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   3225篇
  免费   122篇
  国内免费   18篇
耳鼻咽喉   58篇
儿科学   81篇
妇产科学   66篇
基础医学   406篇
口腔科学   53篇
临床医学   284篇
内科学   792篇
皮肤病学   20篇
神经病学   580篇
特种医学   97篇
外科学   320篇
综合类   8篇
一般理论   2篇
预防医学   129篇
眼科学   28篇
药学   204篇
  1篇
中国医学   11篇
肿瘤学   225篇
  2024年   9篇
  2023年   26篇
  2022年   47篇
  2021年   87篇
  2020年   56篇
  2019年   73篇
  2018年   91篇
  2017年   65篇
  2016年   83篇
  2015年   84篇
  2014年   126篇
  2013年   165篇
  2012年   228篇
  2011年   203篇
  2010年   120篇
  2009年   107篇
  2008年   207篇
  2007年   203篇
  2006年   209篇
  2005年   212篇
  2004年   189篇
  2003年   157篇
  2002年   175篇
  2001年   33篇
  2000年   19篇
  1999年   31篇
  1998年   50篇
  1997年   25篇
  1996年   15篇
  1995年   29篇
  1994年   16篇
  1993年   15篇
  1992年   18篇
  1991年   14篇
  1990年   18篇
  1989年   12篇
  1988年   11篇
  1987年   11篇
  1986年   11篇
  1985年   17篇
  1984年   17篇
  1983年   12篇
  1982年   17篇
  1981年   6篇
  1980年   8篇
  1979年   5篇
  1977年   4篇
  1976年   6篇
  1974年   10篇
  1973年   4篇
排序方式: 共有3365条查询结果,搜索用时 78 毫秒
21.
Cognitive impairment in multiple sclerosis (MS) is common, debilitating and burdensome. Key evidence from trials was reviewed to enable recommendations to be made to guide clinical practice and research. Behavioural and pharmacological interventions on cognition reported in published studies were reviewed. Most studies evaluating behavioural treatment for impairment in learning and memory, deficits of attention and executive function have demonstrated some improvement. Controlled studies in relapsing remitting MS indicate interferon (IFN) β-1b and IFN β-1a were associated with modest cognitive improvement. The effects of symptomatic therapies such as modafinil and donepezil are inconsistent. Most studies yielding positive findings have significant methodological difficulties limiting the confidence in making any broad treatment recommendations. There are no published reports of glatiramer acetate, natalizumab and fingolimod being effective in improving cognition in controlled trials. The effects of disease modifying therapies in other forms of MS and clinically isolated syndrome have not yielded positive results. Data linking behavioural therapy, symptomatic treatment or disease modifying treatment, to either reducing cognitive decline or improving impaired cognition are limited and inconsistent. The treatment and prevention of cognitive impairment needs to remain a key research focus, identifying new interventions and improving clinical trial methodology.  相似文献   
22.
23.
In this work we illustrate the approach of the Maastricht Brain Imaging Center to the PBAIC 2007 competition, where participants had to predict, based on fMRI measurements of brain activity, subject driven actions and sensory experience in a virtual world. After standard pre-processing (slice scan time correction, motion correction), we generated rating predictions based on linear Relevance Vector Machine (RVM) learning from all brain voxels. Spatial and temporal filtering of the time series was optimized rating by rating. For some of the ratings (e.g. Instructions, Hits, Faces, Velocity), linear RVM regression was accurate and very consistent within and between subjects. For other ratings (e.g. Arousal, Valence) results were less satisfactory. Our approach ranked overall second. To investigate the role of different brain regions in ratings prediction we generated predictive maps, i.e. maps of the weighted contribution of each voxel to the predicted rating. These maps generally included (but were not limited to) "specialized" regions which are consistent with results from conventional neuroimaging studies and known functional neuroanatomy. In conclusion, Sparse Bayesian Learning models, such as RVM, appear to be a valuable approach to the multivariate regression of fMRI time series. The implementation of the Automatic Relevance Determination criterion is particularly suitable and provides a good generalization, despite the limited number of samples which is typically available in fMRI. Predictive maps allow disclosing multi-voxel patterns of brain activity that predict perceptual and behavioral subjective experience.  相似文献   
24.
Parry Romberg Syndrome (PRS) is a rare condition of unknown cause and pathophysiology. It is characterized by progressive facial hemiatrophy, and neurological abnormalities are found in 20% of cases. We describe a 50-year-old woman with PRS and severe neurological involvement (lateralised epileptic seizure activity and facial pain refractory to medication). Pain intensity and frequency was reduced and control of epileptic crises was improved using levetiracetam as an additional therapy. In previous published cases associated with facial pain, the most frequent diagnoses were migraine and trigeminal neuralgia. Our findings suggest that in this patient PRS-related persistent pain has peculiar features possibly attributed to the underlying musculoskeletal abnormalities.  相似文献   
25.
BCAAs supplementation has been widely used for post-exercise recovery. However, no evidence is currently available to answer the question of whether BCAAs supplementation can attenuate muscle damage and ameliorate recovery after a bout of change of direction (COD) sprinting, which is an exercise motion frequently used during team sport actions. This study aimed to assess the effect of BCAAs supplementation on muscle damage markers, subjective muscle soreness, neuromuscular performance, and the vascular health of collegiate basketball players during a 72 h recovery period after a standardized COD protocol. Participants orally received either BCAAs (0.17 g/kg BCAAs + 0.17 g/kg glucose) or placebo (0.34 g/kg glucose) supplementation before and immediately after a COD exercise protocol in a randomized, crossover, double-blind, and placebo-controlled manner. Creatine kinase increased immediately after exercise and peaked at 24 h, muscle soreness remained elevated until 72 h, whilst arterial stiffness decreased after exercise for both supplemented conditions. A negligibly lower level of interleukin-6 was found in the BCAAs supplemented condition. In conclusion, the results of this study do not support the benefits of BCAAs supplementation on mitigating muscle damage and soreness, neuromuscular performance, and arterial stiffness after COD for basketball players.  相似文献   
26.
Journal of Neurology - To investigate the prognostic role and the major determinants of serum phosphorylated neurofilament heavy -chain (pNfH) concentration across a large cohort of motor neuron...  相似文献   
27.
The effect of gamma-aminobutyric acid (GABA)receptor stimulation on norepinephrine (NE)-induced metabolism of polyphosphoinositides (PIPs) was studied in rat hippocampal slices. Inositol phosphates (IPs), PIPs, and phosphatidic acid were measured. NE induced formation of IPs and phosphatidic acid in a dose-dependent manner with an EC50 of 4.5 microM. GABA, 3-aminopropanesulphonic acid (3APS) and muscimol did not affect PIPs breakdown, but they strongly increased (greater than 100%) PIPs metabolism induced by 1 microM NE. Their action was antagonized by bicuculline (10 microM). We discuss the implications of these findings in hippocampal neurotransmission.  相似文献   
28.
We evaluated the differences in motor control organization between parkinsonian patients with (seven cases) and without (ten cases) gait disorder. We used positron emission tomography (O15-H2O-PET) to measure regional cerebral blood flow as a correlate for local neuronal activation. This has been assessed during repetitive joystick movements of the right hand, externally triggered using a metronome as an auditory cue. In patients with Parkinson's disease (PD) without gait disorder, the contralateral supplementary motor cortex and the bilateral cerebellum were activated while in PD patients with gait disorder the contralateral Broca's area, the contralateral sensory motor cortex and the homolateral cerebellum were activated. Our results suggest that PD patients with gait disorder creates an internal verbal cue in order to control the output of the movement of joystick, supplying the loss of control of the supplementary motor cortex that is activated in patients without gait disorder.  相似文献   
29.
Head and neck paragangliomas, rare neoplasms of the paraganglia composed of nests of neurosecretory and glial cells embedded in vascular stroma, provide a remarkable example of organoid tumor architecture. To identify genes and pathways commonly deregulated in head and neck paraganglioma, we integrated high-density genome-wide copy number variation (CNV) analysis with microRNA and immunomorphological studies. Gene-centric CNV analysis of 24 cases identified a list of 104 genes most significantly targeted by tumor-associated alterations. The “NOTCH signaling pathway” was the most significantly enriched term in the list (P = 0.002 after Bonferroni or Benjamini correction). Expression of the relevant NOTCH pathway proteins in sustentacular (glial), chief (neuroendocrine) and endothelial cells was confirmed by immunohistochemistry in 47 head and neck paraganglioma cases. There were no relationships between level and pattern of NOTCH1/JAG2 protein expression and germline mutation status in the SDH genes, implicated in paraganglioma predisposition, or the presence/absence of immunostaining for SDHB, a surrogate marker of SDH mutations. Interestingly, NOTCH upregulation was observed also in cases with no evidence of CNVs at NOTCH signaling genes, suggesting altered epigenetic modulation of this pathway. To address this issue we performed microarray-based microRNA expression analyses. Notably 5 microRNAs (miR-200a,b,c and miR-34b,c), including those most downregulated in the tumors, correlated to NOTCH signaling and directly targeted NOTCH1 in in vitro experiments using SH-SY5Y neuroblastoma cells. Furthermore, lentiviral transduction of miR-200s and miR-34s in patient-derived primary tympano-jugular paraganglioma cell cultures was associated with NOTCH1 downregulation and increased levels of markers of cell toxicity and cell death. Taken together, our results provide an integrated view of common molecular alterations associated with head and neck paraganglioma and reveal an essential role of NOTCH pathway deregulation in this tumor type.  相似文献   
30.
Sentinox (STX) is an acid-oxidizing solution containing hypochlorous acid in spray whose virucidal activity against SARS-CoV-2 has been demonstrated. In this paper, results of a randomized controlled trial (RCT) on the efficacy of STX in reducing viral load in mild COVID-19 patients (NCT04909996) and a complementary in vitro study on its activity against different respiratory viruses are reported. In the RCT, 57 patients were randomized (1:1:1) to receive STX three (STX-3) or five (STX-5) times/day plus standard therapy or standard therapy only (controls). Compared with controls, the log10 load reduction in groups STX-3 and STX-5 was 1.02 (p = 0.14) and 0.18 (p = 0.80), respectively. These results were likely driven by outliers with extreme baseline viral loads. When considering subjects with baseline cycle threshold values of 20–30, STX-3 showed a significant (p = 0.016) 2.01 log10 reduction. The proportion of subjects that turned negative by the end of treatment (day 5) was significantly higher in the STX-3 group than in controls, suggesting a shorter virus clearance time. STX was safe and well-tolerated. In the in vitro study, ≥99.9% reduction in titers against common respiratory viruses was observed. STX is a safe device with large virucidal spectrum and may reduce viral loads in mild COVID-19 patients.  相似文献   
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