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   10712篇
  免费   842篇
  国内免费   40篇
耳鼻咽喉   145篇
儿科学   198篇
妇产科学   152篇
基础医学   1213篇
口腔科学   106篇
临床医学   1092篇
内科学   2199篇
皮肤病学   341篇
神经病学   845篇
特种医学   381篇
外科学   2103篇
综合类   140篇
一般理论   11篇
预防医学   901篇
眼科学   229篇
药学   723篇
中国医学   13篇
肿瘤学   802篇
  2024年   15篇
  2023年   157篇
  2022年   229篇
  2021年   590篇
  2020年   301篇
  2019年   491篇
  2018年   551篇
  2017年   368篇
  2016年   381篇
  2015年   405篇
  2014年   569篇
  2013年   677篇
  2012年   1012篇
  2011年   942篇
  2010年   519篇
  2009年   416篇
  2008年   634篇
  2007年   621篇
  2006年   554篇
  2005年   518篇
  2004年   448篇
  2003年   365篇
  2002年   276篇
  2001年   63篇
  2000年   40篇
  1999年   43篇
  1998年   43篇
  1997年   36篇
  1996年   33篇
  1995年   25篇
  1994年   21篇
  1993年   20篇
  1992年   19篇
  1991年   20篇
  1990年   13篇
  1989年   10篇
  1988年   12篇
  1987年   8篇
  1986年   13篇
  1985年   8篇
  1984年   10篇
  1983年   18篇
  1982年   10篇
  1980年   5篇
  1979年   8篇
  1978年   8篇
  1977年   5篇
  1976年   11篇
  1972年   4篇
  1954年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Maternal and Child Health Journal - Alcohol use during pregnancy is a critical public health issue that results in several adverse outcomes for both mother and child. While the prevalence of and...  相似文献   
22.
23.
PurposePrevious reports in the literature demonstrate racial and ethnic disparities for children diagnosed with acute appendicitis, with minorities experiencing worse outcomes. At our institution, we have developed an evidence based patient driven protocol for children following laparoscopic appendectomy. However, the influence of such protocol on mitigating racial and ethnic disparities in outcomes remains unknown. The purpose of our study is to assess the impact of our protocol by evaluating the influence of race and ethnicity on surgical outcomes among children treated for acute appendicitis.Material and methodsA retrospective review of prospectively collected data was conducted. Children undergoing a laparoscopic appendectomy at our freestanding children's hospital between December 2015 and July 2017 were included. Demographic data, post-operative length of stay, same day discharge rates and hospital readmission rates were abstracted from patient medical records. Patients were classified by their race and ethnic background. Comparative analysis was performed in STATA with a p value < .05 determined as significant.ResultsA total of 786 children were included, with the majority being either White (70%, n = 547), Black (8%, n = 62) or Hispanic (17%, n = 133); 569 patients (72%) were found to have non-perforated appendicitis. There was no statistically significant difference in the rates of same day discharge among White, Black or Hispanic children respectively (88% vs. 77% vs. 86%, p = .126). Of the 217 children with perforated appendicitis, Hispanic children had increased rates of perforation (41%, n = 55) compared to White and Black children respectively (23%, n = 128 and 29%, n = 18, p = .001). However, average post-operative length of stay were similar among White, Black and Hispanic children (96 h vs. 95 h vs. 98 h, p = .015). On multivariate analysis, the only significant risk factor for an elevated post-operative length of stay was the presence of a perforation.ConclusionOur evidence based patient driven protocol effectively mitigates racial and ethnic disparities found in children with acute appendicitis. Further prospective investigation into the role of such patient-driven protocols to mitigate healthcare disparities is warranted.Levels of EvidenceTherapeutic study; Level 3.  相似文献   
24.
Intraductal carcinoma (IDC) is a rare salivary gland tumor that is considered analogous to ductal carcinoma in-situ of the breast, demonstrating a complex neoplastic epithelial proliferation surrounded by a continuous layer of presumed non-neoplastic myoepithelial cells. It is subcategorized into intercalated duct, apocrine, and hybrid subtypes based on morphologic and immunohistochemical features, with frequent NCOA4-RET and TRIM27-RET fusions, respectively, seen in intercalated duct and hybrid tumors. However, as an expanding clinicopathologic spectrum of IDC has been documented, controversy has emerged as to whether this tumor type is best defined by its intraductal growth pattern or distinctive molecular and immunophenotypic differentiation. Here, we further explore the nature of IDC by evaluating four cases that arose within intraparotid lymph nodes. These intercalated-duct phenotype tumors with diffuse S100 protein expression demonstrated a crowded and complex epithelial proliferation arranged in cystic, cribriform, and micropapillary architecture, surrounded by an intact myoepithelial cell layer, and were completely intranodal. Of two tumors with tissue available for molecular analysis, one demonstrated a NCOA4-RET fusion and one harbored a STRN-ALK fusion that is novel to IDC. Not only does the intranodal presence of IDC present a challenging differential diagnosis, but the complex nature of this proliferation within lymph node tissue raises questions as to whether the myoepithelial component of IDC is actually non-neoplastic in nature. Furthermore, identification of a STRN-ALK fusion expands the genetic spectrum of IDC and adds to evidence of an emerging role for ALK in salivary gland tumors. Further attention to the nature of the myoepithelial cells and documentation of alternate fusion events in IDC may inform continued discussion about its appropriate classification.  相似文献   
25.
Archives of Sexual Behavior - The current study examined the prevalence and correlates of over 50 sexual practices in a national survey of heterosexual and lesbian women in relationships. Coarsened...  相似文献   
26.
27.
T cell ignorance is a specific form of immunological tolerance. It describes the maintenance of naivety in antigen-specific T cells in vivo despite the presence of their target antigen. It is thought to mainly play a role during the steady state, when self-antigens are presented in absence of costimulatory signals and at low density or to T cells of low affinity. In how far antigen-specific T cells can also remain clonally ignorant to foreign antigens, presented in the inflammatory context of systemic infection, remains unclear. Using single-cell in vivo fate mapping and high throughput flow cytometric enrichment, we find that high-affinity antigen-specific CD8+ T cells are efficiently recruited upon systemic infection. In contrast, most low-affinity antigen-specific T cells ignore the priming antigen and persist in the naïve state while remaining fully responsive to subsequent immunization with a high-affinity ligand. These data establish the widespread clonal ignorance of low-affinity T cells as a major factor shaping the composition of antigen-specific CD8+ T cell responses to systemic infection.  相似文献   
28.
29.
30.
Spontaneous thioguanine-resistant mutants were derived from populations of finite-life-span, diploid human fibroblasts by means of a fluctuation analysis. cDNA was prepared from mutantHPRT mRNA and amplified by the polymerase chain reaction, and the sequence of the product was analyzed. Exon deletions, which very likely arose from mutations in the intron splice site consensus sequences, were found in 10 of the 37 mutants examined (27% of the total). Among the 28 mutations in the coding sequence, base pair substitutions predominated (89%). With the exception of one base pair involved in a tandem mutation, all base pair substitutions resulted in alterations in the predicted amino acid sequence of the protein. In addition there were three frameshift mutations, consisting of the deletion of one or two base pairs. Although mutations occurred throughout the coding sequence, 50% (14/28) were found in the 5 portion of exon 3.  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