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   7260篇
  免费   125篇
  国内免费   13篇
耳鼻咽喉   14篇
儿科学   83篇
妇产科学   79篇
基础医学   255篇
口腔科学   44篇
临床医学   583篇
内科学   3070篇
皮肤病学   275篇
神经病学   335篇
特种医学   325篇
外科学   537篇
综合类   92篇
预防医学   892篇
眼科学   420篇
药学   253篇
  4篇
中国医学   25篇
肿瘤学   112篇
  2023年   405篇
  2022年   463篇
  2021年   786篇
  2020年   659篇
  2019年   889篇
  2018年   799篇
  2017年   315篇
  2016年   93篇
  2015年   119篇
  2014年   545篇
  2013年   325篇
  2012年   162篇
  2011年   231篇
  2010年   136篇
  2009年   190篇
  2008年   238篇
  2007年   272篇
  2006年   106篇
  2005年   116篇
  2004年   57篇
  2003年   66篇
  2002年   31篇
  2001年   18篇
  2000年   19篇
  1999年   33篇
  1998年   23篇
  1997年   23篇
  1996年   14篇
  1995年   12篇
  1994年   12篇
  1993年   10篇
  1992年   18篇
  1991年   10篇
  1990年   12篇
  1989年   15篇
  1988年   18篇
  1987年   14篇
  1986年   19篇
  1985年   22篇
  1984年   14篇
  1983年   20篇
  1982年   15篇
  1981年   17篇
  1980年   13篇
  1979年   8篇
  1978年   2篇
  1977年   5篇
  1976年   3篇
  1974年   3篇
  1973年   1篇
排序方式: 共有7398条查询结果,搜索用时 15 毫秒
81.
82.
ObjectivesThe aim of this study was to evaluate the long-term outcomes of patients with acute coronary syndromes (ACS) with multivessel disease undergoing percutaneous coronary intervention (PCI).BackgroundControversy exists regarding the benefit of multivessel PCI across the spectrum of ACS.MethodsA total of 9,094 patients with ACS and multivessel disease (≥70% stenosis in 2 or more major epicardial vessels) undergoing PCI from the Alberta COAPT (Contemporary Acute Coronary Syndrome Patients Invasive Treatment Strategies) registry (April 1, 2007, to March 31, 2013) were reviewed. Comparisons were made between patients who underwent complete revascularization and those with incomplete revascularization. Complete revascularization was defined as multivessel PCI with a residual angiographic jeopardy score ≤10%. Associations between revascularization status and all-cause death or new myocardial infarction (primary composite endpoint) and all-cause death, new myocardial infarction, or repeat revascularization (secondary composite endpoint) were evaluated.ResultsOf the study cohort, 66.0% underwent complete revascularization. Compared with incomplete revascularization, the primary composite endpoint occurred less frequently with complete revascularization (event rate within 5 years 15.4% vs. 22.2%; inverse probability-weighted hazard ratio [IPW-HR]: 0.78; 95% confidence interval [CI]: 0.73 to 0.84; p < 0.0001). The secondary composite endpoint was less likely to occur with complete revascularization (event rate within 5 years 23.3% vs. 37.5%; IPW-HR: 0.61; 95% CI: 0.58 to 0.65; p < 0.0001). Complete revascularization was associated with a reduction in all-cause death (IPW-HR: 0.79; 95% CI: 0.73 to 0.86; p = 0.0004), new myocardial infarction (IPW-HR: 0.76; 95% CI: 0.69 to 0.84; p < 0.0001), and repeat revascularization (IPW-HR: 0.53; 95% CI: 0.49 to 0.57; p < 0.0001).ConclusionsResults from this large contemporary registry of patients with ACS and PCI for multivessel disease suggest that complete revascularization occurs commonly and is associated with improved clinical outcomes (including survival) within 5 years.  相似文献   
83.
BACKGROUND AND AIMS: The evidence that proton pump inhibitor (PPI) therapy affects symptoms of nonulcer dyspepsia is conflicting. We conducted a systematic review to evaluate whether PPI therapy had any effect in nonulcer dyspepsia and constructed a health economic model to assess the cost-effectiveness of this approach. METHODS: Electronic searches were performed using the Cochrane Controlled Trials Register, MEDLINE, EMBASE, CINAHL, and SIGLE until September 2002. Dyspepsia outcomes were dichotomized into cured/improved versus same/worse. Results were incorporated into a Markov model comparing health service costs and benefits of PPI with antacid therapy over 1 year. RESULTS: Eight trials were identified that compared PPI therapy with placebo in 3293 patients. The relative risk of remaining dyspeptic with PPI therapy versus placebo was .86 (95% confidence interval, .78-.95; P = .003, random-effects model) with a number needed to treat of 9 (95% confidence interval, 5-25). There was statistically significant heterogeneity between trials (heterogeneity chi(2) = 30.05; df = 7; P < .001). The PPI strategy would cost an extra US dollar 278/month free from dyspepsia if the drug cost US dollar 90/month. If a generic price of US dollar 19.99 is used, then a PPI strategy costs an extra US dollar 57/month free from dyspepsia. A third-party payer would be 95% certain that PPI therapy would be cost-effective, provided they were willing to pay US dollar 94/month free from dyspepsia. CONCLUSIONS: PPI therapy may be a cost-effective therapy in nonulcer dyspepsia, provided generic prices are used.  相似文献   
84.
85.
86.
87.

Background and Aims

Physical inactivity, unhealthy diet, smoking and heavy drinking are four key unhealthy lifestyle behaviors (ULB) that may influence body weight and obesity development. More recently, sedentary time has been recognized as another potentially emerging ULB related to obesity. We therefore investigated the association of multiple ULB with overweight/obesity and abdominal obesity among Brazilian adolescents.

Methods and Results

This cross-sectional study involved 62,063 students (12–17 years). Physical inactivity, high screen time, low fiber intake, binge drinking and smoking were self-reported and combined to a ULB risk score, ranging from zero to five. Participants were classified as overweight/obese or with abdominal obesity using sex and age-specific cut-off points for BMI and waist circumference, respectively. Poisson regression models were used to examine the associations between ULB with overweight/obesity and abdominal obesity, adjusted for socio-demographic variables. Overall, 2.3%, 18.9%, 43.9%, 32.3% and 2.6% of participants reported zero, one, two, three and four/five ULB, respectively. Higher ULB risk score was associated with overweight/obesity and abdominal obesity in a dose–response gradient. Among 32 possible combinations of ULB, the three most prevalent combinations (physical inactivity + low fiber intake; high screen time + low fiber intake; physical inactivity + high screen time + low fiber intake) were positively associated with general and abdominal obesity.

Conclusions

Our findings suggest a synergistic relationship between ULB and general and abdominal obesity. Preventive efforts targeting combined ULB should be sought to reduce the prevalence of general and abdominal obesity in Brazilian youth.  相似文献   
88.
89.
BACKGROUND & AIMS: The effect of hepatitis C viral (HCV) infection on patient and allograft survival after orthotopic liver transplantation is controversial. Hepatitis C recurrence after transplant is inevitable, but studies to date have not found a survival difference between recipients with and without HCV. METHODS: Using data from the United Network for Organ Sharing, we performed a retrospective cohort study of 11,036 patients who underwent 11,791 liver transplants between 1992 and 1998. The hazard rates of patient and allograft survival for patients who were HCV-positive as compared with patients who were HCV-negative were assessed by proportional-hazards analysis, with adjustment for potential confounding variables, including donor, recipient, and transplant center characteristics. RESULTS: Liver transplantation in HCV-positive recipients was associated with an increased rate of death (hazard ratio, 1.23; 95% confidence interval [CI], 1.12-1.35) and allograft failure (hazard ratio, 1.30; 95% CI, 1.21-1.39), as compared with transplantation in HCV-negative recipients. This reduction in survival persisted after adjusting for potential confounders. There was an interaction between HCV and sex (P < 0.001) with the effect of HCV on survival being most pronounced in female recipients (patient survival hazard ratio, 1.56; 95% CI, 1.35-1.81; allograft survival hazard ratio, 1.51; 95% CI, 1.34-1.70). CONCLUSIONS: HCV infection significantly impairs patient and allograft survival after liver transplantation.  相似文献   
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