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   806篇
  免费   54篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   14篇
妇产科学   8篇
基础医学   108篇
口腔科学   21篇
临床医学   60篇
内科学   148篇
皮肤病学   18篇
神经病学   69篇
特种医学   14篇
外科学   89篇
综合类   9篇
预防医学   70篇
眼科学   116篇
药学   72篇
中国医学   10篇
肿瘤学   33篇
  2023年   5篇
  2022年   6篇
  2021年   18篇
  2020年   11篇
  2019年   29篇
  2018年   25篇
  2017年   20篇
  2016年   39篇
  2015年   32篇
  2014年   39篇
  2013年   47篇
  2012年   57篇
  2011年   86篇
  2010年   32篇
  2009年   27篇
  2008年   59篇
  2007年   66篇
  2006年   40篇
  2005年   44篇
  2004年   39篇
  2003年   43篇
  2002年   32篇
  2001年   7篇
  2000年   5篇
  1999年   7篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1993年   5篇
  1992年   5篇
  1991年   9篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
排序方式: 共有863条查询结果,搜索用时 31 毫秒
1.
A 70‐year‐old man with a history of coronary artery bypass grafting 15 years back and arteriovenous (AV) fistula creation in the left arm 1 month back presented with acute coronary syndrome (ACS). He had not received dialysis before his referral. We felt the most likely etiology for these complaints was increased cardiac oxygen demand from an increased cardiac output related to the newly formed left AV fistula. Coronary angiography was done to detect any significant stenosis in the native or grafted vessels. This revealed that the left subclavian artery was totally occluded in the ostioproximal segment and the coronary arteries did not have occlusions to explain the ACS setting. CT angiography confirmed the angiographic findings of the totally occluded left subclavian artery followed by a well‐developed and patent left internal mammary artery to left anterior descending artery. This led to the consideration of a steal syndrome from the coronary artery by the subclavian artery distal to the occlusion. A successful percutaneous endovascular intervention on the left subclavian artery occlusion was performed. Subsequently, the patient became asymptomatic and experienced a dramatic increase in left ventricular ejection fraction.  相似文献   
2.
Objectives: This study aimed to determine the prevalence of chronic diseases and occupational accidents and injuries, and to examine their association with the quality of life among a sample of Iranian farmers.

Methods: A cross-sectional study was conducted among 736 male farmers. Data on the prevalence of chronic diseases and occupational accidents and injuries was collected using an author-developed questionnaire, and the SF-36 questionnaire was used to obtain information on quality of life.

Results: The prevalence of chronic diseases was 96.1%. Musculoskeletal diseases (MSDs), eye diseases and neurology diseases were the most prevalent diseases. Almost half of the farmers (42.7%) had experienced an occupational accident during the last 12 months and cuts and fractures accounted for the most frequent injuries. Sick leave was reported by 28.2% of the farmers and from those with history of accidents, 21.4% were hospitalized. A significant association was found between age and education level with quality of life. Most of the chronic diseases showed a significant and inverse association with quality of life, however, the strongest association was found for MSDs and mental disorders. Furthermore, the most important injury associated with quality of life was cuts and fractures.

Conclusions: Based on the results, MSDs, mental disorders, and cut and fractures were the main determinants of the farmers’ quality of life. Hence, a better quality of life among farmers is especially dependent on eliminating ergonomics risk factors leading to developing musculoskeletal disorders, improving psychosocial work climate, and promoting occupational and personal safety culture.  相似文献   

3.
4.
The third trimester of pregnancy is a period of rapid development of fiber bundles in the fetal white matter. Using a recently developed motion‐tracked slice‐to‐volume registration (MT‐SVR) method, we aimed to quantify tract‐specific developmental changes in apparent diffusion coefficient (ADC), fractional anisotropy (FA), and volume in third trimester healthy fetuses. To this end, we reconstructed diffusion tensor images from motion corrected fetal diffusion magnetic resonance imaging data. With an approved protocol, fetal MRI exams were performed on healthy pregnant women at 3 Tesla and included multiple (2–8) diffusion scans of the fetal head (1–2 b = 0 s/mm2 images and 12 diffusion‐sensitized images at b = 500 s/mm2). Diffusion data from 32 fetuses (13 females) with median gestational age (GA) of 33 weeks 4 days were processed with MT‐SVR and deterministic tractography seeded by regions of interest corresponding to 12 major fiber tracts. Multivariable regression analysis was used to evaluate the association of GA with volume, FA, and ADC for each tract. For all tracts, the volume and FA increased, and the ADC decreased with GA. Associations reached statistical significance for: FA and ADC of the forceps major; volume and ADC for the forceps minor; FA, ADC, and volume for the cingulum; ADC, FA, and volume for the uncinate fasciculi; ADC of the inferior fronto‐occipital fasciculi, ADC of the inferior longitudinal fasciculi; and FA and ADC for the corticospinal tracts. These quantitative results demonstrate the complex pattern and rates of tract‐specific, GA‐related microstructural changes of the developing white matter in human fetal brain.  相似文献   
5.
6.
Diabetes, as a low‐grade chronic inflammatory disease, causes disruption in proper function of immune and metabolic system. Chromium is an important element required for normal lipid and glucose metabolism. Chromium deficiency is correlated with elevation in cardiometabolic risk, which results from increased inflammation. This systematic review was conducted to discover the potential roles of chromium on inflammatory biomarkers. Eligible studies were all in vitro, animal and human studies published in English‐language journals from inception until October 2018. PubMed, Scopus, Embase, ProQuest and Google Scholar databases were searched to fined interventional studies from the effects of chromium on inflammatory biomarkers such as tumour necrosis factor a (TNF‐a), C‐reactive protein (CRP), interleukins, monocyte chemoattractant protein–1 (MCP‐1), intercellular adhesion molecule‐1 (ICAM‐1) and adipocytokines in hyperglycaemia and diabetes. Out of 647 articles found in the search, only 14 articles were eligible for analysis, three in vitro studies, eight animal studies and three human studies. Twelve of the 14 studies included in this review, chromium significantly decreased inflammatory factors. The findings of this review indicate, based on in vitro and in vivo studies, that chromium might have potential anti‐inflammatory properties, but some of the studies did not show anti‐inflammatory effects for chromium (two studies). There are only three studies in humans with controversial results. Therefore, more consistent randomized double‐blind controlled trials are needed to reach relevant clinical recommendations, as well as to determine the precise mechanism, of chromium on inflammation in diabetes.  相似文献   
7.
The differentiation procedure of intuitionistic fuzzy sets (IFSs) is very important in multiple criteria decision-making (MCDM). The aim here is to introdu  相似文献   
8.
9.

Objective:

Helicobacter pylori (H. pylori) is the most common chronic bacterial infection in humans. Chronic colonization increases the risk of duodenal ulcer and gastric cancer. The risk factors for acquiring the infection have been extensively studied. However, there are conflicting results on the role of breastfeeding in the prevention of H. pylori infection. We conducted a study to evaluate the effects of breastfeeding on the H. Pylori infection in Kurdish children in Sanandaj, IR Iran.

Methods:

A historical cohort study was carried out from January 2011 through December 2012. Totally 221 children who were going to attain 2 years old during the study period were randomly enrolled. They were divided into two groups, i.e. breastfed and non-breastfed. We used H. pylori stool antigen test to detect infection in the selected group of children after age of 2 years and cessation of breastfeeding. Each group was subdivided into two subgroups, infected and non-infected. The associations of breastfeeding with H. pylori infection was assessed using statistical software.

Findings:

We found no difference in the odds of infection between breastfed and non-breastfed groups (OR=0.809, 95% CI [0.453–1.444]). An association between age and the prevalence of infection was found (P=0.008). There was an increase in the odds of infection as the family size grew (OR=1.93, 95% CI [1.04–3.6]) as well as increasing housing density (OR=2.12, 95% CI [1.10–4.10]).

Conclusion:

The data suggests that breastfeeding in infancy does not protect against H. pylori infection for long duration among studied children in Iran. The protective effects of breastfeeding, if any, are at most transient.  相似文献   
10.
The role of MSX1 in tooth agenesis in Iranians   总被引:1,自引:0,他引:1  
INTRODUCTION: MSX1 gene has a critical role in craniofacial development, the aim of this case-control study is to test the hypothesis that MSX1 mutation contributes to congenital tooth agenesis in Iranians. MATERIALS AND METHODS: The study group consisted of 20 affected individuals with tooth agenesis of lower second premolars or upper lateral incisors with mean age of 24.6. The control group consisted of 20 unaffected individuals. DNA was extracted from all 40 individuals; the polymerase chain reaction (PCR) for MSX1 was carried out with Phenol: Chloroform: Isoamylalchol (PCI) extraction method. Ban II restriction digest and agarose gel electrophoresis of the 20 affected individuals verified the presence of mutation in all 20 affected individuals. The unaffected controls did not show any mutation. Statistical analysis performed by the chi-squared method. RESULTS: Ban II did not digest PCR product (DNA) in the control group (195 bp band on electrophoresis gel) but digested the affected allele (106 bp and 89 bp bands). There is a statistically significant correlation between tooth agenesis and MSX1 mutation (P < 0.001). CONCLUSION: The results indicated that MSX1 gene mutation contributes to tooth agenesis in Iranian individuals. As the timing of tooth calcification can vary, radiographic finding of congenital tooth agenesis can be confirmed by this molecular method during different dental ages to achieve certainty.  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