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   228篇
  免费   22篇
  国内免费   4篇
儿科学   29篇
妇产科学   5篇
基础医学   39篇
口腔科学   8篇
临床医学   21篇
内科学   63篇
皮肤病学   4篇
神经病学   9篇
特种医学   2篇
外科学   21篇
综合类   4篇
预防医学   16篇
眼科学   6篇
药学   20篇
中国医学   1篇
肿瘤学   6篇
  2024年   2篇
  2023年   1篇
  2022年   2篇
  2021年   6篇
  2020年   3篇
  2019年   6篇
  2018年   14篇
  2017年   13篇
  2016年   11篇
  2015年   18篇
  2014年   25篇
  2013年   21篇
  2012年   24篇
  2011年   22篇
  2010年   13篇
  2009年   13篇
  2008年   15篇
  2007年   10篇
  2006年   8篇
  2005年   4篇
  2004年   4篇
  2003年   2篇
  2002年   1篇
  2001年   3篇
  2000年   5篇
  1999年   3篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1987年   1篇
排序方式: 共有254条查询结果,搜索用时 15 毫秒
51.
52.

Introduction

Intraorifice barriers (IOBs) are usually used before internal bleaching for coronal sealing and the prevention of cervical resorption. The aim of this study was to investigate the effect of different IOBs on the fracture resistance (FR) of endodontically treated anterior teeth bleached with various bleaching agents (BAs).

Methods

After performing root canal treatment for 72 extracted bovine upper incisors, the coronal 3 mm of gutta-percha was removed, and samples were classified into 3 based on the type of IOB: calcium-enriched mixture, mineral trioxide aggregate, and resin-modified glass ionomer. After applying IOBs, samples of each group were subdivided into 4 based on the BA: carbamide peroxide 45% (CP), hydrogen peroxide 35% (HP), sodium perborate (PB), and distilled water as the control. At the end of bleaching, the access cavities were restored with composite resin. The FR was measured with a universal testing machine at a crosshead speed of 5 mm/min. The data were analyzed using 2-way analysis of variance and least significant difference post hoc tests (P < .05).

Results

The effect of BAs on the FR was significant (P < .05); however, the effect of the IOB and the interactive effect of these variables were not significant (P > .05). The FR in the HP and PB groups was significantly different from the control (P < .05) but that of CP was not significantly different from the control (P > .05).

Conclusions

Mineral trioxide aggregate and calcium-enriched mixture act similarly to resin-modified glass ionomer as an IOB. CP, unlike HP and PB, did not significantly decrease the FR.  相似文献   
53.
54.
The objective of this study was to determine the incidence of gestational diabetes mellitus (GDM) and compare fetal, maternal and neonatal complications amongst women with GDM and pregnant women with normal glucose tolerance in an urban Iranian population. In a prospective cohort study, universal screening for gestational diabetes mellitus was performed for 1310 pregnant women who were referred from private clinics and community health care centers to Fatemiyeh Hospital in Shahrood City. Screening was performed with a 50 g oral Glucose Challenge Test (GCT) with 130 mg/dl cut-off point, then a diagnostic 100 g Oral Glucose Tolerance Test (OGTT) was done according to Carpenter and Coustan criteria. The incidence of GDM was 4.8%. There were differences in risk factors: age >30 years, family history of diabetes, obesity, previous macrosomia, glycosuria between the two groups (P<0.001). Women with GDM had a higher rate of stillbirth (P<0.001; odds ratio 17.1, 95% CI=4.5-65.5), hydramnios (P<0.001; odds ratio 15.5, 95% CI=4.8-50.5), gestational hypertension (P<0.001; odds ratio 6, 95% CI=2.3-15.3), macrosomia (P<0.05; odds ratio 3.2, 95% CI=1.2-8.6) and caesarean section (P<0.001). We have found that the incidence of GDM in an urban Iranian population is similar to developed countries. Complications were more common in the GDM group than in the normal group and outcomes for women with persistent diabetes post-partum were particularly poor. We recommend screening for GDM in Iran, but further evaluation of selective screening and cost effectiveness will need to be performed. Measures to improve the outcome of GDM pregnancy will also need to be addressed in the future.  相似文献   
55.

Background:

The number of malaria cases is declining worldwide; however, it remains as a serious health problem. Diagnosing unusual cases is the most important issue to manage the problem. This study designed to describe the number of falciparum and vivax malaria infected patients referred to Malaria Reference Laboratory in Tehran University of Medical Science from 2000 to 2012.

Methods:

A retrospective study was conducted based on the collected questionnaires from each patient referred to the laboratory. Diagnosing results and demographic information for positive cases were analyzed using SPSS software. Problematic cases were evaluated for any difficulties in diagnosis or in clinical signs. Scanning and molecular methods were performed whenever there was an atypical case referred to the laboratory. Some of the samples had various difficulties for diagnosing such as presence of fussed gametocytes and schizonts of Plasmodium falciparum in peripheral blood and CCHF like hemoragic disorders.

Results:

Plasmodium vivax caused a large proportion of the cases (76.1%) in contrast with P. falciparum that included smaller proportion (22.8%) and the rest (1.1) belonged to mixed infection. Most of the positive cases (69.6%) were belonged to Afghani people. Men (94.6%) showed more infection than women (5.4%), moreover the most infection (44.5%) was seen at a range of 21–30 yr.

Conclusion:

In the case of existing atypical issues to diagnose, it is needed to perform more precise microscopical examination beyond the current standard conditions. Sometimes molecular method is required to verify the exact agent of the disease.  相似文献   
56.

Background and Aims

Occult hepatitis B infected (OBI) patients can not completely eradicate hepatitis B virus-DNA (HBV-DNA) from their liver and peripheral blood. The main aim of this study was to investigate the Interleukin (IL)-10and IL-17A serum levels in patients suffering from OBI.

Material and Methods

In this observational study, plasma samples of 3700 blood donors were tested for hepatitis Bsurface antigen (HBsAg) and antibodies to the hepatitis B core antigen (anti-HBc), using enzyme-linked immunosorbent assay (ELISA). The HBsAg-/anti-HBc+ samples were selected and screened for HBV-DNA, using the polymerase chain reaction (PCR). HBV-DNA positive samples were assigned as OBI cases and IL-10 and IL-17 serum levels were detected using ELISA.

Results

The results demonstrated that, 352 (9.5%) out of 3700 blood samples were HBsAg-/anti-HBc+ and HBV-DNA was detected in 57/352 (16.1%) of the HBsAg-/anti-HBc+ samples. Our results showed that the IL-10 and IL-17A serum levels increased significantly in the OBI cases in comparison to the controls (P < 0.001).

Conclusions

According to the results of this study the higher level of IL-10 production may suppress the functioning of the immune system against HBV in OBI patients. The elevated IL-17A serum level also indicates a long period of infection in the patients observed.  相似文献   
57.
Serological studies revealed that toxoplasmosis has world wide distribution. Although the infection by Toxoplasma gondii is widely prevalent in humans and animals, the disease is uncommon and most of the acquired infections are asymptomatic. The important aspect of this parasitic infection is the probable danger of congenital transmission and its severe effects on the fetus. There have been many reports about the prevalence of anti-T. gondii antibody among different groups of people in Iran; however the epidemiological data in intellectual disability (ID) persons are rare. This study was performed to evaluate the seroprevalence of toxoplasmosis among the inhabitants of rehabilitation centers of northern Iran. A total of 336 serum samples (161 males, 175 females) were examined for the IgG antibodies by indirect immunofluorescense technique. First of all, 1:50 titer dilution was tested, in the cases of positive result, further dilutions (1:100, 1:200, 1:400, 1:800, 1:1600, and 1:3200) were prepared and the last dilution was recorded. Among 336 sera, 77.4% showed seropositivity by IFAT. The positive rates of males and females were 77.6% (125/161) and 80% (140/175), respectively. However, there were no significant differences between sexes. Comparing the age groups, the highest seropositive rate showed in 19 or higher, and their rates had a tendency to increase with age. Prevalence of the infection in 10 rehabilitation centers was not significant either. Nevertheless, our data (77.4%) in rehabilitation centers in northern Iran suggest that infection is the same as in many other reports in normal population in this area, therefore toxoplasmosis is not a major problem in rehabilitation centers of this geographical area.  相似文献   
58.
Despite increasing reports on nonionic contrast media-induced nephropathy (CIN) in hospitalized adult patients during cardiac procedures, the studies in pediatrics are limited, with even less focus on possible predisposing factors and preventive measures for patients undergoing cardiac angiography. This prospective study determined the incidence of CIN for two nonionic contrast media (CM), iopromide and iohexol, among 80 patients younger than 18 years and compared the rates for this complication in relation to the type and dosage of CM and the presence of cyanosis. The 80 patients in the study consecutively received either iopromide (group A, n = 40) or iohexol (group B, n = 40). Serum sodium (Na), potassium (K), and creatinine (Cr) were measured 24 h before angiography as baseline values, then measured again at 12-, 24-, and 48-h intervals after CM use. Urine samples for Na and Cr also were checked at the same intervals. Risk of renal failure, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage renal damage (RIFLE criteria) were used to define CIN and its incidence in the study population. Accordingly, among the 15 CIN patients (18.75%), 7.5% of the patients in group A had increased risk and 3.75% had renal injury, whereas 5% of group B had increased risk and 2.5% had renal injury. Whereas 33.3% of the patients with CIN were among those who received the proper dosage of CM, the percentage increased to 66.6% among those who received larger doses, with a significant difference in the incidence of CIN related to the different dosages of CM (p = 0.014). Among the 15 patients with CIN, 6 had cyanotic congenital heart diseases, but the incidence did not differ significantly from that for the noncyanotic patients (p = 0.243). Although clinically silent, CIN is not rare in pediatrics. The incidence depends on dosage but not on the type of consumed nonionic CM, nor on the presence of cyanosis, and although CIN usually is reversible, more concern is needed for the prevention of such a complication in children.  相似文献   
59.
Solomon JN  Lewis CA  Ajami B  Corbel SY  Rossi FM  Krieger C 《Glia》2006,53(7):744-753
Amyotrophic lateral sclerosis (ALS) is associated with increased numbers of microglia within the central nervous system (CNS). However, it is unknown whether the microgliosis results from proliferation of CNS resident microglia, or recruitment of bone marrow (BM)-derived microglial precursors. Here we assess the distribution and number of BM-derived cells in spinal cord using transplantation of green fluorescent protein (GFP)-labeled BM cells into myelo-ablated mice over-expressing human mutant superoxide dismutase 1 (mSOD), a murine model of ALS. Transplantation of GFP+ BM did not affect the rate of disease progression in mSOD mice. Mean numbers of microglia and GFP+ cells in spinal cords of control mice were not significantly different from those in asymptomatic mSOD mice and showed no change with animal age. The number of GFP+ cells and microglia (F4/80+ and CD11b+ cells) within the spinal cord of mSOD mice increased compared to age-matched controls at a time when mSOD mice exhibited disease symptoms, continuing up to disease end-stage. Although we observed an increase in the number of GFP+ cells in spinal cords of mSOD mice with disease symptoms, mean numbers of GFP+ F4/80+ cells comprised less than 20% of all F4/80+ cells and did not increase with disease progression. Furthermore, the relative rates of proliferation in CD45+GFP- and CD45+GFP+ cells were comparable. Thus, we demonstrate that the microgliosis present in spinal cord tissue of mSOD mice is primarily due to an expansion of resident microglia and not to the recruitment of microglial precursors from the circulation.  相似文献   
60.
Cytomegalovirus (CMV) belongs to the Herpesviridae family and is also known as human herpesvirus type 5. It is a common virus that usually doesn't cause any symptoms in healthy individuals. However, once infected, the virus remains in the host's body for life and can reactivate when the host's immune system weakens. This virus has been linked to several neurological disorders, including Alzheimer's disease, Parkinson's disease, Autism spectrum disorder, Huntington's disease (HD), ataxia, Bell's palsy (BP), and brain tumours, which can cause a wide range of symptoms and challenges for those affected. CMV may influence inflammation, contribute to brain tissue damage, and elevate the risk of moderate-to-severe dementia. Multiple studies suggest a potential association between CMV and ataxia in various conditions, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, acute cerebellitis, etc. On the other hand, the evidence regarding CMV involvement in BP is conflicting, and also early indications of a link between CMV and HD were challenged by subsequent research disproving CMV's presence. This systematic review aims to comprehensively investigate any link between the pathogenesis of CMV and its potential role in neurological disorders and follows the preferred reporting items for systematic review and meta-analysis checklist. Despite significant research into the potential links between CMV infection and various neurological disorders, the direct cause-effect relationship is not fully understood and several gaps in knowledge persist. Therefore, continued research is necessary to gain a better understanding of the role of CMV in neurological disorders and potential treatment avenues.  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