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   236760篇
  免费   5621篇
  国内免费   212篇
耳鼻咽喉   1911篇
儿科学   7975篇
妇产科学   3844篇
基础医学   24368篇
口腔科学   2479篇
临床医学   18924篇
内科学   44099篇
皮肤病学   1440篇
神经病学   22519篇
特种医学   11043篇
外国民族医学   5篇
外科学   39949篇
综合类   2922篇
一般理论   47篇
预防医学   22204篇
眼科学   3927篇
药学   13719篇
中国医学   694篇
肿瘤学   20524篇
  2024年   50篇
  2023年   456篇
  2022年   741篇
  2021年   2015篇
  2020年   1216篇
  2019年   1816篇
  2018年   23798篇
  2017年   18693篇
  2016年   20910篇
  2015年   2757篇
  2014年   3487篇
  2013年   4098篇
  2012年   12096篇
  2011年   26161篇
  2010年   21491篇
  2009年   14063篇
  2008年   23623篇
  2007年   25913篇
  2006年   4733篇
  2005年   6156篇
  2004年   6943篇
  2003年   7716篇
  2002年   5503篇
  2001年   699篇
  2000年   728篇
  1999年   562篇
  1998年   815篇
  1997年   687篇
  1996年   469篇
  1995年   428篇
  1994年   385篇
  1993年   338篇
  1992年   247篇
  1991年   249篇
  1990年   259篇
  1989年   190篇
  1988年   177篇
  1987年   140篇
  1986年   121篇
  1985年   122篇
  1984年   148篇
  1983年   124篇
  1982年   133篇
  1981年   104篇
  1980年   156篇
  1979年   57篇
  1978年   58篇
  1974年   53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 343 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