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   235947篇
  免费   5567篇
  国内免费   211篇
耳鼻咽喉   1897篇
儿科学   7965篇
妇产科学   3834篇
基础医学   24289篇
口腔科学   2471篇
临床医学   18848篇
内科学   43912篇
皮肤病学   1436篇
神经病学   22491篇
特种医学   10975篇
外国民族医学   5篇
外科学   39732篇
综合类   2919篇
一般理论   47篇
预防医学   22162篇
眼科学   3922篇
药学   13691篇
中国医学   694篇
肿瘤学   20435篇
  2024年   50篇
  2023年   455篇
  2022年   624篇
  2021年   2007篇
  2020年   1213篇
  2019年   1809篇
  2018年   23788篇
  2017年   18685篇
  2016年   20896篇
  2015年   2737篇
  2014年   3456篇
  2013年   4069篇
  2012年   12053篇
  2011年   26128篇
  2010年   21478篇
  2009年   14048篇
  2008年   23598篇
  2007年   25865篇
  2006年   4708篇
  2005年   6119篇
  2004年   6896篇
  2003年   7699篇
  2002年   5483篇
  2001年   675篇
  2000年   712篇
  1999年   536篇
  1998年   804篇
  1997年   674篇
  1996年   461篇
  1995年   419篇
  1994年   379篇
  1993年   324篇
  1992年   234篇
  1991年   241篇
  1990年   248篇
  1989年   183篇
  1988年   164篇
  1987年   135篇
  1986年   112篇
  1985年   109篇
  1984年   136篇
  1983年   117篇
  1982年   132篇
  1981年   99篇
  1980年   150篇
  1979年   50篇
  1978年   55篇
  1974年   50篇
  1938年   61篇
  1932年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Erosive pustular dermatosis of the scalp (EPDS) is an uncommon chronic inflammatory response to scalp trauma that usually resolves with cicatricial alopecia. It most commonly affects elderly patients with a history of actinic damage. Herein, we describe a 16‐year‐old girl with acrofacial dysostosis type 1 presenting after surgery with crusting purulent scalp lesions, whose clinical presentation and histopathologic findings were consistent with EPDS. A review of the literature on EPDS in children is also detailed.  相似文献   
2.
Owing to the frequent incidence of blast-induced traumatic brain injury (bTBI) in recent military conflicts, there is an urgent need to develop effective therapies for bTBI-related pathologies. Blood-brain barrier (BBB) breakdown has been reported to occur after primary blast exposure, making restoration of BBB function and integrity a promising therapeutic target. We tested the hypothesis that treatment with dexamethasone (DEX) after primary blast injury potentiates recovery of an in vitro BBB model consisting of mouse brain endothelial cells (bEnd.3). DEX treatment resulted in complete recovery of transendothelial electrical resistance and hydraulic conductivity 1 day after injury, compared with 3 days for vehicle-treated injured cultures. Administration of RU486 (mifepristone) inhibited effects of DEX, confirming that barrier restoration was mediated by glucocorticoid receptor signaling. Potentiated recovery with DEX treatment was accompanied by stronger zonula occludens (ZO)-1 tight junction immunostaining and expression, suggesting that increased ZO-1 expression was a structural correlate to BBB recovery after blast. Interestingly, augmented ZO-1 protein expression was associated with specific upregulation of the α+ isoform but not the α isoform. This is the first study to provide a mechanistic basis for potentiated functional recovery of an in vitro BBB model because of glucocorticoid treatment after primary blast injury.  相似文献   
3.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
4.
5.
6.
7.
BackgroundThe optimal management of community acquired pneumonia (CAP) depends on the clinical and microbiological profile in the locality.ObjectivesTo determine the clinical and microbiological profile of patients admitted with CAP in Ilorin, Nigeria.MethodsOne hundred and two consenting consecutively selected patients with clinical and radiologic confirmation of CAP were recruited in 12 months. The socio-demographic, physical examination and laboratory/radiologic parameters were documented in a questionnaire. Microbiological evaluation of their sputum was done and blood samples were taken for complete blood count, culture, serum urea and serological evaluation for atypical bacteria and some viral pathogens.ResultsCAP constituted 5.9% of the total medical admissions during the one-year study period. The mean age of the patients was 49 ± 22 years with the largest frequency in those aged 65 years and above. The commonest symptoms were shortness of breath (96.1%) and cough (94.1%), with a median duration of 3 days from symptom onset to admission. Systemic hypertension was the commonest comorbid illness (25/102; 24.5%). Klebsiella pneumoniae was the predominant pathogen isolated (20/102; 28.1%). The susceptible antibiotics were Imipenem, Ceftazidime and Ceftriaxone. Intra-hospital mortality was 17.6%. CURB – 65 score of ≥ 2 and the presence of complications of CAP were the independent predictors of mortality.ConclusionCAP constitutes a significant disease burden in Ilorin, Nigeria. Typical bacteria accounted for over half of the pathogens isolated from the patients with gram negative agents predominating. This highlights a possible shift in the microbiological profile which could guide empirical treatment.  相似文献   
8.
9.
10.
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