收费全文 | 1056篇 |
免费 | 69篇 |
国内免费 | 1篇 |
耳鼻咽喉 | 1篇 |
儿科学 | 58篇 |
妇产科学 | 23篇 |
基础医学 | 160篇 |
口腔科学 | 24篇 |
临床医学 | 77篇 |
内科学 | 310篇 |
皮肤病学 | 24篇 |
神经病学 | 53篇 |
特种医学 | 56篇 |
外科学 | 136篇 |
综合类 | 1篇 |
预防医学 | 57篇 |
眼科学 | 14篇 |
药学 | 82篇 |
中国医学 | 2篇 |
肿瘤学 | 48篇 |
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 6篇 |
2019年 | 21篇 |
2018年 | 32篇 |
2017年 | 12篇 |
2016年 | 29篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 49篇 |
2012年 | 61篇 |
2011年 | 68篇 |
2010年 | 45篇 |
2009年 | 21篇 |
2008年 | 54篇 |
2007年 | 59篇 |
2006年 | 49篇 |
2005年 | 46篇 |
2004年 | 39篇 |
2003年 | 41篇 |
2002年 | 35篇 |
2001年 | 39篇 |
2000年 | 39篇 |
1999年 | 38篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 17篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 4篇 |
Introduction
The diagnosis of microscopic lymph node metastasis in lung cancer is challenging despite the constant advances in tumor staging. The analysis of the methylation status of certain genes in lymph node samples could improve the diagnostic capability of conventional cyto-histological methods. The aim of this study was to demonstrate the feasibility of methylation studies using cytological lymph node samples.Methods
Prospective study including 88 patients with a diagnosis or strong suspicion of non-small cell lung cancer, in which an echobronchoscopy was performed on mediastinal or hilar lymph nodes for diagnostic and/or staging. DNA was extracted from cytological lymph node samples and sodium bisulfite modification was performed. Methylation studies for p16/INK4a and SHOX2 were accomplished by MS-qPCR and pyrosequencing.Results
The methodology used in our study yielded optimal/good DNA quality in 90% of the cases. No differences in DNA concentration were observed with respect to the lymph node biopsied and final diagnosis. Methylation analyses using MS-qPCR and pyrosequencing were not possible in a small number of samples mainly due to low DNA concentration, inadequate purity, fragmentation and/or degradation as a consequence of bisulfite conversion.Conclusion
Methylation quantification using MS-qPCR and pyrosequencing of cytological lymph node samples obtained using echobronchoscopy is feasible if an appropriate DNA concentration is obtained, notably contributing to the identification of epigenetic biomarkers capable of improving decision-making for the benefit of potentially curable lung cancer patients. 相似文献Introduction
One of the pathways involved in pulmonary arterial hypertension (PAH) is the nitric oxide (NO) pathway. A polymorphism in the inducible NO synthase (NOS2) gene has been described, consisting of the CCTTT pentanucleotide repeat, which causes a reduction in NO production. The aim of this study was to determine if this polymorphism increases susceptibility to developing PAH.Methods
Sixty four patients with a diagnosis of PAH groups i and iv and 50 healthy controls were compared. DNA genotyping of the samples for this polymorphism was performed using PCR. The distribution between both groups was compared and correlated with clinical and haemodynamic parameters and therapeutic response.Results
A significantly different distribution was observed in the number of repeats between patients and controls (P < .0001). When the samples were categorised by short forms (both alleles with less than 12 repeats) and long forms (≥ 12 repeats), it was observed that the former had an almost 4-fold risk of developing PAH (odds ratio: 3.83; 95% CI: 1.19-12.32, P = .024). There were no differences between the most common types of PAH, either in therapeutic response or survival. There was no correlation between haemodynamic parameters and the number of repeats in the patients, and only a weak correlation with systolic PAH.Conclusions
There are significant differences in the distribution of the NOS2 promotor CCTTT polymorphism between patients with PAH and the healthy population. A minor CCTTT pentanucleotide repeat in the NOS2 gene may increase the risk of developing PAH. 相似文献To compare clinical aspects of all-ceramic crowns fabricated from conventional and digital impressions.
MethodsThirty patients with 30 posterior teeth with the need of a crown restoration were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (TRIOS®, 3shape) and two-step silicone impression technique. Two external blinded operators evaluated the all-ceramic crowns. Five selection items were assessed of which four were clinical: “marginal fit,” “occlusal contacts,” “interproximal contact points,” and “primary retention.” Then, the last selection item “final selection” was assessed when the operators considering all the variables had to select which of the digital or conventional crown had the best clinical conditions. Data was analyzed using Kappa index test and the Pearson’s chi-square test (α = 0.05).
ResultsFor the items marginal fit and interproximal contact points, moderate agreement between the two operators was described and significant differences were found between the two study groups. Conversely, for the variables primary retention and occlusal contacts, the agreement between the operators was fair and no significant differences were found. For the final selection, a substantial agreement was reached between the two operators and significant differences were found between the two groups (p < 0.05).
ConclusionIn most cases and in a significant way, the digital crowns had better clinical conditions according to both evaluators. The digital crowns were statistically superior for the interproximal contact points and marginal fit. For the variables occlusal contacts and primary retention, no difference between the two groups was observed.
Clinical significanceDigital intraoral impressions can be used for manufacturing ceramic crowns, with the same or better clinical results as conventional impressions.
相似文献