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   379049篇
  免费   24853篇
  国内免费   2805篇
耳鼻咽喉   5187篇
儿科学   8214篇
妇产科学   10091篇
基础医学   53192篇
口腔科学   11848篇
临床医学   30132篇
内科学   78381篇
皮肤病学   8561篇
神经病学   27246篇
特种医学   13953篇
外国民族医学   82篇
外科学   60686篇
综合类   9955篇
现状与发展   1篇
一般理论   64篇
预防医学   17443篇
眼科学   9454篇
药学   31020篇
  1篇
中国医学   2194篇
肿瘤学   29002篇
  2021年   2620篇
  2019年   2729篇
  2018年   4533篇
  2017年   3450篇
  2016年   3538篇
  2015年   4041篇
  2014年   5705篇
  2013年   7393篇
  2012年   10051篇
  2011年   10232篇
  2010年   6216篇
  2009年   5861篇
  2008年   9484篇
  2007年   10313篇
  2006年   10234篇
  2005年   9284篇
  2004年   8804篇
  2003年   8544篇
  2002年   8225篇
  2001年   28270篇
  2000年   28789篇
  1999年   23669篇
  1998年   5171篇
  1997年   4254篇
  1996年   3838篇
  1995年   3483篇
  1994年   3109篇
  1993年   2848篇
  1992年   16057篇
  1991年   14824篇
  1990年   14165篇
  1989年   13972篇
  1988年   12589篇
  1987年   12072篇
  1986年   11115篇
  1985年   10331篇
  1984年   6922篇
  1983年   5604篇
  1982年   2723篇
  1979年   5480篇
  1978年   3348篇
  1977年   2972篇
  1975年   2643篇
  1974年   3065篇
  1973年   2866篇
  1972年   2829篇
  1971年   2773篇
  1970年   2516篇
  1969年   2551篇
  1968年   2251篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
66.
67.
Conclusion  Several quality-control measures take place before (patient and camera preparation) and during SPECT acquisition to achieve high-quality images. Not uncommonly, technologists and physicians are left with suboptimal images that have to be addressed to reach the “right answer” for patient diagnosis and hence management. In many cases patients may be reimaged, especially if the problem is detected early, but in other cases either the patient has left the nuclear laboratory or there is an inevitable problem that, even with reimaging, will not be resolved. In these situations the technologist and physician have to seek the available techniques to obtain the best images possible. These resources are discussed in this issue as an aid in quality control to obtain the best possible images.  相似文献   
68.
69.
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility.  相似文献   
70.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  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