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   1348篇
  免费   89篇
  国内免费   6篇
耳鼻咽喉   15篇
儿科学   41篇
妇产科学   79篇
基础医学   144篇
口腔科学   35篇
临床医学   143篇
内科学   387篇
皮肤病学   18篇
神经病学   117篇
特种医学   16篇
外国民族医学   1篇
外科学   130篇
综合类   23篇
一般理论   1篇
预防医学   101篇
眼科学   20篇
药学   95篇
中国医学   8篇
肿瘤学   69篇
  2023年   16篇
  2022年   20篇
  2021年   53篇
  2020年   37篇
  2019年   54篇
  2018年   64篇
  2017年   35篇
  2016年   36篇
  2015年   42篇
  2014年   59篇
  2013年   67篇
  2012年   116篇
  2011年   116篇
  2010年   64篇
  2009年   42篇
  2008年   92篇
  2007年   104篇
  2006年   68篇
  2005年   70篇
  2004年   57篇
  2003年   55篇
  2002年   44篇
  2001年   3篇
  2000年   7篇
  1999年   13篇
  1998年   13篇
  1997年   5篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1992年   6篇
  1991年   7篇
  1990年   6篇
  1989年   2篇
  1988年   5篇
  1987年   2篇
  1985年   5篇
  1984年   3篇
  1983年   4篇
  1981年   3篇
  1978年   5篇
  1976年   2篇
  1974年   2篇
  1973年   2篇
  1972年   4篇
  1971年   2篇
  1970年   3篇
  1969年   4篇
  1968年   2篇
  1966年   2篇
排序方式: 共有1443条查询结果,搜索用时 15 毫秒
71.
72.
Background: Obesity is a growing epidemic among university students, and the high levels of stress reported by this population could contribute to this issue. Singular relationships between perceived stress; engagement in restrained, uncontrolled, and emotional eating; sleep; dietary risk; and body mass index (BMI) have been reported in the current body of literature; however, these constructs interact with each other, and the complex relationships among them are infrequently examined. Therefore, the aim of the present study was to explore the complex relationships between these constructs using mediation and moderation analyses stratified by gender. Methods: A cross-sectional study, enrolling university students from the United States (U.S.), the Netherlands, South Korea, Malaysia, Ireland, Ghana, and China, was conducted between October 2020 and January 2021 during the COVID-19 pandemic. Perceived stress; maladaptive eating behaviors including restrained, uncontrolled, and emotional eating; sleep duration and quality; dietary risk; and BMI were assessed using validated questionnaires, which were distributed through an online platform. Results: A total of 1392 students completed the online survey (379 male, 973 female, and 40 who self-identified as “other”). Uncontrolled and emotional eating mediated the relationship between perceived stress and dietary risk for both males and females; higher sleep quality weakened this relationship among female students but not males. Emotional eating mediated the relationship between perceived stress and BMI for both males and females, but higher sleep quality weakened this relationship only among females. Conclusions: Our findings suggest that students in higher education are likely to benefit from interventions to reduce uncontrolled and emotional eating. Programs that improve sleep quality, especially during highly stressful periods, may be helpful.  相似文献   
73.
74.
Anterior teeth may have aberrant anatomical variations in the number of roots and root canals. A review of the literature was conducted using appropriate key words in major endodontic journals to identify the available reported cases as well as experimental and clinical investigations on accessory roots and root canals in anterior teeth. After retrieving the full text of related articles, cross‐citations were identified, and the pooled data were then discussed. Results revealed a higher prevalence in accessory root/root canal variations in mandibular anterior teeth than in maxillary counterparts. However, maxillary incisor teeth revealed the highest tendency for accessory root/root canal aberrations caused by anomalies such as dens invaginatus and palato‐gingival groove. Primary anterior teeth may also exhibit external and internal anatomical variations in the root, especially maxillary canines. Therefore, dental practitioners should thoroughly assess all teeth scheduled for root canal treatment to prevent the undesirable consequences caused by inadequate debridement of accessory configurations of the root canal system.  相似文献   
75.
Oxidative stress is one mechanism involved in the pathogenesis of ischemia/reperfusion (/R) retinal injury. The histological, biochemical, and functional changes associated with pomegranate (PMG) treatment prior to retinal I/R were analyzed using 40 adult male albino rats. Rats were divided into four groups: Groups I and II (sham operated and received saline or PMG, respectively); Groups III and IV (I/R rat models with prior administration of saline or 250 mg/kg/day PMG, respectively). Electroretinogram (ERG) results were recorded and eye specimens were taken and processed for light and electron microscopic examinations and for assessment of oxidative status in retinal homogenate. I/R lead to degenerative changes in retinal layers with a significant reduction in nuclear factor erythroid 2-related factor 2 (Nrf2) immunoreactivity in concomitant with significant oxidant–antioxidant disturbance and decreased a- and b-wave amplitude in the ERG. These alterations were ameliorated with prior PMG treatment. In conclusion, PMG treatment, as an antioxidant, attenuated retinal structural and functional I/R injury through activation of Nrf2 which could be a base for future therapy designs.  相似文献   
76.
We evaluated two putative moderators of treatment outcome as well as the role of Headache Management Self-Efficacy (HMSE) in mediating treatment outcomes in the drug and non-drug treatment of chronic tension-type headache (CTTH). Subjects were 169 participants (M = 38 yrs.; 77% female; M headache days/mo. = 22) who received one of four treatments in the treatment of CTTH trial (JAMA, 2001; 285: 2208–15): tricyclic antidepressant medication, placebo, (cognitive-behavioral) stress-management therapy plus placebo, and stress-management therapy plus antidepressant medication. Severity of CTTH disorder and the presence of a psychiatric (mood or anxiety) disorder were found to moderate outcomes obtained with the three active treatments and with placebo, as well as to moderate the role of HMSE in mediating improvements. Both moderator effects appeared to reflect the differing influence of the moderator variable on each of the three active treatments, as well as the fact that the moderator variables exerted the opposite effect on placebo than on the active treatments. HMSE mediated treatment outcomes in the two stress-management conditions, but the pattern of HMSE mediation was complex, varying with the treatment condition, the outcome measure, and the moderator variable. Irrespective of the severity of the CTTH disorder HMSE fully mediated observed improvements in headache activity in the two stress-management conditions. However, for patients with a mood or anxiety disorder HMSE only partially mediated improvements in headache disability, suggesting an additional therapeutic mechanism is required to explain observed improvements in headache disability in the two stress-management conditions.  相似文献   
77.
Summary This paper introduces the concepts of time‐specific weak and strong cross‐section dependence, and investigates how these notions are related to the concepts of weak, strong and semi‐strong common factors, frequently used for modelling residual cross‐section correlations in panel data models. It then focuses on the problems of estimating slope coefficients in large panels, where cross‐section units are subject to possibly a large number of unobserved common factors. It is established that the common correlated effects (CCE) estimator introduced by Pesaran remains asymptotically normal under certain conditions on factor loadings of an infinite factor error structure, including cases where methods relying on principal components fail. The paper concludes with a set of Monte Carlo experiments where the small sample properties of estimators based on principal components and CCE estimators are investigated and compared under various assumptions on the nature of the unobserved common effects.  相似文献   
78.
Oxidative stress significantly contributes to cisplatin (CP)-associated cytotoxicity, and use of antioxidants could counteract such cytotoxic effects of CP. The major biochemical pathway for reactive oxygen species (ROS) formation proceeds through O2 production, which is generated by NADPH oxidase, such oxidative stress can activate p38 MAPK to intensify the cytotoxic effect of CP. We mainly aimed to study the protective effect of oxytocin (OT) on CP-induced nephrotoxicity whereas; it was previously shown to have anti-inflammatory effects in different inflammation models. Administration of OT significantly decreased the gene expression of both NADPH oxidase and P38 MAPK, nitric oxide (NO), myloperoxidase (MPO), and TBARS, furthermore it increased the renal tissue levels of antioxidants; reduced glutathione (GSH), and superoxide dismutase (SOD). Histologically, OT reduced the monocellular infiltration as well as the tubular damage in CP-induced nephrotoxicity. In conclusion OT has a powerful antioxidant effect that can alleviate the CP-induced nephrotoxicity through inhibition of NADPH oxidase and P38 MAPK resulting in improvement of kidney functions.  相似文献   
79.
The pilot investigation evaluated a theatrical intervention program, Social Emotional NeuroScience Endocrinology (SENSE) Theatre, designed to improve socioemotional functioning and reduce stress in children with autism spectrum disorder (ASD). Eight children with ASD were paired with typically developing peers that served as expert models. Neuropsychological, biological (cortisol and oxytocin), and behavioral measures were assessed in a pretest–posttest design. The intervention was embedded in a full musical theatrical production. Participants showed some improvement in face identification and theory of mind skills. The intervention shows potential promise in improving the socioemotional functioning in children with ASD through the utilization of peers, video and behavioral modeling, and a community-based theatrical setting.  相似文献   
80.
Predictive epidemiology is an embryonic field that involves developing informative signatures for disorder and tracking them using surveillance methods. Through such efforts assistance can be provided to the planning and implementation of preventive interventions. Believing that certain minor crimes indicative of gang activity are informative signatures for the emergence of serious youth violence in communities, in this study we aim to predict outbreaks of violence in neighborhoods from pre-existing levels and changes in reports of minor offenses. We develop a prediction equation that uses publicly available neighborhood-level data on disorderly conduct, vandalism, and weapons violations to predict neighborhoods likely to have increases in serious violent crime. Data for this study were taken from the Chicago Police Department ClearMap reporting system, which provided data on index and non-index crimes for each of the 844 Chicago census tracts. Data were available in three month segments for a single year (fall 2009, winter, spring, and summer 2010). Predicted change in aggravated battery and overall violent crime correlated significantly with actual change. The model was evaluated by comparing alternative models using randomly selected training and test samples, producing favorable results with reference to overfitting, seasonal variation, and spatial autocorrelation. A prediction equation based on winter and spring levels of the predictors had area under the curve ranging from .65 to .71 for aggravated battery, and .58 to .69 for overall violent crime. We discuss future development of such a model and its potential usefulness in violence prevention and community policing.  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