首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   199012篇
  免费   45901篇
  国内免费   1112篇
耳鼻咽喉   3305篇
儿科学   5988篇
妇产科学   2389篇
基础医学   34907篇
口腔科学   7807篇
临床医学   23551篇
内科学   43923篇
皮肤病学   11141篇
神经病学   22959篇
特种医学   9300篇
外科学   29468篇
综合类   565篇
现状与发展   3篇
一般理论   48篇
预防医学   10638篇
眼科学   4487篇
药学   16664篇
中国医学   2261篇
肿瘤学   16621篇
  2023年   941篇
  2022年   2778篇
  2021年   5604篇
  2020年   6864篇
  2019年   13133篇
  2018年   13167篇
  2017年   13704篇
  2016年   15266篇
  2015年   16637篇
  2014年   17506篇
  2013年   19041篇
  2012年   15077篇
  2011年   14581篇
  2010年   14563篇
  2009年   10229篇
  2008年   9416篇
  2007年   7977篇
  2006年   7307篇
  2005年   6601篇
  2004年   5824篇
  2003年   5174篇
  2002年   4630篇
  2001年   3780篇
  2000年   3475篇
  1999年   2404篇
  1998年   930篇
  1997年   695篇
  1996年   527篇
  1995年   466篇
  1994年   407篇
  1993年   350篇
  1992年   775篇
  1991年   711篇
  1990年   653篇
  1989年   567篇
  1988年   479篇
  1987年   481篇
  1986年   339篇
  1985年   379篇
  1984年   264篇
  1983年   199篇
  1982年   137篇
  1981年   174篇
  1980年   133篇
  1979年   234篇
  1978年   170篇
  1976年   138篇
  1975年   130篇
  1974年   143篇
  1973年   126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.

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   
6.
7.
8.
9.
Laparoscopic surgery has several advantages over traditional surgery because it has been shown to be less invasive. The next logical step in the evolution of minimally invasive surgery may be to eliminate all abdominal incisions. The natural orifices provide a port of entry via the gastrointestinal tract to the peritoneal cavity. This approach would require the creation of a perforation, which is considered to be a major complication of endoscopy with significant morbidity and mortality. However, there are several recent studies that have described the technical feasibility and safety of a per‐oral transgastric approach to the peritoneal cavity using conventional endoscopes. Theoretically, this approach could reduce postoperative abdominal wall pain, wound infection, hernia formation, and adhesions. This article aims to summarize the current status of transgastric surgery, currently referred to as natural orifice transluminal endoscopic surgery (NOTES), and to address some of its future challenges.  相似文献   
10.
We report the case of a littoral‐cell angioma of the spleen, a recently described benign vascular tumour, whose imaging and pathological characteristics have been discussed only by a few authors. The diagnosis was made after elective splenectomy. The CT images, scintigraphy and histological specimens are presented, and differential diagnoses discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号