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   7183篇
  免费   446篇
  国内免费   21篇
耳鼻咽喉   32篇
儿科学   211篇
妇产科学   192篇
基础医学   1203篇
口腔科学   163篇
临床医学   665篇
内科学   1536篇
皮肤病学   287篇
神经病学   684篇
特种医学   210篇
外科学   599篇
综合类   45篇
一般理论   3篇
预防医学   679篇
眼科学   68篇
药学   510篇
中国医学   26篇
肿瘤学   537篇
  2023年   60篇
  2022年   92篇
  2021年   159篇
  2020年   165篇
  2019年   207篇
  2018年   216篇
  2017年   165篇
  2016年   201篇
  2015年   231篇
  2014年   288篇
  2013年   367篇
  2012年   557篇
  2011年   554篇
  2010年   319篇
  2009年   265篇
  2008年   460篇
  2007年   481篇
  2006年   463篇
  2005年   431篇
  2004年   359篇
  2003年   349篇
  2002年   301篇
  2001年   82篇
  2000年   62篇
  1999年   56篇
  1998年   63篇
  1997年   48篇
  1996年   45篇
  1995年   36篇
  1994年   28篇
  1993年   25篇
  1992年   32篇
  1991年   35篇
  1990年   34篇
  1989年   22篇
  1988年   26篇
  1987年   21篇
  1986年   28篇
  1985年   24篇
  1984年   12篇
  1983年   14篇
  1982年   22篇
  1981年   21篇
  1979年   13篇
  1978年   16篇
  1977年   14篇
  1976年   15篇
  1974年   13篇
  1971年   14篇
  1967年   11篇
排序方式: 共有7650条查询结果,搜索用时 0 毫秒
71.
Background:Although non-ischemic troponin elevation is frequently seen in patients admitted to the emergency department (ED), consensus regarding its management is lacking.Objectives:This study aimed to characterize patients admitted to the ED with non-ischemic troponin elevation and to identify potential mortality predictors in this population.Methods:This retrospective observational study included ED patients with a positive troponin test result between June and July of 2015. Patients with a clinical diagnosis of acute coronary syndrome (ACS) were excluded. Data on patient demographics and clinical and laboratory variables were extracted from medical records. Follow-up data were obtained for 16 months or until death occurred. The statistical significance level was 5%.Results:Troponin elevation without ACS was found in 153 ED patients. The median (IQR) patient age was 78 (19) years, 80 (52.3%) were female and 59(38.6%) died during follow-up. The median (IQR) follow-up period was 477(316) days. Survivors were significantly younger 76 (24) vs. 84 (13) years; p=0.004) and featured a higher proportion of isolated troponin elevation (without creatine kinase or myoglobin elevation) in two consecutive evaluations: 48 (53.9%) vs. 8 (17.4%), p<0.001. Survivors also presented a lower rate of antiplatelet treatment and same-day hospitalization. In the multivariate logistic regression with adjustment for significant variables in the univariate analysis, isolated troponin elevation in two consecutive evaluations showed a hazard ratio= 0.43 (95%CI 0.17–0.96, p=0.039); hospitalization, previous antiplatelet treatment and age remained independently associated with mortality.Conclusions:Isolated troponin elevation in two consecutive measurements was a strong predictor of survival in ED patients with troponin elevation but without ACS.  相似文献   
72.
73.
Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems. The current study delivers a three-dimensional (3D) scaffold prepared by blend centrifugal spinning loaded with the osteogenic supplements (OS) β-glycerol phosphate, ascorbate-2-phosphate and dexamethasone. The OS were successfully encapsulated into a fibrous scaffold and showed sustained release for 30 days. Furthermore, biological testing showed the osteoinductive properties of the scaffolds on a model of human mesenchymal stem cells and stimulatory effect on a model of osteoblasts. The osteoinductive properties were further proved in vivo in critical size defects of rabbits. The amount of bone trabecules was bigger compared to control fibers without OS. The results indicate that due to its long-term drug releasing properties, single step fabrication process and 3D structure, the system shows ideal properties for use as a cell-free bone implant in tissue-engineering.

Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems.  相似文献   
74.
75.
76.
77.

A growing number of investigations are exploring the utility of intranasal insulin as a means of mitigating cognitive decline. However, as a basic tenant of dementia prevention programs is increasing physical activity, it is essential to obtain a preliminary assessment of the safety profile of combining intranasal insulin with physical activity; to ensure that undue risks are not incurred. Utilizing a randomized double-blind placebo-controlled design, a sample of 116 non-diabetic, fasted college-aged adults were randomly assigned to receive a dose of 0-to-120 IU of NovoLog (Insulin Aspart) before being randomized to 20 min of exercise or sitting control condition. The safety of intranasal insulin was assessed by examining the incidence of potential symptoms of hypoglycemia and changes in peripheral blood glucose. The efficacy of a combination therapeutic approach was assessed using behavioral measures of inhibition and sustained attention alongside neuroelectric indices of attentional engagement. The frequency of symptoms reported following administration of intranasal insulin were not observed to interact with exercise so as to make their occurrence any more or less prominent, nor was the frequency observed to relate to the dose of intranasal insulin. However, doses of intranasal insulin of 100 IU or more were observed to result in a 7-fold increase in the likelihood of a level 1 hypoglycemic event for those individuals in the exercise condition. This study provides preliminary evidence to suggest that exercise is not associated with an increase in risk when combined with lower doses of intranasal insulin.

Clinical trial registration The trial is registered at ClinicalTrials.gov, number NCT04292535.

  相似文献   
78.
79.
BACKGROUND AND OBJECTIVE: the close anatomic relationship of the pancreas with the splenic vessels and the spleen is responsible for splenic complications in the course of acute pancreatitis. Our objective was to report two cases of severe acute pancreatitis complicated by splenic infarction. PATIENTS: in a three-month period of time two patients were diagnosed with splenic infarction secondary to acute pancreatitis. In both cases splenic infarction diagnosis and follow-up were carried out using computed tomography. RESULTS: in the first case images clearly showed a narrowing of the splenic artery due to the inflammatory pancreatic condition. In the second case no involvement of the splenic vessels could be demonstrated, hence the only possible etiological explanation was a hypercoagulability state generated by pancreatitis. CONCLUSIONS: it would be advisable that splenic complications were added to the list of relevant extrapancreatic manifestations. CT is very useful for the diagnosis and follow-up of splenic complications arising in acute pancreatitis.  相似文献   
80.
OBJECTIVE: The present work analysed endomyocardial biopsies of patients with acute Chagas' disease in order to evaluate the frequency and intensity of T. cruzi antigens, CD4+ and CD8+ T cells to determine the characteristics of this recurrent disease in Venezuela. MATERIAL AND METHODS: Twelve endomyocardial biopsies of patients with Chagas' disease, 12 to 51 years old, (7M and 5F) were analysed. T. cruzi antigens and CD4+ (helper) and CD8+ (cytotoxic-suppressor) T cells were detected by the immunoperoxidase technique.The presence and intensity of lymphocytic myocarditis was evaluated according to the degree of myocardial fibre injury caused by inflammatory infiltrate. RESULTS: Myocarditis was present in 100% of the cases. The mean numbers of CD4+ T cell and CD8+ T cell were 11.00 (+/- 10.29); 14.69 (+/- 13.08) and the CD4/CD8 T cell ratio was 0.75. T. cruzi antigens were detected in 58%. There was a good correlation between the numbers of CD4 and CD8 T cells of each case and a lack of correlation with the amount of T. cruzi antigens. CONCLUSION: All patients with acute Chagas' disease show some degree of myocarditis that seems to be directly related to the presence of parasitic antigens. Both CD4 and CD8 T cells participate in this process.We are following these patients to see if patients with severe myocarditis and more parasite antigens in the acute phase will develop chronic heart failure.  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