全文获取类型
收费全文 | 197100篇 |
免费 | 2261篇 |
国内免费 | 128篇 |
专业分类
耳鼻咽喉 | 1483篇 |
儿科学 | 7006篇 |
妇产科学 | 3412篇 |
基础医学 | 19469篇 |
口腔科学 | 3194篇 |
临床医学 | 14091篇 |
内科学 | 35967篇 |
皮肤病学 | 1123篇 |
神经病学 | 18079篇 |
特种医学 | 9325篇 |
外科学 | 31834篇 |
综合类 | 2404篇 |
一般理论 | 11篇 |
预防医学 | 19941篇 |
眼科学 | 3080篇 |
药学 | 10927篇 |
中国医学 | 814篇 |
肿瘤学 | 17329篇 |
出版年
2023年 | 232篇 |
2022年 | 382篇 |
2021年 | 911篇 |
2020年 | 562篇 |
2019年 | 754篇 |
2018年 | 22695篇 |
2017年 | 17887篇 |
2016年 | 20048篇 |
2015年 | 1628篇 |
2014年 | 1816篇 |
2013年 | 2058篇 |
2012年 | 8867篇 |
2011年 | 22966篇 |
2010年 | 19803篇 |
2009年 | 12373篇 |
2008年 | 20866篇 |
2007年 | 23046篇 |
2006年 | 1784篇 |
2005年 | 3294篇 |
2004年 | 4298篇 |
2003年 | 5117篇 |
2002年 | 3248篇 |
2001年 | 530篇 |
2000年 | 663篇 |
1999年 | 388篇 |
1998年 | 340篇 |
1997年 | 305篇 |
1996年 | 164篇 |
1995年 | 177篇 |
1994年 | 176篇 |
1993年 | 119篇 |
1992年 | 151篇 |
1991年 | 160篇 |
1990年 | 195篇 |
1989年 | 139篇 |
1988年 | 99篇 |
1987年 | 83篇 |
1986年 | 74篇 |
1985年 | 76篇 |
1984年 | 54篇 |
1983年 | 43篇 |
1982年 | 41篇 |
1980年 | 74篇 |
1978年 | 36篇 |
1974年 | 44篇 |
1970年 | 37篇 |
1969年 | 44篇 |
1938年 | 62篇 |
1932年 | 59篇 |
1930年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
31.
32.
33.
Eduardo Rodrigues‐Pinto Joel Ferreira‐Silva Guilherme Macedo Douglas K. Rex 《Digestive endoscopy》2019,31(5):583-587
Cecal intubation is a critical aspect of effective, complete colonoscopy. Difficult colonoscopy is most often considered as one in which it is challenging or impossible to reach the cecum. It may be a common occurrence due to patient and/or endoscopist factors. Incomplete colonoscopies should be avoided, since patients in this context present an important prevalence of lesions that escape examination. The approach to successful cecal intubation should depend on characterization of the problem as redundant colon or difficult sigmoid colon. Most patients with a prior incomplete colonoscopy can be colonoscoped successfully, if careful attention is paid to technique, using a variety of scopes, colonoscopy methods and additional equipment. Sufficient time should be allotted to make the attempt. 相似文献
34.
35.
Zinc sulfate addition to glass-ionomer-based cements: influence on physical and antibacterial properties, zinc and fluoride release. 总被引:5,自引:0,他引:5
Prudencio W R Osinaga Rosa Helena M Grande Rafael Y Ballester Maria Regina L Simionato Célia Regina M Delgado Rodrigues Antonio Muench 《Dental materials》2003,19(3):212-217
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility. 相似文献
36.
37.
38.
39.
40.