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   33662篇
  免费   2242篇
  国内免费   203篇
耳鼻咽喉   322篇
儿科学   571篇
妇产科学   448篇
基础医学   4732篇
口腔科学   895篇
临床医学   3456篇
内科学   7118篇
皮肤病学   677篇
神经病学   3850篇
特种医学   1958篇
外科学   5310篇
综合类   192篇
一般理论   8篇
预防医学   1450篇
眼科学   687篇
药学   2036篇
中国医学   68篇
肿瘤学   2329篇
  2024年   19篇
  2023年   240篇
  2022年   415篇
  2021年   890篇
  2020年   630篇
  2019年   818篇
  2018年   939篇
  2017年   803篇
  2016年   934篇
  2015年   1145篇
  2014年   1371篇
  2013年   1658篇
  2012年   2703篇
  2011年   2817篇
  2010年   1691篇
  2009年   1511篇
  2008年   2414篇
  2007年   2408篇
  2006年   2254篇
  2005年   2196篇
  2004年   1988篇
  2003年   1815篇
  2002年   1663篇
  2001年   307篇
  2000年   226篇
  1999年   278篇
  1998年   318篇
  1997年   236篇
  1996年   186篇
  1995年   160篇
  1994年   134篇
  1993年   123篇
  1992年   81篇
  1991年   69篇
  1990年   66篇
  1989年   46篇
  1988年   42篇
  1987年   34篇
  1986年   39篇
  1985年   32篇
  1984年   40篇
  1983年   30篇
  1982年   42篇
  1981年   31篇
  1980年   20篇
  1978年   17篇
  1977年   13篇
  1976年   15篇
  1974年   15篇
  1971年   11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