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   2726篇
  免费   155篇
  国内免费   32篇
耳鼻咽喉   17篇
儿科学   27篇
妇产科学   183篇
基础医学   263篇
口腔科学   99篇
临床医学   273篇
内科学   620篇
皮肤病学   29篇
神经病学   264篇
特种医学   137篇
外科学   503篇
综合类   5篇
一般理论   1篇
预防医学   94篇
眼科学   43篇
药学   100篇
中国医学   1篇
肿瘤学   254篇
  2024年   11篇
  2023年   29篇
  2022年   75篇
  2021年   138篇
  2020年   75篇
  2019年   87篇
  2018年   114篇
  2017年   67篇
  2016年   87篇
  2015年   85篇
  2014年   115篇
  2013年   135篇
  2012年   213篇
  2011年   212篇
  2010年   127篇
  2009年   112篇
  2008年   160篇
  2007年   179篇
  2006年   150篇
  2005年   188篇
  2004年   131篇
  2003年   126篇
  2002年   66篇
  2001年   16篇
  2000年   12篇
  1999年   23篇
  1998年   17篇
  1997年   15篇
  1996年   18篇
  1995年   8篇
  1994年   11篇
  1993年   6篇
  1992年   9篇
  1991年   13篇
  1990年   10篇
  1989年   6篇
  1988年   4篇
  1987年   5篇
  1986年   9篇
  1985年   8篇
  1984年   10篇
  1983年   8篇
  1982年   5篇
  1981年   3篇
  1979年   2篇
  1978年   3篇
  1975年   2篇
  1974年   2篇
  1965年   1篇
  1898年   1篇
排序方式: 共有2913条查询结果,搜索用时 15 毫秒
81.
The establishment of chest pain units (CPUs) in the USA and UK has led to improvements in the prognosis of patients with chest pain and myocardial infarction, optimizing access to specialized diagnostic and therapeutic facilities and reducing costs. To establish a uniform implementation of this type of service in Germany, the German Cardiac Society (DGK) founded a 'CPU task force' in 2007, which developed a set of standard requirements and a nationwide certification programme. The recommendations for minimum standard requirements were published in 2008. As of November 2011, 132 CPUs were certified and 36 units were in the certification process. The aim of the DGK is to certify as many as 250 centres (units) throughout Germany within the next 2 years, to provide nationwide coverage. Applications from Switzerland are also being filed. Public awareness campaigns in cooperation with national league soccer teams were organized to raise awareness of the importance for early diagnosis and treatment of cardiac diseases and to publicize the existence of these new facilities. The German model of CPU certification allows nationwide and prospectively European-wide standardization of patient care and to improve adherence to international guidelines. Coupled with awareness campaigns and with the launch of a German CPU Registry, this process is aimed at improving the education and treatment of patients with chest pain and to provide scientific information about the quality of patient care.  相似文献   
82.
We recently reported that heart expresses functional receptors for the anorexigenic glucagon-like peptide (GLP)-2. Activation of these cardiac receptors affected basal heart performance through extracellular regulated kinase (ERK1/2) activation. Since ERK1/2 is considered one of the prosurvival kinases of postconditioning cardioprotective pathways, we hypothesized that GLP-2 directly protects the heart against ischemia/reperfusion (I/R) injury via prosurvival kinases. Wistar rat hearts were retrogradely perfused on a Langendorff perfusion apparatus. After 40-min stabilization, hearts underwent 30-min global ischemia and 120-min reperfusion (I/R group). In GLP-2 group, the hearts received 20-min GLP-2 (10(-7)?M) infusion at the beginning of the 120-min reperfusion. Perfusion pressure and left ventricular pressure (LVP) were monitored. Infarct size was evaluated by nitroblue-tetrazolium staining. Compared with the I/R group, GLP-2-treated hearts showed a significant reduction of infarct size and of postischemic diastolic LVP (index of contracture), together with a sharp improvement of developed LVP recovery (index of contractility). The protective effects were abolished by co-infusion with phosphatidylinositol 3-kinase inhibitor, Wortmannin (WT), the ERK1/2 inhibitor, PD98059, or the mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate. GLP-2 effects were accompanied by increased phosphorylation of protein kinase B (PKB/Akt), ERK1/2 and glycogen synthase kinase (GSK3β). After 7-min reperfusion, WT blocked Akt and GSK3β phosphorylation. After 30-min reperfusion, WT inhibited phosphorylation of all kinases. In conclusion, the data suggest that GLP-2, given in early reperfusion, as postconditioning, protects against myocardial I/R injury, limiting infarct size, and improving post-ischemic mechanical recovery. It seems that the GLP-2-protection of rat heart involves multiple prosurvival kinases and mitochondrial K(ATP) channels.  相似文献   
83.
84.
There is still some debate regarding the prognostic significance of left ventricular longitudinal systolic dysfunction as assessed by tissue Doppler (TD) imaging in patients with chronic heart failure (HF), since previous studies have included patients with postischemic wall motion abnormalities. Thus, this study was designed to ascertain whether TD-derived longitudinal systolic dysfunction may influence the outcome of patients with nonischemic chronic HF. In 200 consecutive patients with chronic HF secondary to dilated cardiomyopathy and no history of ischemic heart disease, peak systolic mitral annular velocity (S(m) ) was measured by pulsed TD at the septal and lateral annular sites. The end points were cardiac death or hospitalization for worsening HF. Mean follow-up duration was 30 months. In a time independent analysis, averaged S(m) calculated as the average of septal and lateral S(m) , resulted to be a significant predictor of outcome in the study population (area under receiver-operator characteristic curve: cardiovascular death, 0.69, P < 0.0001; cardiovascular events, 0.64, P = 0.0005). In a time-dependent analysis, average S(m) was associated with both cardiovascular death (hazard ratio 0.832, P = 0.0019) and cardiovascular events (hazard ratio 0.904, P = 0.039), independently of other clinical risk factors and echocardiographic parameters of systolic function. Septal S(m) but not lateral S(m) was independently associated with the outcome measures. In conclusion, the assessment of systolic mitral annular velocity by pulsed TD is a useful indicator for prognostic stratification of patients with nonischemic dilated cardiomyopathy and chronic HF.  相似文献   
85.
86.
We have analysed concentrations of the p53 protein in advanced oral carcinomas immunohistochemically and genetically to detect the percentage of overexpression of this antioncogene that indicates a high probability of mutation. This would point to it being a useful prognostic factor, if we consider the importance of the relation between genetic alterations of p53 and poor overall survival. Seventy-five non-consecutive patients with oral squamous cell carcinoma and metastatic nodes were enrolled if there was homogeneity in histopathological grading (G2) of their tumours, and they were treated according to a multidisciplinary treatment plan. Monoclonal antibodies, extraction of DNA, and amplification of the polymerase chain reaction (PCR) were used for the immunohistochemical and genetic analyses. There was a significant inverse correlation between p53 overexpression and response to chemotherapy and a stronger association between high P53 overexpression (%) and a genetic mutation of p53 (p = 0.0001). More than 50% overexpression indicated a strong probability of genetic mutation. There was no association between response to chemotherapy and age-groups or TNM classification (p = 0.2), but there was a significant one between sex and site of tumour (p < 0.001). Three prognostic factors were significantly related to prognosis: site of tumour (p = 0.01), response to chemotherapy (p = 0.002), and immuno p53 (p = 0.0001). A tumour that is characterised by p53 overexpression of more than 50% indicates a poor prognosis.  相似文献   
87.
88.
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