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   42992篇
  免费   2545篇
  国内免费   74篇
耳鼻咽喉   401篇
儿科学   1256篇
妇产科学   913篇
基础医学   6661篇
口腔科学   305篇
临床医学   3971篇
内科学   10124篇
皮肤病学   958篇
神经病学   4144篇
特种医学   1227篇
外国民族医学   31篇
外科学   5080篇
综合类   100篇
一般理论   9篇
预防医学   3193篇
眼科学   689篇
药学   3048篇
中国医学   79篇
肿瘤学   3422篇
  2023年   249篇
  2022年   206篇
  2021年   695篇
  2020年   403篇
  2019年   741篇
  2018年   1240篇
  2017年   863篇
  2016年   872篇
  2015年   1063篇
  2014年   1133篇
  2013年   1782篇
  2012年   3025篇
  2011年   2930篇
  2010年   1465篇
  2009年   1144篇
  2008年   2650篇
  2007年   2731篇
  2006年   2558篇
  2005年   2594篇
  2004年   2550篇
  2003年   2313篇
  2002年   2242篇
  2001年   1095篇
  2000年   1155篇
  1999年   951篇
  1998年   240篇
  1997年   166篇
  1996年   174篇
  1995年   152篇
  1994年   125篇
  1993年   110篇
  1992年   543篇
  1991年   476篇
  1990年   482篇
  1989年   454篇
  1988年   405篇
  1987年   393篇
  1986年   345篇
  1985年   341篇
  1984年   237篇
  1983年   189篇
  1982年   121篇
  1979年   171篇
  1974年   122篇
  1973年   110篇
  1972年   113篇
  1971年   118篇
  1970年   113篇
  1969年   140篇
  1968年   115篇
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
31.
32.
33.
The pathogenic mechanisms of accelerated graft fibrosis in hepatitis C recurrence after liver transplantation (LT) are not well established. The aim of the study was to assess whether a greater activation of hepatic stellate cells (HSC), the major collagen-producing cells in the liver, can occur in these patients as compared to non-LT patients with chronic hepatitis C. We determined the amount of activated HSC by computer-based morphometric analysis of alpha-smooth muscle actin (alphaSMA)-positive cells and the hepatic TGFbeta(1) expression by immunohistochemistry in 46 LT patients with hepatitis C recurrence, 35 non-LT patients with chronic hepatitis C, and 16 controls. Hepatic alphaSMA and TGFbeta(1) expression was higher in LT patients with hepatitis C recurrence than in controls and was correlated with fibrosis stage and progression rate. No significant difference in alphaSMA and TGFbeta(1) expression was observed between LT and non-LT patients with hepatitis C, with the exception of a higher transforming growth factor beta-1 (TGFbeta(1)) expression in non-LT patients in the early stages of fibrosis. LT patients receiving cyclosporine (CsA) or tacrolimus (FK) had a similar fibrosis progression rate and alphaSMA and TGFbeta(1) expression. In conclusion, the accelerated fibrosis observed in LT patients with hepatitis C recurrence does not seem to be related to a greater amount of activated HSC and TGFbeta(1) expression in the grafts of these patients as compared to non-LT patients with chronic hepatitis C. In LT patients, the amount of activated HSC and TGFbeta(1) expression correlated with fibrosis stage and progression, without any apparent influence of the type of calcineurin inhibitor administered.  相似文献   
34.
OBJECTIVE: Cell therapy may be a promising alternative or adjunct to current treatment modalities for ischemic heart failure. But little is known on the impact of myogenic cell transplantation in large animal models of non-ischemic cardiomyopathy. The aim of the present study was to explore whether an ovine model of toxin-induced heart disease could benefit from non-cultured skeletal muscle cell transplantation. METHODS: Sequential intracoronary injections of doxorubicin (0.75 mg/kg) were carried out every 2 weeks until echocardiographic detection of myocardial dysfunction. Sheep were then randomly assigned to either non-cultured cell transplantation (n=8) or placebo injection (n=5). For the cell therapy group, a skeletal muscle biopsy (about 10 g) was explanted from each animal approximately 3h before grafting. After thoracotomy, 20 epicardial injections were carried out. The animals were assessed one last time before sacrifice, 2 months after the thoracotomy. Cells were tracked with cmDiI (red fluorescence) and characterized with immunohistochemistry with monoclonal antibodies to a fast skeletal isoform of myosin heavy chain. RESULTS: Two months after intramyocardial grafting, tissue Doppler imaging and conventional echocardiographic assessment of the groups showed a marked improvement in the non-cultured cell therapy group. Ejection fraction (EF) (p<0.05) as well as systolic endocardial velocities (p<0.01) improved versus the placebo group. CmDiI and skeletal myosin heavy chain expression was detected in all animals at 2 months after implantation confirming engraftment of skeletal muscle cells. CONCLUSIONS: In conclusion, our data indicate that non-cultured muscle cell transplantation is feasible and may translate into a functional benefit in an ovine model of dilated heart failure.  相似文献   
35.
The impact of continuous positive airway pressure (CPAP) treatment on the airway responsiveness of asthmatic subjects with obstructive sleep apnoea (OSA) has scarcely been studied. A prospective study was performed comparing the changes in airway responsiveness and quality of life in stable asthmatic OSA patients, before and 6 weeks after their nocturnal CPAP treatment. A total of 20 subjects (11 males and nine females) participated in the study. With the nocturnal CPAP treatment, the apnoea/hypopnoea index dropped from 48.1 +/- 23.6 x h(-1) to 2.6 +/- 2.5 x h(-1). There were no significant changes in airway responsiveness after CPAP treatment (provocative concentration causing a 20% fall in forced expiratory volume in one second (FEV(1); PC(20) 2.5 mg x mL(-1) (1.4-4.5)) compared with baseline (PC(20) 2.2 mg x mL(-1) (1.3-3.5)). There was no significant change in FEV(1) either. However, the asthma quality of life of the subjects improved from 5.0 +/- 1.2 at baseline to 5.8 +/- 0.9 at the end of the study. In conclusion, nocturnal continuous positive airway pressure treatment did not alter airway responsiveness or forced expiratory volume in one second in subjects with stable mild-to-moderate asthma and newly diagnosed obstructive sleep apnoea. However, nocturnal continuous positive airway pressure treatment did improve asthma quality of life.  相似文献   
36.
The author reminds practitioners dealing with varicose disorders by means of surgery that varices of the long saphenous system are not necessarily provoked by valvular incontinence of the saphenofemoral junction. He also reminds us that, for treatment to be effective, there must above all be a completely sure diagnosis, so that appropriate surgery can be carried out in all circumstances. He also asserts that stripping is by no means a guarantee against recidivism. Further to this, he presents statistical data on the factors which lead to persistence or reappearance of post-stripping varices in the long saphenous vein, and attempts to categorize these. The author ends by showing his final conclusions.  相似文献   
37.
38.
39.
40.
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