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   2773篇
  免费   300篇
  国内免费   8篇
耳鼻咽喉   48篇
儿科学   168篇
妇产科学   80篇
基础医学   396篇
口腔科学   87篇
临床医学   425篇
内科学   554篇
皮肤病学   17篇
神经病学   208篇
特种医学   84篇
外科学   347篇
综合类   109篇
一般理论   1篇
预防医学   223篇
眼科学   23篇
药学   188篇
中国医学   3篇
肿瘤学   120篇
  2022年   32篇
  2021年   49篇
  2020年   44篇
  2019年   58篇
  2018年   59篇
  2017年   41篇
  2016年   61篇
  2015年   46篇
  2014年   82篇
  2013年   99篇
  2012年   169篇
  2011年   134篇
  2010年   81篇
  2009年   70篇
  2008年   116篇
  2007年   132篇
  2006年   127篇
  2005年   145篇
  2004年   113篇
  2003年   105篇
  2002年   112篇
  2001年   102篇
  2000年   89篇
  1999年   92篇
  1998年   28篇
  1997年   36篇
  1996年   26篇
  1995年   24篇
  1994年   25篇
  1993年   23篇
  1992年   52篇
  1991年   50篇
  1990年   46篇
  1989年   42篇
  1988年   31篇
  1987年   40篇
  1986年   40篇
  1985年   39篇
  1984年   25篇
  1983年   20篇
  1979年   24篇
  1977年   20篇
  1975年   18篇
  1974年   29篇
  1973年   23篇
  1972年   20篇
  1971年   29篇
  1970年   33篇
  1969年   23篇
  1967年   17篇
排序方式: 共有3081条查询结果,搜索用时 15 毫秒
81.
82.
Background: Falls are the most common cause of injury and hospitalization and one of the principal causes of death and disability in older adults worldwide. This study aimed to determine if a method based on body-worn sensor data can prospectively predict falls in community-dwelling older adults, and to compare its falls prediction performance to two standard methods on the same data set. Methods: Data were acquired using body-worn sensors, mounted on the left and right shanks, from 226 community-dwelling older adults (mean age 71.5 ± 6.7 years, 164 female) to quantify gait and lower limb movement while performing the 'Timed Up and Go' (TUG) test in a geriatric research clinic. Participants were contacted by telephone 2 years following their initial assessment to determine if they had fallen. These outcome data were used to create statistical models to predict falls. Results: Results obtained through cross-validation yielded a mean classification accuracy of 79.69% (mean 95% CI: 77.09-82.34) in prospectively identifying participants that fell during the follow-up period. Results were significantly (p < 0.0001) more accurate than those obtained for falls risk estimation using two standard measures of falls risk (manually timed TUG and the Berg balance score, which yielded mean classification accuracies of 59.43% (95% CI: 58.07-60.84) and 64.30% (95% CI: 62.56-66.09), respectively). Conclusion: Results suggest that the quantification of movement during the TUG test using body-worn sensors could lead to a robust method for assessing future falls risk.  相似文献   
83.
Patients with type 2 diabetes mellitus exhibit considerable platelet dysfunction, though this is poorly characterized in patients with diabetes taking aspirin for the primary prevention of cardiovascular events. We sought to compare platelet function in this patient population with that of a high-risk group of non-diabetic subjects with a history of previous myocardial infarction (MI), and to assess whether glycaemic control impacts on platelet function. Methods: Platelet aggregation was measured in response to incremental concentrations of five platelet agonists using light transmission aggregometry. All patients were taking aspirin, and aspirin insensitivity was defined as ≥ 20% arachidonic acid (AA) mediated aggregation. Patients with diabetes were divided according to glycaemic control (HbA(1c)): optimal ≤ 6.5, good 6.6-7.4 and suboptimal ≥ 7.5%. Results: In total, 85 patients with type 2 diabetes and 35 non-diabetic patients with previous MI were recruited. Compared to MI patients, diabetes patients had increased aggregation in response to multiple concentrations of epinephrine, collagen, adenosine diphosphate and AA. Aspirin insensitivity was more common in type 2 diabetes (15% vs. 0%, p=0.037). Platelet aggregation was increased in response to several agonists patients with suboptimal glycaemic control compared to patients with optimal control. Aspirin insensitivity was also more common in patients with suboptimal glycaemic control compared to those with good or optimal control (26.0% vs. 8.3% vs. 4%, p=0.04). Conclusion: Patients with type 2 diabetes mellitus, without proven vascular disease, exhibit platelet dysfunction and have increased platelet aggregation and aspirin insensitivity compared to non-diabetic patients with previous MI. Platelet dysfunction in diabetes is more severe in patients with suboptimal glycaemic control.  相似文献   
84.
85.
86.
Journal of Autism and Developmental Disorders - Autism spectrum disorder (ASD) is a developmental disorder characterised by deficits in social interactions and communication, with stereotypical and...  相似文献   
87.
Journal of Autism and Developmental Disorders - Performance on a single executive function (EF) task (e.g., a card sorting task) is often taken to represent ability on the underlying subcomponent...  相似文献   
88.
A series of genetic studies have identified the D-amino acid oxidase (DAO) gene as potentially contributing to schizophrenia susceptibility. An interacting gene, D-amino acid oxidase activator (DAOA) has also been implicated and it has been suggested that variation at these genes may influence the efficiency of glutamate gating at N-methyl-D-aspartate-type (NMDA) receptors. However, recent data suggests that DAOA may influence susceptibility to mood episodes across the spectrum of psychotic disorders rather than contributing to a specific psychosis phenotype. The aim of this study was to determine whether risk variation at DAO is similarly associated with affective or other clinical symptoms in psychosis. We have previously reported association between risk variation at DAO and schizophrenia in an Irish case-control sample. In this study we investigated the relationship between a defined genetic risk variant at DAO and PANSS-derived clinical symptom factors in a sample of 249 patients using principal component and Kruskal-Wallis analyses. Carriers of the DAO risk variant scored significantly higher on the 'depression/anxiety' factor than non-carriers (H=9.02, d.f.=2, p=0.01). These data suggest a potential role for DAO in susceptibility to depressive symptoms in schizophrenia, but a more general role for DAO in affective disorders cannot be excluded.  相似文献   
89.
90.
Peritoneal macrophages suppressed T lymphocyte activation by amino acid catabolism. CTLA-4-Ig complemented this form of suppression by blocking the costimulation of T cells. Inhibition of the amino acid catabolizing enzymes or blockade of the IFNgamma signaling essential for macrophage-mediated suppression did not impact CTLA-4-Ig efficacy. Except for phytohemagglutinin, T cell responses to superantigen, mitogen, and anti-CD3 were further reduced when CTLA-4-Ig was combined with peritoneal macrophages. The combination of these complimentary forms of immune regulation potently suppresses adaptive immunity.  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