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   26918篇
  免费   8583篇
  国内免费   175篇
耳鼻咽喉   237篇
儿科学   660篇
妇产科学   499篇
基础医学   5194篇
口腔科学   1007篇
临床医学   4057篇
内科学   6548篇
皮肤病学   559篇
神经病学   2146篇
特种医学   2054篇
外科学   6181篇
综合类   347篇
一般理论   11篇
预防医学   2997篇
眼科学   458篇
药学   1393篇
  1篇
中国医学   11篇
肿瘤学   1316篇
  2021年   379篇
  2020年   278篇
  2018年   371篇
  2017年   399篇
  2016年   562篇
  2015年   908篇
  2014年   1526篇
  2013年   2172篇
  2012年   713篇
  2011年   609篇
  2010年   1215篇
  2009年   1322篇
  2008年   575篇
  2007年   406篇
  2006年   508篇
  2005年   441篇
  2004年   396篇
  2003年   328篇
  2002年   360篇
  2001年   487篇
  2000年   413篇
  1999年   626篇
  1998年   902篇
  1997年   839篇
  1996年   893篇
  1995年   833篇
  1994年   715篇
  1993年   676篇
  1992年   633篇
  1991年   617篇
  1990年   557篇
  1989年   675篇
  1988年   672篇
  1987年   669篇
  1986年   597篇
  1985年   629篇
  1984年   579篇
  1983年   562篇
  1982年   614篇
  1981年   577篇
  1980年   560篇
  1979年   521篇
  1978年   518篇
  1977年   526篇
  1976年   460篇
  1975年   408篇
  1974年   359篇
  1973年   339篇
  1972年   346篇
  1971年   309篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  相似文献   
2.
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates.  相似文献   
3.
4.
5.
In May 2017, the Health and Environmental Sciences Institute's Genetic Toxicology Technical Committee hosted a workshop to discuss whether mode of action (MOA) investigation is enhanced through the application of the adverse outcome pathway (AOP) framework. As AOPs are a relatively new approach in genetic toxicology, this report describes how AOPs could be harnessed to advance MOA analysis of genotoxicity pathways using five example case studies. Each of these genetic toxicology AOPs proposed for further development includes the relevant molecular initiating events, key events, and adverse outcomes (AOs), identification and/or further development of the appropriate assays to link an agent to these events, and discussion regarding the biological plausibility of the proposed AOP. A key difference between these proposed genetic toxicology AOPs versus traditional AOPs is that the AO is a genetic toxicology endpoint of potential significance in risk characterization, in contrast to an adverse state of an organism or a population. The first two detailed case studies describe provisional AOPs for aurora kinase inhibition and tubulin binding, leading to the common AO of aneuploidy. The remaining three case studies highlight provisional AOPs that lead to chromosome breakage or mutation via indirect DNA interaction (inhibition of topoisomerase II, production of cellular reactive oxygen species, and inhibition of DNA synthesis). These case studies serve as starting points for genotoxicity AOPs that could ultimately be published and utilized by the broader toxicology community and illustrate the practical considerations and evidence required to formalize such AOPs so that they may be applied to genetic toxicity evaluation schemes. Environ. Mol. Mutagen. 61:114–134, 2020. © 2019 Wiley Periodicals, Inc.  相似文献   
6.
7.
8.
9.
A cluster randomized experiment was undertaken testing two sets of interventions encouraging enrollment in the Individually Paying Program (IPP), the voluntary component of the Philippines' social health insurance program. In early 2011, 1037 unenrolled IPP‐eligible families in 179 randomly selected intervention municipalities were given an information kit and offered a 50% premium subsidy valid until the end of 2011; 383 IPP‐eligible families in 64 control municipalities were not. In February 2012, the 787 families in the intervention sites who were still IPP‐eligible but had not enrolled had their vouchers extended, were resent the enrollment kits and received SMS reminders. Half the group also received a ‘handholding’ intervention: in the endline interview, the enumerator offered to help complete the enrollment form, deliver it to the insurer's office in the provincial capital, and mail the membership cards. The main intervention raised the enrollment rate by 3 percentage points (ppts) (p = 0.11), with an 8 ppt larger effect (p < 0.01) among city‐dwellers, consistent with travel time to the insurance office affecting enrollment. The handholding intervention raised enrollment by 29 ppts (p < 0.01), with a smaller effect (p < 0.01) among city‐dwellers, likely because of shorter travel times, and higher education levels facilitating unaided completion of the enrollment form. Copyright © The World Bank Health Economics © 2015 John Wiley & Sons, Ltd.  相似文献   
10.
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.  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