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   33941篇
  免费   2235篇
  国内免费   204篇
耳鼻咽喉   320篇
儿科学   568篇
妇产科学   447篇
基础医学   4856篇
口腔科学   911篇
临床医学   3470篇
内科学   7179篇
皮肤病学   696篇
神经病学   3743篇
特种医学   1985篇
外科学   5397篇
综合类   207篇
一般理论   8篇
预防医学   1426篇
眼科学   689篇
药学   2078篇
中国医学   68篇
肿瘤学   2332篇
  2023年   241篇
  2022年   399篇
  2021年   891篇
  2020年   628篇
  2019年   817篇
  2018年   942篇
  2017年   803篇
  2016年   937篇
  2015年   1145篇
  2014年   1372篇
  2013年   1666篇
  2012年   2709篇
  2011年   2810篇
  2010年   1691篇
  2009年   1503篇
  2008年   2403篇
  2007年   2407篇
  2006年   2246篇
  2005年   2182篇
  2004年   1993篇
  2003年   1816篇
  2002年   1669篇
  2001年   306篇
  2000年   232篇
  1999年   289篇
  1998年   321篇
  1997年   236篇
  1996年   192篇
  1995年   165篇
  1994年   139篇
  1993年   131篇
  1992年   84篇
  1991年   75篇
  1990年   62篇
  1989年   56篇
  1988年   62篇
  1987年   45篇
  1986年   41篇
  1985年   39篇
  1984年   57篇
  1983年   50篇
  1982年   49篇
  1981年   39篇
  1980年   29篇
  1979年   21篇
  1978年   21篇
  1977年   21篇
  1975年   20篇
  1974年   22篇
  1973年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 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