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   4097篇
  免费   413篇
  国内免费   236篇
耳鼻咽喉   73篇
儿科学   72篇
妇产科学   13篇
基础医学   570篇
口腔科学   295篇
临床医学   325篇
内科学   1435篇
皮肤病学   67篇
神经病学   57篇
特种医学   70篇
外科学   327篇
综合类   533篇
现状与发展   1篇
预防医学   146篇
眼科学   34篇
药学   371篇
  3篇
中国医学   218篇
肿瘤学   136篇
  2024年   10篇
  2023年   95篇
  2022年   179篇
  2021年   197篇
  2020年   193篇
  2019年   153篇
  2018年   162篇
  2017年   126篇
  2016年   147篇
  2015年   148篇
  2014年   236篇
  2013年   329篇
  2012年   216篇
  2011年   208篇
  2010年   172篇
  2009年   154篇
  2008年   187篇
  2007年   181篇
  2006年   173篇
  2005年   152篇
  2004年   147篇
  2003年   121篇
  2002年   122篇
  2001年   96篇
  2000年   99篇
  1999年   74篇
  1998年   89篇
  1997年   84篇
  1996年   57篇
  1995年   68篇
  1994年   46篇
  1993年   48篇
  1992年   39篇
  1991年   36篇
  1990年   32篇
  1989年   34篇
  1988年   34篇
  1987年   18篇
  1986年   14篇
  1985年   15篇
  1984年   6篇
  1983年   6篇
  1982年   10篇
  1981年   3篇
  1980年   7篇
  1979年   2篇
  1978年   7篇
  1977年   2篇
  1976年   6篇
  1975年   3篇
排序方式: 共有4746条查询结果,搜索用时 31 毫秒
1.
《Digestive and liver disease》2022,54(11):1486-1493
BackgroundCold snare polypectomy (CSP) is a promising technique for the removal of sessile serrated polyps (SSPs) ≥ 10 mm. However, the efficacy and safety of this technique remain undetermined.AimsWe aimed to comprehensively evaluate the efficacy and safety of CSP for SSPs ≥ 10 mm.MethodsPubMed, EMBASE, Web of Science and Cochrane Library were searched up to January 2021.ResultsA total of 10 studies consisting of 1727 SSPs (range, 10–40 mm) from 1021 patients were included. The overall rates of technical success, adverse events (AEs) and residual SSPs were 100%, 0.7% and 2.9%, respectively. Subgroup analysis showed that the rates of technical success and AEs were comparable between CSP and cold endoscopic mucosal resection (EMR) (99.9% vs. 100% and 1.3% vs. 0.5%, respectively), between the proximal and distal colon (100% vs. 99.9% and 0.3% vs. 0, respectively), and between polyps of 10–19 mm and ≥20 mm (99.8% vs. 100% and 0.9% vs. 0, respectively). However, subgroup analysis showed that the rate of residual SSPs was slightly lower in CSP compared with cold EMR (1.3% vs. 3.9%), as well as in polyps of 10–19 mm compared with those ≥20 mm (3.1% vs. 4.7%).ConclusionCSP was an effective and safe technique for removing SSPs ≥ 10 mm.  相似文献   
2.
Endoscopic resections (ERs) are performed for early (T1) cancers mostly of the esophagus, stomach and colorectum, offering a minimally invasive and tissue-preserving alternative to traditional surgical resection. Proper preparation and handling of these specimens is key to allow accurate histological assessment of parameters which will dictate the curative, or non-curative, nature of the procedure. Many histological features have been identified which correlate with risk of recurrence and/or nodal metastases, thereby dictating the need for further management. These include histological subtype of the lesion, grade, depth of invasion, margin status, tumor size, lymphovascular invasion and tumor budding [at least in the colon]. This review article will discuss the ideal specimen preparation and discuss each of these histological parameters in turn, as they pertain to the esophagus, stomach and colorectum, highlighting potential caveats and pitfalls to be aware of when reporting these specimens.  相似文献   
3.
4.
5.
ABSTRACT

Although exclusive breastfeeding has been linked to lower rates of postnatal HIV transmission compared to nonexclusive breastfeeding, mechanisms underlying this are unclear. Across a longitudinally sampled cohort of South African infants, we showed that exclusively breastfed (EBF) infants had altered gut bacterial communities when compared to nonexclusively breastfed (NEBF) infants, as well as reduced peripheral CD4 + T cell activation and lowered chemokine and chemokine receptor expression in the oral mucosa. We further demonstrated that the relative abundance of key taxa was correlated with peripheral CD4 + T cell activation. Here, we supplement those findings by using compositional data analyses to identify shifts in the abundance of several Bifidobacteria strains relative to select strains of Escherichia, Bacteroides, and others that are associated with the transition to NEBF. We illustrate that the abundance ratio of these taxa is tightly correlated with feeding modality and is a strong predictor of peripheral T cell activation. More broadly, we discuss our study in the context of novel developments and explore future directions for the field.  相似文献   
6.
7.
目的 :探讨大鼠胃粘膜与急性胃粘膜损伤之间的关系。方法 :采用原子吸收光谱分析法 ,测定胃粘膜Ca2 +含量。结果 :胃粘膜损伤程度随应激时间延长而加重 ,胃粘膜Ca2 + 含量却下降 ,二者呈明显负相关 ,但是 ,CaCl2 预应激或应用钙通道阻断剂 ,可减轻胃粘膜损伤程度。结论 :Ca2 + 在急性胃粘膜损伤中有一定的作用。  相似文献   
8.
药物传递系统(DDS)Ⅳ腔道给药传递系统   总被引:2,自引:0,他引:2  
腔道给药是能起全身作用、避开肝首过代谢作用、患者便于自用的非损伤性给药途径。本文着重介绍影响鼻腔、阴道给药药物吸收的生物因素和剂型因素及正在开发的腔道给药传递系统。  相似文献   
9.
10.
OBJECTIVE: We report on 3 patients who underwent laparoscopic antireflux procedures for persistent symptoms of GERD after biopolymer injection. METHODS: Experienced laparoscopic surgeons completed all 3 procedures laparoscopically. In 2 patients, there was an extramural extravasation of the polymer outside and adherent to the esophageal wall. In these patients, a partial posterior fundoplication was used. The third patient, who had the polymer material deposits removed preoperatively by endoscopic mucosal resection, underwent a Nissen fundoplication. RESULTS: Postoperative recovery was uneventful in all cases. At follow-up of 6 to 12 months, all patients were symptom free, off medical therapy, and experiencing no dysphagia. CONCLUSION: Surgical therapy for patients after failed biopolymer injection is safe and effective. The choice of surgery may depend on whether the polymer mass can be removed preoperatively.  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