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   1252篇
  免费   107篇
  国内免费   28篇
儿科学   72篇
妇产科学   13篇
基础医学   168篇
口腔科学   57篇
临床医学   190篇
内科学   214篇
皮肤病学   14篇
神经病学   97篇
特种医学   260篇
外科学   90篇
综合类   24篇
预防医学   65篇
眼科学   7篇
药学   60篇
肿瘤学   56篇
  2023年   5篇
  2021年   13篇
  2019年   11篇
  2018年   21篇
  2017年   17篇
  2016年   15篇
  2015年   17篇
  2014年   21篇
  2013年   25篇
  2012年   23篇
  2011年   24篇
  2010年   40篇
  2009年   31篇
  2008年   29篇
  2007年   44篇
  2006年   42篇
  2005年   31篇
  2004年   30篇
  2003年   29篇
  2002年   23篇
  2001年   33篇
  2000年   22篇
  1999年   25篇
  1998年   68篇
  1997年   74篇
  1996年   81篇
  1995年   50篇
  1994年   44篇
  1993年   44篇
  1992年   26篇
  1991年   21篇
  1990年   24篇
  1989年   44篇
  1988年   43篇
  1987年   38篇
  1986年   36篇
  1985年   39篇
  1984年   8篇
  1983年   14篇
  1982年   19篇
  1981年   17篇
  1980年   16篇
  1979年   9篇
  1978年   8篇
  1977年   16篇
  1976年   12篇
  1975年   11篇
  1973年   5篇
  1969年   7篇
  1966年   8篇
排序方式: 共有1387条查询结果,搜索用时 672 毫秒
91.
IntroductionWith the emergence of the COVID-19 pandemic, all elective surgery was temporarily suspended in the UK, allowing for diversion of resource to manage the anticipated surge of critically unwell patients. Continuing to deliver time-critical surgical care is important to avoid excess morbidity and mortality from pathologies unrelated to COVID-19. We describe the implementation and short-term surgical outcomes from a system to deliver time-critical elective surgical care to patients during the COVID-19 pandemic.Materials and methodsA protocol for the prioritisation and safe delivery of time-critical surgery at a COVID-19 ‘clean’ site was implemented at the Nuffield Health Exeter Hospital, an independent sector hospital in the southwest of England. Outcomes to 30 days postoperatively were recorded, including unplanned admissions after daycase surgery, readmissions and complications, as well as the incidence of perioperative COVID-19 infection in patients and staff.ResultsA total of 128 surgical procedures were performed during a 31-day period by a range of specialties including breast, plastics, urology, gynaecology, vascular and cardiology. There was one unplanned admission and and two readmissions. Six complications were identified, and all were Clavien-Dindo grade 1 or 2. All 128 patients had preoperative COVID-19 swabs, one of which was positive and the patient had their surgery delayed. Ten patients were tested for COVID-19 postoperatively, with none testing positive.ConclusionThis study has demonstrated the implementation of a safe system for delivery of time-critical elective surgical care at a COVID-19 clean site. Other healthcare providers may benefit from implementation of similar methodology as hospitals plan to restart elective surgery.  相似文献   
92.
Objectives  The objectives of this study were to define the components of a skilled low-cavity non-rotational vacuum delivery (occiput anterior, vertex at station +2 or below and less than 45-degree rotation from midline) and to facilitate the transfer of skills from expert to trainee obstetricians.
Design  Qualitative study using interviews and video recordings.
Setting  Two university teaching hospitals (St Michael's Hospital, Bristol, and Ninewell's Hospital, Dundee).
Participants  Ten obstetricians and eight midwives identified as experts in conducting or supporting operative vaginal deliveries.
Methods  Semi-structured interviews were carried out using routine clinical scenarios. The experts were also video recorded conducting low-cavity vacuum deliveries in a simulation setting. The interviews and video recordings were transcribed verbatim and analysed using thematic coding. The anonymised data were independently coded by three researchers and compared for consistency of interpretation. The experts reviewed the coded interviews and video data for respondent validation and clarification. The themes that emerged following the final coding were used to formulate a list of skills.
Main outcome measures  Key technical skills of a low-cavity non-rotational delivery.
Results  The final list included detailed technical skills required for conducting a low-cavity vacuum delivery. The combination of semi-structured interviews and simulation videos allowed the formulation of a comprehensive skills tool for future evaluation.
Conclusion  This explicitly defined skills list could aid trainees understanding of the technique of low-cavity vacuum delivery. This is an important first step in evaluating clinical competence in intrapartum procedures.  相似文献   
93.
94.
Title. A systematic review protocol on the use of teaching portfolios for educators in further and higher education. Aim. This paper is a review protocol that will be used to identify, critically appraise and synthesize the best current evidence relating to the use of teaching portfolios for educators in further and higher education. Background. While portfolio use as a means to assist students in further and higher education has undergone extensive research and review, their use as a tool to assist educators has yet to receive systematic attention. Reviews conducted on studies related to portfolio use and undergraduate students have suggested that a teaching portfolio may have a benefit for educators in higher education as a means to provide relevancy and focus to their teaching. Design. The objectives of the review are to evaluate how a teaching portfolio assists educators in teaching and learning; to evaluate the effects of maintaining a teaching portfolio for educators in relation to personal development; to explore the type of portfolio used; to determine whether a teaching portfolio is perceived more beneficial for various grades and professional types; and to determine any motivating factors or workplace incentives behind its implementation and completion. A search of the following databases will be made: MEDLINE, CINAHL, BREI, ERIC and AUEI. The review will follow the Joanna Briggs Institute guidance for systematic reviews of quantitative and qualitative research. Conclusion. The review will offer clarity and direction on the use of teaching portfolios for educators, policymakers, supervisory managers and researchers involved in further and higher education.  相似文献   
95.
96.
在一项随机、平行分组的开放试验中,27例妊娠糖尿病妇女(年龄30.7±6.3岁,HbA1c〈7%)随机分为门冬胰岛素治疗组(餐前5分钟注射)和常规人胰岛素治疗组(餐前30分钟注射)。试验时间为从诊断妊娠糖尿病(18~28周)至产后6周。研究期间两组的总体血糖水平均控制良好(试验开始和结束时HbA1c≤6%)。进餐试验时,试验6周时的平均血糖水平(门冬胰岛素组4.2±0.57mmol/L,常规人胰岛素组4.8±0.86mmol/L)略低于试验0周时(门冬胰岛素组4.9±0.59mmol/L,常规人胰岛素组5.1±0.36mmol/L)。  相似文献   
97.
98.
Visual development was studied in 10 very-low-birth-weight infants (less than 1500 g) with retinopathy of prematurity (ROP) stage 3+ who had been treated with cryocoagulation in both eyes. Binocular visual acuity (acuity cards method) and binocular visual fields (kinetic perimetry) were assessed repeatedly in the first year of life. At 12 months corrected age, visual acuity was normal in seven and impaired in three infants, who appeared to be severely myopic. Normal visual fields were found in eight infants at this age. The results indicate that cryotherapy in cases of ROP stage 3+ does not interfere with visual acuity development. The effect on visual field development needs further investigation.  相似文献   
99.
Little is known about the fate of higher level visual perception and visual mental imagery in the early stages of Alzheimer's disease (AD). In this study, we assessed these abilities in a group of mild-to-moderate AD patients using tasks selected to satisfy two main criteria. First, they have been shown to be sensitive to impairments of perception and imagery caused by other neurological conditions. Second, they test specific stages of visual perception and cognition in a reasonably selective manner. These stages were (in their normal order of occurrence during perception): the segmentation of different local points of the visual field into regions belonging to distinct objects; the representation of the shapes of these segmented regions in the image; the construction of more abstract shape representations that possess constancy over changes in size, location, orientation or illumination (assessed separately for faces and objects); the use of these perceived shape representations to access stored shape representations; and the access of lexical semantic representations from these high-level visual representations. Additional tasks tested the top-down activation of earlier visual representations from the semantic level in visual mental imagery. Our findings indicate small, but in most cases reliable, impairments in visual perception, which are independent of degree of cognitive decline. Deficits in basic shape processing influenced performance on some higher level visual tasks, but did not contribute to poor performance on face processing, or to the profound deficit on object naming. The latter of these is related to semantic-lexical impairment.  相似文献   
100.
The BRCA1 tumor suppressor gene and the HER-2/neu oncogene are located in close proximity on the long arm of chromosome 17 (17q11-21). Absence of BRCA1 or functional overexpression of the HER-2/neu gene presumably contributes to the somatic phenotype of breast cancer in premenopausal women, characterized by unfavorable prognostic features such as high tumor grade, hormone receptor negativity, and high proliferation rate. To examine whether amplification of HER-2/neu contributes to the aggressive biology of BRCA1-associated tumors, we have performed fluorescence in situ hybridization on formalin-fixed paraffin-embedded breast tumor tissue sections from 53 BRCA1 mutation carriers and 41 randomly selected, age-matched sporadic breast cancer cases. Although BRCA1-associated and sporadic tumors were equally likely (19% versus 22%) to exhibit HER-2/neu amplification [defined as a ratio of HER-2/neu copies to chromosome 17 centromere (CEP17) copies > or = 2], 6 (15%) of the sporadic tumors were highly amplified (defined as a ratio greater-than-or-equal 5) versus none of the BRCA1-associated tumors (P = 0.048). HER-2 protein overexpression as measured by immunohistochemical analysis was not observed among the BRCA1-associated cases (P = 0.042). Four of 21 (19%) sporadic tumors exhibited strong membranous staining of HER-2 (intensity level of 3+) as compared with 0 of 39 BRCA1-associated tumors. Our data suggest that a germ-line mutation in the BRCA1 tumor suppressor gene is associated with a significantly lower level of HER-2/neu amplification. Thus, it is possible that BRCA1-associated and HER-2/neu-highly amplified tumors progress through distinct molecular pathways, and the aggressive pathological features of BRCA1-associated tumors appear unrelated to amplification of the adjacent HER-2/neu oncogene.  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