全文获取类型
收费全文 | 21063篇 |
免费 | 1466篇 |
国内免费 | 88篇 |
专业分类
耳鼻咽喉 | 271篇 |
儿科学 | 545篇 |
妇产科学 | 312篇 |
基础医学 | 2742篇 |
口腔科学 | 1179篇 |
临床医学 | 2186篇 |
内科学 | 4503篇 |
皮肤病学 | 446篇 |
神经病学 | 1847篇 |
特种医学 | 780篇 |
外科学 | 2986篇 |
综合类 | 161篇 |
一般理论 | 8篇 |
预防医学 | 1752篇 |
眼科学 | 492篇 |
药学 | 1321篇 |
中国医学 | 95篇 |
肿瘤学 | 991篇 |
出版年
2023年 | 177篇 |
2022年 | 153篇 |
2021年 | 701篇 |
2020年 | 403篇 |
2019年 | 600篇 |
2018年 | 751篇 |
2017年 | 498篇 |
2016年 | 594篇 |
2015年 | 709篇 |
2014年 | 862篇 |
2013年 | 1027篇 |
2012年 | 1685篇 |
2011年 | 1692篇 |
2010年 | 918篇 |
2009年 | 770篇 |
2008年 | 1372篇 |
2007年 | 1317篇 |
2006年 | 1214篇 |
2005年 | 1104篇 |
2004年 | 871篇 |
2003年 | 827篇 |
2002年 | 688篇 |
2001年 | 311篇 |
2000年 | 276篇 |
1999年 | 327篇 |
1998年 | 146篇 |
1997年 | 131篇 |
1996年 | 99篇 |
1995年 | 93篇 |
1994年 | 78篇 |
1993年 | 64篇 |
1992年 | 135篇 |
1991年 | 152篇 |
1990年 | 120篇 |
1989年 | 130篇 |
1988年 | 125篇 |
1987年 | 107篇 |
1986年 | 98篇 |
1985年 | 119篇 |
1984年 | 105篇 |
1983年 | 65篇 |
1982年 | 65篇 |
1981年 | 48篇 |
1980年 | 74篇 |
1979年 | 88篇 |
1978年 | 56篇 |
1975年 | 47篇 |
1974年 | 53篇 |
1973年 | 52篇 |
1972年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
Adilson Cunha Ferreira Edward Araujo Júnior Wellington P. Martins João Francisco Jordão Antônio Hélio Oliani Simon E. Meagher 《The journal of maternal-fetal & neonatal medicine》2015,28(14):1706-1710
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality. 相似文献
8.
Diego Dias da Silva Ana Helena da Rosa Paz Ciro Paz Portinho Elizabeth Obino Cirne Lima Lúcia Maria Kliemann Marcus Vinicius Martins Collares 《Acta cirúrgica brasileira / Sociedade Brasileira para Desenvolvimento Pesquisa em Cirurgia》2020,35(12)
Purpose:This study assessed the regeneration potential of mesenchymal stem cells (MSC) from adipose tissue associated with platelet-rich plasma (PRP) in bone regeneration.Methods:Thirty Wistar rats (Rattus norvegicus albinos) were divided into five groups (according to the grafting material and time to euthanasia): (1) autograft - 14 days (control), (2) autograft - 28 days (control), (3) MSC + PRP - 14 days, (4) MSC + PRP + papaverine - 14 days and (5) MSC + PRP + papaverine - 28 days. After euthanasia, the graft was removed and histological slides were prepared. They were assessed by a blinded pathologist using a previously published histological scale as parameter.Results:There was some degree of neoformed bone trabeculae (NBT) in 93.3% of the samples, as well as osteoblastic activity (OA). The autograft groups (14 and 28 days) had higher levels in the formation of bone trabeculae. Nonparametric data were analyzed using the Wilcoxon-Mann-Whitney test and proved not to be statistically significant at p < 0.05.Conclusions:Experimental parietal bone reconstruction, combining MSC, PRP and papaverine presented regeneration in all groups with no significant difference among them.Key words: Bone Regeneration, Platelet-Rich Plasma, Tissue Engineering, Rats 相似文献
9.
Nirmanmoh Bhatia Buddhadeb Dawn Tariq S. Siddiqui Marcus F. Stoddard 《Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital》2015,42(1):16-24
Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined.In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area.We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry (1.28 ± 0.55 cm2) was underestimated by the standard method (1.05 ± 0.47 cm2; P=0.001), but not by the modified method. Congenital AV morphology and low cardiac index were the only multivariate predictors of horizontal-oval shape. Low cardiac index was the only predictor of noncircular shape.More than half our patients with AS had noncircular LVOTs. Using the modified method reduces mischaracterizations of AS severity. Congenital AV morphology and low cardiac index predict horizontal-oval or noncircular shape. These data suggest the value of direct LVOT measurement to calculate AS severity in patients who have congenital AV or a low cardiac index. 相似文献
10.
Molly Orcutt Wendy C. King Melissa A. Kalarchian Michael J. Devlin Marsha D. Marcus Luis Garcia Kristine J. Steffen James E. Mitchell 《Surgery for obesity and related diseases》2019,15(2):295-303