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   33396篇
  免费   2216篇
  国内免费   202篇
耳鼻咽喉   314篇
儿科学   570篇
妇产科学   447篇
基础医学   4714篇
口腔科学   887篇
临床医学   3427篇
内科学   7091篇
皮肤病学   662篇
神经病学   3720篇
特种医学   1960篇
外科学   5339篇
综合类   185篇
一般理论   7篇
预防医学   1437篇
眼科学   691篇
药学   1971篇
中国医学   68篇
肿瘤学   2324篇
  2024年   19篇
  2023年   241篇
  2022年   409篇
  2021年   892篇
  2020年   630篇
  2019年   817篇
  2018年   937篇
  2017年   802篇
  2016年   935篇
  2015年   1146篇
  2014年   1372篇
  2013年   1655篇
  2012年   2712篇
  2011年   2812篇
  2010年   1686篇
  2009年   1504篇
  2008年   2394篇
  2007年   2390篇
  2006年   2235篇
  2005年   2180篇
  2004年   1962篇
  2003年   1793篇
  2002年   1658篇
  2001年   295篇
  2000年   209篇
  1999年   268篇
  1998年   317篇
  1997年   238篇
  1996年   186篇
  1995年   159篇
  1994年   131篇
  1993年   122篇
  1992年   74篇
  1991年   63篇
  1990年   58篇
  1989年   40篇
  1988年   37篇
  1987年   28篇
  1986年   29篇
  1985年   26篇
  1984年   41篇
  1983年   27篇
  1982年   32篇
  1981年   27篇
  1980年   17篇
  1978年   13篇
  1977年   13篇
  1976年   8篇
  1974年   11篇
  1927年   8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