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   2820篇
  免费   144篇
  国内免费   11篇
耳鼻咽喉   8篇
儿科学   76篇
妇产科学   62篇
基础医学   454篇
口腔科学   63篇
临床医学   232篇
内科学   603篇
皮肤病学   112篇
神经病学   246篇
特种医学   94篇
外科学   404篇
综合类   18篇
预防医学   216篇
眼科学   40篇
药学   150篇
中国医学   7篇
肿瘤学   190篇
  2023年   27篇
  2022年   61篇
  2021年   107篇
  2020年   49篇
  2019年   74篇
  2018年   88篇
  2017年   63篇
  2016年   79篇
  2015年   63篇
  2014年   130篇
  2013年   141篇
  2012年   183篇
  2011年   202篇
  2010年   116篇
  2009年   113篇
  2008年   170篇
  2007年   176篇
  2006年   153篇
  2005年   155篇
  2004年   121篇
  2003年   123篇
  2002年   116篇
  2001年   56篇
  2000年   41篇
  1999年   50篇
  1998年   26篇
  1997年   25篇
  1996年   24篇
  1995年   23篇
  1994年   8篇
  1993年   9篇
  1992年   23篇
  1991年   19篇
  1990年   21篇
  1989年   17篇
  1988年   13篇
  1987年   14篇
  1986年   12篇
  1985年   9篇
  1984年   9篇
  1983年   9篇
  1980年   4篇
  1978年   6篇
  1977年   6篇
  1972年   4篇
  1971年   3篇
  1970年   2篇
  1967年   5篇
  1913年   2篇
  1912年   3篇
排序方式: 共有2975条查询结果,搜索用时 15 毫秒
41.
Mycobacterium genavense infection, a rare nontuberculous mycobacteria infection, occurs in heavily immunocompromised patients (i.e., those with advanced HIV disease, genetic disorders, or acquired immunologic disorders and those undergoing immunosuppressive therapy). We report a case of disseminated M. genavense infection preceding Hodgkin lymphoma in a patient without obvious risk factors for this infection.  相似文献   
42.
43.
A clinical analysis was made of the incidence of cardiac damage during initial attacks of rheumatic fever. The data presented indicate that first attacks of rheumatic polyarthritis are less likely to be accompanied by clinically evident carditis in adults than in children, and that when carditis does occur it is very much less likely to result in serious cardiac damage in the adults.  相似文献   
44.
45.
Adventitial vasa vasorum are physiologic microvessels that nourish artery walls. In the presence of cardiovascular risk factors, these microvessels proliferate abnormally. Studies have reported that they are the first stage of atheromatous disease. Contrast-enhanced ultrasound (CEUS) of the carotid allows direct, quantitative and non-invasive visualization of the adventitial vasa vasorum. Hence, the development of computer-assisted methods that speed image analysis and eliminate user subjectivity is important. We developed methods for automatic analyses and quantification of vasa vasorum neovascularization in CEUS and tested these methods in a cohort of 186 individuals, 63 of whom were healthy volunteers. We implemented alternative automatic strategies for using the images to stratify patients according to their risk group and compare the strategies with respect to diagnostic performance. An automatic single-parameter strategy performs less effectively than the corresponding Arcidiacono method based on manual interpretation of the images (68 < area under the receiver operating characteristic curve [AUROC] for the manual Arcidiacono method < 82; 60 < AUROC for the automatic single-parameter strategy < 63). However, by use of additional image parameters, an automatic multiparameter strategy has significantly improved performance with respect to the manual Arcidiacono method (78 < AUROC < 90). The automatic multiparameter strategy is a valuable alternative to the manual Arcidiacono method, improving both diagnostic speed and diagnostic accuracy.  相似文献   
46.
The interactions and relevance of the soil (total and available) concentrations, accumulation, and acute toxicity of several essential and non-essential trace elements were investigated to determine their importance in environmental soil assessment. Three plant species (T. aestivum, R. sativum, and V. sativa) and E. fetida were simultaneously exposed for 21 days to long-term contaminated soils collected from the surroundings of an abandoned pyrite mine. The soils presented different levels of As and metals, mainly Zn and Cu, and were tested at different soil concentrations [12.5, 25, 50, and 100 % of contaminated soil/soil (w/w)] to increase the range of total and available soil concentrations necessary for the study. The total concentrations in the soils (of both As and metals) were better predictors of earthworm uptake than were the available concentrations. In plants, the accumulation of metals was related to the available concentrations of Zn and Cu, which could indicate that plants and earthworms accumulate elements from different pools of soil contaminants. Moreover, Zn and Cu, which are essential elements, showed controlled uptake at low concentrations. The external metal concentrations predicted earthworm mortality, whereas in plants, the effects on growth were correlated to the As and metal contents in the plants. In general, the bioaccumulation factors were lower at higher exposure levels, which implies the existence of auto-regulation in the uptake of both essential and non-essential elements by plants and earthworms.  相似文献   
47.
48.
Previous in vivo and in vitro studies have reported that low-level diode laser therapy induces a biostimulatory effect, such as cell proliferation. The aim of the present study was to evaluate whether the laser irradiation of osteoblast-like cells (MG-63) can modify alkaline phosphatase activity (ALP), antigenic profile, and phagocytic capacity. The MG-63 cell line was exposed to diode laser (ezLase) of 940 nm at 1–1.5 W/cm2 and 3–4 J. ALP was evaluated by a spectrophotometric technique and antigenic expression analysis (CD 54, CD80, CD86, HLA-DR), and phagocytic activity was analyzed by flow cytometry. At 24 h, the treated groups showed an increased ALP, and the highest increase versus controls (P?=?0.002) was at the dose of 1 W/cm2 and 3 J; this modulation of the antigenic profile translated into a reduced expression of CD54, CD86, and HLA-DR and a slightly decreased phagocytic capacity with respect to the nonirradiated control group at the different intensities and fluencies assayed. These results demonstrate that laser therapy can exert a biostimulatory effect on osteoblastic cells at different levels, which may be clinically useful in the regeneration of bone tissue.  相似文献   
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