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   2636篇
  免费   268篇
  国内免费   39篇
耳鼻咽喉   9篇
儿科学   90篇
妇产科学   7篇
基础医学   332篇
口腔科学   37篇
临床医学   415篇
内科学   168篇
皮肤病学   6篇
神经病学   251篇
特种医学   24篇
外科学   167篇
综合类   384篇
一般理论   2篇
预防医学   621篇
眼科学   36篇
药学   279篇
  10篇
中国医学   82篇
肿瘤学   23篇
  2024年   2篇
  2023年   44篇
  2022年   40篇
  2021年   61篇
  2020年   95篇
  2019年   60篇
  2018年   78篇
  2017年   73篇
  2016年   100篇
  2015年   84篇
  2014年   145篇
  2013年   265篇
  2012年   172篇
  2011年   165篇
  2010年   134篇
  2009年   144篇
  2008年   137篇
  2007年   161篇
  2006年   166篇
  2005年   106篇
  2004年   112篇
  2003年   85篇
  2002年   62篇
  2001年   81篇
  2000年   59篇
  1999年   29篇
  1998年   23篇
  1997年   31篇
  1996年   17篇
  1995年   27篇
  1994年   21篇
  1993年   26篇
  1992年   32篇
  1991年   24篇
  1990年   10篇
  1989年   8篇
  1988年   10篇
  1987年   14篇
  1986年   7篇
  1985年   6篇
  1984年   6篇
  1983年   6篇
  1982年   5篇
  1981年   6篇
  1980年   2篇
  1972年   1篇
  1971年   1篇
排序方式: 共有2943条查询结果,搜索用时 15 毫秒
1.
Objective:The purpose of this study was to provide an updated profile of gambling and problem gambling in Canada and to examine how the rates and pattern of participation compare to 2002.Method:An assessment of gambling and problem gambling was included in the 2018 Canadian Community Health Survey and administered to 24,982 individuals aged 15 and older. The present analyses selected for adults (18+).Results:A total of 66.2% of people reported engaging in some type of gambling in 2018, primarily lottery and/or raffle tickets, the only type in which the majority of Canadians participate. There are some significant interprovincial differences, with perhaps the most important one being the higher rate of electronic gambling machine (EGM) participation in Manitoba and Saskatchewan. The overall pattern of gambling in 2018 is very similar to 2002, although participation is generally much lower in 2018, particularly for EGMs and bingo. Only 0.6% of the population were identified as problem gamblers in 2018, with an additional 2.7% being at-risk gamblers. There is no significant interprovincial variation in problem gambling rates. The interprovincial pattern of problem gambling in 2018 is also very similar to what was found in 2002 with the main difference being a 45% decrease in the overall prevalence of problem gambling.Conclusions:Gambling and problem gambling have both decreased in Canada from 2002 to 2018 although the provincial patterns are quite similar between the 2 time periods. Several mechanisms have likely collectively contributed to these declines. Decreases have also been reported in several other Western countries in recent years and have occurred despite the expansion of legal gambling opportunities, suggesting a degree of inoculation or adaptation in large parts of the population.  相似文献   
2.
以问题为导向的(Problem based learning,PBL)教学法在国内外高等医学教育中应用广泛并进行了不断改良。我们通过建立典型病例的资料库,逐步将病例引导的PBL教学模式应用于烧伤外科的临床见习教学中,强调以学生为中心,充分调动学生的主观能动性,着眼于学生形成正确的临床思维方法和最终分析解决问题的能力,以此来提高烧伤外科见习教学的质量。  相似文献   
3.
4.
This letter responds to the article “On the Authority of Advance Euthanasia Directives for People with Severe Dementia: Reflections on a Dutch Case,” by Henri Wijsbek and Thomas Nys, in the September-October 2022 issue of the Hastings Center Report.  相似文献   
5.
6.
In this paper, we propose some effective one- and two-level domain decomposition preconditioners for elastic crack problems modeled by extended finite element method. To construct the preconditioners, the physical domain is decomposed into the "crack tip" subdomain, which contains all the degrees of freedom (dofs) of the branch enrichment functions, and the "regular" subdomains, which contain the standard dofs and the dofs of the Heaviside enrichment function. In the one-level additive Schwarz and restricted additive Schwarz preconditioners, the "crack tip" subproblem is solved directly and the "regular" subproblems are solved by some inexact solvers, such as ILU. In the two-level domain decomposition preconditioners, traditional interpolations between the coarse and the fine meshes destroy the good convergence property. Therefore, we propose an unconventional approach in which the coarse mesh is exactly the same as the fine mesh along the crack line, and adopt the technique of a non-matching grid interpolation between the fine and the coarse meshes. Numerical experiments demonstrate the effectiveness of the two-level domain decomposition preconditioners applied to elastic crack problems.  相似文献   
7.
8.
ObjectiveThe purpose of this study was to investigate the impact of specific behavioral problems on the health-related quality of life (HRQOL) in children and adolescents with epilepsy.MethodsChildren and adolescents with epilepsy (n=92; age range=6–17 years) and their mothers completed questionnaires about behavioral problems, HRQOL, socio-demographics, and epilepsy-related variables. To determine significant predictor variables of the HRQOL, the stepwise regression analyses and partial correlations were performed to adjust for other behavioral problems and covariates.ResultsThe analyses revealed that an increase in social behavioral problems and delinquent behavior was associated with a decrease in the HRQOL. Lower levels of maternal education and the number of antiepileptic drugs were also associated with a decline in the HRQOL; the HRQOL and social behavioral problems remained significantly correlated after adjusting for maternal education level, number of antiepileptic drugs, and non-social behavioral problems.ConclusionParents and practitioners should provide intervention if behavioral problems, particularly social behavioral problems, are observed in children or adolescents with epilepsy.  相似文献   
9.
Algorithms based on deep neural networks (DNNs) have attracted increasing attention from the scientific computing community. DNN based algorithms are easy to implement, natural for nonlinear problems, and have shown great potential to overcome the curse of dimensionality. In this work, we utilize the multi-scale DNN-based algorithm (MscaleDNN) proposed by Liu, Cai and Xu (2020) to solve multi-scale elliptic problems with possible nonlinearity, for example, the p-Laplacian problem. We improve the MscaleDNN algorithm by a smooth and localized activation function. Several numerical examples of multi-scale elliptic problems with separable or non-separable scales in low-dimensional and high-dimensional Euclidean spaces are used to demonstrate the effectiveness and accuracy of the MscaleDNN numerical scheme.  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