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   368207篇
  免费   12869篇
  国内免费   536篇
耳鼻咽喉   3587篇
儿科学   12624篇
妇产科学   7245篇
基础医学   42902篇
口腔科学   10985篇
临床医学   26541篇
内科学   74914篇
皮肤病学   5663篇
神经病学   32640篇
特种医学   14539篇
外国民族医学   26篇
外科学   52663篇
综合类   3794篇
现状与发展   1篇
一般理论   71篇
预防医学   37489篇
眼科学   6329篇
药学   21321篇
中国医学   1484篇
肿瘤学   26794篇
  2023年   1125篇
  2022年   2482篇
  2021年   4617篇
  2020年   3003篇
  2019年   4311篇
  2018年   27111篇
  2017年   21140篇
  2016年   22977篇
  2015年   5722篇
  2014年   7417篇
  2013年   9044篇
  2012年   19766篇
  2011年   34025篇
  2010年   25293篇
  2009年   17423篇
  2008年   29497篇
  2007年   32015篇
  2006年   10634篇
  2005年   12441篇
  2004年   12931篇
  2003年   12942篇
  2002年   9145篇
  2001年   5551篇
  2000年   5670篇
  1999年   4810篇
  1998年   1899篇
  1997年   1587篇
  1996年   1476篇
  1995年   1270篇
  1994年   1251篇
  1993年   1098篇
  1992年   2804篇
  1991年   2756篇
  1990年   2530篇
  1989年   2485篇
  1988年   2230篇
  1987年   2031篇
  1986年   1902篇
  1985年   1824篇
  1984年   1328篇
  1983年   1078篇
  1982年   621篇
  1981年   539篇
  1980年   591篇
  1979年   959篇
  1978年   637篇
  1977年   502篇
  1975年   570篇
  1974年   591篇
  1973年   580篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
71.
ObjectiveTo present, the process of development and evaluation of an educational software on the Child Health Handbook proposed for the continuing education of primary care nurses and physicians.MethodsQuantitative study of methodological development. For software development, the following steps were followed: definition of objectives; determination of the target audience; choice of pedagogical and theoretical reference for content; content selection and structuring; software development and evaluation by experts (five nurses and four physicians). All responded to an instrument that included four domains: pedagogical; content; functionality; system presentation and usability. The evaluation criteria were arranged on a Likert-type scale. The percentage of agreement and Content Validity Index were used for the quantitative analysis of the degree of agreement, considering a Content Validity Index cutoff point equal to 0.80.ResultsThe overall agreement index, calculated by the arithmetic mean of the Contents Validity Index of the evaluated domains, was 0.96, with scores ranging from 0.90 to 1.00. The average percentage of agreement of the experts per domain was 92.86%, with lower agreement in the content (80.95%), presentation, and usability (90.48%) domains. 100% of percentage of agreement was observed in the pedagogical and functionality domains among the evaluated specialists.ConclusionThe percentage of agreement, Content Validity Index and overall agreement index of the Child Health Handbook educational software in the context of primary care disclosed the software adequacy as an educational resource for continuing education of primary care nurses and physicians. Considering the assessed dimensions, it can also be used by other health professionals and undergraduate students.  相似文献   
72.
73.
74.
75.
76.
77.
Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (TMDTE). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and TMDTE are more appropriate than EC50 and IC50 for toxicity assessments, except for long exposure times.  相似文献   
78.
79.
80.
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