全文获取类型
| 收费全文 | 81711篇 |
| 免费 | 5183篇 |
| 国内免费 | 839篇 |
专业分类
| 耳鼻咽喉 | 1513篇 |
| 儿科学 | 964篇 |
| 妇产科学 | 1195篇 |
| 基础医学 | 13755篇 |
| 口腔科学 | 2142篇 |
| 临床医学 | 7246篇 |
| 内科学 | 15059篇 |
| 皮肤病学 | 2915篇 |
| 神经病学 | 6208篇 |
| 特种医学 | 4686篇 |
| 外科学 | 10796篇 |
| 综合类 | 346篇 |
| 现状与发展 | 3篇 |
| 一般理论 | 24篇 |
| 预防医学 | 3825篇 |
| 眼科学 | 1873篇 |
| 药学 | 7454篇 |
| 中国医学 | 980篇 |
| 肿瘤学 | 6749篇 |
出版年
| 2023年 | 609篇 |
| 2022年 | 1950篇 |
| 2021年 | 2989篇 |
| 2020年 | 1526篇 |
| 2019年 | 2016篇 |
| 2018年 | 2512篇 |
| 2017年 | 1923篇 |
| 2016年 | 2772篇 |
| 2015年 | 3859篇 |
| 2014年 | 4472篇 |
| 2013年 | 5176篇 |
| 2012年 | 7632篇 |
| 2011年 | 7029篇 |
| 2010年 | 4163篇 |
| 2009年 | 3466篇 |
| 2008年 | 4883篇 |
| 2007年 | 4461篇 |
| 2006年 | 3779篇 |
| 2005年 | 3494篇 |
| 2004年 | 2924篇 |
| 2003年 | 2477篇 |
| 2002年 | 2168篇 |
| 2001年 | 1762篇 |
| 2000年 | 1611篇 |
| 1999年 | 1201篇 |
| 1998年 | 516篇 |
| 1997年 | 382篇 |
| 1996年 | 299篇 |
| 1995年 | 259篇 |
| 1994年 | 229篇 |
| 1993年 | 205篇 |
| 1992年 | 443篇 |
| 1991年 | 458篇 |
| 1990年 | 403篇 |
| 1989年 | 364篇 |
| 1988年 | 345篇 |
| 1987年 | 331篇 |
| 1986年 | 260篇 |
| 1985年 | 229篇 |
| 1984年 | 172篇 |
| 1983年 | 156篇 |
| 1982年 | 87篇 |
| 1981年 | 91篇 |
| 1979年 | 137篇 |
| 1978年 | 111篇 |
| 1975年 | 103篇 |
| 1974年 | 91篇 |
| 1972年 | 91篇 |
| 1971年 | 87篇 |
| 1970年 | 85篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
21.
22.
Comparative outcomes of vascular access in patients older than 70 years with end-stage renal disease
Deokbi Hwang Sujin Park Hyung-Kee Kim Seung Huh 《Journal of vascular surgery》2019,69(4):1196-1206.e5
Objective
The advantage of arteriovenous fistulas (AVFs) in older patients requiring dialysis is controversial. We reviewed our vascular access experience in patients ≥70 years of age (older group) compared with younger patients.Methods
We analyzed consecutive patients who underwent access surgery between 2013 and 2016. Primary success (PS) and primary patency (PP) data were analyzed between the older and younger groups before and after propensity score matching of the patients' characteristics and access composition. PS was defined as the achievement of access function that was amenable to two sessions of successful cannulation without early occlusion or maturation failure requiring revision. PP was defined as the time with uninterrupted patency without intervention.Results
A total of 594 consecutive accesses were created among 563 patients, of whom 119 were allocated into each group after propensity score matching. In the whole cohort, 193 accesses (32.5%) were performed in older patients. AVFs were performed in 130 (67.4%) older patients and 293 (73.1%) younger patients. Regarding AVFs, the PS rate (83.6% in the older group vs 94.3% in the younger group; P = .001) and the overall PP at 6 and 12 months (73.1% and 57.1%, respectively, in the older group vs 86.7% and 77.7%, respectively, in the younger group; P = .009) were lower in the older group than in the younger group. However, no differences were found in the PS and PP rates for arteriovenous grafts between groups. Regarding the AVF location, the PS rate for forearm AVFs was significantly lower in the older group than in the younger group (76% vs 93%; P < .001); however, the PS rate of the upper arm was not different between the groups (94% vs 97%; P = .425). In the patients with PS, the PP rate of AVFs was similar between the two groups. In the older group with forearm AVFs, the median diameter of the radial artery was larger in the patients with PS than in the patients without PS (2.20 mm with PS vs 2.00 mm without PS; P = .008). The propensity score matching results demonstrated similar trends for the whole cohort, with lower PS (P = .042) and PP rates (P = .023) for AVF in the older group.Conclusions
The outcomes after AVF were poorer in the older group than in the younger group, which was primarily due to unsatisfactory outcomes in patients with forearm AVFs. Thus, stricter criteria, especially regarding the radial artery diameter, should be applied for forearm AVFs in older patients, and additional research is necessary to delineate the risk factors for primary failure. 相似文献23.
24.
A typical time series in functional magnetic resonance imaging (fMRI) exhibits autocorrelation, that is, the samples of the time series are dependent. In addition, temporal filtering, one of the crucial steps in preprocessing of functional magnetic resonance images, induces its own autocorrelation. While performing connectivity analysis in fMRI, the impact of the autocorrelation is largely ignored. Recently, autocorrelation has been addressed by variance correction approaches, which are sensitive to the sampling rate. In this article, we aim to investigate the impact of the sampling rate on the variance correction approaches. Toward this end, we first derived a generalized expression for the variance of the sample Pearson correlation coefficient (SPCC) in terms of the sampling rate and the filter cutoff frequency, in addition to the autocorrelation and cross‐covariance functions of the time series. Through simulations, we illustrated the importance of the variance correction for a fixed sampling rate. Using the real resting state fMRI data sets, we demonstrated that the data sets with higher sampling rates were more prone to false positives, in agreement with the existing empirical reports. We further demonstrated with single subject results that for the data sets with higher sampling rates, the variance correction strategy restored the integrity of true connectivity. 相似文献
25.
26.
27.
28.
29.
30.
Miju Bae Sung Woon Chung Chung Won Lee Up Huh Min Su Kim Seung Hwan Song 《Asian journal of surgery / Asian Surgical Association》2019,42(1):235-239