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   46506篇
  免费   3337篇
  国内免费   166篇
耳鼻咽喉   700篇
儿科学   1079篇
妇产科学   700篇
基础医学   5700篇
口腔科学   756篇
临床医学   5223篇
内科学   8946篇
皮肤病学   606篇
神经病学   4125篇
特种医学   1808篇
外国民族医学   2篇
外科学   8083篇
综合类   760篇
现状与发展   1篇
一般理论   32篇
预防医学   3710篇
眼科学   993篇
药学   3504篇
  1篇
中国医学   75篇
肿瘤学   3205篇
  2023年   309篇
  2022年   468篇
  2021年   1219篇
  2020年   642篇
  2019年   1197篇
  2018年   1414篇
  2017年   1019篇
  2016年   1037篇
  2015年   1264篇
  2014年   1855篇
  2013年   2365篇
  2012年   3599篇
  2011年   3850篇
  2010年   2106篇
  2009年   1777篇
  2008年   3098篇
  2007年   3414篇
  2006年   3233篇
  2005年   3090篇
  2004年   2706篇
  2003年   2695篇
  2002年   2397篇
  2001年   341篇
  2000年   220篇
  1999年   343篇
  1998年   484篇
  1997年   332篇
  1996年   288篇
  1995年   290篇
  1994年   242篇
  1993年   202篇
  1992年   155篇
  1991年   136篇
  1990年   137篇
  1989年   146篇
  1988年   136篇
  1987年   123篇
  1986年   102篇
  1985年   130篇
  1984年   146篇
  1983年   128篇
  1982年   163篇
  1981年   138篇
  1980年   156篇
  1979年   78篇
  1978年   87篇
  1977年   61篇
  1976年   51篇
  1975年   53篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
The presence of depression was evaluated in a cross-section of 50 outpatients with dementia using the self-rated Geriatric Depression Scale and the clinician-rated Cornell Depression Scale. Impaired insight, as manifested by unawareness of dementia, correlated with dementia severity and discriminated a group of patients in whom the self-rated scale failed to show evidence of depression. Discrepancy between the two types of scales occurred among mildly as well as moderately demented patients when insight was impaired. Recognition of this discrepancy suggests that reliance on self-ratings may underestimate the presence and degree of depression among patients with dementia.  相似文献   
42.
43.
44.
Analysis of in vivo short TE 1H spectra is complicated by broad baseline signal contributions and resonance line-shape distortions. Although the assumptions of ideal metabolite resonance line-shapes and slowly varying baseline signals can be used to separate these signals, the presence of broad or asymmetric line-shapes can invalidate this model. More complex line-shape models are computationally expensive or difficult to constrain, particularly for the low signal-to-noise commonly found for in vivo MR spectroscopic imaging applications. In this study, two time-domain models for fitting variable spectral line-shapes are examined, one using B-splines and another using summed sinusoids. The methods were verified using both phantom and human data, and Monte Carlo simulations were used to evaluate variations in calculated metabolite amplitudes due to interactions between the baseline and line-shape estimations. Additional studies investigated the use of prior line-shape information, obtained from either a water MRSI measurement or calculations from B(0) maps, to determine parameter starting values or optimization constraints. Both line-shape models showed the ability to fit the variety of line-shapes present in both the phantom and human MRSI data, with similar or improved accuracy over a Gaussian line-shape model; however, this improvement resulted in only minor improvement for the high-SNR phantom data and moderate improvements in regions with asymmetry for the fitted in vivo metabolite images. The use of prior line-shape information was of most benefit when applied toward setting optimization constraints but was of limited benefit when used to define initial starting values.  相似文献   
45.
46.
The most common types of barrier membranes used for bone or tissue regeneration are made of expanded-polytetrafluoroethylene (e-PTFE) or resorbable materials, such as collagen. Both the e-PTFE and resorbable membranes require primary soft tissue coverage. This article explores the use of a dense-polytetrafluoroethylene (d-PTFE) membrane, which does not require primary soft tissue coverage. The advantages of d-PTFE in contrast to the other more commonly used types of barrier membranes and the clinical significance of these advantages for implant surgical and restorative treatment are discussed.  相似文献   
47.
Histoplasmosis is a fungal disease that affects humans and is caused by Histoplasma capsulatum. The presentation of the infection may be acute, chronic, or disseminated. The disseminated form has extrapulmonary manifestations which may include oral manifestation a. A patient with AIDS sought treatment and he had disseminated histoplasmosis with oral manifestations. The purpose of this case report and literature review is to emphasize the role the dental team has in the diagnosis of disseminated disease when a patient presents with oral manifestations associated with the disease. This case report is clinically relevant because it is not uncommon for oral manifestations to be one of the first signs of systemic disease.  相似文献   
48.
49.
50.
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