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   37004篇
  免费   2451篇
  国内免费   207篇
耳鼻咽喉   379篇
儿科学   668篇
妇产科学   638篇
基础医学   5256篇
口腔科学   945篇
临床医学   3767篇
内科学   7820篇
皮肤病学   781篇
神经病学   4085篇
特种医学   2098篇
外科学   5821篇
综合类   205篇
一般理论   7篇
预防医学   1569篇
眼科学   765篇
药学   2236篇
中国医学   68篇
肿瘤学   2554篇
  2023年   243篇
  2022年   435篇
  2021年   926篇
  2020年   656篇
  2019年   859篇
  2018年   975篇
  2017年   848篇
  2016年   988篇
  2015年   1189篇
  2014年   1439篇
  2013年   1744篇
  2012年   2815篇
  2011年   2956篇
  2010年   1789篇
  2009年   1606篇
  2008年   2544篇
  2007年   2567篇
  2006年   2408篇
  2005年   2328篇
  2004年   2128篇
  2003年   1921篇
  2002年   1792篇
  2001年   423篇
  2000年   377篇
  1999年   387篇
  1998年   355篇
  1997年   290篇
  1996年   229篇
  1995年   198篇
  1994年   153篇
  1993年   159篇
  1992年   173篇
  1991年   149篇
  1990年   140篇
  1989年   113篇
  1988年   94篇
  1987年   75篇
  1986年   79篇
  1985年   87篇
  1984年   77篇
  1983年   83篇
  1982年   54篇
  1981年   57篇
  1980年   40篇
  1979年   47篇
  1978年   40篇
  1977年   39篇
  1974年   33篇
  1973年   34篇
  1972年   33篇
排序方式: 共有10000条查询结果,搜索用时 828 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