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   3053篇
  免费   164篇
  国内免费   4篇
耳鼻咽喉   34篇
儿科学   116篇
妇产科学   109篇
基础医学   377篇
口腔科学   36篇
临床医学   160篇
内科学   716篇
皮肤病学   75篇
神经病学   266篇
特种医学   215篇
外科学   467篇
综合类   82篇
一般理论   1篇
预防医学   108篇
眼科学   122篇
药学   209篇
中国医学   5篇
肿瘤学   123篇
  2023年   23篇
  2022年   27篇
  2021年   77篇
  2020年   34篇
  2019年   57篇
  2018年   92篇
  2017年   62篇
  2016年   73篇
  2015年   89篇
  2014年   110篇
  2013年   120篇
  2012年   219篇
  2011年   209篇
  2010年   105篇
  2009年   95篇
  2008年   147篇
  2007年   161篇
  2006年   162篇
  2005年   128篇
  2004年   145篇
  2003年   115篇
  2002年   94篇
  2001年   106篇
  2000年   85篇
  1999年   60篇
  1998年   29篇
  1997年   17篇
  1996年   15篇
  1995年   11篇
  1993年   12篇
  1992年   43篇
  1991年   34篇
  1990年   38篇
  1989年   33篇
  1988年   27篇
  1987年   31篇
  1986年   34篇
  1985年   25篇
  1984年   29篇
  1983年   20篇
  1982年   19篇
  1979年   14篇
  1978年   16篇
  1977年   15篇
  1975年   13篇
  1974年   13篇
  1973年   13篇
  1970年   12篇
  1968年   13篇
  1967年   13篇
排序方式: 共有3221条查询结果,搜索用时 31 毫秒
51.
52.
Entertainment-education is an effective health communication strategy that combines or embeds educational messages into entertainment programs to bring about social and behavior change. For years, scholars have considered how entertainment-education works. Some contemporary theories posit that entertainment-education does not engender behavior change directly but does so through mediating variables. This study adds to the literature on this topic by exploring the direct relationship between exposure and social norms instead of their relationship through behavior as a mediator. Novel to this study is the use of encoded exposure, a continuous and recognition-based measure of exposure that includes ever watching, recall, involvement, and dose in its operationalization. Using cross-sectional data from Kyunki … Jeena Issi Ka Naam Hai, an entertainment-education program in India, this exploratory analysis indicates a positive and significant relationship between encoded exposure and social norms. How can this finding be applied to future programs? Questions remain, and replication is needed, but if it is not essential to go through behavior in order to change social norms, then implications emerge for the theory and practice of entertainment-education.  相似文献   
53.
54.
Background: Extrahepatic portal venous obstruction (EHPVO) developing due to thrombotic occlusion of the portal vein in children is generally considered a benign disease. Whether hepatic dysfunction develops in these patients in the absence of a gastrointestinal bleed has not been well studied. Materials and methods: Forty‐three patients with EHPVO who had not bled in the last 3 months were studied. Patients were divided into those with (group I) or without ascites (group II). Matched cirrhotic patients with ascites (group III) served as controls. Clinical, biochemical, ultrasonographic, and histopathological evaluation was carried out. Portal biliopathy was assessed in five patients in group I and in 12 patients in group II by cholangiography. Results: Of 43 EHPVO patients, ascites was seen in nine (21%) patients (group I). Thirty‐four patients had no ascites (group II). Serum ALT (54±24 vs. 34±10 IU/l, P<0.01), albumin (3.2±0.3 vs. 3.7±0.4 g/dl, P<0.01), and prothrombin time difference (9.0±4.5 vs. 2.4±1.9 s, P<0.05) were deranged in patients in group I compared with group II. Patients in group I were 4 years older, and the duration of portal hypertension was longer than in group II (11.5 vs. 5.6 year, P<0.05). Portal biliopathy changes were significantly more severe in group I than in group II patients. Ascites was high gradient in all the patients in group I and the serum‐ascitic albumin gradient was comparable between groups I and III. None of the EHPVO patients, but four cirrhotic patients, developed spontaneous bacterial peritonitis during a follow‐up of 11±4 months. Conclusions: Hepatic dysfunction in the form of ascites and deranged liver functions is not uncommon in patients with EHPVO, more so in patients with prolonged portal hypertension. Based on our data it would be worthwhile to study whether prolonged portal vein thrombosis in EHPVO patients could lead to progressive liver disease.  相似文献   
55.
56.
Long-term follow-up of untreated patients with sleep apnoea syndrome   总被引:3,自引:0,他引:3  
Obstructive sleep apnoea (OSA) is a common disorder with numerous potential sequelae. Although the majority of these consequences can be reduced with appropriate treatment, only limited data exist regarding the natural progression ofthis disorder in untreated individuals. We hereby report a long-term follow-up of all untreated patients (n = 40) followed-up in the Technion Sleep Clinic, using both subjective and objective measurements. In addition, we report a long-term follow-up of 11 patients who attempted dietary weight loss. The average time interval between the first and second polysomnographies for the untreated group was 5.0 +/- 2.8 yrs, and 2.5 +/- 2.3 yrs for the weight reduction group. There was no significant change in Body Mass Index (BMI) or Respiratory Disturbance Index (RDI) between the two Polysomnographic (PSG) evaluations in the untreated patients. However, eight patients developed hypertension (n=5) or ischaemic heart disease (IHD) (n=3) between the two evaluations. RDI, age and BMI at the time ofthe initial evaluation were not predictive of changes in RDI, snoring intensity or minimal oxygen saturation. However, the patients who developed hypertension/IHD had significantly higher RDI than the patients who did not (46 +/- 27 vs. 23 +/- 17 h(-1), P < 0.005). In the weight-loss group, BMI decreased by a mean of 3.1 kg m(-2), and RDI decreased by 20events h(-1), P<0.05 for both.There was a significant correlation between the weight loss and improvement in RDI (R = 0.75, P = 0.005). We conclude that in untreated obstructive sleep apnoea patients RDI does not necessarily increase over time, but associated hypertension or ischaemic heart disease may develop.When weight loss is successfully achieved, sleep apnoea significantly improves with a high correlation between the extent of weight loss and the improvement in apnoea status.  相似文献   
57.
Minimally invasive mitral valve surgery   总被引:1,自引:0,他引:1  
BACKGROUND: To reduce surgical trauma and the drawbacks associated with sternotomy, we performed robotically controlled, video-assisted mitral valve surgery, using either the port-access or the transthoracic clamp technique. METHODS AND RESULTS: Between September 1997 and September 2000, 221 patients (78 males, 143 females) underwent mitral valve surgery through a small right minithoracotomy using the port-access endovascular cardiopulmonary bypass system. Mitral valve exposure was facilitated with an endoscope attached to a voice-controlled robotic arm (AESOP 3000) allowing stabilization and voice-activated camera positioning. Twenty-six patients underwent mitral valve repair and 195 had valve replacement. In 197 patients, mitral valve surgery was the primary operation, while 24 were redo cases. Skin-to-skin mean operating time was 3.5 +/- 1.2 hours and aortic cross-clamp time was 58 +/- 16 min, mean intensive care unit stay was 22 +/- 7 hours and hospital stay 6.4 +/- 1.2 days. There was no re-exploration for bleeding. There was no late death or re-operation on mean follow-up of 16.4 +/- 12.2 months. Patients showed improvement in their NYHA functional class from 2.6 +/- 0.5 to 1.4 +/- 0.8 postoperatively. Outcomes were compared with those of our previous 220 patients who underwent mitral valve surgery with the median sternotomy approach. CONCLUSIONS: The use of video and robotic assistance in port-access mitral valve surgery not only minimizes the length of the incision, but also gives full visualization of the entire mitral valve apparatus. This approach provides comparable results with the sternotomy approach, as well as marked advantages of reduced intensive care unit stay. ,ower blood transfusion requirement, better cosmesis and earlier hospital discharge.  相似文献   
58.
BACKGROUND: Coronary angioplasty and stent implantation is effective as primary intervention in acute myocardial infarction. Because of fewer puncture site complications and improved patient comfort, transradial access has been increasingly used as an alternative to transfemoral access for percutaneous coronary interventions. METHODS AND RESULTS: We studied 103 patients (94 men, 9 women: mean age 52.5 +/- 11.96 years) with a diagnosis of acute myocardial infarction (<12 hours after onset), who underwent primary percutaneous coronary intervention. Transradial access was used in all patients with a normal Allen's test and transfemoral access was used additionally only if intra-aortic balloon counterpulsation was required. Follow-up duration was 6 months. Transradial access was successfully achieved in all patients. Radial artery cannulation took <2 min in more than 85% patients. During percutaneous coronary intervention, cannulation to balloon inflation times and total procedure times were 11.3 +/- 5.2 min and 19.9 +/- 10.8 min, respectively. Stents were implanted in 99 (96.1%) patients andplain balloon angioplastywas performed in 3.9%. The primary success rate was 98.1%, with no major bleeding complications. Total length of hospitalization averaged 2.4 +/- 0.8 days. In-hospital major adverse clinical events rate was 5.9%. Six-month clinical follow-up was achieved for 84 (86.6%) patients. Six (7.1%) patients died during follow-up. Follow-up coronary angiography was performed in 22 (26.2%) patients. After 6 months, 7 patients required revascularizationof the target lesion. The rate of survival without myocardial infarction, bypass surgery or repeat coronary angioplasty was 88.5% at 6 months. CONCLUSIONS: Transradial access may represent a safe and feasible technique for performing primary percutaneous coronary intervention with good acute results and without major bleeding complications.  相似文献   
59.
Thirty-one patients with chronic severe anemia of more than 3 months' duration (hemoglobin less than 7 gm/dl) and no underlying heart disease were studied by means of M-mode, two-dimensional, and Doppler echocardiography; an equal number of normal control subjects was also studied. There are conflicting reports regarding the influence of chronic severe anemia on systolic myocardial function, but diastolic function has not been systematically assessed. It is also uncertain whether anemia alone can cause heart failure in a structurally normal heart. We therefore performed a detailed study of echocardiographic indexes of systolic and diastolic left ventricular function in these patients. We found that patients with anemia have significantly faster heart rates and lower diastolic and mean blood pressures than normal subjects. They also have a significantly elevated cardiac output and stroke volume and larger left ventricles. Left ventricular contractility, assessed by the end-systolic stress-dimension relationship, was enhanced. There was no systematic evidence of diastolic dysfunction by Doppler assessment of mitral inflow. There was also no clinical evidence of congestive heart failure. We conclude that chronic severe anemia leads to a hyperdynamic state with systolic hyperfunction and no impairment of diastolic function. Anemia does not lead to congestive heart failure in the absence of underlying heart disease.  相似文献   
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