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   792篇
  免费   58篇
  国内免费   3篇
耳鼻咽喉   6篇
儿科学   16篇
妇产科学   35篇
基础医学   123篇
口腔科学   27篇
临床医学   90篇
内科学   141篇
皮肤病学   18篇
神经病学   62篇
特种医学   7篇
外科学   74篇
综合类   17篇
一般理论   1篇
预防医学   57篇
眼科学   28篇
药学   75篇
中国医学   5篇
肿瘤学   71篇
  2023年   11篇
  2022年   20篇
  2021年   55篇
  2020年   41篇
  2019年   46篇
  2018年   50篇
  2017年   33篇
  2016年   33篇
  2015年   38篇
  2014年   44篇
  2013年   47篇
  2012年   85篇
  2011年   64篇
  2010年   35篇
  2009年   16篇
  2008年   51篇
  2007年   48篇
  2006年   37篇
  2005年   27篇
  2004年   30篇
  2003年   20篇
  2002年   15篇
  1998年   2篇
  1997年   1篇
  1996年   3篇
  1994年   1篇
排序方式: 共有853条查询结果,搜索用时 15 毫秒
71.

Background:

Non-alcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease. Several studies suggest that pentoxifylline (PTX) can improve the disease outcome.

Objectives:

We aimed to compare the effect of pentoxifylline with placebo on liver aminotransferases and cytokines, including interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and interleukin 8 (IL-8) in patients with NASH.

Patients and Methods:

Thirty patients with NASH were included in the study, based on ultrasonography and 1.5-fold mean change from baseline serum levels of liver aminotransferases. Patients with NASH were randomized to receive 1200 mg PTX (the intervention group) or placebo (the placebo group) for 6 months. The serum levels of liver aminotransferases and cytokines were compared between the intervention and placebo groups, at various time points.

Results:

The serum levels of liver aminotransferases were significantly reduced at 3 months and at 6 months, compared with baseline, in both groups. The serum levels of IL-6 were significantly decreased, in both groups, only at 6 months, compared with baseline. Compared to the placebo group, the serum level of TNF-α was significantly decreased in the intervention group, at 6 months. The serum level of IL-8 was increased, in both groups, after 6 months, without reaching clinical significance. There was no significant difference in serum levels of liver aminotransferases and cytokines, between intervention and placebo groups.

Conclusions:

Decreases in the serum levels of liver aminotransferases and cytokines, in both groups, are related to low-calorie diets and exercise, rather than PTX.  相似文献   
72.

Objectives

This is a confirmatory study to evaluate the effect of photoinitiator type and concentration, matrix monomer chemical structure, and nanoparticle incorporation on the physical and mechanical properties of an experimental dentin bonding agent.

Materials and methods

Different concentrations of camphorquinone-amine (CQ-A) system, butanedione (BD), and phenylpropanedione (PPD), as photoinitiator, BTDMA, as a comonomer containing carboxylic acid groups, and silica nanoparticles as reinforcing inorganic filler were incorporated into a methacrylate base experimental dental adhesive. The effect of these ingredients, as independent variables, on the shrinkage kinetics, flexural strength and modulus, and microshear bond strength of the adhesives were then investigated. The results were analyzed using one-way ANOVA and Tukey’s post-hoc test at the significance level of 0.05.

Results

The results indicate that the efficiency of CQ-A initiator system is diminished in the presence of the acidic monomer BTDMA while the photopolymerization is efficiently progressed with BD as initiator. PPD shows the lowest efficiency in the photopolymerization of the adhesives. BTDMA as a monomer with the capability of interaction with tooth structure provides adhesive with improved microshear bond strength to dentin. Incorporation of silica nanoparticles at low concentrations enhances the flexural and microshear strength of the dentin bonding agent.

Significance

Understanding the structure–property relationship in dental adhesives may help the material selection in clinical dentistry. The study elucidates the relationship between monomer structure, initiator type, and nanofiller and physical and mechanical properties in dental adhesives.  相似文献   
73.
74.

Background

Hepatitis infection represents one of the important causes of morbidity and mortality in developing countries, however there is not any effective vaccine against hepatitis C which is one of the significant problems in vaccine project.

Objectives

The aim of the present study is to evaluate the role of HCV core protein in inducing IFN-Gamma secretion and TCL activities as a vaccine in Balb/C mice.

Material and Methods

Our previous cloned plasmid (HCV Core gene into pETDuet-1) applied for protein expression in bacteria. The expressed and purified recombinant protein together with Freund’s adjuvant was injected to 15 Balb/c mice. The total IgG and IgG2a of immunized mice sera were evaluated after a week. Two weeks after booster injection, we studied the proliferation and IFNγ secretion of spleens, inguinal and popliteal lymph nodes lymphocytes by ELISA and ELISPOT.

Results

The FSFC (Frequency of spot forming cells) of secreting cells of immunized mice with HCV/Core protein and sera IgG2a were considerably higher than the control groups.

Conclusions

The core protein together with proper adjuvant can be a candidate vaccine against of HCV infection.  相似文献   
75.
Aim: Low back pain (LBP) is the second most frequent reason for seeking medical advice. Various treatments are proposed from no intervention, to analgesics, rest, exercises, local interventions and surgical procedures. Results and outcomes are differently reported. Back School (BS), a combination of patient education and physical exercises, seems to have good results. The aim of this study was to check the effect of BS in factory workers. Patients and Methods: All (70) workers were interviewed and 26 of them (37.1%) had chronic LBP. Secondary causes were excluded. Anatomy, physiology, biomechanics of the spine, correct postures at work and back exercises were taught. Pain on a visual analog scale (VAS) of 0–100, and Short Form (SF)‐36 health survey were applied, before, at the end of BS sessions, and 3 months after BS. Analysis was done by t‐test, Wilcoxon and Pearson’s correlation test. Results: The mean VAS on pain before BS was 43.4 ± 22.3, improving to 38.6 ± 17.5 at the end of BS. The difference was not significant (P = 0.19). The mean VAS improved to 27.5 ± 20 at 3 months after BS. The difference was significant compared to before BS (P = 0.001). The quality of life measured by the SF‐36 questionnaire, did not improve significantly, except for two of its eight subgroups (Role Physical, Social Functioning) at the end of BS, and two of its subgroup (Mental Health, Social Functioning) at 3 months after BS. Conclusion: Among industrial workers, BS is mainly effective on pain, but is less evident on SF‐36.  相似文献   
76.
AIM: To investigate the associations of hepatitis B virus (HBV) genotype with HBeAg and anti-HBe status, alanine aminotransferase (ALT) levels and HBV-DNA detection in different groups of HBV-infected patients in southwest Iran. METHODS: A total of 89 HBsAg-positive serum samples were collected from the same number of patients. All sera were then investigated to determine HBV DNA and serological markers. For all the polymerase chain reaction (PCR)-positive samples, biochemical, histopathological assays and genotyping were also performed. RESULTS: Genotype D was the only type of HBV foundin different clinical forms of acute and chronic infections. There was a high prevalence of HBeAg-negative HBV- infected patients with chronic hepatitis (52.7%). Out of 55 patients with chronic hepatitis, seven (12.7%) were diagnosed with cirrhosis. A significant association between the presence of anti-HBe antibody and an increase in ALT level, among either HBeAg-negative (P = 0.01) or HBeAg-positive (P = 0.026) patients, was demonstrated. No significant differences were observed between the clinical outcomes of HBeAg-positive and -negative individuals (P = 0.24). CONCLUSION: Genotype D has been recognized as the only type of HBV found in different clinical forms of HBV infections, including cirrhosis, among the residents of southwest Iran. Anti-HBe possibly plays a role in disease progression in some patients with chronic hepatitis, at least for a period of disease.  相似文献   
77.
The purpose of this study was to determine the initial rates of intravenous gamma-globulin treatment (IVIG) failure in Kawasaki disease (KD) and their predisposing factors. This study was a retrospective analysis of the initial response to IVIG (2 g/kg), assessed from the medical reports of all patients admitted to Namazee Hospital pediatric ward, from March 1998 to March 2002, and who fulfilled the criteria for KD. Data were available for 64 patients, 58 of whom (90.6%) became afebrile 48 hours after completion of the initial dose of IVIG (Group I) and six (9.4%) who remained febrile (Group II). Two patients had a prompt response to a second dose of IVIG. In Group I, five patients (8.6%) developed coronary artery disease, seen on echocardiography. In Group II, two patients (33.3%) developed coronary artery disease. No significant difference was found in the prevalence of coronary artery disease between the two groups (p = 0.12), or in age or gender. The rate of initial treatment failure was 9.4% in this cohort of patients, which is comparable with previous reports. No predictive factors such as coronary artery disease, age or gender were found for initial treatment failure in KD.  相似文献   
78.
Immunoglobulin class switch recombination deficiencies (Ig CSR deficiencies) or Hyper IgM syndromes (HIGM) are a group of primary immunodeficiency diseases, characterized by defective CD40 signaling of B cells, resulting in reduced CSR and somatic hypermutation. The affected patients are characterized by low serum levels of IgG and IgA, and normal or elevated levels of IgM, which lead to an increased susceptibility to infections. We describe a 3 year-old boy with frequent bacterial infections of the skin and respiratory tract, mucosal ulcers, and diarrhea. He experienced onychomadesis of both fingernails and toenails during a recent bacterial infection. Quantitative immunoglobulin measurements revealed high levels of serum IgM and very low levels of IgG, IgA, and IgE. Clinical and immunologic studies supported the diagnosis of HIGM. Exclusion of CD40L, CD40, AID and UNG genes by molecular analysis in this patient may suggest a new form of selective CSR deficiency.  相似文献   
79.

Background

There is limited information on the extent and clinical importance of the delay in hospital presentation of acute pulmonary thromboembolism (PTE).

Objective

The aim of this study was to investigate the delay in hospital presentation of PTE and its association with clinical and imaging findings in PTE.

Methods

This prospective study was conducted on patients admitted to our hospital with a diagnosis of acute PTE between September 2007 and September 2011. Relationships between delay in hospital presentation and clinical findings, risk factors, imaging findings, and in-hospital mortality were analyzed.

Results

Of the 195 patients enrolled, 84 (43.1%) patients presented 3 days after the onset of symptoms. Patients with chest pain, history of immobility for more than 3 days, recent surgery, and estrogen use had significantly less delayed presentation. Right ventricular dysfunction was significantly more frequent in patients with delayed presentation (odds ratio [OR] = 2.38; 95% confidence interval [CI] 1.27−4.44; p = 0.006); however, no relationship was found between delay in presentation and pulmonary computed tomographic angiography or color Doppler sonography findings. Patients with delayed presentation were at higher risk of in-hospital mortality (OR = 4.32; 95% CI 1.12−16.49; p = 0.021).

Conclusions

Our study showed that a significant portion of patients with acute PTE had delayed presentation. Also, patients with delayed presentation had worse echocardiographic findings and higher in-hospital mortality.  相似文献   
80.
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