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   3860篇
  免费   230篇
  国内免费   7篇
耳鼻咽喉   22篇
儿科学   241篇
妇产科学   82篇
基础医学   419篇
口腔科学   46篇
临床医学   266篇
内科学   619篇
皮肤病学   54篇
神经病学   196篇
特种医学   182篇
外科学   550篇
综合类   173篇
预防医学   424篇
眼科学   178篇
药学   304篇
中国医学   16篇
肿瘤学   325篇
  2023年   22篇
  2022年   38篇
  2021年   84篇
  2020年   67篇
  2019年   73篇
  2018年   93篇
  2017年   55篇
  2016年   74篇
  2015年   85篇
  2014年   146篇
  2013年   173篇
  2012年   243篇
  2011年   315篇
  2010年   178篇
  2009年   155篇
  2008年   245篇
  2007年   219篇
  2006年   177篇
  2005年   184篇
  2004年   180篇
  2003年   147篇
  2002年   103篇
  2001年   72篇
  2000年   65篇
  1999年   59篇
  1998年   25篇
  1997年   21篇
  1996年   15篇
  1995年   18篇
  1992年   37篇
  1991年   33篇
  1990年   25篇
  1989年   38篇
  1988年   34篇
  1987年   30篇
  1986年   28篇
  1985年   29篇
  1984年   24篇
  1983年   21篇
  1982年   15篇
  1979年   40篇
  1978年   31篇
  1977年   18篇
  1974年   26篇
  1973年   21篇
  1972年   16篇
  1971年   20篇
  1970年   26篇
  1969年   15篇
  1966年   17篇
排序方式: 共有4097条查询结果,搜索用时 31 毫秒
1.
2.
No study has yet been done to investigate the changes in endothelial cell size, perimeter, and density that may result from the warming of corneas in MK (McCarey-Kaufman) medium for specular microscopy. In the present investigation eye bank eyes were stored in MK medium at 4 degrees C and rewarmed daily for six days at 37 degrees C before specular photography of the endothelium was performed. These photographs were compared with wet mount preparations stained with trypan blue and alizarin red made from the same corneas and those stored without rewarming for six days. In addition all corneas were qualitatively analysed with the scanning electron microscope (SEM). The data from serial specular photography were insufficient to allow significant conclusions to be drawn about day to day changes in cell morphology. However, analysis of wet mount preparations revealed that cell density and perimeter varied significantly between those corneas rewarmed daily and those held in cold storage for six days. SEM studies showed an intact cell monolayer with cell loss along the folds of corneal endothelium. We therefore concluded that repeated rewarming at 37 degrees C of corneas stored in MK medium at 4 degrees has a deleterious effect on cell morphology and that folds induced by swelling of corneal tissue result in endothelial cell damage with some loss.  相似文献   
3.
Atrial fibrillation (AF) is the most common post-operative complication in patients undergoing coronary artery bypass grafting, with an increased incidence associated with advancing age. This study aims to determine whether off-pump coronary artery bypass (OPCAB) reduces the incidence of AF in a generalized population (mean age <70 years). A meta-analysis was performed including all randomised and propensity score matched non-randomised studies published between 2001 and 2003 reporting a comparison between the two techniques in a generalised patient group (average age <70 years). The primary outcome of interest was post-operative AF. Sensitivity analysis was performed to evaluate consistency of the calculated treatment effect. Fourteen studies fulfilled our inclusion criteria, including a total of 16,505 subjects. The incidence of AF was 19% (1612/8265) in the off-pump group versus 24% (1976/8240) in the on-pump group. When considering only the 11 randomised studies (2207 subjects), we found a significant reduction in the incidence of post-operative AF in the off-pump group using a random-effect model (odds ratio (OR)=0.60, 95% confidence interval (CI)=0.45-0.82, and chi-square of heterogeneity=18.02, P=0.05). Sensitivity analysis highlighted one randomised study causing funnel plot asymmetry, exclusion of which resulted in a significant reduction in the incidence of post-operative AF in the off-pump group (OR=0.71, 95% CI=0.57-0.90), with a non-significant heterogeneity of 3.91 (P=0.92). When only studies of high quality were considered (898 patients), no significant difference was seen between on and off-pump groups (OR=0.78, 95% CI=0.57-1.07, and heterogeneity=0.53, P=0.91). This may be due to small number of patients in this group. Our results suggest that although OPCAB surgery may reduce the incidence of post-operative AF in a generalised population (age <70 years) this finding is not clearly supported by high quality randomised trials. Although previous evidence suggests that the incidence of post-operative AF is reduced in an elderly population (>70 years) with off-pump surgery, our results show that the evidence is less clear in a younger population group. The question of whether off-pump surgery in this patient group results in a lower rate of post-operative AF remains to be answered by further high quality randomised research.  相似文献   
4.
Gall bladder perforation is a potentially life-threatening condition. Spontaneous perforation is infrequent and rarely seen in the absence of gallstones but gall bladder perforation is an occasional complication of typhoid fever. If such perforations are not treated in time, mortality rates are very high. We report a case of gall bladder perforation complicating typhoid fever following enteric perforation of the ileum necessitating sequential laparotomies during the same admission.  相似文献   
5.
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup.  相似文献   
6.
A total of 168 strains of Salmonella were isolated in the Command Pathology Laboratory (WC) Delhi Cantt during the year 1990. Out of this, 143 were Salmonella typhi, 17 Salmonella paratyphi A, 7 Salmonella typhimurium and 1 Salmonella manhattan. The commonest phage type and biotype of Salmonella typhi was type E1 and type 1 respectively. The dominant biotype of Salmonella paratyphi A was type I. There was a very high degree of multidrug resistance of most of the strains. But all the strains were sensitive to ciprofloxacin and norfloxacin.  相似文献   
7.
8.
Introduction Hydatid cysts of the lung are quite frequent in our country. Some patients have additional cysts in the liver. Though most of the liver cysts remain asymptomatic for long time, but may be symptomatic with increasing size. Surgical removal is the treatment of choice for both lung & liver cysts. Aim of the study was to establish suitability of one stage surgery for pulmonary & hepatic hydatid cysts. Methods From 1996 through 2003 we operated on 216 pulmonary hydatid cysts, out of which 42 patients had hydatid cysts in the right lung as well as in the right lobe of liver. Right thoracotomy was done to remove the lung hydatids followed by phrenotomy to remove the liver cysts. Results Right thoracotomy was done in 42 patients having hydatid cysts of lung & liver. In 36 patients, cysts were removed, bronchial leaks were sutured & residual cavities were obliterated. Out of rest 6 patients, having dense adhesions or destruction of pulmonary parenchyma, 4 had segmentectomy & 2 had lobectomy. Right phrenotomy was then done with radial incision above the palpated liver cysts. Hydatid cyst was removed from liver. Cavity and remaining pericystic liver tissue was inverted with sutures. Water seal chest drain & subdiaphragmatic drain were placed. Post operative albendazole was continued for 3 months in the dose of 10–20 mg/kg with a gap of 2 weeks after each month. Post operative recovery was uneventful in most of the cases. However, air leak continued for almost 3 weeks in 4 patients & 3 months in one patient. There was no death. Conclusion Surgical management of pulmonary and hepatic hydatids with one stage right thoracotomy & phrenotomy is a suitable option. It avoids additional laparotomy and thereby additional cost & hospital stay. Results are quite satisfactory.  相似文献   
9.
10.
Poliomyelitis in India.   总被引:1,自引:0,他引:1  
R N Basu 《Indian pediatrics》1991,28(6):589-592
  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