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   749篇
  免费   38篇
  国内免费   39篇
耳鼻咽喉   1篇
儿科学   30篇
妇产科学   9篇
基础医学   69篇
口腔科学   18篇
临床医学   86篇
内科学   168篇
皮肤病学   7篇
神经病学   82篇
特种医学   170篇
外科学   38篇
综合类   17篇
预防医学   12篇
眼科学   5篇
药学   76篇
中国医学   2篇
肿瘤学   36篇
  2022年   1篇
  2021年   8篇
  2020年   4篇
  2019年   5篇
  2018年   12篇
  2017年   11篇
  2016年   5篇
  2015年   11篇
  2014年   23篇
  2013年   18篇
  2012年   13篇
  2011年   17篇
  2010年   20篇
  2009年   31篇
  2008年   13篇
  2007年   30篇
  2006年   9篇
  2005年   11篇
  2004年   6篇
  2003年   6篇
  2002年   9篇
  2001年   9篇
  2000年   9篇
  1999年   16篇
  1998年   51篇
  1997年   47篇
  1996年   39篇
  1995年   29篇
  1994年   24篇
  1993年   34篇
  1992年   13篇
  1991年   15篇
  1990年   14篇
  1989年   30篇
  1988年   29篇
  1987年   26篇
  1986年   17篇
  1985年   25篇
  1984年   21篇
  1983年   18篇
  1982年   14篇
  1981年   18篇
  1980年   19篇
  1979年   5篇
  1978年   13篇
  1977年   7篇
  1976年   9篇
  1975年   7篇
  1974年   1篇
  1973年   3篇
排序方式: 共有826条查询结果,搜索用时 0 毫秒
821.
Generalized anxiety disorder (GAD) is a common psychiatric disorder characterized by constant worry or anxiety over every day life activities and events. The neurobiology of the disorder is thought to involve a wide cortical and subcortical network that includes but is not limited to the amygdala and the bed nucleus of the stria terminalis (BNST). These two regions have been hypothesized to play different roles in stress and anxiety; the amygdala is thought to regulate responses to brief emotional stimuli while the BNST is thought to be involved in more chronic regulation of sustained anxiety. In this study, we exposed medication-free GAD patients as well as non-anxious controls to a gambling game where one of the conditions involved non-contingent monetary loss. This condition of high uncertainty was intended to elicit a stressful response and sustained anxiety. Functional MRI scans were collected simultaneously to investigate BOLD activity in the amygdala and BNST during performance of this task. Compared to controls, we found that GAD patients demonstrated decreased activity in the amygdala and increased activity in the BNST. Skin conductance measures showed a consistent early versus late effect within block where GAD patients demonstrated higher arousal than controls late in the task blocks. Based on these results, we hypothesize that GAD patients disengage the amygdala and its response to acute stress earlier than non-anxious controls making way for the BNST to maintain a more sustained response. Future studies are needed to investigate the temporal dynamics of activation and deactivation in these regions.  相似文献   
822.
BACKGROUND: The diagnostic evaluation of patients with thyroid nodules is imprecise. Despite the benefits of fine-needle aspiration (FNA), most patients who are referred for surgery because of abnormal cytology prove to have benign disease. Recent technologic and procedural advances suggest that this shortcoming can be mitigated, although few data confirm this benefit in unselected patients. METHODS: A total of 2587 sequential patients were evaluated by thyroid ultrasound and were offered ultrasound-guided FNA (UG-FNA) of all thyroid nodules that measured > or =1 cm during a 10-year period. Results of aspiration cytology were correlated with histologic findings. The prevalence of thyroid cancer in all patients and in those who underwent surgery was determined. Surgical risk was calculated. RESULTS: Tumors that measured > or =1 cm were present in 14% of patients: Forty-three percent of patients had tumors that measured <2 cm in greatest dimension, and 93% had American Joint Committee on Cancer stage I or II disease. The cytologic diagnoses 'positive for malignancy' and 'no malignant cells' were 97% predictive and 99.7% predictive, respectively. Repeat FNA of initial insufficient aspirates, as well as more detailed classification of inconclusive aspirates, improved preoperative assessment of cancer risk and reduced surgical intervention. Fifty-six percent of patients who were referred for surgery because of abnormal cytology had cancer compared with from 10% to 45% of patients historically. An analysis of operative complications from a subset of 296 patients demonstrated a 1% risk of permanent surgical complications. CONCLUSIONS: The current findings demonstrated the benefits of UG-FNA and of a more detailed classification of inconclusive aspirates in the preoperative risk assessment of thyroid nodules, supporting adherence to recently published guidelines.  相似文献   
823.
中药材X-射线衍射图谱研究   总被引:66,自引:0,他引:66  
为探讨中药材道地性的客观规律,以期建立相应的评估指标系统,本文选择常用中药材茜草类、贝母类、山药类三组样品,应用X-射线粉末衍射法进行图谱分析,获得了可用于标识中药材的衍射图形几何拓扑规律与图谱特征标记峰,由此观察到:不同产地茜草样品的相似性及其与欧茜草的差别;同属不同种贝母样品的相似性与差异;不同产地山药样品的相似性及与伪品的区别。本文结果预示着这一方法在揭示中药材道地性客观规律方面的广阔应用前景。  相似文献   
824.
Autoimmune hepatitis (AIH) is a severe chronic autoimmune disease and has a significant impact on the patient’s quality of life, in particular regarding psychological problems such as anxiety and depression. Consistent evidence on which patient-related, disease-related or physician-related factors cause health-related quality of life (HRQoL) impairment in patients with AIH is lacking. Current studies on HRQoL in AIH are mainly single-centered, comprising small numbers of patients, and difficult to compare because of the use of different questionnaires, patient populations, and cutoff values. Literature in the pediatric field is sparse, but suggests that children/adolescents with AIH have a lower HRQoL. Knowledge of HRQoL and cohesive factors in AIH are important to improve healthcare for AIH patients, for example by developing an AIH-specific chronic healthcare model. By recognizing the importance of quality of life beyond the concept of biochemical and histological remission, clinicians allow us to seek enhancements and possible interventions in the management of AIH, aiming at improved health.  相似文献   
825.
826.
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