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   3140篇
  免费   155篇
  国内免费   14篇
耳鼻咽喉   47篇
儿科学   60篇
妇产科学   77篇
基础医学   594篇
口腔科学   110篇
临床医学   235篇
内科学   706篇
皮肤病学   94篇
神经病学   240篇
特种医学   99篇
外科学   321篇
综合类   20篇
预防医学   228篇
眼科学   46篇
药学   223篇
中国医学   24篇
肿瘤学   185篇
  2023年   25篇
  2022年   29篇
  2021年   72篇
  2020年   47篇
  2019年   71篇
  2018年   111篇
  2017年   84篇
  2016年   83篇
  2015年   97篇
  2014年   114篇
  2013年   163篇
  2012年   257篇
  2011年   275篇
  2010年   141篇
  2009年   81篇
  2008年   172篇
  2007年   193篇
  2006年   183篇
  2005年   174篇
  2004年   156篇
  2003年   165篇
  2002年   158篇
  2001年   26篇
  2000年   31篇
  1999年   26篇
  1997年   8篇
  1996年   8篇
  1992年   14篇
  1991年   21篇
  1990年   8篇
  1989年   18篇
  1988年   21篇
  1987年   15篇
  1986年   16篇
  1985年   25篇
  1984年   20篇
  1983年   13篇
  1981年   6篇
  1979年   8篇
  1978年   11篇
  1977年   8篇
  1976年   12篇
  1974年   11篇
  1973年   9篇
  1972年   7篇
  1971年   15篇
  1970年   12篇
  1969年   7篇
  1968年   7篇
  1966年   9篇
排序方式: 共有3309条查询结果,搜索用时 15 毫秒
51.
52.
BACKGROUND AND AIMS OF THE STUDY: Left ventricular (LV) contraction is slowed in patients with aortic stenosis (AS). Although the possible role of LV systolic function abnormalities in the assessment of AS severity has been evaluated, current echocardiographic techniques cannot offer precise quantification of LV motion velocity. The study aim was to evaluate an automated segmental motion analysis (ASMA) system to assess AS severity. METHODS: Twenty-two patients with AS, sinus rhythm and preserved LV ejection fraction were studied prospectively. Patients underwent both conventional Doppler echocardiography to measure transaortic gradient and aortic valve area by the continuity equation, and ASMA of the interventricular septum. The ASMA line graph mode displays changes in area through the cardiac cycle. The RR interval and time from the R-wave to peak maximum area shortening were measured, and an ASMA index was calculated. RESULTS: A significant and strong inverse correlation was found between aortic valve area and ASMA index (r = -0.78; 95% CI -0.90 to -0.55; p <0.001). The area under the ROC curve in the diagnosis of severe AS (aortic valve area < or =0.8 cm2) was 0.97 (95% CI 0.90-1.0). Sensitivity, specificity, positive and negative predictive values and overall accuracy for an ASMA index >0.40 were 100, 91.7, 92.3, 100 and 95.8%, respectively. CONCLUSION: The ASMA system may be valuable in evaluating AS, as it offers a strong correlation with aortic valve area calculated by the continuity equation, and very high sensitivity and specificity in the diagnosis of severe AS.  相似文献   
53.
Complications of acute pancreatitis usually occur in pancreas and its contiguous organs. The prevalence of colonic invasion is rare, however, the consequence is fatal, with mortality above 50%. The initial symptoms and onset times are variable and major affected sites are transverse colon and splenic flexure. The spread of inflammatory exudates into the colon is the main mechanism of colonic invasion. If the colonic stenosis develops, it is necessary to manage it surgically. We report a case who arrived at the hospital with watery diarrhea and abdominal distension in the recovery period of acute alcoholic pancreatitis and was diagnosed as a colonic obstruction in the splenic flexure. The patient underwent loop ileostomy instead of the resection of the lesion because of severe adhesion around the splenic flexure. The patient died due to sepsis 5 days after the operation.  相似文献   
54.

Purpose of Review

Here, we review the known relations between hypertension and obesity to inflammation and postulate the endogenous protective effect of melatonin and its potential as a therapeutic agent. We will describe the multiple effects of melatonin on blood pressure, adiposity, body weight, and focus on mitochondrial-related anti-inflammatory and antioxidant protective effects.

Recent Findings

Hypertension and obesity are usually associated with systemic and tissular inflammation. The progressive affection of target-organs involves multiple mediators of inflammation, most of them redundant, which make anti-inflammatory strategies ineffective. Melatonin reduces blood pressure, body weight, and inflammation. The mechanisms of action of this ancient molecule of protection involve multiple levels of action, from subcellular to intercellular. Mitochondria is a key inflammatory element in vascular and adipose tissue and a potential pharmacological target. Melatonin protects against mitochondrial dysfunction.

Summary

Melatonin reduces blood pressure and adipose tissue dysfunction by multiple anti-inflammatory/antioxidant actions and provides potent protection against mitochondria-mediated injury in hypertension and obesity. This inexpensive and multitarget molecule has great therapeutic potential against both epidemic diseases.
  相似文献   
55.
56.
ObjectivesBeetroot juice (BJ) supplementation has been reported to enhance skeletal muscle contractile function; however, it is currently unclear whether BJ supplementation elicits comparable improvements in power output during different types of skeletal muscle contractions. The purpose of the current study was to assess the effect of BJ supplementation on power output during concentric (CON) and eccentric (ECC) muscle contractions during a half-squat.DesignIn a randomized, double-blind placebo-controlled crossover design, eighteen adult males (age: 22.8 ± 4.9 y) completed two experimental testing sessions 2.5 h following the acute ingestion of 140 mL nitrate-rich BJ concentrate or a placebo.MethodsEach experimental session comprised four sets of eight all-out half-squat repetitions with each set completed with a different moment intertia (0.025, 0.050, 0.075 and 0.100 kg·m?2).ResultsCompared to placebo, BJ supplementation increased mean power output (MP) during the CON (ES: 0.61–1.01) and ECC (ES: 0.54–0.89; all p < 0.05) movement phases to a similar extent. Moreover, comparable increases in peak power output (PP) during the CON (ES: 0.86–1.24) and ECC (ES: 0.6–1.08; all p < 0.05) movement phases were observed following BJ supplementation.ConclusionAcute BJ supplementation increased mean and peak lower limb power output in the concentric and eccentric movement phases of a half-squat. These findings improve understanding of the effects of BJ supplementation on skeletal muscle contractile function and might have implications for enhancing sports performance in events where muscle power output is a key performance determinant.  相似文献   
57.
58.
During the past ten years, the efforts to improve and organize the national transplantation system in Croatia have resulted in a steadily growing donor rate, which reached its highest level in 2011, with 33.6 utilized donors per million population (p.m.p.). Nowadays, Croatia is one of the leading countries in the world according to deceased donation and transplantation rates. Between 2008 and 2011, the waiting list for kidney transplantation decreased by 37.2% (from 430 to 270 persons waiting for a transplant) and the median waiting time decreased from 46 to 24 months. The Croatian model has been internationally recognized as successful and there are plans for its implementation in other countries. We analyzed the key factors that contributed to the development of this successful model for organ donation and transplantation. These are primarily the appointment of hospital and national transplant coordinators, implementation of a new financial model with donor hospital reimbursement, public awareness campaign, international cooperation, adoption of new legislation, and implementation of a donor quality assurance program. The selection of key factors is based on the authors'' opinions; we are open for further discussion and propose systematic research into the issue.Transplantation is a widely accepted and successful life-saving treatment providing the best therapeutic benefit for hundreds of thousands of patients (1). Unfortunately, many people die while awaiting an organ transplant. A global shortage of organs available for transplantation raises many bioethical concerns, including the dilemma how to allocate limited resources to an unlimited number of needs and thus offer a fair and equal access to organ transplantation to all patients. Great efforts have been made to increase organ donation worldwide, but with only a moderate success in most of the countries. In contrast with this general trend, Croatia has recently experienced a boom in organ donation and transplantation. In 2011, Croatia had the highest rates of utilized cadaveric donors, kidney transplantations, and liver transplantations in the world (2-5) (Figure 1).Open in a separate windowFigure 1The number of kidney transplantations and the number of patients on the waiting list in Croatia between 2008 and 2011.Remarkably, only one decade ago, Croatia was lagging far behind other European countries with a low donation rate (2.7 donors per million population [p.m.p.] in 2000). The continuous improvement of the organization of the Croatian transplant program resulted in a steadily growing donor rate, which reached the highest level in 2011, with 33.6 utilized donors p.m.p (2). We analyzed the factors that might have contributed mostly to this great success.  相似文献   
59.
60.
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