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   2214篇
  免费   122篇
  国内免费   9篇
耳鼻咽喉   65篇
儿科学   109篇
妇产科学   99篇
基础医学   215篇
口腔科学   156篇
临床医学   186篇
内科学   485篇
皮肤病学   30篇
神经病学   150篇
特种医学   118篇
外科学   377篇
综合类   43篇
一般理论   2篇
预防医学   60篇
眼科学   63篇
药学   115篇
中国医学   3篇
肿瘤学   69篇
  2024年   4篇
  2023年   37篇
  2022年   63篇
  2021年   119篇
  2020年   58篇
  2019年   82篇
  2018年   92篇
  2017年   76篇
  2016年   93篇
  2015年   94篇
  2014年   112篇
  2013年   128篇
  2012年   153篇
  2011年   189篇
  2010年   79篇
  2009年   77篇
  2008年   143篇
  2007年   139篇
  2006年   111篇
  2005年   120篇
  2004年   106篇
  2003年   74篇
  2002年   61篇
  2001年   15篇
  2000年   18篇
  1999年   9篇
  1998年   3篇
  1995年   4篇
  1992年   3篇
  1991年   5篇
  1990年   6篇
  1989年   3篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1985年   5篇
  1984年   9篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   4篇
  1979年   6篇
  1976年   3篇
  1975年   3篇
  1974年   5篇
  1970年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1965年   1篇
排序方式: 共有2345条查询结果,搜索用时 15 毫秒
81.

Background

Ulcerative colitis (UC) is characterized with chronic, progressive inflammation of the gastrointestinal tract. The association of UC with cardiovascular disease is still a matter of debate.

Aim

The aim of this study was to investigate whether carotid intima-media thickness (CIMT) and carotid-femoral pulse wave velocity (cf-PWV) as surrogates of atherosclerosis and arterial stiffness are increased in patients with UC.

Methods

Our study was cross-sectional and observational in design. Baseline characteristics were recorded during interview with the patient. Patients with previous cardiovascular disease, rheumatoid arthritis, chronic renal failure, and infectious and inflammatory disorders other than UC were excluded. Thirty-seven consecutive patients with UC and 30 control participants underwent cf-PWV assessment and CIMT measurement. The diagnosis of UC was based on clinical, radiologic, endoscopic, and histological findings.

Results

CIMT, cf-PWV, and C reactive protein were significantly higher in patients with UC. Although linear regression analyses identified UC as an independent predictor of CIMT (β ± SE, 0.39 ± 0.08; p < 0.001), only age independently predicted cf-PWV (β ± SE, 0.08 ± 0.03; p = 0.003) in our study population. Moreover, we revealed higher CIMT and PWV values in patients with higher disease activity and more extensive involvement, compared to patients with mild activity and limited disease.

Conclusion

We revealed increased pulse wave velocity and CIMT in patients with UC. UC appears to be associated with arterial stiffness and atherosclerotic burden, but the underlying mechanisms require further studies to be identified.  相似文献   
82.
Purpose: Oral rinses are widely used to promote periodontal health with provisional restorations during the interim period. The aim of this study was to compare the discoloration of provisional restoration materials with different oral rinses.Material and Methods: A total of 140 disc-shaped specimens (shade A2) (10 mm x 2 mm) were prepared from one PMMA-based (TemDent Classic®) and three different bis-acrylic-based (Protemp II®, Luxatemp® and Fill-In®) provisional restoration materials (n=7). The color values (L*, a*, and b*) of each specimen were measured before and after exposure with a colorimeter, and the color changes (∆E) were calculated according to the CIE L*a*b* system. The specimens were immersed in each of the 4 oral rinses (alcohol-containing mouthwash, chlorhexidine, benzydamine HCl, benzydamine HCl and chlorhexidine) twice a day for 2 minutes. After 2 minutes of immersion in the oral rinses, the specimens were immersed in artificial saliva. The specimens were exposed to the oral rinses and the artificial saliva for 3 weeks. Two-way ANOVA, the Bonferroni test and the paired sample t-test were used for statistical analyses (p<0.05).Results: Comparison of the discoloration from the oral rinses after immersion for three weeks revealed no significant differences (p>0.05). The lowest color change was observed in PMMA-based Temdent in all oral rinses (p<0.05). There were no significant differences between the bis-acryl composites after immersion in saliva or the mixture of benzydamine HCl and chlorhexidine and the alcohol-containing mouthwash for 3 weeks (p>0.05). After immersion in chlorhexidine, the color change values of Protemp II and Fill-in showed significant differences (p=0.018). Protemp II also showed less discoloration than the other bis-acryl composites, and this color change was statistically significant (p <0.05). For all oral rinses, the L* value decreased while b* values increased, and this color change was found to be statistically significant (p <0.05). A* values were found to be significantly higher with oral rinses (p<0.05), except Protemp II immersed in benzydamine HCl or alcohol-containing mouthwash.Conclusions: The type of the oral rinse did not affect the discoloration process. For long-term esthetic results, choosing MMA-based materials for provisional restorations appears to be more effective.  相似文献   
83.
Healthcare workers (HCWs) are at increased risk of SARS-CoV-2 infection. The aim of the study was to estimate the SARS-CoV-2 seroprevalence among HCWs in Cochabamba, Bolivia and to determine the potential risk factors. In January 2021, a cross-sectional SARS-CoV-2 seroprevalence study was conducted in 783 volunteer clinical and non-clinical HCWs in tertiary care facilities. It was based on IgG detection using ELISA, chemiluminiscence, and seroneutralisation tests from dried blood spots. Analysis revealed a high seroprevalence (43.4%) of SARS-CoV-2 IgG antibodies. The combination of anosmia and ageusia (OR: 68.11; 95%-CI 24.83–186.80) was predictive of seropositivity. Belonging to the cleaning staff (OR: 1.94; 95%-CI 1.09–3.45), having more than two children in the same house (OR: 1.74; 95%-CI 1.12–2.71), and having been in contact with a close relative with COVID-19 (OR: 3.53; 95%-CI 2.24–5.58) were identified as risk factors for seropositivity in a multivariate analysis. A total of 47.5% of participants had received medication for COVID-19 treatment or prevention, and only ~50% of symptomatic subjects accessed PCR or antigenic testing. This study confirms a massive SARS-CoV-2 attack rate among HCWs in Cochabamba by the end of January 2021. The main risk factors identified are having a low-skilled job, living with children, and having been in contact with an infected relative in the household.  相似文献   
84.
AIM: To investigate effects of ethanol on activity markers of atherosclerosis in an in vitro endothelial cell model. METHODS: After 24 h incubation with ethanol (0.0095%), human umbilical vein endothelial cells were stimulated for 1 h with lipopolysaccharide, and were then incubated in direct contact with activated platelets. Following this incubation, the expression of CD40L and CD62P on platelets, and the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), urokinase plasminogen activator receptor (uPAR), and membrane-type 1 matrix metalloproteinase (MT1-MMP) on endothelial cells were measured by flow cytometry. RESULTS: The increased expression of VCAM-1 and uPAR on endothelial cells by proinflammatory stimulation with activated platelets was significantly reduced through pre-incubation with ethanol (P<0.05). Furthermore, platelets in direct contact with ethanol and with endothelial cells pre-incubated in ethanol showed a significant reduction in their CD40L expression (P<0.05). Ethanol had no significant effect on ICAM-1 and MT1-MMP expression on endothelial cells. CONCLUSION: Ethanol directly attenuates platelet activation and has significant endothelial cell-mediated effects on selected markers of atherosclerosis in vitro . These findings underline possible protective effects of ethanol on atherosclerosis.  相似文献   
85.
Background/aimCertain constituents in migraine food triggers and non-steroidal anti-inflammatory drugs (NSAIDs) inhibit sulfotransferases (SULTs) that detoxify drugs/chemicals and play role in the metabolism of neurotransmitters. We aimed to dissect SULT1A1 modulation of CSD susceptibility and behavior in an in vivo experimental model using hesperidin, a SULT1A1 inhibitor found in citrus fruits (known migraine triggers) and mefenamic acid (SULT1A1 inhibitor), an NSAID to simulate medication overuse.MethodsHesperidin was used as SULT1A1 inhibitor found in citrus fruits, known migraine triggers and mefenamic acid (NSAID), another SULT1A1 inhibitor, was used to induce MO in rats. The groups were; 1) Hesperidin (ip) or its vehicle-DMSO (ip) 2) Chronic (4 weeks) mefenamic acid (ip) or its vehicle (ip) 3) Chronic mefenamic acid+hesperidin (ip) or DMSO (ip). CSD susceptibility was evaluated and behavioral testing was performed. SULT1A1 enzyme activity was measured in brain samples.ResultsSingle-dose of hesperidin neither changed CSD susceptibility nor resulted in any behavioral change. Chronic mefenamic acid exposure resulted in increased CSD susceptibility, mechanical-thermal hypersensitivity, increased head shake, grooming and freezing and decreased locomotion. Single dose hesperidin administration after chronic mefenamic acid exposure resulted in increased CSD susceptibility and mechanical-thermal hypersensitivity, increased freezing and decreased locomotion. SULT1A1 enzyme activity was lower in mefenamic acid and mefenamic acid+hesperidin groups compared to their vehicles.ConclusionMefenamic acid and hesperidin have synergistic effect in modulating CSD susceptibility and pain behavior. Sulfotransferase inhibition may be the common mechanism by which food triggers and NSAIDs modulate migraine susceptibility. Further investigations regarding human provocation studies using hesperidin in migraine patients with medication overuse are needed.  相似文献   
86.
Benign recurrent intrahepatic cholestasis (BRIC) is a rare disease characterized by recurrent severe itching and jaundice. Coronavirus disease 2019 (COVID‐19) is a multisystemic acute viral disease and the liver is frequently affected. Here, we wanted to present a BRIC case triggered by COVID‐19 infection, discussing it together with current information.  相似文献   
87.
BACKGROUND: Smoking causes an increase in the thickness of gingival epithelium, which is the outcome of increased keratinocyte proliferation or loss. Smoking-related changes in the proliferative activity of the gingival epithelium are largely uncharacterized for periodontal diseases. The aim of the present study was to determine the effects of smoking on the proliferation of the epithelium in periodontally diseased marginal gingiva by comparing the expression patterns of two different proliferation markers. METHODS: Gingival biopsies (N=60) were obtained from smokers who had clinically healthy gingiva (n=10), smokers with gingivitis (n=10), smokers with periodontitis (n=10), non-smokers with clinically healthy gingiva (n=10), non-smokers with gingivitis (n=10), and non-smokers with periodontitis (n=10). The quantitative measurement of maximum epithelial thickness was performed on hematoxylin and eosin-stained sections. The expression patterns for proliferating cell nuclear antigen (PCNA) and Ki67 were evaluated immunohistochemically. RESULTS: The percentage of PCNA-positive cells was higher than the percentage of Ki67-positive cells in all groups (P<0.001). When the mean values of PCNA and Ki67 were compared in each group, a statistically significant difference was observed only in the healthy smoker group (P=0.003). Significant differences in PCNA proliferation indices were only found between the smoker group and the non-smoker healthy group (P=0.015). CONCLUSIONS: Smoking had an affect on the proliferation of cells in the oral gingival epithelium, regardless of periodontal status. The increase in thickness of the epithelium was not associated with smoking; periodontal status and inflammation seemed to be more important factors. Smoking induced the replication activity of gingival epithelium and induced DNA repair.  相似文献   
88.
The purpose of the present study was to assess the effect of solvents on root canal transportation in endodontic retreatment. Sixty extracted human permanent mandibular first molars with curved root canals were selected. All of the root canals were prepared using Twisted File Adaptive instruments (SybronEndo, Orange, CA, USA) and filled with gutta‐percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the cold lateral compaction technique. The teeth were assigned to four retreatment groups as follows (n = 15): eucalyptol, chloroform, orange oil and control. The canals were scanned using cone‐beam computed tomography scanning before and after instrumentation. The chloroform group showed a significantly higher mean transportation value than the orange oil and control groups at the 3 and 5 mm levels (P = 0.011 and P = 0.003, respectively). There was no significant difference among the orange oil, eucalyptol and control groups in terms of canal transportation (P > 0.61). The chloroform led to more canal transportation than the eucalyptol and orange oil during endodontic retreatment.  相似文献   
89.
BACKGROUND: Bioabsorbable membranes have been successfully used for guided tissue regeneration (GTR) and local delivery systems because they are biocompatible and do not require second surgery for removal. Several studies have demonstrated that metronidazole, when applied topically, produced immediate effects on microbiological and clinical parameters, most notably a reduction in probing depth and loss of attachment. The purpose of this study was to evaluate the regenerative potential of a metronidazole-loaded biodegradable (polylactide/glycolide) (PLGA) GTR membrane in dogs. METHODS: Six male adult dogs with 36 created osseous defects were enrolled. Bilateral dehiscence type defects in 5 mm diameter were created at buccal aspect of the alveolar bone in maxillary premolar teeth. After full thickness flap elevation, exposed root surfaces were thoroughly planed. In the experimental sites, PLGA membranes with or without metronidazole were fitted and placed over the defects. On the control defects only root planing was performed. Gingival flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 60 days. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJE), new cementum height (NCH), new bone height (NBH), and new gingival connective tissue height (NCTH). RESULTS: Postoperative clinical healing was similar in the 3 groups. There were no statistically significant differences between the 2 experimental groups in any parameters. Statistically significant differences were observed for AEJE, NCH, NBH, and NCTH in experimental groups when compared with the controls. Statistically significantly greater NCH, NBH, and NCTH were seen in the experimental groups than the controls and control defects showed longer AEJE than the experimental defects. CONCLUSIONS: These results suggest that PLGA membranes with and without metronidazole may have a beneficial effect on periodontal regeneration.  相似文献   
90.
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