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   484篇
  免费   39篇
  国内免费   8篇
耳鼻咽喉   2篇
儿科学   13篇
妇产科学   60篇
基础医学   39篇
口腔科学   25篇
临床医学   34篇
内科学   76篇
皮肤病学   8篇
神经病学   51篇
特种医学   30篇
外科学   83篇
综合类   10篇
预防医学   61篇
眼科学   4篇
药学   18篇
中国医学   1篇
肿瘤学   16篇
  2023年   2篇
  2022年   9篇
  2021年   20篇
  2020年   17篇
  2019年   26篇
  2018年   22篇
  2017年   10篇
  2016年   17篇
  2015年   17篇
  2014年   28篇
  2013年   29篇
  2012年   41篇
  2011年   24篇
  2010年   18篇
  2009年   29篇
  2008年   26篇
  2007年   30篇
  2006年   23篇
  2005年   27篇
  2004年   21篇
  2003年   10篇
  2002年   8篇
  2001年   6篇
  2000年   4篇
  1999年   6篇
  1998年   4篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1992年   10篇
  1991年   2篇
  1990年   6篇
  1989年   1篇
  1988年   3篇
  1987年   5篇
  1986年   2篇
  1983年   1篇
  1981年   1篇
  1978年   2篇
  1976年   2篇
  1975年   1篇
  1973年   3篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   4篇
  1961年   2篇
排序方式: 共有531条查询结果,搜索用时 15 毫秒
1.
OBJECTIVES: To critically review and integrate, from a developmental perspective, recent magnetic resonance imaging (MRI) studies of 4 childhood psychiatric disorders: schizophrenia, bipolar disorder (BD), attention-deficit hyperactivity disorder (ADHD), and major depressive disorder (MDD). METHOD: We reviewed published reports in refereed journals. We briefly describe the major findings with respect to the brain morphometry, chemistry, and function of children with psychiatric disorders and synthesize the reports in a summary to update clinicians. RESULTS: Some cortical grey matter abnormalities associated with schizophrenia appear to predate the onset of frank psychosis and continue to advance after the onset of psychosis, at least in more severe cases. Pediatric BD is associated with abnormalities in a circuit, thought to be involved in mood regulation, that encompasses the amygdala, striatum, and ventral PFC. Frontostriatal abnormalities are reported consistently in ADHD, potentially reflecting abnormalities in the development of cognitive control. Children with MDD show prefrontal cortical alterations that may differ in familial and nonfamilial subtypes of MDD. CONCLUSIONS: Results from neuroimaging studies of childhood psychopathology reveal abnormalities in the developmental trajectories observed in healthy children. Although MRI has increased our understanding of the pathophysiology of these disorders, routine neuroimaging for children with severe emotional disturbances is not indicated for diagnostic purposes.  相似文献   
2.
3.
The airway epithelium is the first cellular component of the lung to be encountered by the particles and pathogens present in inhaled air. In addition to its role as a physical barrier, the immunological activity of the airway epithelium is an essential part of the pulmonary immune system. This means that the symptoms of lung diseases that involve immunological mechanisms are frequently exacerbated by infection of the airway epithelium with respiratory viruses. The virus-induced enhancement of immunological activity in infected epithelial cells is well characterized. However, the effects that contaminants of inhaled air have upon the infectivity and replication of respiratory viruses and the inflammation they cause, are comparatively unknown. In this study, we have shown that pre-exposure of airway epithelial cells to bacterial lipopolysaccharides or a proteolytically active house dust mite allergen, is able to, respectively, inhibit or enhance the level of cellular infection with respiratory syncytial virus and similarly alter virus-induced expression of the inflammatory chemokine interleukin-8. These results suggest that respiratory syncytial virus infection and the inflammation caused by respiratory syncytial virus may be modified by the biologically active contaminants of indoor air.  相似文献   
4.
Older adults walk more slowly, take shorter steps, and spend more time with both legs on the ground compared to young adults. Although many studies have investigated the effects of aging on the kinematics and kinetics of gait, little is known about the corresponding changes in muscle function. The aim of this study was to describe and compare the actions of the lower-limb muscles in accelerating the body's center of mass (COM) in healthy young and older adults. Three-dimensional gait analysis and subject-specific musculoskeletal modeling were used to calculate lower-limb muscle forces and muscle contributions to COM accelerations when both groups walked at the same speed. The orientations of all body segments during walking, except that of the pelvis, were invariant to age when these quantities were expressed in a global reference frame. The older subjects tilted their pelves more anteriorly during the stance phase. The mean contributions of the gluteus maximus, gluteus medius, vasti, gastrocnemius and soleus to the vertical, fore-aft and mediolateral COM accelerations (support, progression and balance, respectively) were similar in the two groups. However, the gluteus medius contributed significantly less to support (p < 0.05) while the gluteus maximus and contralateral erector spinae contributed significantly more to balance (p < 0.05) during early stance in the older subjects. These results provide insight into the functional roles of the individual leg muscles during gait in older adults, and highlight the importance of the hip and back muscles in controlling mediolateral balance.  相似文献   
5.
6.
7.
This study describes services provided by family support specialists (FSS), peer advocates in programs for children with serious psychiatric conditions, to delineate differences between recommended components of FSS services and services actually provided. An analysis of qualitative interview and observational data and quantitative survey data from 63 staff at 21 mental health programs in New York identified that FSS and other staff have generally similar ideas about FSS services, and that these perceptions of activities are generally congruent with what FSS actually did. Implications of findings are discussed in the context of developing competencies and quality indicators for FSS.  相似文献   
8.
9.
The patient, a 40-yr-old female with fibrodysplasia ossificansprogressiva, first presented in her teens with pain and stiffnessof  相似文献   
10.
PURPOSE: To report the need for multiple surgical interventions to treat recurrent aortic aneurysms in a patient with Cogan syndrome. CASE REPORT: A 17-year-old Chinese man with clinical Marfanoid features had a left common carotid artery pseudoaneurysm electively repaired with an autologous saphenous vein graft. Four months later, he presented with acute chest pain. Computed tomography (CT) revealed a 1-cm pseudoaneurysm at the mid descending aorta; a 24 x 100-mm Talent stent-graft was implanted to exclude the pseudoaneurysm. He was also found to have increasing left-sided hearing loss. A month later, the patient was re-admitted with vertigo and keratitis, which were treated appropriately. Nine months following stent-graft insertion, he was admitted with acute hemoptysis. Urgent CT showed a rupture at the proximal end of the stent-graft, with hemorrhage into the lung parenchyma. In an emergent procedure, the stent-graft was removed, and the descending thoracic aorta was repaired. Intraoperatively, a large pseudoaneurysm was found arising from the proximal part of the stented aorta, which appeared thickened. His postoperative recovery was uneventful. Nine months after the thoracotomy, a routine CT revealed an aneurysm at the distal descending thoracic aorta. On re-thoracotomy, a de novo saccular aneurysm was found 2.5 cm from the distal anastomosis. The affected segment was replaced with a Dacron graft. The distal aorta appeared thickened and edematous; histology confirmed aortitis. The patient was subsequently diagnosed with Cogan syndrome and given corticosteroids and methotrexate. There is no evidence of recurrence at nearly 2 years after the last intervention. CONCLUSION: This case highlights the pitfalls of stent-graft repair in a patient with presumed connective tissue disease.  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