收费全文 | 585篇 |
免费 | 47篇 |
国内免费 | 3篇 |
耳鼻咽喉 | 4篇 |
儿科学 | 28篇 |
妇产科学 | 8篇 |
基础医学 | 65篇 |
口腔科学 | 51篇 |
临床医学 | 56篇 |
内科学 | 144篇 |
皮肤病学 | 11篇 |
神经病学 | 13篇 |
特种医学 | 66篇 |
外科学 | 53篇 |
综合类 | 9篇 |
预防医学 | 23篇 |
眼科学 | 51篇 |
药学 | 29篇 |
1篇 | |
中国医学 | 2篇 |
肿瘤学 | 21篇 |
2022年 | 7篇 |
2021年 | 10篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 26篇 |
2014年 | 20篇 |
2013年 | 23篇 |
2012年 | 25篇 |
2011年 | 27篇 |
2010年 | 28篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 15篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 14篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 13篇 |
2000年 | 4篇 |
1999年 | 10篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 30篇 |
1995年 | 15篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 21篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1968年 | 4篇 |
Objectives
To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement.Material and Methods
White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05).Results
The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05).Conclusions
The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated. 相似文献Objective
This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF4 and NaF varnishes, with different concentrations, for 12 h.Material and Methods
Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF4 varnish (0.95% F, pH 1.0); 3.10% TiF4 varnish (1.90% F, pH 1.0); 3.10% and 4% TiF4 varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni''s test were applied for the statistical analysis (p<0.05).Results
TiF4 varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF4 varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva.Conclusions
The 3.10% and 4% TiF4 -based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF4 varnish on tooth surface. 相似文献Objective
This study aimed to assess the impact of in vitro erosion provoked by different cola-based drinks (Coke types), associated or not with toothbrushing, to bonding to enamel.Material and Methods
Fifty-six bovine enamel specimens were prepared and randomly assigned into seven groups (N=8): C- Control (neither eroded nor abraded), ERO-RC: 3x/1-minute immersion in Regular Coke (RC), ERO-LC: 3x/1-minute immersion in Light Coke (LC), ERO-ZC: 3x/1-minute immersion in Zero Coke (ZC) and three other eroded groups, subsequently abraded for 1-minute toothbrushing (EROAB-RC, EROAB-LC and EROAB-ZC, respectively). After challenges, they were stored overnight in artificial saliva for a total of 24 hours and restored with Adper Single Bond 2/Filtek Z350. Buildup coronal surfaces were cut in 1 mm2 -specimens and subjected to a microtensile test. Data were statistically analyzed by two-way ANOVA/Bonferroni tests (α=0.05). Failure modes were assessed by optical microscopy (X40). The interface of the restorations were observed using Confocal Laser Scanning Microscopy (CLSM).Results
All tested cola-based drinks significantly reduced the bond strength, which was also observed in the analyses of interfaces. Toothbrushing did not have any impact on the bond strength. CLSM showed that except for Zero Coke, all eroded specimens resulted in irregular hybrid layer formation.Conclusions
All cola-based drinks reduced the bond strength. Different patterns of hybrid layers were obtained revealing their impact, except for ZC. 相似文献Methods: The serum level of CD226 was measured using a suitable ELISA kit and the CD226 rs763361 gene polymorphism was typed by PCR-RFLP for 112 RA patients and 100 healthy controls.
Results: Significant association with RA was found with CD226 T allele (OR (95%CI) = 1.6 (1.04–2.4), P = 0.032), and higher CD226 serum level (P = 0.001). Higher CD226 levels were associated with higher ESR values (P = 0.035), positive CRP (0.048), increased number of tender joints (P = 0.045), and higher DAS score (P = 0.035). Serum CD226 is an independent risk factor for the prediction of RA (P = 0.001). No correlations were found between the serum level of CD226 and different CD226 genotypes and also between them and RA activity grades.
Conclusion: The CD226 T allele may be susceptibility risk factors for the development of RA and the higher serum level of CD226 may be involved in the pathogenesis of RA in Egyptian patients. The serum level of CD226 and not CD226 genotypes could be considered as an independent risk factor for the prediction of RA within healthy individuals and also for RA disease activity. 相似文献