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   2525篇
  免费   158篇
  国内免费   11篇
耳鼻咽喉   16篇
儿科学   158篇
妇产科学   66篇
基础医学   341篇
口腔科学   80篇
临床医学   234篇
内科学   395篇
皮肤病学   46篇
神经病学   448篇
特种医学   86篇
外科学   256篇
综合类   6篇
预防医学   270篇
眼科学   21篇
药学   79篇
中国医学   5篇
肿瘤学   187篇
  2024年   5篇
  2023年   19篇
  2022年   31篇
  2021年   51篇
  2020年   52篇
  2019年   47篇
  2018年   66篇
  2017年   51篇
  2016年   74篇
  2015年   82篇
  2014年   84篇
  2013年   110篇
  2012年   141篇
  2011年   162篇
  2010年   101篇
  2009年   82篇
  2008年   122篇
  2007年   154篇
  2006年   142篇
  2005年   153篇
  2004年   109篇
  2003年   99篇
  2002年   114篇
  2001年   47篇
  2000年   49篇
  1999年   44篇
  1998年   25篇
  1997年   22篇
  1996年   31篇
  1995年   23篇
  1994年   14篇
  1993年   14篇
  1992年   33篇
  1991年   24篇
  1990年   29篇
  1989年   35篇
  1988年   26篇
  1987年   29篇
  1986年   22篇
  1985年   26篇
  1984年   26篇
  1983年   31篇
  1982年   10篇
  1981年   7篇
  1980年   5篇
  1979年   16篇
  1978年   7篇
  1974年   5篇
  1968年   5篇
  1967年   6篇
排序方式: 共有2694条查询结果,搜索用时 31 毫秒
71.
European Child & Adolescent Psychiatry - The Strengths and Difficulties Questionnaire (SDQ) is widely used, based on evidence of its value for screening. This evidence primarily regards the...  相似文献   
72.
73.
74.
75.
76.

Purpose

Hypoxia is an important factor influencing tumor progression and treatment efficacy. The aim of this study was to investigate the repeatability of hypoxia PET imaging with [18F]HX4 in patients with head and neck and lung cancer.

Methods

Nine patients with lung cancer and ten with head and neck cancer were included in the analysis (NCT01075399). Two sequential pretreatment [18F]HX4 PET/CT scans were acquired within 1 week. The maximal and mean standardized uptake values (SUVmax and SUVmean) were defined and the tumor-to-background ratios (TBR) were calculated. In addition, hypoxic volumes were determined as the volume of the tumor with a TBR >1.2 (HV1.2). Bland Altman analysis of the uptake parameters was performed and coefficients of repeatability were calculated. To evaluate the spatial repeatability of the uptake, the PET/CT images were registered and a voxel-wise comparison of the uptake was performed, providing a correlation coefficient.

Results

All parameters of [18F]HX4 uptake were significantly correlated between scans: SUVmax (r?=?0.958, p?<?0.001), SUVmean (r?=?0.946, p?<?0.001), TBRmax (r?=?0.962, p?<?0.001) and HV1.2 (r?=?0.995, p?<?0.001). The relative coefficients of repeatability were 15 % (SUVmean), 17 % (SUVmax) and 17 % (TBRmax). Voxel-wise analysis of the spatial uptake pattern within the tumors provided an average correlation of 0.65?±?0.14.

Conclusion

Repeated hypoxia PET scans with [18F]HX4 provide reproducible and spatially stable results in patients with head and neck cancer and patients with lung cancer. [18F]HX4 PET imaging can be used to assess the hypoxic status of tumors and has the potential to aid hypoxia-targeted treatments.
  相似文献   
77.
78.
79.
BACKGROUNDThere has been an increase in cases of inflammatory bowel disease (IBD) in recent years. There is also greater access and availability of immunosuppressive and biological agents, which increase the risk of opportunistic infection despite improving the quality of life and promoting mucosal healing. Tuberculosis (TB) remains a public health problem, and it has a high incidence in several countries. Therefore, knowledge of the risk of developing TB in patients with IBD is important.AIMTo evaluate the risk of active TB in patients with IBD under treatment from an endemic area in Latin America.METHODSA standard questionnaire included demographic variables, clinical aspects of IBD disease, history of active TB during treatment, active TB characteristics and evolution, initial screening and results and time from the start of anti-tumor necrosis factor alpha (TNFα) to TB development.RESULTSAzathioprine, anti-TNFα and the combination of these two drugs were associated with a higher risk of active TB incidence. The TNFα blockers increased the relative risk of developing active TB compared to other treatments. All four multivariable models showed that the use of TNFα blockers alone or in combination with azathioprine was an important risk factor for the incidence of active TB. After adjustment for sex, age, type of IBD and latent TB, anti-TNFα with azathioprine increased the relative risk to 17.8 times more than conventional treatment. Late TB, which was diagnosed 3 mo after the start of anti-TNFα, was the most frequent.CONCLUSIONTreatment with anti-TNFα increased the risk of active TB in IBD patients from an endemic area in Latin America. This risk was increased when anti-TNFα was combined with azathioprine. The time from the beginning of the treatment to the active TB diagnosis suggests a new TB infection.  相似文献   
80.
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