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   1685篇
  免费   74篇
  国内免费   7篇
耳鼻咽喉   19篇
儿科学   269篇
妇产科学   58篇
基础医学   137篇
口腔科学   84篇
临床医学   119篇
内科学   349篇
皮肤病学   39篇
神经病学   166篇
特种医学   50篇
外科学   185篇
综合类   18篇
预防医学   50篇
眼科学   97篇
药学   65篇
中国医学   5篇
肿瘤学   56篇
  2024年   2篇
  2023年   21篇
  2022年   40篇
  2021年   72篇
  2020年   40篇
  2019年   49篇
  2018年   52篇
  2017年   41篇
  2016年   62篇
  2015年   61篇
  2014年   72篇
  2013年   108篇
  2012年   125篇
  2011年   123篇
  2010年   70篇
  2009年   62篇
  2008年   103篇
  2007年   109篇
  2006年   123篇
  2005年   106篇
  2004年   88篇
  2003年   75篇
  2002年   75篇
  2001年   19篇
  2000年   11篇
  1999年   13篇
  1998年   7篇
  1997年   7篇
  1996年   7篇
  1995年   6篇
  1994年   1篇
  1993年   3篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1979年   1篇
  1975年   1篇
排序方式: 共有1766条查询结果,搜索用时 15 毫秒
11.
GM1 gangliosidosis is an autosomal recessive glycosphingolipid storage disease caused by defects in the enzyme beta-galactosidase. Three clinical forms (infantile-, juvenile-, and adult-onset) of the disease are recognized. Patients with infantile GM1 gangliosidosis present at birth or shortly thereafter with somatic and bony changes, followed by severe neurological deterioration ultimately leading to death within the first 2 years of life. We present the brain CT, MRI and MR spectroscopy (MRS) findings in a 17-month-old Turkish girl with infantile GM1 gangliosidosis. Neuroimaging findings in patients with infantile GM1 gangliosidosis have been reported only in a few cases. In this study, MRS of the thalamus was performed to study the metabolic changes in GM1 gangliosidosis. We showed a a decreased NAA/Cr ration and an increased Cho/Cr ratio. To our knowledge, this is the first report of magnetic resonance spectroscopy findings in type-1 GM1 gangliosidosis.  相似文献   
12.
Objective:C1q/tumor necrosis factor-related proteins (CTRPs) are recently described members of the adipokine family. CTRP-13, a new member of this family, has been shown to increase insulin sensitivity and had an anorexigenic effect on food intake in experimental studies. The aim was to investigate serum CTRP-13 levels in children with obesity, and its relationship with other adipokines, metabolic parameters, or binge eating disorder (BED).Methods:A cross-sectional study was conducted with 105 pubertal children attending a single center. Clinical (metabolic syndrome, BED) and biochemical (glucose, insulin, lipids, leptin, adiponectin, CTRP-13 levels) parameters were assessed.Results:Sixty children with obesity [24 males (40%); median age 14.7 (13.0-16.4) years] and 45 healthy controls [15 males (33.3%); median age 15.2 (14.1-16.5) years] were included. Serum adiponectin and CTRP-13 levels were significantly lower in children with obesity than controls (7.1 vs 20.1 μg/mL, p<0.001; 64.7 vs 103.8 ng/mL, p<0.001, respectively). CTRP-13 levels correlated negatively with body mass index (Spearman rho=-0.230, p=0.018) and positively with high-density lipoprotein-cholesterol levels (Spearman rho=0.218, p=0.026). There was no significant difference in serum CTRP-13 concentrations in terms of the presence of metabolic syndrome or BED.Conclusion:Childhood obesity seems to be causing dysregulation in adipokine production and function, including the down-regulation of CTRP-13. The positive correlation between CTRP-13 and HDL-C levels suggested a possible effect of this adipokine on lipid metabolism. Thus CTRP-13 may be a novel biomarker for dyslipidemia in childhood obesity.  相似文献   
13.
Organizational learning is the process of increasing effective organizational activities through knowledge and understanding. Innovation is the creation of any product, service or process, which is new to a business unit. Significant amount of research on organizational learning place a central meaning on the fact that there is a positive relationship between organizational learning and innovation. Both organizational learning and innovation are essential for organizations to prepare for change. The aim of this study is to determine to what extent the identified learning organization dimensions are associated with innovation. The study used a quantitative non‐experimental design employing statistical analysis via multiple regression and correlation methods to identify the relationships between the variables examined. Because the research was conducted in a non‐experimental way, learning organization dimensions are referred to as predictor variables, and innovation is referred to as the criterion variable. Watkins and Marsick's Dimensions of the Learning Organization Questionnaire was used in the study. Questionnaires were distributed to 498 hospital managers and, 243 valid responses were used in this study. Therefore, 243 hospital managers working at 250 Ministry of Health (public) hospitals across Turkey participated in the study. Results demonstrate that there are significant and positive correlations between learning organization dimensions and innovation. Intercorrelations between learning organization dimensions and correlations between learning organization dimensions and innovation were average and high, respectively. Results further indicate that the dimensions of the learning organizations explained 66.5% of the variance for the innovation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
14.
15.
Churg–Strauss syndrome (CSS) is a rare type of necrotizing vasculitis affecting small to medium-sized vessels typically characterized by asthma, lung infiltrates, necrotizing granulomas and hypereosinophilia. Herein, we describe a case of CSS presenting severe and aggressive course. A 35-year-old male patient with weight loss, dyspepsia, dyspnea and hemoptysis was admitted. The laboratory analyses indicated a remarkable eosinophilia, elevated levels of serum total IgE and positive cANCA. Thorax CT findings were suggestive of alveolar hemorrhage. Bronchoalveolar lavage revealed alveolar hemorrhage with eosinophilia and transbronchial lung biopsy showed eosinophilic vasculitis. Cardiac enzymes were increased and murmurs were audible revealing cardiomyopathy proven by echocardiography. Pulse cyclophosphamide and methyl prednisolone was immediately started. On the 21st day, intestinal perforation developed and urgent surgery was performed. During a follow-up, although a radiological improvement was observed in the chest X-ray, cardiac failure, peripheral neuropathy and skin lesions developed and high-dose intravenous immunoglobulin and anti-TNF therapy (adalimumab) were applied. Despite the therapy, he died from heart failure and septicemia at 68th day of therapy.  相似文献   
16.
The aim of this study was to evaluate the bone mineral density (BMD) in familial Mediterranean fever (FMF) and to search the effects of genetic factors, family history of FMF and types of clinical attacks on BMD. Forty-four attack-free patients with FMF and 36 healthy voluntary subjects were included in the study. BMD measurements of lumbar spine and left proximal femur were performed by dual energy X-ray absorptiometry (DEXA). There was no statistically significant difference between patient and control groups regarding median values of lumbar BMD (P?=?0.06), lumbar T (P?=?0.08) and Z (P?=?0.12) scores, femoral neck BMD (P?=?0.13), femoral T (P?=?0.22) and Z (P?=?0.16) scores and total femur BMD (P?=?0.14), T (P?=?0.19) and Z (P?=?0.27) scores. Patients with negative FMF family history had significantly lower femoral neck BMD (P?=?0.018), femoral neck T (P?=?0.009) and Z (P?=?0.01) scores and total femur BMD (P?=?0.033) than patients with positive FMF family history. There was no significant difference among the groups regarding mutation characteristic and types of attacks in lumbar BMD, T and Z scores, femoral neck BMD, T and Z scores and total femur BMD, T and Z scores (P?>?0.05). We found that the bone loss of patients with FMF is not different from that of the controls. The increased bone loss in the patients with negative family history for FMF should be further investigated with larger patient groups taking into consideration of the risk factors related to family history for osteoporosis.  相似文献   
17.
Background: The widespread use of percutaneous mitral commissurotomy (PMC) has led to an increase in restenosis cases. The data regarding follow‐up results of repeat PMC are quite limited. The aim of this retrospective analysis is to evaluate the immediate and midterm results of the second PMC, in patients with symptomatic mitral restenosis after a succesful first procedure. Methods: Twenty patients (95% female, mean age 37 ± 4 years) who have undergone a second PMC, 6.3 ± 2.5 years after a first successful intervention built the study group. All were in sinus rhythm, with a mean Wilkins score of 8.5 ± 1.2. Results: The valve area increased from 1.2 ± 0.2 to 1.9 ± 0.2 cm2 and mean gradient decreased from 10.5 ± 3.4 to 6.1 ± 1.1 mmHg. There were no complications except for a transient embolic event without sequela (5%) and two cases (10%) of severe mitral regurgitation. The immediate success rate was 90%. The mean follow‐up was 70 ± 29 months (36–156 months). The 5‐year restenosis and intervention (repeat PMC or valve replacement) rates were 9.1 ± 5.2% and 3.6 ± 3.3%, respectively. The intervention free 5‐year survival in good functional capacity (New York Heart Association [NYHA] I–II) was 95.1 ± 5.5% and restenosis and intervention free 5‐year survival with good functional capacity was 89.7 ± 6.8%. Conclusions: Although from a limited number of selected patients, these findings indicate that repeat PMC is a safe and effective method, with follow‐up results similar to a first intervention and should be considered as the first therapeutic option in suitable patients. (Echocardiography 2010;27:765‐769)  相似文献   
18.
AIM: To assess the myocardial velocities of the mitral annulus, left ventricular lateral wall, and midseptum in healthy children, and to compare these parameters with transmitral and pulmonary venous velocities. METHODS AND RESULTS: We examined 72 children, half being male, who had no systemic or cardiac pathologies. Their mean age was 6.73 +/- 5.10 years, with a range from 0.1 to 17.75 years, and a median age of 6.71 years. Each parameter was measured twice, at end inspiration and end expiration. The tissue velocities are similar in males and females (p > 0.05). The longitudinal velocity of the heart in early diastole has a positive correlation with age (p < 0.05; midseptum velocity r = 0.57, left ventricular lateral wall velocity r = 0.56, mitral annulus velocity r = 0.56), and the tissue velocities are not influenced by respiration (p > 0.05). The myocardial velocities of different segments of the left ventricle are not correlated with the transmitral or pulmonary venous flows (p < 0.05). When age is controlled for heart rate, age mainly affects the systolic velocity of the mitral annulus and the early diastolic velocity of the midseptum in longitudinal axis, as well as the early diastolic velocity of the midseptum in transverse axis (p > 0.05 for all, r = 0.34, 0.29, 0.30 respectively). CONCLUSION: This study, which has determined reference values for tissue velocities in a large healthy group of children, will now set the scene for further studies in children with heart disease.  相似文献   
19.
20.

Objectives

To investigate the prevalence of pregnancy-related low back pain (PRLBP) in women in Turkey, identify the factors associated with PRLBP and predict the risk of PRLBP.

Materials and methods

This cross-sectional study included a total of 1500 pregnant women admitted to a prenatal care clinic in a secondary care hospital in Turkey between August 2011 and September 2014. All participants were asked to complete a survey questionnaire. The pregnant women who reported recurrent or continuous pain in the lumbar spine or pelvis for more than 1 week were offered a clinical examination for PRLBP by the spine physiatrist. The main outcome measure was the presence of PRLBP. We collected data on sociodemographic factors, previous obstetric history, daily habits, history of LBP, and functional disability scores as assessed by the Oswestry Disability Index (ODI).

Results

The mean age of the 1500 women was 26.5 ± 5.5 years. The prevalence of PRLBP was 53.9%, mostly in the third trimester. Women with PRLBP in the third trimester were more disabled than those in the first and second trimesters (mean ODI 40.0 ± 16.7 vs. 34.9 ± 19.2 and 37.4 ± 15.3, respectively). Risk factors of PRLBP were history of LBP, PRLBP, and menstruation-related LBP as well as no housework assistance (OR = 5.394, 95% CI: 3.128–9.300, P < 0.001; 3.692, 2.745–4.964, P < 0.001; 2.141, 1.563–2.932, P < 0.001; 1.300, 1.029–1.64, P = 0.028, respectively).

Conclusion

This cross-sectional study is the largest study of PRLBP in the literature and showed that about 1 in 2 women have PRLBP in any stage of pregnancy. History of LBP related and unrelated to previous pregnancy and menstruation are strong risk factors for PRLBP. Receiving no housework assistance is another risk factor.  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