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   2594篇
  免费   200篇
  国内免费   25篇
耳鼻咽喉   22篇
儿科学   74篇
妇产科学   75篇
基础医学   333篇
口腔科学   91篇
临床医学   228篇
内科学   660篇
皮肤病学   35篇
神经病学   365篇
特种医学   54篇
外科学   197篇
综合类   7篇
预防医学   243篇
眼科学   12篇
药学   179篇
中国医学   3篇
肿瘤学   241篇
  2024年   4篇
  2023年   48篇
  2022年   40篇
  2021年   138篇
  2020年   71篇
  2019年   90篇
  2018年   105篇
  2017年   87篇
  2016年   99篇
  2015年   118篇
  2014年   131篇
  2013年   142篇
  2012年   245篇
  2011年   233篇
  2010年   103篇
  2009年   108篇
  2008年   177篇
  2007年   175篇
  2006年   146篇
  2005年   141篇
  2004年   99篇
  2003年   107篇
  2002年   84篇
  2001年   16篇
  2000年   6篇
  1999年   17篇
  1998年   14篇
  1997年   9篇
  1996年   12篇
  1995年   9篇
  1994年   2篇
  1993年   3篇
  1992年   7篇
  1991年   2篇
  1990年   2篇
  1988年   2篇
  1987年   5篇
  1985年   2篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
  1974年   1篇
  1973年   4篇
  1972年   2篇
  1970年   1篇
  1967年   1篇
  1964年   1篇
  1963年   1篇
  1960年   1篇
排序方式: 共有2819条查询结果,搜索用时 31 毫秒
1.
2.
3.
The purpose of this study has been to explore young children's understandings and experiences of friendship as these manifested in children's behaviours, in a reception class setting. Drawing on an evolutionary, ecological framework, friendship is seen as not only the expression and further development of social understandings and cognitive advances; more than that, making and maintaining friends is seen as an evolutionary trait and a ‘drive’ to relate to similarly minded others. Through ‘niche picking’, children select the environments and opportunities that suit them in order to develop their dispositions and individual traits. The research employed a participatory design in order to capture the children's views and experiences. It took place in a reception class setting, where children's everyday experiences were observed and discussed with them. The study identified six themes of analysis and offered some suggestions about creating enabling educational environments that allow the ‘space’ for niche construction.  相似文献   
4.
PURPOSE: The purpose to clarify what kind of managerial challenges employees experience regarding organisational justice in hospitals. DESIGN/METHODOLOGY/APPROACH: This exploratory study of 8,971 employees working in 14 hospitals and examines the concept of organisational justice in management with qualitative and quantitative methods. FINDINGS: An inductive content analysis of the comments revealed five integrative frames describing challenges in hospital management at respondents' workplaces. These frames should be regarded as major managerial challenges in hospitals. These findings illustrate important antecedents of organisational justice and suggest that work units tend to share the same perceptions of justice. They also reveal that individually produced comments reflect collective experiences in organisational justice. Further, the results indicate that problems in management and policies are often experienced in a complex way, and people making justice judgements do not separate procedural and interactional factors. RESEARCH LIMITATIONS/IMPLICATIONS: Although the commentators producing qualitative data represented many organisational hierarchy levels, the results should not be generalised to apply to horizontal, informal social relationships. PRACTICAL IMPLICATIONS: This paper gives useful information regarding challenges in human resources management in hospitals. ORIGINALITY/VALUE: The paper suggests that people making fairness judgements do not make a distinction between procedural and interpersonal factors. Instead, they use any information available to judge the righteousness of the management events. This paper serves to guide hospital managers towards a better understanding of the importance of organisational justice and its collective nature.  相似文献   
5.
This study compares the cost-effectiveness of mitral valve reconstruction and replacement. Published clinical data were used to determine the effectiveness of each procedure. Both direct and indirect costs were calculated. The findings indicate that reconstruction has lower costs per year of life extended than replacement due to better outcomes. Changing outcome probabilities and discount rates did not alter these results. Cost savings in excess of 40% may be achieved by early reconstruction for suitable patients. These results suggest that the prevailing practice of delaying surgery until replacement is needed should be reconsidered, especially for patients who could benefit from reconstruction.  相似文献   
6.
The afferent nervous supply to the thymus gland has been investigated by means of the retrograde transport of horseradish peroxidase. It has been shown that the thymus receives an afferent supply from the nodose ganglia of the vagus and from the dorsal root ganglia C1–C7. The afferent innervation of the right and left thymic lobes is bilaterally organized; the fibers of a small celled population of nodose ganglion neurons cross outside the thymus and those of a larger celled population cross within the thymus gland. The functional implications of these findings are discussed in the context of central nervous system-immune system interactions.  相似文献   
7.
BACKGROUND: Antisocial personality disorder (ASPD) in DSM-IV is unique among personality disorder diagnoses in requiring the individual to satisfy a number of childhood criteria in addition to relevant traits exhibited in adulthood. We examined the validity of this childhood requirement. METHODS: Personality disordered individuals assessed using the International Personality Disorder Examination and exhibiting a sufficient number of adult antisocial traits to meet criterion A of DSM-IV were subdivided into those who exhibited antisocial traits in both adulthood and childhood and those who had such traits in adulthood only. The two groups were then compared on a number of historical, clinical, and self-report measures. RESULTS: Thirty individuals meeting both childhood and adult criteria (ASPD) were compared with 39 meeting adult antisocial criteria only (ASS). Few differences were found between the two groups on the measures examined, although those in the ASPD group appeared more severe and had higher anger scores on the STAXI-2 psychometric test. CONCLUSIONS: This failure to find clinically important differences between the two groups is in agreement with previous reports and needs to be taken into account in future revisions of ASPD in DSM.  相似文献   
8.
N‐acyl‐dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N‐oleoyl‐dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a short‐run study design, following injections of [3H]N‐oleoyl‐dopamine (0.4 µCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [3H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15‐min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [3H]N‐oleoyl‐dopamine, which was a significant 3–4‐fold increase over that following similar administration of [3H]dopamine. Intravenous injections of [3H]N‐oleoyl‐dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [3H]dopamine. Qualitative thin‐layered chromatography screening showed the presence of unchanged N‐oleoyl‐dopamine in the brain following injections. We conclude that N‐oleoyl‐dopamine has an appreciable ability to cross the blood‐brain barrier, which contrasts the limited transfer of dopamine alone. N‐oleoyl‐dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N‐oleoyl‐dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217–224, 2003. © 2003 Wiley‐Liss, Inc.  相似文献   
9.
10.
Influenza nucleoprotein (NP)-specific T-cell receptor transgenic mice (F5) were crossed with transgenic mice expressing the cognate antigenic protein under the control of the H- 2Kb promoter. Double-transgenic mice show negative selection of thymocytes at the CD4+8+TCR10 to CD4+8+TCRhi transition stage. A few CD8 T cells, however, escape clonal deletion, and in the peripheral lymphoid organs of these mice, they exhibit low levels of the transgenic receptor and upregulated levels of the CD44 memory marker. Such cells do not proliferate upon exposure to antigen stimulation in vivo or ex vivo, however, they can develop low but detectable levels of antigen-specific cytotoxic function after stimulation in vitro in the presence of IL-2.  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