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   57329篇
  免费   4005篇
  国内免费   193篇
耳鼻咽喉   632篇
儿科学   1154篇
妇产科学   899篇
基础医学   7279篇
口腔科学   763篇
临床医学   5309篇
内科学   13680篇
皮肤病学   575篇
神经病学   5420篇
特种医学   2219篇
外科学   9129篇
综合类   720篇
一般理论   65篇
预防医学   4097篇
眼科学   1109篇
药学   3496篇
中国医学   145篇
肿瘤学   4836篇
  2023年   329篇
  2022年   658篇
  2021年   1526篇
  2020年   963篇
  2019年   1399篇
  2018年   1733篇
  2017年   1204篇
  2016年   1289篇
  2015年   1562篇
  2014年   2306篇
  2013年   2691篇
  2012年   4588篇
  2011年   4548篇
  2010年   2571篇
  2009年   2304篇
  2008年   4011篇
  2007年   4114篇
  2006年   3959篇
  2005年   3932篇
  2004年   3484篇
  2003年   3224篇
  2002年   2893篇
  2001年   427篇
  2000年   335篇
  1999年   438篇
  1998年   531篇
  1997年   472篇
  1996年   383篇
  1995年   346篇
  1994年   281篇
  1993年   257篇
  1992年   228篇
  1991年   198篇
  1990年   177篇
  1989年   145篇
  1988年   149篇
  1987年   128篇
  1986年   120篇
  1985年   140篇
  1984年   146篇
  1983年   131篇
  1982年   163篇
  1981年   126篇
  1980年   105篇
  1979年   60篇
  1978年   75篇
  1977年   66篇
  1976年   66篇
  1975年   48篇
  1974年   51篇
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
1.
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.

Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.

Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.

Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion.  相似文献   
2.
3.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  相似文献   
4.
5.
There is a large and growing population of long-term cancer survivors. Primary care physicians (PCPs) are playing an increasingly greater role in the care of these patients across the continuum of cancer survivorship. In this role, PCPs are faced with the responsibility of managing a range of medical and psychosocial late effects of cancer treatment. In particular, the sexual side effects of treatment which are common and have significant impact on quality of life for the cancer survivor, often go unaddressed. This is an area of clinical care and research that has received increasing attention, highlighted by the presentation of this special issue on Cancer and Sexual Health. The aims of this review are 3-fold. First, we seek to overview common presentations of sexual dysfunction related to major cancer diagnoses in order to give the PCP a sense of the medical issues that the survivor may present with. Barriers to communication about sexual health issues between patient/PCPs in order are also described in order to emphasize the importance of PCPs initiating this important conversation. Next, we provide strategies and resources to help guide the PCP in the management of sexual dysfunction in cancer survivors. Finally, we discuss case examples of survivorship sexual health issues and highlight the role that a PCP can play in each of these case examples.  相似文献   
6.
7.
8.
9.
10.
This study explored the relationship between active mediation, exposure to Daniel Tiger’s Neighborhood, and key indicators of preschoolers’ social and emotional development. One hundred and twenty-seven children aged 2–6 either watched or did not watch 10 episodes of Daniel Tiger’s Neighborhood over a two-week period. Results revealed that preschoolers who watched the program exhibited higher levels of empathy, self-efficacy, and emotion recognition when their regular TV-watching experiences are frequently accompanied by active mediation. This was especially true for younger preschoolers and preschoolers from low-income families. Implications for policy-makers, parents, producers of prosocial programming, and educators are discussed.  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