cingulate gyrus, but not in the anterior cingulate gyrus. On the other hand, the scores obtained in two categories of BEHAVE-AD (delusional thought/ activity disturbances) were negatively related with NAA/Cr and positively related with mI/Cr in the anterior cingulate gyrus, but not in the posterior cingulate gyrus. CONCLUSION: We conclude that BPSD and the decline in cognitive function in AD might have separate pathologies.  相似文献   
8.
BACKGROUND AND PURPOSE: Empirical studies to clarify the outcomes in Vascular Cognitive Impairment (VCI) are needed. We compared cognitive, functional, and behavioural outcomes in patients with VCI to patients with no cognitive impairment (NCI), and Alzheimer's disease (AD). METHODS: Secondary analysis of the Consortium to Investigate Vascular Impairment of Cognition (CIVIC), a multi-centre Canadian memory clinic 30-month cohort study. RESULTS: Of 1347 patients, 938 were eligible for follow-up, of whom 239 (24.5%) were lost and 29 (3%) had died. Of the remaining 697 patients, 125 had NCI, 229 had VCI, and 343 had AD at baseline. Compared to people with NCI, of whom 20-40% showed progression based on cognitive and functional measures, those with VCI were more likely to progress (50-65%), as were people with AD (50-80%) (p<0.01). More people with VCI showed progression of affective symptoms (30%) than those with NCI (12%) or AD (15% p<0.01). Progression of impaired judgment (rated clinically) in VCI (15%) was similar to AD (11%) but more common than in NCI (4%, p<0.01). CONCLUSIONS: Most people with VCI show readily detectable progression by 30 months. Depressive symptoms were more common and more progressive in VCI than in Alzheimer's disease, whereas clinical evidence of progressive executive dysfunction was common in both AD and VCI.  相似文献   
9.
Intra-individual variability in reaction time increases with age and with neurological disorders, but the neural correlates of this increased variability remain uncertain. We hypothesized that both faster mean reaction time (RT) and less intra-individual RT variability would be associated with larger corpus callosum (CC) size in older adults, and that these associations would be stronger in adults with mild cognitive disorders. A normative sample (n=432) and a sample with mild cognitive disorders (n=57) were compared on CC area, RT mean and RT variability adjusting for age, sex, education, APOE genotype, smoking, alcohol consumption, grip strength, visual acuity, handedness and lung function. Samples did not differ in CC area or intra-cranial volume. In the normative sample, simple RT (SRT) and choice RT (CRT) were negatively associated with CC area but there were minimal associations between CC area and intra-individual RT variability. In the mild cognitive disorders sample, SRT, CRT and intra-individual variability on the SRT task were associated with CC area. Increased RT variability explained up to 12.7 percent of the variance in CC area in the sample with mild cognitive disorders, but less than 1 percent of the variance in CC area in the normative sample. There were no associations with APOE genotype. We conclude that intra-individual variability is associated with CC area in mild cognitive disorders, but not in normal aging. We propose that biological limits on reserve capacity must occur in mild cognitive disorders that result in stronger brain-behavior relationships being observed.  相似文献   
10.
Evidence suggests that dopaminergic mechanisms in the basal ganglia (BG) are important in the learning of sequential associations. To test the specificity of this hypothesis, we assessed never-medicated patients with Parkinson's disease (PD) and amnestic mild cognitive impairment (aMCI) using a chaining task. In the training phase of the chaining task, each link in a sequence of stimuli leading to reward is trained step-by-step using feedback after each decision, until the complete sequence is learned. In the probe phase of the chaining task, the context of stimulus-response associations must be used (the position of the associations in the sequence). Results revealed that patients with PD showed impaired learning during the training phase of the chaining task, but their performance was spared in the probe phase. In contrast, patients with aMCI with prominent medial temporal lobe (MTL) dysfunctions showed intact learning during the training phase of the chaining task, but their performance was impaired in the probe phase of the chaining task. These results indicate that when dopaminergic mechanisms in the BG are dysfunctional, series of stimulus-response associations are less efficiently acquired, but their sequential manner is maintained. In contrast, MTL dysfunctions may result in a non-sequential learning of associations, which may indicate a loss of contextual information.  相似文献   
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