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   3603篇
  免费   217篇
  国内免费   11篇
耳鼻咽喉   33篇
儿科学   108篇
妇产科学   84篇
基础医学   449篇
口腔科学   255篇
临床医学   306篇
内科学   767篇
皮肤病学   126篇
神经病学   306篇
特种医学   103篇
外科学   380篇
综合类   30篇
一般理论   3篇
预防医学   239篇
眼科学   100篇
药学   187篇
中国医学   3篇
肿瘤学   352篇
  2023年   32篇
  2022年   38篇
  2021年   96篇
  2020年   60篇
  2019年   87篇
  2018年   81篇
  2017年   63篇
  2016年   85篇
  2015年   89篇
  2014年   108篇
  2013年   148篇
  2012年   240篇
  2011年   263篇
  2010年   157篇
  2009年   124篇
  2008年   211篇
  2007年   243篇
  2006年   232篇
  2005年   240篇
  2004年   203篇
  2003年   169篇
  2002年   170篇
  2001年   41篇
  2000年   27篇
  1999年   32篇
  1998年   37篇
  1997年   49篇
  1996年   23篇
  1995年   15篇
  1994年   39篇
  1993年   25篇
  1992年   19篇
  1991年   22篇
  1990年   22篇
  1989年   27篇
  1988年   32篇
  1987年   22篇
  1986年   20篇
  1985年   23篇
  1984年   27篇
  1983年   20篇
  1982年   18篇
  1981年   16篇
  1980年   10篇
  1979年   8篇
  1978年   18篇
  1977年   17篇
  1976年   8篇
  1969年   7篇
  1961年   6篇
排序方式: 共有3831条查询结果,搜索用时 15 毫秒
41.
We examined whether challenging upright stance influences the execution of a grasping task. Participants reached to grasp a small sphere while standing either on a stable surface or on foam. Before reaching for the sphere, participants exhibited more body sway and greater fluctuations in the centre of pressure when standing on foam. While reaching for the sphere, the overall body posture changed less when standing on foam than when standing on the stable surface. The digits’ and wrist's movements towards the sphere were no different when standing on foam than when standing on the stable surface. Presumably, the redundancy in the way movements can be performed is exploited to choose the most suitable changes in joint angles to achieve the desired movements of the digits under the prevailing conditions.  相似文献   
42.
Bacterial vaginosis (BV) is the most common gynecological infection in the United States. Diagnosis based on Amsel''s criteria can be challenging and can be aided by laboratory-based testing. A standard method for diagnosis in research studies is enumeration of bacterial morphotypes of a Gram-stained vaginal smear (i.e., Nugent scoring). However, this technique is subjective, requires specialized training, and is not widely available. Therefore, a highly accurate molecular assay for the diagnosis of BV would be of great utility. We analyzed 385 vaginal specimens collected prospectively from subjects who were evaluated for BV by clinical signs and Nugent scoring. We analyzed quantitative real-time PCR (qPCR) assays on DNA extracted from these specimens to quantify nine organisms associated with vaginal health or disease: Gardnerella vaginalis, Atopobium vaginae, BV-associated bacteria 2 (BVAB2, an uncultured member of the order Clostridiales), Megasphaera phylotype 1 or 2, Lactobacillus iners, Lactobacillus crispatus, Lactobacillus gasseri, and Lactobacillus jensenii. We generated a logistic regression model that identified G. vaginalis, A. vaginae, and Megasphaera phylotypes 1 and 2 as the organisms for which quantification provided the most accurate diagnosis of symptomatic BV, as defined by Amsel''s criteria and Nugent scoring, with 92% sensitivity, 95% specificity, 94% positive predictive value, and 94% negative predictive value. The inclusion of Lactobacillus spp. did not contribute sufficiently to the quantitative model for symptomatic BV detection. This molecular assay is a highly accurate laboratory tool to assist in the diagnosis of symptomatic BV.  相似文献   
43.
44.
The article reports and reflects on a study of kindergarten staff member’s gendered attitudes. The empirical part consists of answers to a questionnaire from some 700 staff members of all 80 kindergartens in two Danish municipalities. The theoretical approach is informed by the framework of Pierre Bourdieu and the Mary Douglas’ Grid Group Cultural Theory. The common strong point of view is that men are an exceptional educational resource in kindergartens and for the sake of gender equality on the labour market, one is to promote a higher proportion of male workers in kindergartens and in several other sectors, where women commonly are in the majority. We examine these premises in respect of Denmark and Norway and then confront the notion of kindergartens to be gender-segregated in pedagogical and professional terms. In conclusion, it is proposed a renewal of the starting point of the educational gender research.  相似文献   
45.
ObjectiveTo assess the role of the computerized tomography (CT) scanner in cross-transmission of carbapenem-resistant Acinetobacter baumannii between hospitalized patients undergoing CT scan.MethodsA single-centre retrospective observational analysis of inpatients undergoing CT scans. Patient-unique CT scans were defined as ‘index cases’ (patients undergoing CT scan with carbapenem-resistant Acinetobacter baumannii (CRAB) colonization documented during the previous 60 days), ‘incident cases’ (patients found colonized with CRAB within 14 days following CT scan), and ‘negative cases’ (negative for CRAB before and after CT scan). CRAB acquisition was analysed by time interval between CT scan and CT scan of the prior index-case patient.ResultsAmongst 73 047 CT scans performed over 5 years, 4834 scans were performed within 12 hours of an index case. CRAB acquisition was detected in 20 patients (incident cases), including 16/2725 (5.8/1000 scans) who underwent CT scan within 6 hours of an index-case CT scan and 4/2109 (1.9/1000 scans) who had their CT scan 7–12 hours after the CT scan of an index-case patient (p 0.033, risk ratio 3.1, 95%CI 1.03–9.25). Patient characteristics for the two time periods were similar. While not the only significant predictor of CRAB acquisition (others included age and length of hospital stay prior to the CT scan), the time elapsed from an index case remained a significant predictor for CRAB acquisition on multivariate analysis (OR 0.84, 95%CI 0.74–0.95, p 0.007).ConclusionsPerforming a CT scan within 6 hours of a CT scan performed in a CRAB-positive patient was an independent predictor of CRAB acquisition, approximately tripling the risk. This probably reflects poor infection control practice in the CT suite.  相似文献   
46.
PurposePre-exposure prophylaxis (PrEP)—an effective and safe intervention to prevent HIV transmission—was recently approved by the Food and Drug Administration for use by adolescents. Informed by studies of sexual behavior and PrEP adherence, retention, and promotion, we model the potential impact of PrEP use among at-risk adolescent sexual minority males.MethodsWe simulate an HIV epidemic among men who have sex with men (MSM) aged 13–39. We assume adult MSM ages 19–39 have had PrEP available for 3 years with 20% coverage among eligible MSM based on the Centers for Disease Control and Prevention guidelines. PrEP interventions for ages 16–18 are then simulated using adherence and retention profiles drawn from the ATN113 and Enhancing Preexposure Prophylaxis in Community studies across a range of uptake parameters (10%–100%). Partnerships across age groups were modeled using parameterizations from the RADAR study. We compare the percent of incident infections averted (impact), person-years on PrEP per infection averted (efficiency), and changes in prevalence over 10 years.ResultsAs compared to no PrEP use, baseline PrEP adherence and retention among adolescent sexual minority males drawn from the ATN113 and Enhancing Preexposure Prophylaxis in Community studies averted from 2.8% to 41.0% of HIV infections depending on the fraction of eligible adolescent sexual minority males that initiated PrEP at their annual health-care visit. Improved adherence and retention achieved with an array of focused interventions from real-world settings increased the percent of infections averted by as much as 26%–70%.ConclusionsEmpirically demonstrated improvements in the PrEP continuum of care in response to existing interventions can substantially reduce incident HIV infections among adolescent sexual minority males.  相似文献   
47.
In the situation of an irreparable meniscus tear, an implant comparable to a normal meniscus is an attractive option. Using a canine model, we assessed the early and late histologic response to a tissue engineered meniscal collagen scaffold (CS). All animals received bilateral arthrotomies, and all joints receiving the CS had an 80% resection of the meniscus. Animals were sacrificed at 3 and 6 weeks, and 12, 13, and 17 months. The CS/tissue complex and host meniscal rim were sectioned for histologic examination with specific focus on the extracellular matrix, angiogenesis, cellular resorption of the scaffold, scaffold appearance, and CS/Host integration. Early histologic samples (3–6 weeks) revealed active angiogenesis and fibrin clots evolving into cellular granulation type tissue. At 12 months, a mature fibrochondrocytic matrix was depositing with gradations of dissolution and integration of the CS implant. Maturing CS/host integration was observed at 18 months. Active cellular resorption of the implant decreased over time. Four cases showed a mild non‐specific chronic inflammation and one additional case showed inflammatory engulfment of the scaffold with giant cells at 3 weeks. No evidence of infection either clinically or histologically was observed at any time point. Overall, this histologic analysis demonstrated the active integration of a meniscal like cartilage into a tissue engineered biological scaffold in a canine model. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1914–1919, 2013  相似文献   
48.
Matched vaginal and cervical specimens from 96 subjects were analyzed by quantitative PCR for the presence and concentration of bacterial vaginosis-associated microbes and commensal Lactobacillus spp. Detection of these microbes was 92% concordant, indicating that microbial floras at these body sites are generally similar.  相似文献   
49.
Historically treated with surgery, current practice recommends anal carcinoma to be treated with a combination of chemotherapy and radiation. This review will examine the anatomy, modes of disease spread and recurrence, and evaluate the existing evidence for treatment options for these tumors. An in-depth examination of specific radiation therapy (RT) techniques—such as conventional 3D-conformal RT and intensity-modulated RT—will be discussed along with modern dose constraints. RT field arrangement, patient setup, and recommended gross and clinical target volume (CTV) contours will be considered. Areas in need of further investigation, such as the role in treatment for positron emission tomography (PET) will be explored.  相似文献   
50.
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