全文获取类型
收费全文 | 2087篇 |
免费 | 106篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 94篇 |
妇产科学 | 24篇 |
基础医学 | 384篇 |
口腔科学 | 24篇 |
临床医学 | 152篇 |
内科学 | 227篇 |
皮肤病学 | 14篇 |
神经病学 | 257篇 |
特种医学 | 139篇 |
外科学 | 156篇 |
综合类 | 189篇 |
预防医学 | 182篇 |
眼科学 | 11篇 |
药学 | 198篇 |
中国医学 | 23篇 |
肿瘤学 | 158篇 |
出版年
2023年 | 25篇 |
2022年 | 72篇 |
2021年 | 67篇 |
2020年 | 71篇 |
2019年 | 71篇 |
2018年 | 70篇 |
2017年 | 60篇 |
2016年 | 73篇 |
2015年 | 72篇 |
2014年 | 165篇 |
2013年 | 152篇 |
2012年 | 103篇 |
2011年 | 127篇 |
2010年 | 74篇 |
2009年 | 100篇 |
2008年 | 111篇 |
2007年 | 100篇 |
2006年 | 75篇 |
2005年 | 68篇 |
2004年 | 54篇 |
2003年 | 40篇 |
2002年 | 34篇 |
2001年 | 36篇 |
2000年 | 29篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 23篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 21篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 21篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 18篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 13篇 |
1976年 | 19篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有2242条查询结果,搜索用时 15 毫秒
101.
Tatsuji Hasegawa Kei Yamada Takenori Tozawa Tomohiro Chiyonobu Sachiko Tokuda Akira Nishimura Hajime Hosoi Masafumi Morimoto 《Brain & development》2018,40(9):743-752
Purpose
Cerebellar injury is well established as an important finding in preterm infants with cerebral palsy (CP). In this study, we investigated associations between injury to the cerebellar peduncles and motor impairments in preterm infants using quantitative tractography at term-equivalent age, which represents an early phase before the onset of motor impairments.Methods
We studied 64 preterm infants who were born at <33?weeks gestational age. These infants were divided into three groups: CP, Non-CP (defined as infants with periventricular leukomalacia but having normal motor function), and a Normal group. Diffusion tensor imaging was performed at term-equivalent age and motor function was assessed no earlier than a corrected age of 2?years. Using tractography, we measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the superior cerebellar peduncles (SCP) and middle cerebellar peduncles (MCP), as well as the motor/sensory tracts.Results
The infants in the CP group had significantly lower FA of the SCP and sensory tract than those in the other groups. There was no significant difference in FA and ADC of the motor tract among the three groups. Severity of CP had a significant correlation with FA of the MCP, but not with the FA of other white matter tracts.Conclusion
Our results suggested that the infants with CP had injuries of the ascending tracts (e.g. the SCP and sensory tract), and that additional MCP injury might increase the severity of CP. Quantitative tractography assessment at term-equivalent age may be useful for screening preterm infants for prediction of future motor impairments. 相似文献102.
BackgroundCongenital cytomegalovirus (cCMV) infection is the most important etiology of non-hereditary childhood hearing loss and an important cause of neurodevelopmental delay. The current study aimed to investigate the early motor development of symptomatic and asymptomatic cCMV infected children with and without sensorineural hearing loss (SNHL).MethodsSixty-four children with a cCMV infection, without cerebral palsy, were compared to a control group of 107 normal hearing children. They were assessed around the ages of 6, 12, and 24 months with the Peabody Developmental Motor Scales-2 (PDMS-2), Alberta Infant Motor Scales (AIMS), and Ghent Developmental Balance Test (GDBT). The cCMV infected children were subdivided into a symptomatic (n = 26) and asymptomatic cCMV group (n = 38) but also into a cCMV group with SNHL (n = 19) and without SNHL (n = 45).ResultsSymptomatic cCMV infected children and cCMV infected children with SNHL performed significantly weaker for all gross motor outcome measures.ConclusionA congenital CMV infection is a risk factor for a delay in the early motor development. Follow-up will be necessary to gain insight into the exact cause of this motor delay and to define the predictive value of early motor assessment of cCMV infected children. 相似文献
103.
OBJECTIVE: To investigate the impact of EEG frequency band biofeedback (neurofeedback) training on spectral EEG topography, which is presumed to mediate cognitive-behavioural training effects. In order to assess the effect of commonly applied neurofeedback protocols on spectral EEG composition, two studies involving healthy participants were carried out. METHODS: In Experiment 1, subjects were trained on low beta (12-15 Hz), beta1 (15-18 Hz), and alpha/theta (8-11 Hz/5-8 Hz) protocols, with spectral resting EEG assessed before and after training. The specific associations between learning indices of each individual training protocol and changes in absolute and relative spectral EEG topography was assessed by means of partial correlation analyses. Results of Experiment 1 served to generate hypotheses for Experiment 2, where subjects were randomly allocated to independent groups of low beta, beta1, and alpha/theta training. Spectral resting EEG measures were contrasted prior and subsequent to training within each group. RESULTS: Only few associations between particular protocols and spectral EEG changes were found to be consistent across the two studies, and these did not correspond to expectations based on the operant contingencies trained. Low-beta training was found to be somewhat associated with reduced post-training low-beta activity, while more reliably, alpha/theta training was associated with reduced relative frontal beta band activity. CONCLUSIONS: The results document that neurofeedback training of frequency components does affect spectral EEG topography in healthy subjects, but that these effects do not necessarily correspond to either the frequencies or the scalp locations addressed by the training contingencies. The association between alpha/theta training and replicable reductions in frontal beta activity constitutes novel empirical neurophysiological evidence supporting inter alia the training's purported role in reducing agitation and anxiety. SIGNIFICANCE: These results underline the complexity of the neural dynamics involved EEG self-regulation and emphasize the need for empirical validation of predictable neurophysiological outcomes of training EEG biofeedback protocols. 相似文献
104.
Event-related potentials in the auditory oddball as a function of EEG alpha phase at stimulus onset.
Robert J Barry Jacqueline A Rushby Stuart J Johnstone Adam R Clarke Rodney J Croft Carlie A Lawrence 《Clinical neurophysiology》2004,115(11):2593-2601
OBJECTIVE: We aimed to examine the relation between the phase of electroencephalogram (EEG) alpha activity at stimulus onset and event-related potentials (ERPs) in a fixed-inter-stimulus interval auditory 'oddball' task, using a novel conceptualisation of orthogonal phase effects (cortical negativity versus positivity, negative driving versus positive driving, waxing versus waning). METHODS: EEG responses to button-press targets, from 14 subjects presented with 4 blocks of 150 stimuli (50% target probability), were examined. Pre-stimulus alpha activity (8-13 Hz) at Pz was assessed for each trial by digital filtering of the EEG. The alpha cycle at Pz, starting from a negative-going zero crossing, was used to sort trials into 4 phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz, and Pz. RESULTS: Preferred brain states in this paradigm were indicated by an 8% greater occurrence of negative driving than positive driving, and a 33% greater occurrence of waxing than waning phases. Negative driving phases were associated with increased N1 latencies and decreased N2 amplitudes. Latencies of N1 and P2 were reduced in waxing phases. These reflected systematic changes in alpha frequency and amplitude at stimulus onset. CONCLUSIONS: In a fixed-inter-stimulus interval paradigm, component frequencies of the EEG are dynamically adjusted in order to provide brain states at the moment of stimulus presentation which differentially affect the EEG correlates of stimulus processing. SIGNIFICANCE: The results add to our understanding of the genesis of the ERP, indicating the importance of the dynamic interplay between instantaneous EEG activity and stimulus processing reflected in the ERP. 相似文献
105.
106.
盐酸坦索罗辛治疗输尿管下段结石的临床疗效 总被引:2,自引:0,他引:2
目的评价α1受体阻滞剂盐酸坦索罗辛治疗输尿管下段结石的临床疗效。方法70例输尿管下段结石患者随机分为两组各35例,对照组口服非甾体类抗炎药塞来昔布胶囊(西乐葆)100mg2次/d;实验组口服西乐葆100mg2次/d及盐酸坦索罗辛0.4mg1次/d。随访4周评估两组间结石排出率、结石排出时间、肾绞痛发生次数及药物副作用。结果实验组和对照组结石完全排出率分别为85.7%(30/35)和57.1%(20/35),总有效病例实验组为32例,对照组为24例,两组比较差异有统计学意义(P〈0.05);实验组排石时间、肾绞痛发生次数明显少于对照组,差异具有统计学意义(P〈0.05);两组病例均未出现明显药物副作用。结论盐酸坦索罗辛有效促进输尿管下段结石的排出,并显著减少排石过程中肾绞痛的发生。 相似文献
107.
Glioblastoma (GBM) is a malignant cerebral neoplasm carrying poor prognosis. The importance of extent of resection (EoR) in GBM patient outcomes has been argued in the literature. Previous studies included tumors in eloquent regions of the brain. This confounds the role of EoR by including patients with intrinsically worse outcomes but will be over-represented in the reduced EoR category. In a homogenous group of patients in whom GTR was considered achievable, we investigated the effect of increasing EoR on survival. A retrospective review of 51 patients was undertaken. Quantitative, volumetric analysis of pre-operative and post-operative magnetic resonance image was compared with corresponding clinical details. The primary outcome measured was post-operative overall survival. Median overall survival was 18.3 months for GTR patients compared to 11.6 months for non-GTR (p = 0.025). Median pre-operative contrast-enhancing tumor volume for GTR patients was 54.7 cm3 and 24.9 cm3 for non-GTR. Post-operative median residual tumor volume was 1.1 cm3 in the non-GTR cohort. In multivariate analyses, GTR (HR [95% CI] = 0.973 [0.954–0.994], p = 0.00559) and increasing EoR (HR [95% CI] = 0.964 [0.944–0.985], p = 0.000665) remained predictors of survival. Centile dichotomization of EoR revealed 74% (HR [95% CI] = 0.351 [0.128–0.958], p = 0.0409) as the lowest threshold conferring statistically significant survival benefit. Where technically feasible, both GTR and EoR remained as independent prognostic factors for survival. GTR remains the gold standard for surgical treatment of GBM in patients, 74% being the minimum EoR required to confer survival benefit. 相似文献
108.
IntroductionThe reduction of background activity and the increase of low-frequency powers on electroencephalogram (EEG) correlate with cognitive impairment and have been suggested to be underpinned by cholinergic deficit. We aimed to investigate the ratio between α and θ band power (α/θ ratio), as a synoptic index of quantitative EEG (qEEG) slowing-down, in a peculiar group of patients with mild cognitive impairment (MCI) due to an early-stage Lewy body disease (MCI-LBD), as compared to de novo PD patients without cognitive impairment (PD-MOT), to patients with MCI due to Alzheimer's disease (MCI-AD), and to healthy controls (HC).MethodsTwelve patients with MCI-LBD (8 males; mean age 74.8 ± 3.6), 11 PD-MOT, 11 MCI-AD and 24 HC subjects undergoing qEEG were matched for gender, age, and education. Following logarithmic transformation, the α/θ ratio was compared among groups and brain regions by repeated measures ANOVA, also exploring group*regions interactions.ResultsA significant effect of group (p = 0.0003), regions (p = 0.0001), and group*regions interaction (p = 0.0001) on the α/θ ratio was observed. At post-hoc analysis, α/θ ratio was significantly lower in MCI-LBD (p = 0.001) and in PD-MOT (p = 0.02) compared to HC, and in MCI-LBD than MCI-AD (p = 0.05). No significant differences were found between MCI-AD and HC, as well as between MCI-LBD and PD-MOT.ConclusionThe α/θ power ratio as a synoptic index of EEG background slowing-down could be a simple and easy-to-use qEEG index which might indirectly mirror a cholinergic failure, useful to pick-up those MCI patients at higher risk of developing a Lewy-body disease. 相似文献
109.
《Clinical neurophysiology》2014,125(8):1689-1699
ObjectiveThis study explored event-related desynchronization (ERD) and synchronization (ERS) in amyotrophic lateral sclerosis (ALS) to quantify cortical sensorimotor processes during volitional movements. We furthermore compared ERD/ERS measures with clinical scores and movement-related cortical potential (MRCP) amplitudes.MethodsElectroencephalograms were recorded while 21 ALS patients and 19 controls performed two self-paced motor tasks: sniffing and right index finger flexion. Based on Wavelet analysis the alpha and beta frequency bands were selected for subsequent evaluation.ResultsPatients generated significantly smaller resting alpha spectral power density (SPD) and smaller beta ERD compared to controls. Additionally patients exhibited merely unilateral post-movement ERS (beta rebound) whereas this phenomenon was bilateral in controls. ERD/ERS amplitudes did not correlate with corresponding MRCPs for either patients or controls.ConclusionsThe smaller resting alpha SPD and beta ERD and asymmetrical appearance of beta ERS in patients compared to controls could be the result of pyramidal cell degeneration and/or corpus callosum involvement in ALS.SignificanceThese results support the notion of reduced movement preparation in ALS involving also areas outside the motor cortex. Furthermore post-movement cortical inhibition seems to be impaired in ALS. ERD/ERS and MRCP are found to be independent measures of cortical motor functions in ALS. 相似文献
110.
目的 探讨端粒酶逆转录酶(TERT)启动子突变、α-地中海贫血伴智力低下综合征基因(ATRX)表达水平在人脑胶质瘤病人预后评估中的价值.方法 回顾性分析2016年6月~2018年6月手术治疗的102例人脑胶质瘤的临床资料.术后检测脑胶质瘤组织TERT启动子突变及ATRX表达情况.所有病人术后随访2年.结果 102例中,... 相似文献