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   140篇
  国内免费   3篇
耳鼻咽喉   3篇
儿科学   20篇
妇产科学   43篇
基础医学   136篇
口腔科学   113篇
临床医学   136篇
内科学   342篇
皮肤病学   10篇
神经病学   73篇
特种医学   89篇
外科学   124篇
综合类   20篇
预防医学   130篇
眼科学   4篇
药学   124篇
肿瘤学   34篇
  2023年   13篇
  2021年   18篇
  2020年   22篇
  2019年   21篇
  2018年   27篇
  2017年   27篇
  2016年   27篇
  2015年   27篇
  2014年   34篇
  2013年   42篇
  2012年   58篇
  2011年   60篇
  2010年   46篇
  2009年   44篇
  2008年   43篇
  2007年   47篇
  2006年   43篇
  2005年   47篇
  2004年   42篇
  2003年   39篇
  2002年   41篇
  2001年   44篇
  2000年   37篇
  1999年   36篇
  1998年   30篇
  1997年   26篇
  1996年   22篇
  1995年   15篇
  1994年   19篇
  1993年   14篇
  1992年   13篇
  1991年   17篇
  1990年   24篇
  1989年   32篇
  1988年   23篇
  1987年   23篇
  1986年   24篇
  1985年   16篇
  1984年   17篇
  1983年   21篇
  1982年   11篇
  1981年   18篇
  1980年   10篇
  1979年   14篇
  1978年   17篇
  1977年   14篇
  1976年   14篇
  1975年   9篇
  1974年   13篇
  1972年   9篇
排序方式: 共有1401条查询结果,搜索用时 15 毫秒
991.
Changes in rank‐dependent income‐related health inequality measures over time may usefully be decomposed into contributions due to changes in health outcomes and changes in individuals' positions in the income distribution. This paper establishes the normative implications of this type of decomposition by embedding it within a broader analysis of changes in the ‘health achievement’ index. We further show that the choice of health inequality measure implies a particular vertical equity judgement, which may be expressed on a common scale in terms of the concentration index of health changes that would be inequality preserving. We illustrate the empirical implications of this choice by reporting results from a longitudinal analysis of changes in income‐related health inequality in Great Britain using the concentration, the Erreygers and Wagstaff indices of health attainments and the concentration index of health shortfalls. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
992.
993.
Nutritional concerns for the child and adolescent competitor   总被引:2,自引:0,他引:2  
With exercise for sports competition in children and adolescents, acute nutrient needs will change. Fluid intake to ensure the replacement of water and minerals (electrolytes) lost in sweat is important. Energy needs also increase because of the elevated energy expenditure with physical activity. Arguably carbohydrate is the recommended source of training needs, although research has yet to be done to show performance benefits in young athletes on a high-carbohydrate diet. In the majority of sports, an increased intake of food naturally occurs to accommodate the day-to-day nutrient needs of young athletes, and unlike non-athlete, young competitors typically come closer to meeting their requirements for micronutrients. Nonetheless, certain athletic groups may be at risk for shortfalls in their diet. Compared to athletes in team sports, participants in weight-control sports may be at greater risk of failing to meet requirements for energy, protein, and some micronutrients. Endurance athletes, particularly female distance runners, may have intake deficits for the minerals iron and calcium. Acute issues such as heat illness and chronic concerns that include impaired growth and development, and the risk of injuries that include stress fractures may be an outcome of inadequate nutrition during physical training.  相似文献   
994.
995.
996.
Weight loss is common in systemic immunoglobulin light chain amyloidosis but there are limited data on the impact of nutritional status on outcome. Using the Patient-Generated Subjective Global Assessment (PG-SGA) score, we prospectively examined nutritional status in 110 consecutive newly-diagnosed, treatment-naïve patients with immunoglobulin light chain amyloidosis attending the UK National Amyloidosis Centre. At study entry, 72 of 110 (66%) patients had a PG-SGA score of 4 or over, indicating malnutrition requiring specialist nutritional intervention. Number of amyloidotic organs, elevated alkaline phosphatase, presence of autonomic neuropathy and advanced Mayo disease stage were independently associated with poor nutritional status (P<0.05). Quality of life was substantially poorer among those with higher PG-SGA scores (P<0.001). Furthermore, PG-SGA score was a powerful independent predictor of patient survival (P=0.02). Malnutrition is prevalent and is associated with poor quality of life and reduced survival among patients with systemic immunoglobulin light chain amyloidosis. The PG-SGA score would be an appropriate tool to evaluate whether nutritional intervention could improve patient outcomes.  相似文献   
997.
Peripartum cardiomyopathy (PPCM) is a cause of pregnancy‐associated heart failure. It typically develops during the last month of, and up to 6 months after, pregnancy in women without known cardiovascular disease. The present position statement offers a state‐of‐the‐art summary of what is known about risk factors for potential pathophysiological mechanisms, clinical presentation of, and diagnosis and management of PPCM. A high index of suspicion is required for the diagnosis, as shortness of breath and ankle swelling are common in the peripartum period. Peripartum cardiomyopathy is a distinct form of cardiomyopathy, associated with a high morbidity and mortality, but also with the possibility of full recovery. Oxidative stress and the generation of a cardiotoxic subfragment of prolactin may play key roles in the pathophysiology of PPCM. In this regard, pharmacological blockade of prolactin offers the possibility of a disease‐specific therapy.  相似文献   
998.

Background

Left ventricular ejection fraction (LVEF) is a powerful prognostic marker after acute myocardial infarction and is dependent on infarct magnitude. Contrast-enhanced cardiac magnetic resonance (ceCMR) represents the current criterion standard means of LVEF and infarct size measurement. Infarct size and LVEF can be estimated from the 12-lead electrocardiogram (ECG) using the Selvester QRS score. We examined for the first time the relationship between serial measures of LVEF and infarct size by ceCMR and ECG in patients with reperfused anterior ST-elevation myocardial infarction (STEMI) and depressed LVEF.

Methods

Thirty-four patients (mean ± SD age, 59 ± 11.8 years; 70.6% male) underwent ceCMR and simultaneous ECG at mean 93 hours after admission and at 12 and 24 weeks. The QRS score was calculated on each ECG, from which infarct size and LVEF were estimated and compared with the equivalent ceCMR measurements.

Results

Infarct size on ceCMR was higher than that by QRS score at each time-point (P < .001) with modest correlation (r = 0.56-0.78, P < .001). Left ventricular ejection fraction was consistently significantly higher on CMR than on ECG, with weak correlation (r = 0.37-0.51, P < .05). We derived a novel equation relating QRS score to CMR-measured LVEF in the subacute phase of infarction: LVEF = 61 − (1.7 × QRS score) (%).

Conclusions

In patients with reperfused anterior ST-elevation myocardial infarction and depressed LVEF, ceCMR is moderately correlated with the QRS in the serial measurement of infarct size and LVEF. Infarct size (measured by ceCMR) and LVEF are consistently higher than those calculated on the QRS score in the acute and subacute phases of infarction.  相似文献   
999.
Single doses of bucindolol 50, 100 and 200 mg were compared to placebo and single doses of oxprenolol 40, 80 and 160 mg in seven patients with mild hypertension, in a double-blind randomized study. Both bucindolol and oxprenolol inhibited exercise induced tachycardia. The mean maximum inhibition of exercise heart rate was similar after each dose of both drugs (20%, P less than 0.001). Bucindolol produced a significantly greater reduction in blood pressure than either oxprenolol or placebo. This was most apparent in standing systolic and diastolic and post-exercise systolic blood pressures between 1 and 2 h after dosing and was dose-related. All seven patients experienced adverse effects related to hypotension within the first 2 h after ingestion of bucindolol 200 mg. Plasma concentrations of oxprenolol, bucindolol or 5-hydroxy-bucindolol, sampled 2 h after dosing, could not be related to either the changes in blood pressure or to the occurrence of symptoms. The results emphasise the need for careful dose-finding of new drugs prior to their more widespread evaluation in phase 3 studies.  相似文献   
1000.
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