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   13475篇
  免费   686篇
  国内免费   53篇
耳鼻咽喉   113篇
儿科学   891篇
妇产科学   295篇
基础医学   1347篇
口腔科学   290篇
临床医学   845篇
内科学   2713篇
皮肤病学   347篇
神经病学   728篇
特种医学   374篇
外国民族医学   1篇
外科学   2313篇
综合类   350篇
一般理论   13篇
预防医学   570篇
眼科学   619篇
药学   1313篇
中国医学   61篇
肿瘤学   1031篇
  2023年   106篇
  2022年   249篇
  2021年   501篇
  2020年   252篇
  2019年   354篇
  2018年   425篇
  2017年   314篇
  2016年   385篇
  2015年   394篇
  2014年   545篇
  2013年   719篇
  2012年   1033篇
  2011年   1091篇
  2010年   584篇
  2009年   454篇
  2008年   749篇
  2007年   718篇
  2006年   611篇
  2005年   544篇
  2004年   524篇
  2003年   418篇
  2002年   380篇
  2001年   295篇
  2000年   294篇
  1999年   247篇
  1998年   100篇
  1997年   67篇
  1996年   84篇
  1995年   66篇
  1994年   49篇
  1993年   45篇
  1992年   117篇
  1991年   162篇
  1990年   126篇
  1989年   107篇
  1988年   107篇
  1987年   75篇
  1986年   85篇
  1985年   89篇
  1984年   65篇
  1983年   68篇
  1979年   66篇
  1978年   44篇
  1977年   35篇
  1975年   34篇
  1973年   38篇
  1972年   41篇
  1971年   44篇
  1969年   32篇
  1968年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
IntroductionAdaptive techniques to deliver radiotherapy to the bladder may ensure treatment accuracy whilst sparing organs at risk. This study assesses the frequency of when an alternative plan to the current standard may be beneficial and establish the treatment resource implications of adaptive techniques. Assess the variation in accuracy of skeletal surrogate compared to the target. Additionally describes a training package for therapeutic radiographers evaluating CBCT datasets for adaptive techniques.MethodsA library of three plans was created for each patient, small, standard and large. Weekly CBCT and planar imaging data were acquired from 10 bladder cancer patients receiving radical radiotherapy. Bladder volumes from weekly CBCT were compared to the planning scan. Image registration was performed using bone and soft tissue structures on the CBCT images. A database of images was created to develop competency assessment and a training package.ResultsMatching to a skeletal surrogate may under estimate movement of the target. Bladder volume can vary significantly during the course of treatment, even in the presence of bladder preparation protocols. The additional time required to implement this technique is 4 min per fraction compared to standard treatment with planar imaging.ConclusionsThis feasibility study is a useful process to facilitate the implementation of adaptive techniques. However a limitation of this study is the low number of CBCT datasets evaluated. The advent of IGRT and adaptive techniques gives increased confidence to reduce margins, consequently facilitating hypo-fractionation, and may provide a gain in linear accelerator efficiency and reduce the number of hospital visits for the patient. CBCT paired with a development programme for therapeutic radiographers is an effective and efficient means of implementing adaptive radiotherapy.  相似文献   
193.
194.
195.
A series of difluorinated propanediones were synthesized and evaluated for in vitro cytotoxic activity by Sulforhodamine B (SRB) assay against a panel of four human cancer cell lines. Though the compounds showed varying degrees of cytotoxicity in the tested cell lines, most marked effect was observed in breast cancer cell line (MCF7), wherein nine of the ten synthesized chalcones showed good antiproliferative activity.  相似文献   
196.
197.
198.
BackgroundMeta-analyses of oral hypoglycemic agents (OHAs) revealed that rosiglitazone increased the risk of myocardial infarction (MI) and heart failure (HF) and that pioglitazone increased the risk of HF and decreased the risk of MI.ObjectiveTo characterize the change in the pattern of use of OHAs immediately after the publication of these meta-analyses on May 21, 2007.MethodsPharmacy and medical claims data for a managed care organization were analyzed for patients continuously enrolled from January 1, 2005, to November 30, 2007, with at least 1 pharmacy claim for OHA in the 13-month period between November 1, 2006, and November 30, 2007. A 5-month pre-publication period (November 1, 2006, through March 31, 2007) was compared with a 5-month post-publication period (July 1, 2007, through November 30, 2007) using a differences-in-differences multinomial logistic regression. This regression explored discontinuation; continuation with monotherapy or adding another drug; and switching to a drug different from the index monotherapy drug after adjusting for gender, age, type of insurance, past 1-year history of MI or HF, and risk factors for MI and HF in the past 1 year.ResultsThe relative rate of switching to nonindex drug in the postpublication relative to prepublication was 2.64 (P = .046) for monotherapy rosiglitazone users and 0.72 (P = .583) for monotherapy pioglitazone users. The differences-in-differences estimate of the rate of switching to nonindex drugs for monotherapy rosiglitazone users was 3.64 (P = .090) times higher relative to the estimate for monotherapy pioglitazone users.ConclusionThe pattern of use differed fundamentally between monotherapy rosiglitazone users and users of all other monotherapy OHAs in the postperiod. Not only were monotherapy rosiglitazone patients switching to non-rosiglitazone drugs at a higher rate, but the rate also was more than 3 times higher than similar switches among monotherapy pioglitazone users in the postperiod relative to the preperiod. This shows that the market response as observed by patient/prescriber decisions to the adverse news was interpreted narrowly to monotherapy rosiglitazone, and there is little or no spillover to the other drugs. Therefore, this study found that there was a differential effect of meta-analyses on the use of the 2 drugs.  相似文献   
199.
200.
Spontaneous, complete resolution of inflammatory pseudotumour (IPT) of lungs is exceptionally rare. A 44-year-old male was referred for evaluation for «non resolving pneumonitis». He had cough and minimal expectoration for 5 months, chest pain, haemoptysis and fever for a fortnight. Computed tomography of thorax (CT-thorax) confirmed the presence of a homogenous mass with irregular borders in right middle lobe with areas of breakdown and air bronchogram. Transbronchial lung biopsy was suggestive of «plasma cell granuloma». Thoracotomy disclosed a hard mass in right middle lobe adherent to lower lobe, chest wall and mediastinum which could not be removed. A wedge biopsy confirmed IPT. Chest radiograph after 4 weeks revealed significant resolution. CT-thorax a year later showed fibrotic scar. Till date, there are only five reports documenting 6 patients with spontaneous resolution of IPT of lungs and in 4 this occurred within 3 months of an invasive diagnostic intervention.  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