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   1258篇
  免费   80篇
  国内免费   7篇
耳鼻咽喉   6篇
儿科学   42篇
妇产科学   29篇
基础医学   137篇
口腔科学   6篇
临床医学   112篇
内科学   296篇
皮肤病学   13篇
神经病学   149篇
特种医学   50篇
外科学   166篇
综合类   5篇
一般理论   1篇
预防医学   113篇
眼科学   4篇
药学   40篇
中国医学   2篇
肿瘤学   174篇
  2023年   16篇
  2022年   24篇
  2021年   60篇
  2020年   37篇
  2019年   54篇
  2018年   55篇
  2017年   38篇
  2016年   47篇
  2015年   49篇
  2014年   57篇
  2013年   67篇
  2012年   113篇
  2011年   96篇
  2010年   51篇
  2009年   41篇
  2008年   57篇
  2007年   52篇
  2006年   31篇
  2005年   37篇
  2004年   29篇
  2003年   24篇
  2002年   31篇
  2001年   9篇
  2000年   20篇
  1999年   21篇
  1998年   7篇
  1997年   8篇
  1996年   5篇
  1995年   8篇
  1994年   4篇
  1992年   13篇
  1991年   8篇
  1990年   13篇
  1989年   20篇
  1988年   14篇
  1987年   9篇
  1986年   10篇
  1985年   25篇
  1984年   17篇
  1983年   10篇
  1982年   6篇
  1980年   4篇
  1979年   4篇
  1978年   7篇
  1977年   4篇
  1976年   6篇
  1975年   4篇
  1972年   6篇
  1971年   2篇
  1966年   5篇
排序方式: 共有1345条查询结果,搜索用时 18 毫秒
91.
Several epidemiological studies described poor asthma control in children. However, the diagnosis of childhood asthma in these studies is uncertain, and asthma control in children of an outpatient clinic population during treatment by a paediatrician is unknown. (1) to investigate the hypothesis that asthma control in a paediatric outpatient clinic population is better than epidemiological surveys suggest; (2) to find possible explanations for suboptimal asthma control. Asthmatic children aged 6–16 years, known for at least 6 months by a paediatrician at the outpatient clinic, were selected. During a normal visit, both the responsible physicians and parent/children completed a standardised questionnaire about asthma symptoms, limitation of daily activities, treatment, asthma attacks and emergency visits. Overall, excellent asthma control of 8.0% in this study was not significantly better than of 5.8% in the European AIR study (Chi‐square, p = 0.24). Separate GINA goals like minimal chronic symptoms and no limitation of activities were better met in our study. Good to excellent controlled asthma was perceived by most children/parents (83%), but was less frequently indicated by the paediatrician (73%), or by objective criteria of control (45%) (chi‐square, p = 0.0001). The agreement between patient‐perceived and doctor assessed control was low, but improved in poorly controlled children. Patients were not able to perceive the difference between ‘excellent asthma control’ and ‘good control’ (p = 0.881).Too little children with uncontrolled disease got step‐up of their asthma treatment. Although separate GINA goals like ‘minimal chronic symptoms’ and ‘no limitation of activities’ were significantly better in our study, overall, asthma control in this outpatient clinic population, treated by a paediatrician, was not significantly better than in the European AIR study. Poorly controlled disease was related to several aspects of asthma management, which are potentially accessible for improvements.  相似文献   
92.
BACKGROUND: Plasma B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are promising markers for heart failure diagnosis, prognosis, and treatment. Insufficient data on the intraindividual biological variation (CV(i)) of BNP and NT-proBNP hamper interpretation of changes in concentration on disease progression or treatment optimization. We therefore investigated CV(i) values in stable heart failure patients. METHODS: We recruited 43 patients with stable chronic heart failure living in Curacao (22 males, 21 females; median age, 63 years; range, 20-86 years; New York Heart Association classes I-III). Samples were collected for within-day CV(i) (n = 6; every 2 h starting at 0800), day-to-day CV(i) (n = 5; samples collected between 0800 and 1000 on 5 consecutive days), and week-to-week CV(i) (n = 6; samples collected between 0800 and 1000 on the same day of the week for 6 consecutive weeks). NT-proBNP (Roche) and BNP (Abbott) were measured by immunoassay. RESULTS: Median (range) concentrations were 134 (0-1630) ng/L (BNP) and 570 (17-5048) ng/L (NT-proBNP). Analytical variation, week-to-week CV(i), and reference change values were 8.4%, 40%, and 113% (BNP), and 3.0%, 35%, and 98% (NT-proBNP). Week-to week CV(i)s were inversely related to median BNP concentrations. Week-to week CV(i)s for BNP were 44% (BNP < or =350 ng/L) and 30% (BNP >350 ng/L). Both BNP and NT-proBNP increased between 0800 and 1000. Median NT-proBNP/BNP ratios were inversely related to median BNP concentrations. CONCLUSIONS: The high CV(i)s hamper interpretation of changes in BNP and NT-proBNP concentrations and may partly explain their poor diagnostic values in chronic heart failure. Easily modifiable determinants to lower CV(i) have not been identified. The value of BNP and NT-proBNP for chronic heart failure diagnosis, and especially for follow-up and treatment optimization of individuals, remains largely to be established.  相似文献   
93.
94.
Subgroup analyses are an essential part of fully understanding the complete results from confirmatory clinical trials. However, they come with substantial methodological challenges. In case no statistically significant overall treatment effect is found in a clinical trial, this does not necessarily indicate that no patients will benefit from treatment. Subgroup analyses could be conducted to investigate whether a treatment might still be beneficial for particular subgroups of patients. Assessment of the level of evidence associated with such subgroup findings is primordial as it may form the basis for performing a new clinical trial or even drawing the conclusion that a specific patient group could benefit from a new therapy. Previous research addressed the overall type I error and the power associated with a single subgroup finding for continuous outcomes and suitable replication strategies. The current study aims at investigating two scenarios as part of a nonconfirmatory strategy in a trial with dichotomous outcomes: (a) when a covariate of interest is represented by ordered subgroups, eg, in case of biomarkers, and thus, a trend can be studied that may reflect an underlying mechanism, and (b) when multiple covariates, and thus multiple subgroups, are investigated at the same time. Based on simulation studies, this paper assesses the credibility of subgroup findings in overall nonsignificant trials and provides practical recommendations for evaluating the strength of evidence of subgroup findings in these settings.  相似文献   
95.
96.
Background: During fibrogenesis in the liver, in which excessive remodelling of the extracellular matrix (ECM) occurs, both the quantity of type III collagen (CO3) and levels of matrix metalloproteinases (MMPs), including MMP‐9, increase significantly. MMPs play major roles in ECM remodelling, via their activity in the proteolytic degradation of extracellular macromolecules such as collagens, resulting in the generation of specific cleavage fragments. These neo‐epitopes may be used as markers of fibrosis. Aims: The current study investigated whether a novel enzyme‐linked immunosorbent assay (ELISA) assay specifically measuring an MMP‐9‐cleaved sequence of type III collagen located at position 610 (CO3‐610C) may be used as a marker of liver fibrosis. Material and methods: Bile duct ligation (BDL) was performed in 20 rats, with sham operations performed on another 20 rats. Serum levels of the neo‐epitope CO3‐610C (MMP‐mediated type III collagen degradation) were determined with an ELISA at 14 and 28 days post‐surgery. Liver fibrosis was evaluated by quantitative digital image analysis of Sirius red‐stained formalin‐fixed and paraffin‐embedded sections. Western blot and densitometry were performed to confirm the CO3‐610C ELISA data. Results: CO3‐610C levels in serum increased significantly in BDL rats compared with those undergoing sham operations (% increase: 14 days=153%, P<0.0001; 28 days=134%, P=0.0014). This increase was confirmed by Western blot and densitometry of the identified bands. The CO3‐610C levels correlated to liver fibrosis (R2=0.23 and P=0.01), as evaluated by quantitative digital histology. Discussion and conclusion: The data suggest that MMP‐9‐mediated CO3 turnover is a central event in the pathogenesis of fibrosis, and that the neo‐epitope generated may be a novel biochemical marker.  相似文献   
97.
During noncardiac surgery, patients may be at risk for developing cardiac events, related to underlying coronary artery disease. Therefore, perioperative cardiac complications remain an area of clinical interest and concern in patients undergoing noncardiac surgery. Over the years, perioperative risk assessment has evolved significantly to detect surgical patients with myocardium at risk due the coronary artery disease. In addition, many efforts have been made to reduce the cardiac risk of patients undergoing noncardiac surgery. The present review article will focus on the definition of high cardiac risk surgery and will discuss patient-related cardiac risk factors. In addition, the preoperative cardiac tests available to detect patients with coronary artery disease and strategies to reduce perioperative cardiac risk, as recommended in most recent perioperative guidelines, will be outlined.  相似文献   
98.
99.
In the mucosa, the immune pathways discriminating between colonizing and invasive Candida, thus inducing tolerance or inflammation, are poorly understood. Th17 responses induced by Candida albicans hyphae are central for the activation of mucosal antifungal immunity. An essential step for the discrimination between yeasts and hyphae and induction of Th17 responses is the activation of the inflammasome by C. albicans hyphae and the subsequent release of active IL-1β in macrophages. Inflammasome activation in macrophages results from differences in cell-wall architecture between yeasts and hyphae and is partly mediated by the dectin-1/Syk pathway. These results define the dectin-1/inflammasome pathway as the mechanism that enables the host immune system to mount a protective Th17 response and distinguish between colonization and tissue invasion by C. albicans.  相似文献   
100.
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