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   577014篇
  免费   50871篇
  国内免费   21484篇
耳鼻咽喉   5226篇
儿科学   10701篇
妇产科学   6481篇
基础医学   90625篇
口腔科学   12276篇
临床医学   48654篇
内科学   90480篇
皮肤病学   10102篇
神经病学   32745篇
特种医学   13112篇
外国民族医学   190篇
外科学   45766篇
综合类   87060篇
现状与发展   91篇
一般理论   31篇
预防医学   31380篇
眼科学   9887篇
药学   67156篇
  102篇
中国医学   24425篇
肿瘤学   62879篇
  2024年   431篇
  2023年   7805篇
  2022年   10876篇
  2021年   20624篇
  2020年   18744篇
  2019年   19997篇
  2018年   19469篇
  2017年   18905篇
  2016年   19320篇
  2015年   21561篇
  2014年   33727篇
  2013年   37318篇
  2012年   32432篇
  2011年   36726篇
  2010年   31034篇
  2009年   31384篇
  2008年   30883篇
  2007年   32042篇
  2006年   29216篇
  2005年   26368篇
  2004年   21965篇
  2003年   19578篇
  2002年   15508篇
  2001年   13846篇
  2000年   11467篇
  1999年   9966篇
  1998年   7737篇
  1997年   7135篇
  1996年   6481篇
  1995年   6564篇
  1994年   5867篇
  1993年   4960篇
  1992年   4325篇
  1991年   3904篇
  1990年   3205篇
  1989年   2903篇
  1988年   2713篇
  1987年   2198篇
  1986年   1926篇
  1985年   2883篇
  1984年   2840篇
  1983年   1958篇
  1982年   2112篇
  1981年   1705篇
  1980年   1521篇
  1979年   1219篇
  1978年   888篇
  1977年   708篇
  1976年   720篇
  1975年   489篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
BackgroundIschemia reperfusion (I/R) play an imperative role in the expansion of cardiovascular disease. Sinomenine (SM) has been exhibited to possess antioxidant, anticancer, anti-inflammatory, antiviral and anticarcinogenic properties. The aim of the study was scrutinized the cardioprotective effect of SM against I/R injury in rat.MethodsRat were randomly divided into normal control (NC), I/R control and I/R + SM (5, 10 and 20 mg/kg), respectively. Ventricular arrhythmias, body weight and heart weight were estimated. Antioxidant, inflammatory cytokines, inflammatory mediators and plasmin system indicator were accessed.ResultsPre-treated SM group rats exhibited the reduction in the duration and incidence of ventricular fibrillation, ventricular ectopic beat (VEB) and ventricular tachycardia along with suppression of arrhythmia score during the ischemia (30 and 120 min). SM treated rats significantly (P < 0.001) altered the level of antioxidant parameters. SM treatment significantly (P < 0.001) repressed the level of creatine kinase MB (CK-MB), creatine kinase (CK) and troponin I (Tnl). SM treated rats significantly (P < 0.001) repressed the tissue factor (TF), thromboxane B2 (TXB2), plasminogen activator inhibitor 1 (PAI-1) and plasma fibrinogen (Fbg) and inflammatory cytokines and inflammatory mediators.ConclusionOur result clearly indicated that SM plays anti-arrhythmia effect in I/R injury in the rats via alteration of oxidative stress and inflammatory reaction.  相似文献   
2.
3.
4.
A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on modal energy coefficients is proposed to detect troubled cells, where discontinuities exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR method. Numerical investigations show that the proposed subcell limiting strategy on unstructured quadrilateral meshes is robust in shock-capturing.  相似文献   
5.
6.
田玥  邹健 《现代肿瘤医学》2022,(23):4377-4382
胃癌作为临床最常见的肿瘤之一,常因确诊疾病较晚而影响治疗效果,胃镜活检后的病理虽然作为确诊的金标准,但是由于此方式过程痛苦,操作复杂,费用较高,且具有侵入性,可能会导致患者拒绝操作而难普及于临床,因此积极找寻胃癌有效的监测指标十分必要。近年来,很多学者研究维生素与胃癌的相关关系,并试图通过摄取某些维生素降低胃癌发生率,延缓病情及改善预后,也有通过检测血清中维生素的水平给早期胃癌的诊断提供帮助。本文就同型半胱氨酸、维生素D、维生素C、维生素E、维生素B12及叶酸在胃癌中的作用机制,及其在血清中水平与胃癌关系的相关研究进展进行简要综述,为临床胃癌诊疗提供新思路。  相似文献   
7.
8.
Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma (EAC). Progression to cancer typically occurs in a stepwise fashion through worsening dysplasia and ultimately, invasive neoplasia. Established EAC with deep involvement of the esophageal wall and/or metastatic disease is invariably associated with poor long-term survival rates. This guides the rationale of surveillance of Barrett’s in an attempt to treat lesions at an earlier, and potentially curative stage. The last two decades have seen a paradigm shift in management of Barrett’s with rapid expansion in the role of endoscopic eradication therapy (EET) for management of dysplastic and early neoplastic BE, and there have been substantial changes to international consensus guidelines for management of early BE based on evolving evidence. This review aims to assist the physician in the therapeutic decision-making process with patients by comprehensive review and summary of literature surrounding natural history of Barrett’s by histological stage, and the effectiveness of interventions in attenuating the risk posed by its natural history. Key findings were as follows. Non-dysplastic Barrett’s is associated with extremely low risk of progression, and interventions cannot be justified. The annual risk of cancer progression in low grade dysplasia is between 1%-3%; EET can be offered though evidence for its benefit remains confined to highly select settings. High-grade dysplasia progresses to cancer in 5%-10% per year; EET is similarly effective to and less morbid than surgery and should be routinely performed for this indication. Risk of nodal metastases in intramucosal cancer is 2%-4%, which is comparable to operative mortality rate, so EET is usually preferred. Submucosal cancer is associated with nodal metastases in 14%-41% hence surgery remains standard of care, except for select situations.  相似文献   
9.
《Cancer cell》2022,40(11):1392-1406.e7
  1. Download : Download high-res image (241KB)
  2. Download : Download full-size image
  相似文献   
10.
BackgroundSurgical resection is recommended for patients with resectable acinar cell carcinoma (ACC). The aim of this study was to investigate the clinical characteristics and surgical outcomes of resectable ACC in comparison to pancreatic ductal adenocarcinoma (PDAC).MethodA retrospective analysis was performed on all patients who consecutively underwent radical resection with pathologically confirmed ACC and PDAC from December 2011 to December 2018. Clinicopathologic characteristics and follow-up information were analyzed. A 1:3 propensity score matching (PSM) method was used to minimize the bias between ACC and PDAC.ResultsA total of 26 patients with ACC and 1351 with PDAC were included. Compared to PDAC, ACC tended to be larger (4.5 vs. 3.0 cm; p < 0.001) and more frequently located in the pancreatic body/tail (61.5% vs. 36.6%, p = 0.009), with lower total bilirubin levels, lower neutrophil lymphocyte ratio (NLR) levels and lower carbohydrate antigen 19-9 (CA19-9) levels and carcinoembryonic antigen (CEA) levels. There was no difference in postoperative morbidities in patients with ACC and PDAC. The median OS and RFS were longer in ACC when compared to PDAC (OS: 43.5 mo vs. 19.0 mo, p = 0.004; RFS: 24.5 mo vs. 11.6 mo, p = 0.023). After the 1:3 PSM, ACC remained to be a better histological type for OS (p = 0.024), but had comparable RFS with PDAC (p = 0.164).ConclusionPatients with ACC after radical resection had better OS than that with PDAC. However, ACC is also an aggressive tumor with a similar trend of RFS with PDAC after the matching, necessitating the multidisciplinary treatment for resectable ACC disease.  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