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   1937篇
  免费   94篇
  国内免费   81篇
耳鼻咽喉   6篇
儿科学   89篇
妇产科学   13篇
基础医学   202篇
口腔科学   23篇
临床医学   313篇
内科学   433篇
皮肤病学   35篇
神经病学   115篇
特种医学   309篇
外科学   100篇
综合类   37篇
预防医学   172篇
眼科学   7篇
药学   160篇
肿瘤学   98篇
  2021年   25篇
  2019年   26篇
  2018年   14篇
  2017年   20篇
  2016年   30篇
  2015年   26篇
  2014年   22篇
  2013年   53篇
  2012年   43篇
  2011年   58篇
  2010年   66篇
  2009年   67篇
  2008年   52篇
  2007年   88篇
  2006年   59篇
  2005年   61篇
  2004年   28篇
  2003年   40篇
  2002年   44篇
  2001年   37篇
  2000年   47篇
  1999年   53篇
  1998年   98篇
  1997年   89篇
  1996年   113篇
  1995年   87篇
  1994年   89篇
  1993年   75篇
  1992年   26篇
  1991年   39篇
  1990年   34篇
  1989年   40篇
  1988年   50篇
  1987年   34篇
  1986年   48篇
  1985年   42篇
  1984年   20篇
  1983年   31篇
  1982年   25篇
  1981年   30篇
  1980年   24篇
  1979年   19篇
  1978年   25篇
  1977年   22篇
  1976年   18篇
  1975年   14篇
  1974年   7篇
  1973年   8篇
  1972年   6篇
  1971年   6篇
排序方式: 共有2112条查询结果,搜索用时 203 毫秒
1.
Treatment of dogs for 21 days with oral levodopa (100 mg b.i.d.) plus benserazide (25 mg b.i.d.) induced a significant increase in the number of platelet alpha 2-adrenoceptors labelled by [3H] yohimbine with no change in Kd. The rise was maximal at the end of the treatment and remained significant during the month following the cessation of treatment. Plasma catecholamine levels did not vary. Competition experiments showed a low affinity of both dopamine and levodopa for platelet alpha 2-adrenoceptors. These results suggest that levodopa treatment regulates alpha 2-adrenoceptor number in dog platelets.  相似文献   
2.
3.
4.
5.
6.
7.
8.
Multiple structural and functional imaging modalities are available to localize the epileptogenic focus. In pre-surgical evaluation of children with pharmacoresistant epilepsy, investigations with the maximum yield should be considered in order to reduce the complexity of the workup. OBJECTIVE: To determine the extent to which PET, ictal/interictal SPECT and its co-registration with the patient's MRI contributes to correct localization of the epileptogenic focus, surgical intervention and to the post surgical outcome in paediatric patients. METHODS: The study population included children and adolescents with pharmacoresistant epilepsy (n = 50) who underwent preoperative evaluation, surgery and had postoperative follow-up for at least 12 months. Outcome was measured by postoperative seizure frequency using Engel's classification. RESULTS: Thirty-nine patients (78%) became completely seizure free after surgical intervention. The likelihood to benefit from surgical treatment was significantly higher if localization with more imaging modalities (MRI, PET, SPECT) were concordant with respect to the resected brain area (p < 0.01). Preoperative PET examination provided better localizing information in patients with extratemporal epilepsy and/or dysplastic lesions, whereas SPECT was found to be superior to PET in patients with temporal lobe epilepsy and/or tumors (p < 0.05). No significant difference was noted in the surgical outcome in younger or older age group, in children with or without special education needs. CONCLUSION: In paediatric epilepsy pre-surgical evaluation, the combined use of multiple functional imaging modalities for a precise localisation of the epileptogenic focus is worthwhile for both extratemporal and temporal lobe epilepsy, also when EEG and MRI alone are non-contributive, given the potential benefit of complete postoperative seizure control.  相似文献   
9.
BACKGROUND: Knowledge of the prevalence of peripheral arterial disease (PAD) in patients with chronic renal failure (CRF) is limited because of a lack of uniformity in disease definition and recognition. Furthermore, little is known of the prevalence of medial arterial calcification (MAC) in patients with CRF. Our goal is to study the prevalence of PAD and MAC defined by ankle brachial index (ABI) or toe brachial index (TBI) measurements in a Finnish population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients. METHODS: We examined 136 patients with CRF and 59 control subjects. Fifty-nine of the patients with CRF had moderate to severe predialysis CRF, 36 patients were on dialysis treatment, and 41 were renal transplant recipients. Mean age of patients was 51.9 +/- 11.5 years, and 39 patients (29%) had diabetes. ABI and TBI were measured by means of photoplethysmography. The definition of PAD required an ABI value of 0.90 or less, a TBI value of 0.60 or less, or a previous positive lower-extremity angiogram result. ABI values of 1.3 or greater or incompressible arteries at ankle level indicated MAC. The presence of claudication was determined by an interview. RESULTS: Prevalences of PAD on this study were 22.0% in patients with predialysis CRF, 30.6% in patients on dialysis treatment, 14.6% in renal transplant recipients, and 1.7% in the control group (P = 0.001). Prevalences of MAC were 23.7%, 41.7%, 23.1%, and 3.4% (P < 0.001), respectively. Only 9 patients had claudication, and 6 of those patients had PAD. CONCLUSION: Both asymptomatic PAD and MAC are common in patients with CRF. Therefore, we recommend the use of both ABI and TBI measurements in the evaluation of PAD in patients with CRF.  相似文献   
10.
We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.  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