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   2574篇
  免费   155篇
  国内免费   13篇
耳鼻咽喉   29篇
儿科学   56篇
妇产科学   132篇
基础医学   247篇
口腔科学   70篇
临床医学   212篇
内科学   536篇
皮肤病学   30篇
神经病学   184篇
特种医学   114篇
外国民族医学   3篇
外科学   470篇
综合类   28篇
一般理论   3篇
预防医学   113篇
眼科学   107篇
药学   172篇
中国医学   2篇
肿瘤学   234篇
  2024年   3篇
  2023年   25篇
  2022年   53篇
  2021年   113篇
  2020年   78篇
  2019年   105篇
  2018年   160篇
  2017年   111篇
  2016年   87篇
  2015年   90篇
  2014年   123篇
  2013年   145篇
  2012年   225篇
  2011年   220篇
  2010年   140篇
  2009年   92篇
  2008年   161篇
  2007年   155篇
  2006年   126篇
  2005年   119篇
  2004年   109篇
  2003年   113篇
  2002年   98篇
  2001年   12篇
  2000年   7篇
  1999年   8篇
  1998年   8篇
  1997年   8篇
  1996年   12篇
  1995年   13篇
  1994年   2篇
  1993年   3篇
  1992年   4篇
  1991年   3篇
  1990年   4篇
  1988年   1篇
  1986年   1篇
  1983年   2篇
  1982年   2篇
  1979年   1篇
排序方式: 共有2742条查询结果,搜索用时 15 毫秒
21.
Aortic arch aneurysm is a relatively rare entity in cardiac surgery. Repair of such aneurysms, either in isolation or combined with other cardiac procedures, remains a challenging task. The need to produce a relatively bloodless surgical field with circulatory arrest, while at the same time protecting the brain, is the hallmark of this challenge. However, a clear understanding of the topic allows a better and less morbid approach to such a complex surgery.Literature has shown the advantage of selective cerebral perfusion techniques in comparison with only circulatory arrest. Ability to perfuse the brain has allowed circulatory arrest temperatures at moderate hypothermia without the need for deep hypothermia. Even though cannulation site selection appears to be a minor issue, literature has shown that the subclavian/axillary route has the best outcomes and that femoral cannulation should only be reserved for no access patients. Although different techniques for arch anastomosis have been described, we routinely perform the distal first technique as we find it to be less cumbersome and easiest to reproduce.In this review our aim is to outline a systematic approach to aortic arch surgery. Starting with indications for intervention and proceeding with approaches on site of cannulation, approaches to brain protection with hypothermia and selective cerebral perfusion and finally surgical steps in performing the distal and arch vessels anastomosis.  相似文献   
22.
23.
Journal of Assisted Reproduction and Genetics - Ferroptosis is associated with oxidative stress (OS) and is caused by iron-dependent lipid-peroxidative damage, but its role in PE is unclear. The...  相似文献   
24.
25.
Aim: Several tests are available for aphasia screening following stroke. However, some of them have shortcomings such as need of specialist knowledge, low sensitivity and/or specificity and lengthy administration time. Our study aims to evaluate the language component of the Addenbrooke's Cognitive Examination – Revised (ACE‐R) as a screening tool for aphasia in stroke patients. Methods: The language component of ACE‐R was administered to consecutive patients admitted to a post‐acute stroke unit. Patients who were medically unstable or had a significant history of sensory impairment or mental health issues were excluded. The test was administered by two junior doctors with basic training in ACE‐R administration. Patients recruited were also assessed by an experienced speech and language therapist (SLT). The results of the two assessments were documented by a different member of the team and the SLT results were used as the benchmark to calculate the ACE‐R language component sensitivity and specificity. Results: Fifty‐nine participants were recruited and 27 of them were women. The mean age was 72 (SD 11.9). Thirty‐four participants had left and 11 right hemisphere stroke. Fourteen had bilateral affection. Six participants were left handed. A cut‐off value of 22/26 of ACE‐R language component showed 100% specificity and 83.1% sensitivity, while a cut‐off value of 16/26 had 88.2% specificity and 100% sensitivity. Conclusion: Our results suggest that the language component of ACE‐R has a satisfactory sensitivity and specificity compared with other screening tests used in strokes. It is easy to administer and free to use.  相似文献   
26.
27.
28.
29.
CONTEXT: Genetic aberration in phosphatidylinositol 3-kinase (PI3K)/AKT pathway has been detected in numerous and diverse human cancers. PIK3CA, which encodes for the catalytic subunit of p110alpha of PI3K, is amplified in some cases of papillary thyroid cancer (PTC). Mutations in the PIK3CA have also been identified in thyroid cancers and, although relatively common in anaplastic thyroid carcinoma, are uncommon in PTC. OBJECTIVE: The objective of the study was to investigate genetic alterations like PIK3CA gene mutation, PIK3CA amplification, RAS, and RAF mutations and to further explore the relationship of these genetic alterations with various clinicopathological characteristics in Middle Eastern PTC. DESIGN: We used the fluorescence in situ hybridization technique for analysis of PIK3CA amplification from 536 PTC cases, and selected amplified samples were further validated by real-time quantitative PCR. Mutation analysis was done by direct DNA sequencing of PIK3CA, N2-RAS, and BRAF genes. RESULTS: PIK3CA amplification was seen in 265 of 499 PTC cases analyzed (53.1%); PIK3CA gene mutations in four of 207 PTC (1.9%); N2-RAS mutations in 16 of 265 PTC (6%); and BRAF mutations in 153 of 296 PTC (51.7%). N-RAS mutations were-associated with an early stage (P = 0.0465) and lower incidence of extrathyroidal extension (P = 0.027), whereas BRAF mutations were-associated with metastasis (P = 0.0274) and poor disease-free survival (P = 0.0121) in PTCs. CONCLUSION: A higher incidence of PIK3CA alterations and the possible synergistic effect of PIK3CA alterations and BRAF mutations suggest their major role in Middle Eastern PTC tumorigenesis and argue for therapeutic targeting of PI3K/AKT and MAPK pathways.  相似文献   
30.
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