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   12119篇
  免费   1791篇
  国内免费   252篇
耳鼻咽喉   142篇
儿科学   728篇
妇产科学   97篇
基础医学   1956篇
口腔科学   363篇
临床医学   1503篇
内科学   1607篇
皮肤病学   230篇
神经病学   881篇
特种医学   280篇
外国民族医学   1篇
外科学   753篇
综合类   1431篇
现状与发展   1篇
预防医学   2152篇
眼科学   125篇
药学   728篇
  1篇
中国医学   764篇
肿瘤学   419篇
  2023年   411篇
  2022年   312篇
  2021年   331篇
  2020年   261篇
  2019年   238篇
  2018年   370篇
  2017年   159篇
  2016年   509篇
  2015年   844篇
  2014年   818篇
  2013年   779篇
  2012年   609篇
  2011年   525篇
  2010年   579篇
  2009年   582篇
  2008年   422篇
  2007年   306篇
  2006年   258篇
  2005年   369篇
  2004年   704篇
  2003年   236篇
  2002年   234篇
  2001年   201篇
  2000年   110篇
  1999年   127篇
  1998年   225篇
  1997年   293篇
  1996年   288篇
  1995年   272篇
  1994年   390篇
  1993年   245篇
  1992年   290篇
  1991年   289篇
  1990年   263篇
  1989年   202篇
  1988年   206篇
  1987年   103篇
  1986年   130篇
  1985年   120篇
  1984年   103篇
  1983年   69篇
  1982年   114篇
  1981年   79篇
  1980年   46篇
  1979年   36篇
  1978年   29篇
  1977年   27篇
  1976年   17篇
  1975年   15篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
21.
Causal attributions may interact with other variables to determine staff responses to challenging behaviour. Furthermore, staff perceptions of the causes of challenging behaviour are likely to change as a result of theoretical and practical training. However, there is no established simple method for measuring staff attributions that could facilitate research in these areas. The present paper describes the development and preliminary psychometric analysis of the Challenging Behaviour Attributions Scale (CHABA).  相似文献   
22.
23.
The mechanism by which early intervention with beta-blockers reduces mortality in acute myocardial infarction is unclear. Therefore the effects of intravenous, followed by oral, metoprolol on indices of infarct size were studied in a double-blind fashion with a median delay of 6.75 hours from onset of symptoms. In 129 patients peak enzyme release and QRS score on the electrocardiogram were assessed, while myocardial perfusion score on thallium-201 scintigraphy was studied in 45 patients. There was a close correlation between all the indices of infarct size. While the correlation coefficients did not appear to be influenced by metoprolol treatment, the slope of the regression was affected. Peak aspartate aminotransferase and lactic dehydrogenase were lower by 11 and 7%, respectively, in the metoprolol-treated group, but no reduction was noted in QRS score or in thallium-201 perfusion defect size in the actively treated group. Thus, it seems likely that early intervention with metoprolol in acute myocardial infarction reduces mortality, not by limiting infarct size, but by some other mechanism.  相似文献   
24.
绿茶对小鼠Lewis肺癌生长的抑制及免疫调节   总被引:3,自引:0,他引:3  
为了研究茶叶防癌作用,以接种Lewis肺癌细胞的C57/BL6J小鼠为实验模型,研究绿茶对带瘤小鼠肿瘤生长的抑制及免疫调节作用。结果表明,接种Lewis肺癌细胞后,C57/BL6J小鼠胸腺重量及其指数减轻,T淋巴细胞CD4亚群阳性百分数及CD+4/CD+8比值下降,外周血白细胞本底化学发光降低,受酵母多糖刺激产生的化学发光增高以及脾IgM抗体生成细胞数减少。绿茶对小鼠体内Lewis肺癌的生长有明显抑制作用,并对上述各项指标的不良改变有不同程度的保护效果  相似文献   
25.
Automatic analysis of electromyography (EMG) signals, first operated in 1950 with analogic machines, steeply expanded from 1980 when fast computers and worthwhile programs became available. On-line measurement of response area and latency, averaging of low amplitude waves, fast sorting of motor unit potential shape parameters, computation of the “jitter” between two muscle fibers, turns/amplitude and spectral analysis of interferential pattern records, are some examples of programs currently offered in modern EMG machines. Other techniques are still reserved for research purposes: scanning EMG, decomposition of nerve and muscle compound potentials, measurement of the threshold and firing rate of motor units, trace analysis using tracking models. Finally, the credit for artificial intelligence systems (knowledge based systems, fuzzy logic, neuronal networks) is still not clearly stated.  相似文献   
26.
Australian nursing has undergone rapid academization in the past 10 years and this radical change has tended to meld the somewhat different academic traditions of North America and Britain. The introduction of doctoral education in nursing in 1987 has led to a massive increase in scholarly activity and to the preparation of talented leaders. We concur with the view expressed by Henry (1997), "I am convinced that the problems we face in the nursing services would be much more creatively solved if the majority of our doctoral programs prepared young, energetic nurses, early in their career, for clinical practice, not for research and teaching" (p. 162).  相似文献   
27.
28.
本文应用改良的血浆凝块技术和共培养系统研究特发性血小板减少性紫癜(ITP)患者T细胞在体外对异体骨髓巨核细胞生成作用的影响,以探讨ITP的发病机制。实验结果表明,从总体来看,ITP患者的T细胞当加到培养物中和靶细胞共培养时,对巨核系祖细胞集落形成单位(CFU-MK)的集落效应无明显的影响。其中三例PAIgG升高患者的T细胞对CFU-MK有不同程度的抑制作用。以上结果提示ITP的发病机制相当复杂。除体液免疫机制外,也有细胞免疫机制参与,T细胞或其亚群对巨核系祖细胞生成抑制在ITP的发病机制中可能起着一定的作用。  相似文献   
29.
Background: Fluctuations in the level of mite allergens in domestic house dust are the result of changes in the balance between synthesis, removal and decay. Purely physical forces as well as enzymatic degradation, mediated by house dust inhabiting microbes, may contribute to the decay of allergens in domestic dust. Knowledge about the speed of decay is essential for an understanding of the dynamics of allergen levels. Objective: The present study is a quantitative assessment of the speed of decay at nine combinations of temperature (15°C, 20°C and 25°C) and relative humidity (33%, 55% and 75%). Methods: Samples of mite infested material of an old rug were stored at these temperature/relative humidity-combinations for 6, 12 or 18 months, after the mites were killed by cither a freezing treatment or an acaricide (lindane). The microbes living in the rug presumably survive these treatments. Concentrations of Der p I and Der p II + Der f II. in extracts of the rug material, were measured by a radio immunoassay. Results: No significant changes in the levels of Der p I and Der p II +Der f II, could be detected even after 11/2 year at a high temperature and humidity. Conclusion: These findings incidate that mite allergens can be extremely stable under normal domestic circumstances.  相似文献   
30.
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