全文获取类型
收费全文 | 1925745篇 |
免费 | 149652篇 |
国内免费 | 7281篇 |
专业分类
耳鼻咽喉 | 24625篇 |
儿科学 | 62379篇 |
妇产科学 | 51353篇 |
基础医学 | 274892篇 |
口腔科学 | 54461篇 |
临床医学 | 173660篇 |
内科学 | 386791篇 |
皮肤病学 | 45371篇 |
神经病学 | 151125篇 |
特种医学 | 76156篇 |
外国民族医学 | 346篇 |
外科学 | 295661篇 |
综合类 | 43752篇 |
现状与发展 | 4篇 |
一般理论 | 567篇 |
预防医学 | 151619篇 |
眼科学 | 42169篇 |
药学 | 138992篇 |
8篇 | |
中国医学 | 4402篇 |
肿瘤学 | 104345篇 |
出版年
2018年 | 20441篇 |
2017年 | 15856篇 |
2016年 | 18551篇 |
2015年 | 20752篇 |
2014年 | 28573篇 |
2013年 | 42891篇 |
2012年 | 54242篇 |
2011年 | 57991篇 |
2010年 | 35341篇 |
2009年 | 33948篇 |
2008年 | 53885篇 |
2007年 | 57577篇 |
2006年 | 58623篇 |
2005年 | 56082篇 |
2004年 | 54043篇 |
2003年 | 52019篇 |
2002年 | 49757篇 |
2001年 | 93928篇 |
2000年 | 96233篇 |
1999年 | 80058篇 |
1998年 | 22977篇 |
1997年 | 20226篇 |
1996年 | 21210篇 |
1995年 | 21112篇 |
1994年 | 19668篇 |
1993年 | 18322篇 |
1992年 | 65153篇 |
1991年 | 63793篇 |
1990年 | 61656篇 |
1989年 | 59427篇 |
1988年 | 54786篇 |
1987年 | 53656篇 |
1986年 | 50693篇 |
1985年 | 48497篇 |
1984年 | 36542篇 |
1983年 | 30801篇 |
1982年 | 18541篇 |
1981年 | 16672篇 |
1980年 | 15762篇 |
1979年 | 33001篇 |
1978年 | 23724篇 |
1977年 | 20032篇 |
1976年 | 18663篇 |
1975年 | 19832篇 |
1974年 | 23302篇 |
1973年 | 22262篇 |
1972年 | 20698篇 |
1971年 | 19141篇 |
1970年 | 17783篇 |
1969年 | 16562篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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
12.
13.
14.
15.
Hanna Lee Mary K. Tan Andrew T. Yan Paul Angaran Paul Dorian Claudia Bucci Jean C. Gregoire Alan D. Bell Martin S. Green Peter L. Gross Allan Skanes Charles R. Kerr L. Brent Mitchell Jafna L. Cox Vidal Essebag Brett Heilbron Krishnan Ramanathan Carl Fournier Shaun G. Goodman 《The Canadian journal of cardiology》2019,35(2):160-168
Background
Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.Methods
We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).Results
Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.Conclusions
Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation. 相似文献16.
17.
N. V. Bashmakova G. N. Chistiakova I. A. Gazieva Y. M. Trapeznikova D. O. Mazurov 《Gynecological endocrinology》2015,31(10):31-33
AbstractThis study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos. 相似文献
18.
K.-C. Sung D.-C. Seo S.-J. Lee M.-Y. Lee S.H. Wild C.D. Byrne 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(5):489-495
Background and aims
It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.Methods and results
As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.Conclusions
In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes. 相似文献19.
Christopher N. Cooley Tyler J. Beranek Matthew A. Warpinski Robert Alexander Amanda O. Esquivel 《The American journal of emergency medicine》2019,37(2):199-203
Introduction
In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.Methods
We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.Results
A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.Conclusion
The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department. 相似文献20.
Anand Dayama Nikolaos Tsilimparis Stephen Kolakowski Nathaniel M. Matolo Misty D. Humphries 《Journal of vascular surgery》2019,69(1):156-163.e1