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   60946篇
  免费   3937篇
  国内免费   1773篇
耳鼻咽喉   853篇
儿科学   3011篇
妇产科学   347篇
基础医学   4356篇
口腔科学   512篇
临床医学   7670篇
内科学   12643篇
皮肤病学   674篇
神经病学   2034篇
特种医学   963篇
外国民族医学   5篇
外科学   4083篇
综合类   10576篇
现状与发展   10篇
一般理论   2篇
预防医学   3552篇
眼科学   222篇
药学   5721篇
  45篇
中国医学   3953篇
肿瘤学   5424篇
  2024年   130篇
  2023年   964篇
  2022年   1865篇
  2021年   2533篇
  2020年   2243篇
  2019年   2006篇
  2018年   1942篇
  2017年   2037篇
  2016年   2268篇
  2015年   2360篇
  2014年   4833篇
  2013年   4603篇
  2012年   4065篇
  2011年   4487篇
  2010年   3436篇
  2009年   3030篇
  2008年   2794篇
  2007年   2719篇
  2006年   2298篇
  2005年   1985篇
  2004年   1650篇
  2003年   1327篇
  2002年   1072篇
  2001年   1014篇
  2000年   818篇
  1999年   802篇
  1998年   653篇
  1997年   526篇
  1996年   599篇
  1995年   569篇
  1994年   526篇
  1993年   445篇
  1992年   421篇
  1991年   360篇
  1990年   344篇
  1989年   327篇
  1988年   307篇
  1987年   235篇
  1986年   202篇
  1985年   323篇
  1984年   272篇
  1983年   171篇
  1982年   214篇
  1981年   159篇
  1980年   158篇
  1979年   145篇
  1978年   109篇
  1977年   91篇
  1976年   90篇
  1975年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Chronic obstructive pulmonary disease (COPD) is a significant health problem in developed countries. We aimed to estimate the prevalence of COPD in a single Spanish healthcare area. We also aimed to assess if there are any differences in prevalence and spirometry use among primary care services by utilizing already registered information. We designed a cross-sectional study to determine the prevalence of COPD and the performance of spirometries in each primary care service. A total of 8,444 patients were diagnosed with COPD, with a prevalence of 2.6% for individuals older than 39 years. The prevalence increased with age and was much higher in men. Significant heterogeneity was found in the prevalence of COPD and spirometry use among primary care services. COPD was underdiagnosed and there was wide variability in spirometry use in our area. Greater efforts are needed to diagnose COPD in order to improve its clinical outcomes and to refine registries so that they can be used as reliable sources of information  相似文献   
2.
3.
4.
Treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted by drug delivery to the back of the eye. In recent years, concerted efforts in drug delivery have been made to prolong the residence time of drugs injected in the vitreous humor of the eye. Our previous studies demonstrated that poly(ortho ester) (POE) nanoparticles were biodegradable/biocompatible and were capable of long-term sustained release. The objective of the present study was to investigate the safety and localization of POE nanoparticles in New Zealand white rabbits and C57BL/6 mice after intravitreal administration for the treatment of chronic posterior ocular diseases. Two concentration levels of POE nanoparticles solution were chosen for intravitreal injection: 1.5?mg/ml and 10?mg/ml. Our results demonstrate that POE nanoparticles were distributed throughout the vitreous cavity by optical coherence tomography (OCT) examination 14 days post-intravitreal injection. Intraocular pressure was not changed from baseline. Inflammatory or adverse effects were undetectable by slit lamp biomicroscopy. Furthermore, we demonstrate that POE nanoparticles have negligible toxicity assessed at the cellular level evidenced by a lack of glia activation or apoptosis estimation after intravitreal injection. Collectively, POE nanoparticles are a novel and nontoxic as an ocular drug delivery system for the treatment of posterior ocular diseases.  相似文献   
5.
Context: We sought to describe our experience with the Hybrid Assistive Limb® (HAL®) for active knee extension and voluntary ambulation with remaining muscle activity in a patient with complete paraplegia after spinal cord injury.

Findings: A 30-year-old man with complete paraplegia used the HAL® for 1 month (10 sessions) using his remaining muscle activity, including hip flexor and upper limb activity. Electromyography was used to evaluate muscle activity of the gluteus maximus, tensor fascia lata, quadriceps femoris, and hamstring muscles in synchronization with the Vicon motion capture system. A HAL® session included a knee extension session with the hip flexor and voluntary gait with upper limb activity. After using the HAL® for one month, the patient’s manual muscle hip flexor scores improved from 1/5 to 2/5 for the right and from 2/5 to 3/5 for the left knee, and from 0/5 to 1/5 for the extension of both knees.

Conclusion/clinical relevance: Knee extension sessions with HAL®, and hip flexor and upper-limb-triggered HAL® ambulation seem a safe and feasible option in a patient with complete paraplegia due to spinal cord injury.  相似文献   

6.
7.
Abstract

The purpose of this study was to investigate the strength of the relationships between self-efficacy and (i) functional exercise capacity and (ii) physical activity in chronic obstructive pulmonary disease (COPD), and whether self-efficacy assessment type (i.e., COPD symptoms, exercise-task, exercise-barrier, general, falls) and physical activity assessment type (i.e., self-report vs. objective) are moderators. A systematic search of COPD and self-efficacy concepts was conducted using eight databases from inception to 23 January 2019. Studies were included if they provided correlation coefficients of the relationship between self-efficacy and functional exercise capacity or physical activity, were conducted in adults diagnosed with COPD, and were published in English-language journals. A total of 14 correlation coefficients were included in the self-efficacy and functional exercise capacity meta-analysis, and 16 in the self-efficacy and physical activity meta-analysis. Data were screened, reviewed, and extracted independently by two reviewers, with discrepancies resolved by a third reviewer. Stronger self-efficacy was associated with better functional exercise capacity (weighted r?=?0.38, 95%CI [0.25, 0.50]), and greater physical activity (weighted r?=?0.25, 95%CI [0.17, 0.34]). Exercise-task self-efficacy had the strongest relationship to functional exercise capacity (weighted r?=?0.64, 95% CI [0.51, 0.73]). For physical activity, the type of self-efficacy most strongly related was inconclusive. In COPD, self-efficacy has a relationship to functional exercise capacity and physical activity, the strength of which is influenced by the choice of self-efficacy measure. An understanding of these relationships will assist clinicians in selecting the self-efficacy measure most closely related to the outcome of interest.  相似文献   
8.
9.
慢性肾衰竭急性加重的临床特征及相关因素分析   总被引:2,自引:0,他引:2  
目的:探讨慢性肾衰竭(CRF)急性加重因素及其治疗措施对预后的影响。方法:对2001年1月~2005年6月住院治疗的CRF急性加重患者42例,按其加重原因、基础疾病、治疗方式和疗效进行回顾性总结。结果:CRF急性加重因素依次为各种感染(45.2%)、原发病加重(19.0%)、高血压未控制(14.3%)、水电解质紊乱(11.9%)、肾毒性药物(11.9%)、心功能不全(9.5%)、尿路梗阻(4.8%)、血高粘滞状态(2.4%),7例同时存在≥2种上述病因(16.7%)。CRF急性加重原发病以慢性肾小球肾炎(52.4%)和糖尿病肾病(11.9%)为主。积极治疗后肾功能恢复达到或接近原来水平者40例,死亡2例,死亡2例的年龄均在60岁以上。结论:对于CRF肾功能急剧恶化的患者,应积极寻找其加重因素,并采取非透析和透析相结合治疗,改善肾功能,降低病死率,延长患者生命。  相似文献   
10.
We describe a familial case of Marfan's syndrome with associated intrathoracic stomach detected during the neonatal period. The patient developed a primitive leukemia at 3 months of age. Acute leukemia in a patient with Marfan's syndrome has not previously been reported.  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