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   3581篇
  免费   89篇
  国内免费   25篇
耳鼻咽喉   180篇
儿科学   143篇
妇产科学   133篇
基础医学   233篇
口腔科学   80篇
临床医学   292篇
内科学   786篇
皮肤病学   53篇
神经病学   311篇
特种医学   180篇
外科学   785篇
综合类   27篇
预防医学   78篇
眼科学   171篇
药学   174篇
中国医学   3篇
肿瘤学   66篇
  2023年   15篇
  2022年   33篇
  2021年   60篇
  2020年   48篇
  2019年   68篇
  2018年   80篇
  2017年   73篇
  2016年   87篇
  2015年   100篇
  2014年   142篇
  2013年   204篇
  2012年   269篇
  2011年   224篇
  2010年   155篇
  2009年   163篇
  2008年   264篇
  2007年   300篇
  2006年   276篇
  2005年   303篇
  2004年   251篇
  2003年   192篇
  2002年   134篇
  2001年   49篇
  2000年   40篇
  1999年   29篇
  1998年   13篇
  1997年   23篇
  1996年   18篇
  1995年   11篇
  1994年   9篇
  1993年   7篇
  1992年   7篇
  1991年   5篇
  1990年   7篇
  1989年   13篇
  1988年   3篇
  1987年   6篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
排序方式: 共有3695条查询结果,搜索用时 15 毫秒
41.

Aim

Willis-Ekbom disease (RLS/WED) is common in chronic obstructive pulmonary disease (COPD). Patients with RLS/WED have poorer quality of sleep and more fatigue and depressive symptoms. The prevalence of RLS/WED in patients with COPD has been reported to vary between 29.1 and 36.8 %. However, during exacerbation, the prevalence can increase up to 54 %. These rates are higher than those seen in general population. We have not enough knowledge regarding the association between RLS and COPD. In this study, we aimed to determine the frequency of RLS in patients with stable COPD without comorbid conditions. In addition, we also aimed to determine possible related causative factors.

Method

We included 80 COPD patients without comorbid conditions who presented to our outpatient clinic between April 2013 and September 2013 for RLS/WED evaluation. Three cases that have polyneuropathy and one case that refused undergoing electromyography (EMG) examination were excluded from the study. Demographic data, P-A chest X-rays, pulmonary function tests (PFT), biochemical parameters (including hemogram), and dyspnea scales were evaluated for each patient. In addition, the RLS/WED rating scale and Epworth Sleep Scale (ESS) were applied. Further, each patient diagnosed with RLS/WED underwent a detailed neurological examination (performed by a neurologist) and an EMG examination to rule out polyneuropathy.

Results

Out of 76 COPD cases included in our study, 26.3 % (n?=?20) were diagnosed with RLS/WED (mean age 60.4?±?7.5 years, 20 males). The cases with RLS/WED had significantly lower body mass index (BMI) than cases without RLS/WED (p?=?0.009). There were no significant differences between cases with and without RLS/WED with respect to PFT, dyspnea scales, and arterial blood gas values. However, ESS was significantly different (p?=?0.016). There were no significant differences in RLS/WED scores and mean hs-CRP levels between COPD stages (p?=?0.424; p?=?0.518, respectively), while ESS was significantly different (p?=?0.016). ESS was significantly higher in stage B COPD than in stages A and D (p?=?0.005, p?=?0.008, respectively). Based on our model, we found that exacerbations and iron binding capacity (UIBC) were predictive factors for RLS/WED (p?<?0.100)

Conclusion

RLS/WED is a common disease in cases with stable COPD. Despite our hypothesis suggesting that the prevalence of RLS/WED in COPD is related with systemic inflammation, we did not find a significant association between hs-CRP and COPD cases with RLS/WED. However, we did find that UIBC is a predictive factor for the development of RLS/WED. Nonetheless, further studies are needed to understand the relationships between UIBC, low BMI, and the development of RLS/WED in COPD.
  相似文献   
42.

Purpose

To evaluate the efficiency of perforated punctal plug in acquired punctal stenosis.

Materials and methods

Forty-five eyes of 33 patients who had epiphora due to punctal stenosis were included in this study. After biomicroscopic examination and lacrimal dilatation punctal stenosis was managed with the perforated punctal plugs in all patients. In the following period epiphora, plug tolerance, lacrimal drainage were evaluated and graded. Lacrimal drainage was evaluated with fluorescein dye disappearing test.

Results

The age of the patients ranged between 31 and 80 (mean 55.78 ± 13.11). Preoperatively punctal dilatation and lacrimal system irrigations were performed on all patients. Lacrimal system irrigation was positive in all patients. Perforated punctal plugs were placed in the inferior puncti in all patients. The plugs were explanted 6 months after operation. The follow-up period ranged between 6 and 24 months. Plug tolerance was good in 97.8% of the eyes in the 1st month visit. Epiphora decreased remarkably in 88.9% of the patients 1 month after plug implantation, except one whose plug dropped off spontaneously in 2 weeks. Fluorescein disappearing times were found under 3 min in 97.8% of the eyes after plug explanations.

Conclusion

Punctum stenosis is one of the several disorders that cause lacrimal drainage obstruction. Perforated punctal plugs are found convenient and effective in managing punctal stenosis.  相似文献   
43.
International Journal of Legal Medicine - This study aimed to evaluate the accuracy and precision of the Cameriere European formula, Demirjian, Haavikko, and Willems methods for estimating dental...  相似文献   
44.
Tetanus is a preventable disease that continues to affect people in both developing and developed countries. The aim of the present study was to evaluate the immunity profile to tetanus in patients with Type II diabetes mellitus (DM) and to compare them with healthy controls. The tetanus antitoxin levels in 310 diabetic patients (104 males and 206 females) and in 200 healthy controls (72 males and 128 females) were measured by ELISA (Virotech, Germany). The mean antitoxin concentration in patient and control groups were 0.8238+/-1.61 and 0.9978+/-1.49 IU/ml, respectively. There was a statistically significant difference between the two groups (z=-3.520, P=.0001 and odds ratio was 2.367). There was a definitive inverse correlation between the duration of diabetes and tetanus antibody titers (Spearman's correlation analysis, r=-.155, P=.006). A gender-dependent difference in the susceptibility to tetanus was present in the diabetic group with antibody titers being significantly higher in males compared with females (z=-2.267, P=.023). For both of control (chi(2)=20.207, P=.003) and patient (chi(2)=43.532, P=.0001) groups, there was a significant inverse correlation between the tetanus immunity levels and age. Statistically, a significant drop in antibody titers of both groups was found as the period past from the last immunization increased (Pearson correlation analysis: for patient group r=-.364, P=.0001; for control group r=-.143, P=.044). The tetanus antitoxin levels were significantly increased in individuals who had primary immunization during childhood (for patient group chi(2)=17.191, P=.0001; for control group chi(2)=9.911, P=.007). A significant reduction in the level of antitoxin immunity to tetanus in association with an increased susceptibility to infections in patients with diabetes may implicate the need for improving vaccination rates in this patient group.  相似文献   
45.
BACKGROUND: Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of arterial aneurysms through increased proteolysis of extracellular matrix proteins. Increased proteolysis due to elevated matrix degrading enzyme activity in the arterial wall may act as a susceptibility factor for the development of coronary aneurysms. Plasmin strongly stimulates pro-MMP enzyme conversion to the active form. Plasmin hyperactivity due to decreased plasminogen activator inhibitor-1 (PAI-1) may cause MMP over activity and coronary aneurysms. The aim of this study was to investigate the association between PAI-1 and presence of coronary aneurysms. METHODS: Twenty-three patients with aneurysmal coronary artery disease and stable angina were enrolled into study (Group 1). Twenty-two patients without coronary aneurysm were selected as a control group (Group 2). PAI-1 was measured in peripheral venous blood. RESULTS: The plasma PAI-1 level was lower in the coronary artery aneurysmatic patients compared to the control group (8.41 +/- 4.28 vs. 13.32 +/- 10.05 ng/ml, p = 0.037). Serum C-reactive protein (CRP) values were not significantly different between groups (3.83 +/- 1.08 vs. 4.01 +/- 1.35 mg/l, p >0.05). CONCLUSION: Increased matrix degrading enzyme activity can cause arterial wall destruction through increased proteolysis of extracellular matrix proteins. Unregulated plasmin hyperactivity due to decreased inhibition by PAI-1 may play an important role in coronary aneurysm formation.  相似文献   
46.
Diaphragmatic hernias are the most common abnormalities of gastrointestinal system especially in elderly patients. The radiographic findings of diaphragmatic hernias on esophagram are well known, but when incidentally found in an asymptomatic patient on axial computed tomography (CT) sections, the appearance of diaphragmatic hernia may mimic many other conditions. Our purpose is to present the CT findings of sliding hernia in an incidentally found asymptomatic patient, and to differentiate it from the other abnormalities that can be located in the distal paraesophageal area with the same appearance characteristics.  相似文献   
47.
48.
Prospective data of 3,120 consecutive patients who had elective coronary artery bypass were analyzed to identify patient profile, cost, outcome and predictors of those readmitted to the intensive care unit. Group A (n=3,002) had a single intensive care unit admission and group B (n=118) were readmitted within 30 days after surgery. Parsonnet score, EuroSCORE, age, body mass index, chronic obstructive airway disease, peripheral vascular disease, renal dysfunction, unstable angina, congestive cardiac failure, and poor left ventricular function were higher in group B. Bypass and crossclamp times were longer, and the prevalence of inotropic and balloon pump support, arrhythmias, myocardial infarction, re-exploration, blood loss and transfusion, cerebrovascular accident, wound infection, sternal dehiscence, and multisystem failure were higher in group B. Despite a 4-fold increase in cost of care, the mortality rate (32.4%) of patients readmitted to intensive care was 23-times higher than routine patients (1.4%). Crossclamp time>80 min, Parsonnet score>10, EuroSCORE>9, sternal dehiscence, ventricular arrhythmias, and renal failure predicted readmission.  相似文献   
49.
50.
The pathophysiology and treatment of depression have been the focus of intense research and while there is much that remains unknown, modern neurobiological approaches are making progress. This work demonstrates that stress and depression are associated with atrophy of neurons and reduced synaptic connectivity in brain regions such as the hippocampus and prefrontal cortex that contribute to depressive behaviors, and conversely that antidepressant treatment can reverse these deficits. The role of neurotrophic factors, particularly brain‐derived neurotrophic factor (BDNF), has been of particular interest as these factors play a key role in activity‐dependent regulation of synaptic plasticity. Here, we review the literature demonstrating that exposure to stress and depression decreases BDNF expression in the hippocampus and PFC and conversely that antidepressant treatment can up‐regulate BDNF in the adult brain and reverse the effects of stress. We then focus on rapid‐acting antidepressants, particularly the NMDA receptor antagonist ketamine, which produces rapid synaptic and antidepressant behavioral actions that are dependent on activity‐dependent release of BDNF. This rapid release of BDNF differs from typical monoaminergic agents that require chronic administration to produce a slow induction of BDNF expression, consistent with the time lag for the therapeutic action of these agents. We review evidence that other classes of rapid‐acting agents also require BDNF release, demonstrating that this is a common, convergent downstream mechanism. Finally, we discuss evidence that the actions of ketamine are also dependent on another growth factor, vascular endothelial growth factor (VEGF) and its complex interplay with BDNF.  相似文献   
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