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   3057篇
  免费   209篇
  国内免费   9篇
耳鼻咽喉   20篇
儿科学   86篇
妇产科学   18篇
基础医学   290篇
口腔科学   48篇
临床医学   357篇
内科学   584篇
皮肤病学   20篇
神经病学   236篇
特种医学   135篇
外国民族医学   1篇
外科学   571篇
综合类   41篇
一般理论   2篇
预防医学   406篇
眼科学   49篇
药学   240篇
肿瘤学   171篇
  2023年   9篇
  2022年   15篇
  2021年   45篇
  2020年   27篇
  2019年   51篇
  2018年   49篇
  2017年   49篇
  2016年   57篇
  2015年   69篇
  2014年   87篇
  2013年   158篇
  2012年   217篇
  2011年   252篇
  2010年   126篇
  2009年   129篇
  2008年   180篇
  2007年   209篇
  2006年   201篇
  2005年   235篇
  2004年   220篇
  2003年   200篇
  2002年   183篇
  2001年   41篇
  2000年   38篇
  1999年   53篇
  1998年   40篇
  1997年   37篇
  1996年   20篇
  1995年   16篇
  1994年   15篇
  1993年   28篇
  1992年   25篇
  1991年   24篇
  1990年   32篇
  1989年   16篇
  1988年   12篇
  1987年   11篇
  1986年   9篇
  1985年   10篇
  1984年   10篇
  1983年   6篇
  1982年   14篇
  1981年   6篇
  1980年   10篇
  1979年   8篇
  1978年   3篇
  1977年   4篇
  1973年   3篇
  1967年   3篇
  1960年   2篇
排序方式: 共有3275条查询结果,搜索用时 109 毫秒
71.
72.
Guided endodontics has been used for the treatment of anterior teeth with a successful outcome. This approach is not only limited to anterior teeth because it can also be used for the treatment of premolars and molars. However, in such cases, space may be a limitation because a long bur has to be used in addition to the guide being placed on top of the teeth. The aim of this case report was to present a novel guided endodontics technique using a sleeveless 3-dimensional–printed guide. This design can reduce vertical space, allowing an open view of the tooth and irrigation during drilling. A 46-year-old female patient consulted the endodontic department with intermittent pain around tooth #5. Tooth #5 presented pain upon percussion and responded negative to a cold test. The initial periapical radiograph revealed an apical radiolucency with pulp canal obliteration. Clinically, there was no sinus tract. The tooth was diagnosed with pulp necrosis and symptomatic apical periodontitis. Guided endodontic treatment was performed with a sleeveless 3-dimensional–printed guide and long neck carbide bur with a head diameter of 1 mm to drill a minimally invasive access cavity up to the root canal. A completely healed apical area of tooth #5 was visible after 1 year on periapical radiographs. This technique seems to be a promising alternative in comparison with the conventional guided endodontic guide design for the negotiation of pulp canal obliteration in cases in which vertical space is limited.  相似文献   
73.
This study examines trends and geographical differences in total and live birth prevalence of trisomies 21, 18 and 13 with regard to increasing maternal age and prenatal diagnosis in Europe. Twenty-one population-based EUROCAT registries covering 6.1 million births between 1990 and 2009 participated. Trisomy cases included live births, fetal deaths from 20 weeks gestational age and terminations of pregnancy for fetal anomaly. We present correction to 20 weeks gestational age (ie, correcting early terminations for the probability of fetal survival to 20 weeks) to allow for artefactual screening-related differences in total prevalence. Poisson regression was used. The proportion of births in the population to mothers aged 35+ years in the participating registries increased from 13% in 1990 to 19% in 2009. Total prevalence per 10 000 births was 22.0 (95% CI 21.7–22.4) for trisomy 21, 5.0 (95% CI 4.8–5.1) for trisomy 18 and 2.0 (95% CI 1.9–2.2) for trisomy 13; live birth prevalence was 11.2 (95% CI 10.9–11.5) for trisomy 21, 1.04 (95% CI 0.96–1.12) for trisomy 18 and 0.48 (95% CI 0.43–0.54) for trisomy 13. There was an increase in total and total corrected prevalence of all three trisomies over time, mainly explained by increasing maternal age. Live birth prevalence remained stable over time. For trisomy 21, there was a three-fold variation in live birth prevalence between countries. The rise in maternal age has led to an increase in the number of trisomy-affected pregnancies in Europe. Live birth prevalence has remained stable overall. Differences in prenatal screening and termination between countries lead to wide variation in live birth prevalence.  相似文献   
74.
75.
Graft rinse prior reperfusion in liver transplantation (LT) is believed to reduce the incidence of postreperfusion syndrome and improve clinical outcome. A MEDLINE search was performed to obtain a comprehensive review of the published literature dealing with graft rinse in LT. Moreover, all thirty‐four LT centers in the Eurotransplant (ET) region were invited to participate in an online survey to whether or not graft rinse is performed and whether further research in the field is needed. Seventeen reports have been found to investigate graft rinse protocols in 1894 LT recipients. Eighteen of the thirty centers that participated in the online survey performed graft rinse prior reperfusion in LT. The most commonly used rinse solution was albumin. Nineteen centers stated interest in participating in a multicenter RCT in the field. The published literature does not provide concluding appraisal of the benefit of graft rinse in LT. Graft rinse protocols are not standardized and are based on personal experience. Appropriately designed clinical trials addressing the topic are demanded. The online survey appears to be a helpful tool for the evaluation of clinical practice and future research topics in the transplant community.  相似文献   
76.
Although xenografts have always held immeasurable potential as an inexhaustible source of donor organs, immunological barriers and physiological incompatibility have proved to be formidable obstacles to clinical utility. An exciting, new regenerative medicine‐based approach termed “semi‐xenotransplantation” (SX) seeks to overcome these obstacles by combining the availability and reproducibility of animal organs with the biocompatibility and functionality of human allografts. Compared to conventional xenotransplantation wherein the whole organ is animal‐derived, SX grafts are cleansed of their antigenic cellular compartment to produce whole‐organ extracellular matrix scaffolds that retain their innate structure and vascular channels. These scaffolds are then repopulated with recipient or donor human stem cells to generate biocompatible semi‐xenografts with the structure and function of native human organs. While numerous hurdles must be still overcome in order for SX to become a viable treatment option for end‐stage organ failure, the immense potential of SX for meeting the urgent needs for a new source of organs and immunosuppression‐free transplantation justifies the interest that the transplant community is committing to the field.  相似文献   
77.
78.
79.
80.
A low threshold for computed tomography (CT) scanning in patients with previous appendicectomy and right iliac fossa pain helps facilitate timely diagnosis and exclusion of other differential diagnoses. Here, we present a rare cause which has significant medicolegal ramifications and is accurately diagnosed with CT.  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