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   80206篇
  免费   44832篇
  国内免费   159篇
耳鼻咽喉   1571篇
儿科学   4365篇
妇产科学   671篇
基础医学   16415篇
口腔科学   5254篇
临床医学   12871篇
内科学   24235篇
皮肤病学   7555篇
神经病学   13660篇
特种医学   2440篇
外国民族医学   1篇
外科学   14758篇
综合类   349篇
现状与发展   1篇
一般理论   21篇
预防医学   4508篇
眼科学   1386篇
药学   6092篇
  1篇
中国医学   1089篇
肿瘤学   7954篇
  2023年   99篇
  2022年   255篇
  2021年   1481篇
  2020年   5168篇
  2019年   10981篇
  2018年   10226篇
  2017年   11599篇
  2016年   12237篇
  2015年   12098篇
  2014年   12033篇
  2013年   12530篇
  2012年   4374篇
  2011年   4345篇
  2010年   9077篇
  2009年   5401篇
  2008年   2291篇
  2007年   1174篇
  2006年   1207篇
  2005年   1000篇
  2004年   947篇
  2003年   944篇
  2002年   1004篇
  2001年   1014篇
  2000年   947篇
  1999年   497篇
  1998年   133篇
  1997年   104篇
  1996年   78篇
  1995年   64篇
  1994年   68篇
  1993年   63篇
  1992年   154篇
  1991年   157篇
  1990年   133篇
  1989年   136篇
  1988年   129篇
  1987年   141篇
  1986年   119篇
  1985年   90篇
  1984年   69篇
  1983年   40篇
  1982年   37篇
  1979年   41篇
  1978年   37篇
  1975年   36篇
  1974年   50篇
  1972年   33篇
  1971年   31篇
  1970年   37篇
  1967年   32篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Tissue microarrays (TMAs) represent a powerful method for undertaking large‐scale tissue‐based biomarker studies. While TMAs offer several advantages, there are a number of issues specific to their use which need to be considered when employing this method. Given the investment in TMA‐based research, guidance on design and execution of experiments will be of benefit and should help researchers new to TMA‐based studies to avoid known pitfalls. Furthermore, a consensus on quality standards for TMA‐based experiments should improve the robustness and reproducibility of studies, thereby increasing the likelihood of identifying clinically useful biomarkers. In order to address these issues, the National Cancer Research Institute Biomarker and Imaging Clinical Studies Group organized a 1‐day TMA workshop held in Nottingham in May 2012. The document herein summarizes the conclusions from the workshop. It includes guidance and considerations on all aspects of TMA‐based research, including the pre‐analytical stages of experimental design, the analytical stages of data acquisition, and the postanalytical stages of data analysis. A checklist is presented which can be used both for planning a TMA experiment and interpreting the results of such an experiment. For studies of cancer biomarkers, this checklist could be used as a supplement to the REMARK guidelines.  相似文献   
992.
993.
994.
A 9‐year‐old black African boy was hospitalized for heart failure revealing a severe left ventricular dysfunction associated with dilated cardiomyopathy, two submitral aneurysms, occlusion of the circumflex artery and a giant coronary artery aneurysm on the proximal left anterior descending artery. The boy was coinfected with human immunodeficiency virus and Mycobacterium tuberculosis. Though rare, association of Takayasu arteritis and submitral aneurysm leads to rethinking the pathogenesis of submitral aneurysm and suggests that some of them may be acquired. In our case, a common inflammatory process, possibly triggered by tuberculosis or HIV, may underlie Takayasu and submitral aneurysms.  相似文献   
995.
Please cite this paper as: Yuan et al. (2012) Initial HRCT findings of novel influenza A (H1N1) infection. Influenza and Other Respiratory Viruses 6(601), e114–e119. Objectives The aim of our study was to describe the presentation and illustrate the imaging features of chest high‐resolution computed tomography (HRCT) of patients with novel influenza A (H1N1) virus infection. Methods Data were collected from 163 hospitalized patients between November 2009 and March 2011, who fulfilled the clinical criteria for H1N1 influenza infection and underwent HRCT examinations within 24 hours of admission. Results Abnormal findings were observed in 40·5% of the patients. The patients with positive imaging findings were significantly older than patients with normal HRCT findings (P = 0·02). The most common finding was ground‐glass opacity (GGO) (n = 35). Interlobular septal thickening (n = 31) and centrilobular nodules (n = 30) were the second most frequent findings. Other common findings were consolidation, reticulation, and linear shadow. The most common imaging finding for lung involvement was GGO with a patchy pattern. Pulmonary involvement of the disease may be extensive and variable, but the total volume of affected lung was mostly <1 lobe. Conclusion The baseline HRCT may be valuable and suggestive even for non‐severe H1N1 infections. When a severe case or a evolution is suspected, chest CT could be essential both for determining the precise extent of parenchymal damage and for monitoring its evolution.  相似文献   
996.
997.
Nitrofurantoin (NF) was labeled with iodine‐125 via electrophilic substitution reaction. Some factors affecting the radiochemical yield of 125I‐NF, such as NF concentration, chloramine‐T (CAT) concentration, pH of the reaction mixture, reaction time, temperature, and reaction medium, were studied. The maximum yield of 125I‐NF (90%) was obtained by using 3.7 MBq of Na125I, 1 mM CAT, 1 mM NF in DMF, at pH 2 and 60 °C within 5 min. The specific activity of 125I‐NF reaches 33.3 MBq/0.2 mmol, and the 125I‐NF was completely separated and purified by means of high pressure liquid chromatography. The biological distribution in normal mice indicates the suitability of radioiodinated NF for urinary tract imaging. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
998.
John Cunningham virus (JCV) encodes an oncogenic T‐antigen, which is capable of interacting with key growth regulatory pathways. JCV definite role as causal agent of human cancer, still awaits final confirmation. The present study was conducted to assess the possible role of JCV in Egyptian colorectal carcinoma (CRC) and correlate the expression with the clinicopathological features and survival. JCV in situ hybridization (ISH) signals and large T antigen immunoreactivity were examined in 87 colonic specimens. Positive glandular JCV ISH signals were detected in 20%, 25% and 40% of normal, adenoma and CRC cases respectively. Stromal JCV ISH signals were identified in 26% of CRC cases and 5% of adenoma however, normal mucosa did not show stromal positivity with significant difference (p = 0.03). Glandular JCV expression was significantly associated with high grade (p = 0.03), high mitotic index (p=0.02) and low apoptotic index (p = 0.00). Positive stromal signals were significantly associated with low apoptosis (p = 0.00). No positive nuclear immunostaining of JCV large T antigen was detected in all specimens. JCV stromal expression was the 2nd most powerful indicator of short survival and bad prognosis (p = 0.03) in CRC patients. JCV might play an etiological role in CRC tumorogenesis and short survival in Egyptian CRC patients.  相似文献   
999.
1000.
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