首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   215076篇
  免费   17731篇
  国内免费   6863篇
耳鼻咽喉   1250篇
儿科学   7630篇
妇产科学   1542篇
基础医学   18969篇
口腔科学   3599篇
临床医学   22861篇
内科学   54495篇
皮肤病学   2721篇
神经病学   25707篇
特种医学   6223篇
外国民族医学   4篇
外科学   16468篇
综合类   29885篇
现状与发展   32篇
一般理论   9篇
预防医学   17074篇
眼科学   2332篇
药学   15025篇
  184篇
中国医学   9916篇
肿瘤学   3744篇
  2024年   223篇
  2023年   4345篇
  2022年   5834篇
  2021年   10869篇
  2020年   10965篇
  2019年   8332篇
  2018年   8250篇
  2017年   8196篇
  2016年   8516篇
  2015年   8224篇
  2014年   15582篇
  2013年   17067篇
  2012年   12757篇
  2011年   13792篇
  2010年   10850篇
  2009年   10441篇
  2008年   10448篇
  2007年   10104篇
  2006年   9006篇
  2005年   7426篇
  2004年   6319篇
  2003年   5425篇
  2002年   4573篇
  2001年   3950篇
  2000年   3270篇
  1999年   2719篇
  1998年   2442篇
  1997年   2093篇
  1996年   1862篇
  1995年   1926篇
  1994年   1778篇
  1993年   1513篇
  1992年   1453篇
  1991年   1280篇
  1990年   1011篇
  1989年   859篇
  1988年   807篇
  1987年   734篇
  1986年   633篇
  1985年   737篇
  1984年   617篇
  1983年   379篇
  1982年   446篇
  1981年   377篇
  1980年   283篇
  1979年   247篇
  1978年   185篇
  1977年   164篇
  1976年   136篇
  1975年   49篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
目前在中医界已发布的冠心病痰湿证辨证标准是以主症、次症形式定性地给出,存在主观性较强的问题。本文引入约束隐结构分析,该方法将主症、次症的语义作为约束条件加入隐结构分析过程,得到含有主症、次症语义约束的定量化中医证候辨证规则。使用该方法对冠心病痰湿证患者556条无标签数据的分析,得到其约束隐结构模型,最后建立定量化痰湿证辨证规则,舌胖边有齿痕(3.16)、苔腻(3.12)、苔白滑(4.72)、胸闷(1.73)、脉濡或滑(6.04);次症:肢体困重(0.48)、口黏(0.63)、体胖(0.49)、大便粘滞(1.38)、脘腹痞满(0.97)、面色晦浊(0.79)、嗜睡(1.18)、纳差(1.07)。与经典隐结构模型得到规则和中医界已发布的定性化辨证规则相比,约束隐结构得到的规则客观性强,具有可重复性。在证候类大小、规则的量化合理度上较好地反映了主症、次症的特点,得到的规则切合中医实际,为冠心病痰湿证辨证标准的定量化研究提供帮助和参考。  相似文献   
102.
103.
《Clinical neurophysiology》2021,132(2):315-322
ObjectivePrevious studies have demonstrated voluntary movement alterations as well as motor cortex excitability and plasticity changes in patients with mild cognitive impairment (MCI). To investigate the pathophysiology of movement abnormalities in MCI, we tested possible relationships between movement abnormalities and primary motor cortex alterations in patients.MethodsFourteen amnestic MCI (aMCI) patients and 16 healthy controls were studied. Cognitive assessment was performed using clinical scales. Finger tapping was recorded by a motion analysis system. Transcranial magnetic stimulation was used to test the input/output curve of motor evoked potentials, intracortical inhibition, and short-latency afferent inhibition. Primary motor cortex plasticity was probed by theta burst stimulation. We investigated correlations between movement abnormalities, clinical scores, and cortical neurophysiological parameters.ResultsMCI patients showed less rhythmic movement but no other movement abnormalities. Cortical excitability measures were normal in patients, whereas plasticity was reduced. Movement rhythm abnormalities correlated with frontal dysfunction scores.ConclusionOur study in MCI patients demonstrated abnormal voluntary movement and plasticity changes, with no correlation between the two. Altered rhythm correlated with frontal dysfunction.SignificanceOur results contribute to the understanding of pathophysiological mechanisms of motor impairment in MCI.  相似文献   
104.
105.
ObjectivesDespite its use in determining nigrostriatal degeneration, the lack of a consistent interpretation of nigrosome 1 susceptibility map-weighted imaging (SMwI) limits its generalized applicability. To implement and evaluate a diagnostic algorithm based on convolutional neural networks for interpreting nigrosome 1 SMwI for determining nigrostriatal degeneration in idiopathic Parkinson's disease (IPD).MethodsIn this retrospective study, we enrolled 267 IPD patients and 160 control subjects (125 patients with drug-induced parkinsonism and 35 healthy subjects) at our institute, and 24 IPD patients and 27 control subjects at three other institutes on approval of the local institutional review boards. Dopamine transporter imaging served as the reference standard for the presence or absence of abnormalities of nigrosome 1 on SMwI. Diagnostic performance was compared between visual assessment by an experienced neuroradiologist and the developed deep learning-based diagnostic algorithm in both internal and external datasets using a bootstrapping method with 10000 re-samples by the “pROC” package of R (version 1.16.2).ResultsThe area under the receiver operating characteristics curve (AUC) (95% confidence interval [CI]) per participant by the bootstrap method was not significantly different between visual assessment and the deep learning-based algorithm (internal validation, .9622 [0.8912–1.0000] versus 0.9534 [0.8779-0.9956], P = .1511; external validation, 0.9367 [0.8843-0.9802] versus 0.9208 [0.8634-0.9693], P = .6267), indicative of a comparable performance to visual assessment.ConclusionsOur deep learning-based algorithm for assessing abnormalities of nigrosome 1 on SMwI was found to have a comparable performance to that of an experienced neuroradiologist.  相似文献   
106.
IntroductionThe main challenge of Parkinson's disease in women of childbearing age is managing symptoms and drugs during pregnancy and breastfeeding. The increase in the age at which women are having children makes it likely that these pregnancies will become more common in future.ObjectivesThis study aims to define the clinical characteristics of women of childbearing age with Parkinson's disease and the factors affecting their lives, and to establish a series of guidelines for managing pregnancy in these patients.ResultsThis consensus document was developed through an exhaustive literature search and a discussion of the available evidence by a group of movement disorder experts from the Spanish Society of Neurology.ConclusionsParkinson's disease affects all aspects of sexual and reproductive health in women of childbearing age. Pregnancy should be well planned to minimise teratogenic risk. A multidisciplinary approach should be adopted in the management of these patients in order to take all relevant considerations into account.  相似文献   
107.
Recent frameworks in cognitive neuroscience and behavioral neurology underscore interoceptive priors as core modulators of negative emotions. However, the field lacks experimental designs manipulating the priming of emotions via interoception and exploring their multimodal signatures in neurodegenerative models. Here, we designed a novel task that involves interoceptive and control-exteroceptive priming conditions followed by post-interoception and post-exteroception facial emotion recognition (FER). We recruited 114 participants, including healthy controls (HCs) as well as patients with behavioral variant frontotemporal dementia (bvFTD), Parkinson''s disease (PD), and Alzheimer''s disease (AD). We measured online EEG modulations of the heart-evoked potential (HEP), and associations with both brain structural and resting-state functional connectivity patterns. Behaviorally, post-interoception negative FER was enhanced in HCs but selectively disrupted in bvFTD and PD, with AD presenting generalized disruptions across emotion types. Only bvFTD presented impaired interoceptive accuracy. Increased HEP modulations during post-interoception negative FER was observed in HCs and AD, but not in bvFTD or PD patients. Across all groups, post-interoception negative FER correlated with the volume of the insula and the ACC. Also, negative FER was associated with functional connectivity along the (a) salience network in the post-interoception condition, and along the (b) executive network in the post-exteroception condition. These patterns were selectively disrupted in bvFTD (a) and PD (b), respectively. Our approach underscores the multidimensional impact of interoception on emotion, while revealing a specific pathophysiological marker of bvFTD. These findings inform a promising theoretical and clinical agenda in the fields of nteroception, emotion, allostasis, and neurodegeneration.SIGNIFICANCE STATEMENT We examined whether and how emotions are primed by interoceptive states combining multimodal measures in healthy controls and neurodegenerative models. In controls, negative emotion recognition and ongoing HEP modulations were increased after interoception. These patterns were selectively disrupted in patients with atrophy across key interoceptive-emotional regions (e.g., the insula and the cingulate in frontotemporal dementia, frontostriatal networks in Parkinson''s disease), whereas persons with Alzheimer''s disease presented generalized emotional processing abnormalities with preserved interoceptive mechanisms. The integration of both domains was associated with the volume and connectivity (salience network) of canonical interoceptive-emotional hubs, critically involving the insula and the anterior cingulate. Our study reveals multimodal markers of interoceptive-emotional priming, laying the groundwork for new agendas in cognitive neuroscience and behavioral neurology.  相似文献   
108.
Study objectivesTo evaluate neurophysiological alterations of visual function in idiopathic REM sleep Behavior Disorder (iRBD) both as markers and predictors of neurodegenerative disorders.MethodsIn a longitudinal follow-up study of 46 consecutive iRBD patients (follow-up duration 8.4 ± 3.4 years), the baseline parameters in luminance-contrast pattern (VEPp), red-green color (VEPc) and motion-onset (VEPm) Visual Evoked Potentials in iRBD were compared to early (ePD) and advanced (aPD) Parkinson's Disease subjects. Parameters of latency and amplitude of iRBD converters to neurodegenerative disease were compared with those of the non-converters.ResultsThe VEP P100 mean latency values for both eyes and for both stimulation checks (30′ and 15’) were significantly longer in all the three groups of patients as compared to controls; moreover latencies were longer in aPD than in the iRBD group who did not differ from the ePD group. The same held true when we analyzed the number of abnormal subjects belonging to each diagnostic group with a higher number of abnormal subjects in the aPD group compared to both the ePD and in iRBD groups. Chromatic and motion potentials were not different from controls and did not differ in the 3 diagnostic groups. The iRBD subjects who converted to a neurodegenerative disorder showed longer P100 latencies and a higher occurrence of VEPp abnormalities than those who did not convert. Again chromatic and motion VEPs were not different depending on conversion.ConclusionsIn iRBD patients the detection of an abnormal VEPp should be considered as a red flag for possible synnucleinopathy, eventually contributing in stratifying the risk of phenoconversion.  相似文献   
109.
IntroductionHigher prevalence of motor and non-motor features has been observed in non-manifesting mutation carriers of Parkinson's Disease (PD) compared to Healthy Controls (HC). The aim was to detect the differences between GBA and LRRK2 mutation carriers without PD and HC on neuropsychiatric symptoms.MethodsThis is a cross-sectional retrospective study of non-manifesting GBA and LRRK2 mutation carriers and HC enrolled into Parkinson's Progression Markers Initiative (PPMI). Data extracted from the PPMI database contained: demographics and performance in MoCA scale and MDS-UPDRS scale part 1A (neuropsychiatric symptoms). All six features were treated as both continuous (MDS-UPDRS individual scores) and categorical variables (MDS-UPDRS individual score>0 and MDS-UPDRS individual score = 0). Logistic regression analyses were applied to evaluate the association between mutation carrying status and neuropsychiatric symptoms.ResultsIn this study, the neuropsychiatric evaluation was performed in 285 GBA non-manifesting carriers, 369 LRRK2 non-manifesting carriers and 195 HC. We found that GBA non-manifesting mutation carriers were 2.6 times more likely to present apathy compared to HC, even after adjustment for covariates (adjusted OR = 2.6, 95% CI = 1.1–6.3, p = 0.031). The higher percentage of apathy for LRRK2 carriers compared to HC was marginally non-significant. GBA carriers were 1.5 times more likely to develop features of anxiety compared to LRRK2 carriers (adjusted OR = 1.5, 95% CI = 1.1–2.2, p = 0.015). Other neuropsychiatric symptoms, such as psychotic or depressive manifestations, did not differ between groups.ConclusionSymptoms of apathy could be present in the prediagnostic period of non-manifesting mutation carriers, especially, GBA. Longitudinal data, including detailed neuropsychiatric evaluation and neuroimaging, would be essential to further investigate the pathophysiological basis of this finding.  相似文献   
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号