全文获取类型
收费全文 | 2350021篇 |
免费 | 171586篇 |
国内免费 | 3332篇 |
专业分类
耳鼻咽喉 | 32081篇 |
儿科学 | 75895篇 |
妇产科学 | 62688篇 |
基础医学 | 348189篇 |
口腔科学 | 63635篇 |
临床医学 | 211381篇 |
内科学 | 457335篇 |
皮肤病学 | 51728篇 |
神经病学 | 185273篇 |
特种医学 | 88016篇 |
外国民族医学 | 489篇 |
外科学 | 353886篇 |
综合类 | 47511篇 |
现状与发展 | 12篇 |
一般理论 | 848篇 |
预防医学 | 182733篇 |
眼科学 | 54327篇 |
药学 | 175105篇 |
11篇 | |
中国医学 | 4575篇 |
肿瘤学 | 129221篇 |
出版年
2021年 | 18982篇 |
2019年 | 19544篇 |
2018年 | 27075篇 |
2017年 | 20368篇 |
2016年 | 22754篇 |
2015年 | 25648篇 |
2014年 | 36103篇 |
2013年 | 53956篇 |
2012年 | 74692篇 |
2011年 | 79420篇 |
2010年 | 47063篇 |
2009年 | 44567篇 |
2008年 | 74618篇 |
2007年 | 79488篇 |
2006年 | 80317篇 |
2005年 | 77793篇 |
2004年 | 74380篇 |
2003年 | 71697篇 |
2002年 | 69369篇 |
2001年 | 108741篇 |
2000年 | 111455篇 |
1999年 | 93496篇 |
1998年 | 26990篇 |
1997年 | 23659篇 |
1996年 | 24056篇 |
1995年 | 22715篇 |
1994年 | 20893篇 |
1993年 | 19712篇 |
1992年 | 72001篇 |
1991年 | 70070篇 |
1990年 | 68391篇 |
1989年 | 65663篇 |
1988年 | 60303篇 |
1987年 | 59126篇 |
1986年 | 55217篇 |
1985年 | 53004篇 |
1984年 | 39312篇 |
1983年 | 33396篇 |
1982年 | 19858篇 |
1979年 | 35866篇 |
1978年 | 25651篇 |
1977年 | 21230篇 |
1976年 | 20332篇 |
1975年 | 21817篇 |
1974年 | 26148篇 |
1973年 | 24802篇 |
1972年 | 23201篇 |
1971年 | 22039篇 |
1970年 | 20247篇 |
1969年 | 19315篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Melatonin reduces oxidative stress and improves vascular function in pulmonary hypertensive newborn sheep 下载免费PDF全文
Flavio Torres Alejandro González‐Candia Camilo Montt Germán Ebensperger Magdalena Chubretovic María Serón‐Ferré Roberto V. Reyes Aníbal J. Llanos Emilio A. Herrera 《Journal of pineal research》2015,58(3):362-373
Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial‐ and muscular‐dependent pathways. This was associated with an enhanced nitric oxide‐dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN. 相似文献
32.
33.
Characteristics of hyperparathyroid states in the Canadian multicentre osteoporosis study (CaMos) and relationship to skeletal markers 下载免费PDF全文
34.
35.
36.
37.
38.
Accuracy and Precision of Acetabular Component Placement With Imageless Navigation in Obese Patients
Leonard T. Buller Alexander S. McLawhorn Jose A. Romero Peter K. Sculco David J. Mayman 《The Journal of arthroplasty》2019,34(4):693-699
Background
Obesity is a risk factor for acetabular component malposition when total hip arthroplasty is performed with manual techniques. The utility of imageless navigation in obese patients remains unknown. This study compared the accuracy and precision of imageless navigation for component orientation between obese and nonobese patients.Methods
A total of 459 total hip arthroplasties performed for osteoarthritis using imageless navigation were reviewed from a single surgeon’s institutional review board–approved database. Einzel-Bild-Roentgen Analyse determined component orientation on 6-week postoperative anteroposterior radiographs. Mean orientation error (accuracy) and precision were compared between obese (body mass index ≥ 30 kg/m2) and nonobese patients. Regression analysis evaluated the influence of obesity on component position.Results
The difference in mean inclination and anteversion between obese and nonobese groups was 1.1° (43.0° ± 3.5°; range, 35.8°-57.8° vs 41.9° ± 4.4°; range, 33.0°-57.1° and 24.9° ± 6.3°; range, 14.2°-44.3° vs 23.8° ± 6.6°; range, 7.0°-38.6°, respectively). Inclination precision was better for nonobese patients. No difference in inclination accuracy or anteversion accuracy or precision was detected between groups. And 83% of components were placed within the target range. There was no relationship between obesity (dichotomized) and component placement outside the target ranges for inclination, anteversion, or both. As a continuous variable, increased body mass index correlated with higher odds of inclination outside the target zone (odds ratio, 1.06; P = .001).Conclusion
Using imageless navigation, inclination orientation was less precise for obese patients, but the observed difference is likely not clinically relevant. Accurate superficial registration of landmarks in obese patients is achievable, and the use of imageless navigation similarly improves acetabular component positioning in obese and nonobese patients.Level of Evidence
Therapeutic Level IV. 相似文献39.
Emma J. Walker Noni E. MacDonald Nehal Islam Nicole Le Saux Karina A. Top Deshayne B. Fell 《Vaccine》2019,37(13):1725-1735