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   3099篇
  免费   137篇
  国内免费   17篇
耳鼻咽喉   27篇
儿科学   39篇
妇产科学   25篇
基础医学   313篇
口腔科学   162篇
临床医学   361篇
内科学   721篇
皮肤病学   39篇
神经病学   305篇
特种医学   102篇
外科学   368篇
综合类   6篇
一般理论   1篇
预防医学   123篇
眼科学   21篇
药学   322篇
中国医学   9篇
肿瘤学   309篇
  2023年   20篇
  2022年   52篇
  2021年   81篇
  2020年   63篇
  2019年   59篇
  2018年   81篇
  2017年   66篇
  2016年   74篇
  2015年   69篇
  2014年   129篇
  2013年   150篇
  2012年   249篇
  2011年   225篇
  2010年   129篇
  2009年   110篇
  2008年   192篇
  2007年   197篇
  2006年   200篇
  2005年   180篇
  2004年   169篇
  2003年   155篇
  2002年   141篇
  2001年   24篇
  2000年   31篇
  1999年   28篇
  1998年   26篇
  1997年   21篇
  1996年   21篇
  1995年   26篇
  1994年   14篇
  1993年   19篇
  1992年   19篇
  1991年   15篇
  1990年   13篇
  1989年   17篇
  1988年   9篇
  1987年   15篇
  1986年   17篇
  1985年   12篇
  1984年   14篇
  1983年   15篇
  1982年   15篇
  1981年   13篇
  1980年   11篇
  1979年   7篇
  1978年   5篇
  1973年   4篇
  1972年   5篇
  1939年   3篇
  1937年   3篇
排序方式: 共有3253条查询结果,搜索用时 15 毫秒
81.
82.
83.
BackgroundItaly has been one of the most affected countries in the world by COVID-19. There has been increasing concern regarding the impact of COVID‐19 on patients with inflammatory bowel disease (IBD), particularly in patients treated with immunosuppressants or biologics. The aim of our study is to understand the incidence of COVID-19 in a large cohort of patients with IBD. Furthermore, we analyzed possible risk factors for infection and severity of COVID-19.MethodsThis was an observational study evaluating the impact of COVID-19 on IBD patients in a single tertiary center. A 23 multiple-choice-question anonymous survey was administered to 1200 patients with IBD between March 10th and June 10th 2020.Results1158 questionnaires were analyzed. The majority of patients had Crohn's disease (CD) (60%) and most of them were in clinical remission. Among the 26 patients (2.2%) who tested positive for COVID-19, only 5 (3CD) were on biological treatment and none required hospitalization. Two patients died and were on treatment with mesalazine only. Of the 1158 patients, 521 were on biological therapy, which was discontinued in 85 (16.3%) and delayed in 195 patients (37.4%). A worsening of IBD symptoms was observed in 200 patients on biological therapy (38.4%). Most of these patients, 189 (94.5%), had stopped or delayed biological treatment, while 11 (5.5%) had continued their therapy regularly (p<0.001).ConclusionsOur data are in line with the current literature and confirm a higher incidence compared to the general population. Biological therapy for IBD seems to not be a risk factor for infection and should not be discontinued in order to avoid IBD relapse.  相似文献   
84.
The incidence of pediatric adrenal cortical carcinoma (ACC) in southern Brazil is 10-15 times higher than that of pediatric ACC worldwide. Because childhood ACC is associated with Li-Fraumeni syndrome, we examined the cancer history and p53 status of 36 Brazilian patients and their families. Remarkably, 35 of 36 patients had an identical germ-line point mutation of p53 encoding an R337H amino acid substitution. Differences within intragenic polymorphic markers demonstrated that at least some mutant alleles arose independently, thus eliminating a founder effect. In tumor cells, the wild-type allele was deleted, and mutant p53 protein accumulated within the nuclei. Although these features are consistent with Li-Fraumeni syndrome-associated adrenal tumors, there was no history of increased cancer incidence among family members. Therefore, this inherited R337H p53 mutation represents a low-penetrance p53 allele that contributes in a tissue-specific manner to the development of pediatric ACC.  相似文献   
85.
Nerve-growth factor is known to cause a considerable increase in the number of neurons putting out processes and surviving in cell cultures of dissociated dorsal-root and sympathetic ganglia from embryonic chicks. Similar effects of nerve-growth factor have now been noted with cultures of dissociated dorsal-root ganglia from newborn mice or rats. In all three sensory ganglionic systems, the effects of the nerve-growth factor on fiber production and neuronal survival could be mimicked, in the absence of the factor, by adequate increase of the non-neuronal cells in the cultures. The results suggest a hypothesis that views the role of the nerve-growth factor as subordinate to that of the non-neuronal cells.  相似文献   
86.
87.
Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document will focus on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.  相似文献   
88.

Purpose

Late cure after a previously failed ablation of ventricular arrhythmias (VAs) is a relatively common phenomenon. The present study sought to delineate the incidence and electrophysiological characteristics of late cure in idiopathic VA patients.

Methods

Totally, 45 idiopathic VA cases (mean age 44?±?18 years, 27 males) either failed acutely or recurred within 12 h were enrolled in this study. Based on intensive clinical observations in the acute period, 19 (42%) patients demonstrated late cure in the first week after the procedure.

Results

The late cure patients had significantly better acute and cumulative ablation effects during the procedure than did those without a late cure. Additionally, they had a prediction that originated from the right ventricular outflow tract, aortic-mitral continuum, and left summit area relative to other sites (13/18 vs 6/27, p?<?0.01). In a median follow-up of 24 [14, 46] months, 7/19 (37%) patients had their VAs recurred. The late cure group had significantly more patients cured at long-term follow-up than those without (12/19 vs 0/26, p?<?0.01). A cutoff value of the “time to eliminate VAs” >?7.0 s was able to predict a long-term recurrence of the VAs with 62.5% sensitivity and 85.7% specificity.

Conclusions

The late cure of VAs occurs in more than one third of patients who have a seemingly unsuccessful ablation session, which is clustered in the first week after the procedure. However, long-term recurrence of VAs occurred in 37% of the late cure patients, emphasizing the importance of long-term follow-up.
  相似文献   
89.
90.
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