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   4769篇
  免费   393篇
  国内免费   60篇
耳鼻咽喉   40篇
儿科学   138篇
妇产科学   94篇
基础医学   676篇
口腔科学   93篇
临床医学   462篇
内科学   1049篇
皮肤病学   195篇
神经病学   386篇
特种医学   167篇
外科学   495篇
综合类   68篇
一般理论   5篇
预防医学   506篇
眼科学   109篇
药学   394篇
中国医学   22篇
肿瘤学   323篇
  2023年   46篇
  2022年   82篇
  2021年   150篇
  2020年   82篇
  2019年   123篇
  2018年   161篇
  2017年   124篇
  2016年   129篇
  2015年   177篇
  2014年   195篇
  2013年   269篇
  2012年   380篇
  2011年   344篇
  2010年   225篇
  2009年   171篇
  2008年   272篇
  2007年   311篇
  2006年   290篇
  2005年   273篇
  2004年   210篇
  2003年   183篇
  2002年   172篇
  2001年   54篇
  2000年   49篇
  1999年   45篇
  1998年   49篇
  1997年   48篇
  1996年   38篇
  1995年   31篇
  1994年   36篇
  1993年   32篇
  1992年   22篇
  1991年   36篇
  1990年   23篇
  1989年   29篇
  1988年   34篇
  1987年   17篇
  1986年   26篇
  1985年   15篇
  1984年   27篇
  1983年   24篇
  1982年   15篇
  1981年   15篇
  1980年   17篇
  1979年   15篇
  1978年   9篇
  1976年   14篇
  1972年   8篇
  1840年   13篇
  1838年   8篇
排序方式: 共有5222条查询结果,搜索用时 15 毫秒
121.
Early in the 1980s three categories of T-cell chronic lymphocytic leukaemia were recognized: CD4+ CD8 knobby type, CD4 CD8+ azurophilic type and CD4+ CD8 adult T-cell leukaemia (ATL) type. Both azurophilic and ATL types were later shown to be distinctive disorders, whereas the knobby type has been largely neglected and even considered non-existent by some authors. In this report we describe two patients with leukaemia of CD3+ CD4+ CD8 post-thymic T lymphocytes presenting with marked lymphocytosis, generalized lymphadenopathy and hepatosplenomegaly. We believe that CLL of post-thymic T-lymphocytes is a distinct entity, and merits a separate designation from other T-cell leukaemias.  相似文献   
122.
123.
124.
125.
126.

Purpose

Anemia of prematurity is frequent in preterm infants, for which red blood cell (RBC) transfusion remains the treatment of choice. In this study, we attempted to evaluate the characteristics and risk factors of anemia of prematurity, and suggest ways to reduce anemia and the need for multiple transfusions.

Materials and Methods

Preterm infants weighing less than 1500 g (May 2008-May 2009) were divided into two groups depending on whether they received RBC transfusions (transfusion group and non transfusion group). Hemoglobin (Hb) concentration, phlebotomy blood loss, and the amount of RBC transfusion were analyzed. Risk factors of anemia and RBC transfusions were analyzed.

Results

Fifty infants that survived were enrolled in the present study: 39 in the transfusion group and 11 in the non transfusion group. Hb concentrations gradually decreased by eight weeks. In the transfusion group, gestational age and birth weight were smaller, bronchopulmonary dysplasia and sepsis were more frequent, full feeding was delayed, parenteral nutrition and days spent in the hospital were prolonged, and phlebotomy blood loss was greater than that in the non transfusion group.

Conclusion

Anemia of prematurity was correlated with increased laboratory blood loss, decreased birth weight, prolonged parenteral nutrition, and delayed body weight gain. Accordingly, reducing laboratory phlebotomy loss and parenteral nutrition, as well as improving body weight gain, may be beneficial to infants with anemia of prematurity.  相似文献   
127.
128.
SARS-CoV-2 infection causes an abrupt response by the host immune system, which is largely responsible for the outcome of COVID-19. We investigated whether the specific immune responses in the peripheral blood of 276 patients were associated with the severity and progression of COVID-19. At admission, dramatic lymphopenia of T, B, and NK cells is associated with severity. Conversely, the proportion of B cells, plasmablasts, circulating follicular helper T cells (cTfh) and CD56CD16+ NK-cells increased. Regarding humoral immunity, levels of IgM, IgA, and IgG were unaffected, but when degrees of severity were considered, IgG was lower in severe patients. Compared to healthy donors, complement C3 and C4 protein levels were higher in mild and moderate, but not in severe patients, while the activation peptide of C5 (C5a) increased from the admission in every patient, regardless of their severity. Moreover, total IgG, the IgG1 and IgG3 isotypes, and C4 decreased from day 0 to day 10 in patients who were hospitalized for more than two weeks, but not in patients who were discharged earlier. Our study provides important clues to understand the immune response observed in COVID-19 patients, associating severity with an imbalanced humoral response, and identifying new targets for therapeutic intervention.  相似文献   
129.
Research on the attachment-dialogue link has largely focused on infant–mother attachment. This study investigated longitudinal associations between infant–mother attachment and maternal attachment representations and subsequent mother–child emotion dialogues (N = 50). Maternal attachment representations were assessed using the Adult Attachment Interview when children were 3 months, infant–mother attachment was assessed using the Strange Situation Procedure at 13 months, and mother–child emotion dialogues were assessed using the Autobiographical Emotional Events Dialogue at 3.5 years. Consistent with past research, the three organized categories of infant–mother attachment relationships were associated with later mother–child emotion dialogues. Disorganized attachment relationships were associated with a lack of consistent and coherent strategy during emotion dialogues. Autonomous mothers co-constructed coherent narratives with their children; Dismissing and Preoccupied mothers created stories that were less narratively organized. Although the Unresolved category was unrelated to classifications of types of mother–child discourse, mothers’ quality of contribution to the dialogues was marginally lower compared to the quality of their children’s contributions to the emotion discussion. Secure children showed highest levels of child cooperation and exploration. Autonomous mothers displayed highest levels of maternal sensitive guidance during emotion dialogues. We provide preliminary evidence for role reversal in dialogues between Preoccupied and Unresolved mothers and their children.  相似文献   
130.

Background

Consensus guidelines have recommended that decision aids include a process for helping patients clarify their values. We sought to examine the theoretical and empirical evidence related to the use of values clarification methods in patient decision aids.

Methods

Building on the International Patient Decision Aid Standards (IPDAS) Collaboration’s 2005 review of values clarification methods in decision aids, we convened a multi-disciplinary expert group to examine key definitions, decision-making process theories, and empirical evidence about the effects of values clarification methods in decision aids. To summarize the current state of theory and evidence about the role of values clarification methods in decision aids, we undertook a process of evidence review and summary.

Results

Values clarification methods (VCMs) are best defined as methods to help patients think about the desirability of options or attributes of options within a specific decision context, in order to identify which option he/she prefers. Several decision making process theories were identified that can inform the design of values clarification methods, but no single “best” practice for how such methods should be constructed was determined. Our evidence review found that existing VCMs were used for a variety of different decisions, rarely referenced underlying theory for their design, but generally were well described in regard to their development process. Listing the pros and cons of a decision was the most common method used. The 13 trials that compared decision support with or without VCMs reached mixed results: some found that VCMs improved some decision-making processes, while others found no effect.

Conclusions

Values clarification methods may improve decision-making processes and potentially more distal outcomes. However, the small number of evaluations of VCMs and, where evaluations exist, the heterogeneity in outcome measures makes it difficult to determine their overall effectiveness or the specific characteristics that increase effectiveness.
  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