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   38870篇
  免费   2639篇
  国内免费   214篇
耳鼻咽喉   383篇
儿科学   708篇
妇产科学   584篇
基础医学   5558篇
口腔科学   976篇
临床医学   3955篇
内科学   8314篇
皮肤病学   802篇
神经病学   4052篇
特种医学   2246篇
外国民族医学   1篇
外科学   6344篇
综合类   222篇
一般理论   10篇
预防医学   1615篇
眼科学   831篇
药学   2337篇
中国医学   76篇
肿瘤学   2709篇
  2023年   248篇
  2022年   396篇
  2021年   950篇
  2020年   676篇
  2019年   873篇
  2018年   1013篇
  2017年   872篇
  2016年   1024篇
  2015年   1267篇
  2014年   1513篇
  2013年   1831篇
  2012年   2945篇
  2011年   3091篇
  2010年   1827篇
  2009年   1657篇
  2008年   2653篇
  2007年   2675篇
  2006年   2502篇
  2005年   2448篇
  2004年   2187篇
  2003年   2024篇
  2002年   1854篇
  2001年   464篇
  2000年   411篇
  1999年   459篇
  1998年   390篇
  1997年   309篇
  1996年   243篇
  1995年   214篇
  1994年   182篇
  1993年   173篇
  1992年   178篇
  1991年   165篇
  1990年   160篇
  1989年   160篇
  1988年   105篇
  1987年   98篇
  1986年   104篇
  1985年   86篇
  1984年   91篇
  1983年   67篇
  1982年   70篇
  1981年   61篇
  1980年   49篇
  1979年   82篇
  1978年   51篇
  1974年   61篇
  1973年   44篇
  1972年   50篇
  1971年   53篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
5.
6.
7.

Forensic age estimation generally involves considerable amounts of uncertainty. Forensic age indicators such as teeth or skeleton images predict age only approximately, and this is likely to remain true even for future forensic age indicators. Thus, forensic age assessment should aim to make the best possible decisions under uncertainty. In this paper, we apply mathematical theory to make statistically optimal decisions to age assessment. Such an application is fairly straightforward assuming there is a standardized procedure for obtaining age indicator information from individuals, assuming we have data from the application of this procedure to a group of persons with known ages, and assuming the starting point for each individual is a probability distribution describing prior knowledge about the persons age. The main problem is then to obtain such a prior. Our analysis indicates that individual priors rather than a common prior for all persons may be necessary. We suggest that caseworkers, based on individual case information, may select a prior from a menu of priors. We show how information may then be collected over time to gradually increase the robustness of the decision procedure. We also show how replacing individual prior distributions for age with individual prior odds for being above an age limit cannot be recommended as a general method. Our theoretical framework is applied to data where the maturity of the distal femur and the third molar is observed using MRI. As part of this analysis we observe a weak positive conditional correlation between maturity of the two body parts.

  相似文献   
8.
9.
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis.  相似文献   
10.
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