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   894篇
  免费   44篇
耳鼻咽喉   8篇
儿科学   43篇
妇产科学   7篇
基础医学   136篇
口腔科学   13篇
临床医学   121篇
内科学   180篇
皮肤病学   5篇
神经病学   141篇
特种医学   14篇
外科学   72篇
综合类   9篇
一般理论   1篇
预防医学   112篇
眼科学   14篇
药学   33篇
中国医学   1篇
肿瘤学   28篇
  2024年   1篇
  2023年   9篇
  2022年   10篇
  2021年   30篇
  2020年   16篇
  2019年   34篇
  2018年   50篇
  2017年   32篇
  2016年   26篇
  2015年   23篇
  2014年   41篇
  2013年   54篇
  2012年   72篇
  2011年   65篇
  2010年   46篇
  2009年   34篇
  2008年   72篇
  2007年   63篇
  2006年   65篇
  2005年   46篇
  2004年   52篇
  2003年   21篇
  2002年   39篇
  2001年   5篇
  2000年   5篇
  1999年   6篇
  1998年   6篇
  1997年   7篇
  1996年   4篇
  1995年   2篇
  1993年   1篇
  1992年   1篇
排序方式: 共有938条查询结果,搜索用时 15 毫秒
81.
The use of behavioral indicators as a measure of satiation was a procedure developed by O'Reilly et al. (Journal of Applied Behavior Analysis, 42, 773–783, 2009) to systematically manipulate presession access to a tangible reinforcer. In order to gain a better understanding of the utility of behavioral indicators of satiation in applied settings, a systematic literature review was conducted identifying nine additional studies that implemented this procedure. This review synthesized the research in terms of participant characteristics, use of behavioral indicators, dependent variables, and study outcomes. Results suggest this procedure is an effective way to decrease challenging behaviors and increase adaptive, on-task behaviors, adding to the literature in regard to the manipulation of abolishing operations as well as serving to identify future investigations into the use of behavioral indicators as a measure of satiation.  相似文献   
82.
Objective: To assess standard grief measures through cognitive interviews with bereaved adolescents in Free State, South Africa, and make recommendations designed to improve the measurement of grief in this and similar populations.

Methods: Twenty-one parentally bereaved adolescents participated in semi-structured cognitive interviews about the Core Bereavement Items (CBI) questionnaire, Grief Cognitions Questionnaire for Children (GCQ-C), or Intrusive Griefs Thoughts Scale (IGTS).

Results: Interviewees offered valuable insights for improving grief measurement with this population (e.g., consensus that not thinking frequently about a deceased loved one was shameful, aversion to terms including “died”). Participants were better able to apply response options denoting specific frequencies (e.g., “once or twice a week”) versus general ones (e.g., “a little bit of the time”). Questions intended to gauge grief commonly elicited responses reflecting the impact of loss on adolescents’ basic survival instead of psychological wellbeing.

Conclusions: The need for psychological support is high among orphans and vulnerable children. Tools for measuring psychological outcomes can provide evidence of programme effects and guide decision making about investment. Grief measures used with adolescents in South Africa should account for the issues raised by cognitive interviewees in the study, including question and response option complexity, linguistic preferences, and cultural norms.  相似文献   

83.
Objective: Families of children with autism spectrum disorder are barraged by different treatment options. Some of these options have the support of empirical evidence while others do not. Stimulant treatments are typically utilized to treat symptoms of ADHD indicating an on-label use of such treatment. Methods: This study examines the association of stimulant treatment with the on- (symptoms of ADHD) and off- (symptoms of ASD) label symptoms among children with ASD via a non-clinical, population-based sample. Results: Results indicate no significant association of stimulant treatment with a reduction of on- or off-label symptoms among children with ASD. Conclusion: Stimulant medications utilized in the treatment of DSM core symptoms of autism spectrum disorder would be considered an off-label use because there is limited evidence to support that stimulants are effective in treating core symptoms of ASD, which is supported by the results of the current study.  相似文献   
84.
Schizophrenia and Attention-Deficit/Hyperactivity Disorder (ADHD) are associated with similar deficits in working memory, attention, and inhibition. Both disorders also involve abnormalities of white matter integrity, possibly reflecting neural communication disruptions. There are likely some regional white matter abnormalities that underlie the common cognitive impairment, though also some regional abnormalities unique to each disorder. We used diffusion tensor imaging (DTI) to compare white matter integrity, as indicated by fractional anisotropy (FA), in adolescents with schizophrenia (n = 15) or ADHD (n = 14) and healthy controls (n = 26). Schizophrenia patients had uniquely low FA, relative to the other two groups, in bilateral cerebral peduncles, anterior and posterior corpus callosum, right anterior corona radiata, and right superior longitudinal fasciculus. ADHD patients had uniquely high FA in left inferior and right superior frontal regions. Both clinical groups had lower FA than controls in left posterior fornix. The two disorders generally demonstrated distinct patterns of abnormal connectivity suggesting that common cognitive and behavioral deficits derive from distinct sources, though the posterior fornix may be involved in both disorders. Schizophrenia was associated with abnormally low FA in widespread circuitry indicative of general connectivity disruptions, whereas ADHD was associated with abnormally high FA in frontal networks that may indicate impaired branching of fibers.  相似文献   
85.
86.
87.
Patients with genetic defects of the cyclic (c) adenosine-monophosphate (AMP)-signaling pathway and those with neonatal-onset multisystem inflammatory disease (NOMID) develop tumor-like lesions of the long bones. The molecular basis of this similarity is unknown. NOMID is caused by inappropriate caspase-1 activity, which in turn activates the inflammasome. The present study demonstrates that NOMID bone lesions are derived from the same osteoblast progenitor cells that form fibroblastoid tumors in mice and humans with defects that lead to increased cAMP-dependent protein kinase A (PKA) signaling. NOMID tumor cells showed high PKA activity, and an increase in their cAMP signaling led to PKA-specific activation of caspase-1. Increased PKA led to inflammation-independent activation of caspase-1 via over-expression of the proto-oncogene (and early osteoblast factor) Ets-1. In NOMID tumor cells, as in cells with defective PKA regulation, increased prostaglandin E2 (PGE2) led to increased cAMP levels and activation of Wnt signaling, like in other states of inappropriate PKA activity. Caspase-1 and PGE2 inhibition led to a decrease in cell proliferation of both NOMID and cells with abnormal PKA. These data reveal a previously unsuspected link between abnormal cAMP signaling and defective regulation of the inflammasome and suggest that caspase-1 and PGE2 inhibition may be therapeutic targets in bone lesions associated with defects of these two pathways.  相似文献   
88.
In this study, ascorbate (Asc) and glutathione (GSH) concentrations were quantified noninvasively using double-edited (1)H MRS at 4 T in the occipital cortex of healthy young [age (mean ± standard deviation) = 20.4 ± 1.4 years] and elderly (age = 76.6 ± 6.1 years) human subjects. Elderly subjects had a lower GSH concentration than younger subjects (p < 0.05). The Asc concentration was not significantly associated with age. Furthermore, the lactate (Lac) concentration was higher in elderly than young subjects. Lower GSH and higher Lac concentrations are indications of defective protection against oxidative damage and impaired mitochondrial respiration. The extent to which the observed concentration differences could be associated with physiological differences and methodological artifacts is discussed. In conclusion, GSH and Asc concentrations were compared noninvasively for the first time in young vs elderly subjects.  相似文献   
89.
INTRODUCTION: One hypothesis that unifies the diversity of symptoms associated with schizophrenia involves the disruption of connectivity between brain regions. As white matter provides rapid and efficient communication between brain regions, this study was initiated to assess the early disruption of white matter pathways in children and adolescent with schizophrenia. MATERIALS AND METHODS: Diffusion tensor images were acquired on 14 children and adolescents with schizophrenia, one subject with schizoaffective disorder, and 15 age and gender matched controls. The DTI images were acquired in twelve directions on a 3 T Siemens Trio scanner. The images were transformed into fractional anisotropy and mean diffusivity maps and a group analysis was performed using SPM2. RESULTS: Children and adolescent patients with schizophrenia demonstrated a significant decrease in FA and associated increase in AD in the left posterior hippocampus (p<0.001, Bonferroni corrected on the cluster-level). These diffusion differences were not statistically significant when IQ was used as a covariate in the analysis. DISCUSSION: These findings suggest hippocampal white matter abnormalities that present early in the development of schizophrenia. The lack of significant differences when IQ is used as a covariate suggests that this hippocampal region is associated with cognitive changes associated with schizophrenia.  相似文献   
90.
In 38 African AIDS patients initiating generic HAART, GB virus C (GBV-C) RNA-positive patients retained GBV-C viraemia during 52 weeks of HAART, had a faster decline in HIV viral load (P = 0.03), fewer opportunistic infections (14.3 versus 50%, P = 0.18), and suffered no serious adverse events (none versus 61%, P = 0.008) compared with patients without GBV-C. GBV-C co-infection may be associated with a beneficial effect on African AIDS patients treated with generic HAART.  相似文献   
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