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   4937篇
  免费   432篇
  国内免费   9篇
耳鼻咽喉   39篇
儿科学   160篇
妇产科学   129篇
基础医学   706篇
口腔科学   37篇
临床医学   670篇
内科学   953篇
皮肤病学   71篇
神经病学   568篇
特种医学   106篇
外科学   432篇
综合类   31篇
一般理论   11篇
预防医学   659篇
眼科学   122篇
药学   307篇
中国医学   8篇
肿瘤学   369篇
  2023年   64篇
  2022年   29篇
  2021年   154篇
  2020年   113篇
  2019年   206篇
  2018年   181篇
  2017年   146篇
  2016年   165篇
  2015年   188篇
  2014年   222篇
  2013年   279篇
  2012年   420篇
  2011年   412篇
  2010年   215篇
  2009年   173篇
  2008年   331篇
  2007年   314篇
  2006年   310篇
  2005年   285篇
  2004年   256篇
  2003年   266篇
  2002年   214篇
  2001年   27篇
  2000年   18篇
  1999年   31篇
  1998年   25篇
  1997年   32篇
  1996年   17篇
  1995年   27篇
  1994年   25篇
  1993年   20篇
  1992年   15篇
  1991年   9篇
  1990年   15篇
  1989年   10篇
  1988年   4篇
  1987年   8篇
  1986年   4篇
  1984年   6篇
  1983年   11篇
  1982年   14篇
  1981年   6篇
  1980年   10篇
  1979年   6篇
  1978年   10篇
  1977年   5篇
  1973年   4篇
  1971年   4篇
  1965年   5篇
  1935年   3篇
排序方式: 共有5378条查询结果,搜索用时 62 毫秒
1.
2.
Rift Valley fever virus (RVFV) poses a major threat of introduction to several continents, including North America. Such an introduction could cause significant losses to the livestock industry, in addition to substantial human morbidity and mortality. Because of the opportunistic blood host selection of Culex tarsalis mosquitoes, we hypothesized that this species could be an important bridge vector of RVFV near feedlots in the event of an introduction. We investigated the mosquito community composition at livestock feedlots and surrounding natural and residential areas to determine differences in mosquito relative abundance and blood feeding patterns attributed to cattle feeding operations. DNA extracted from abdomens of blood‐fed mosquitoes were sequenced to determine host identity. Multivariate regression analyses revealed differences between mosquito community assemblages at feedlots and non‐feedlot sites (p < 0.05), with this effect driven largely by differential abundances of Aedes vexans (padj < 0.05). Mosquito diversity was lower on feedlots than surrounding areas for three out of four feedlots. Culex tarsalis was abundant at both feedlots and nearby sites. Diverse vertebrate blood meals were detected in Cx. tarsalis at non‐feedlot sites, with a shift towards feeding on cattle at feedlots. These data support a potential for Cx. tarsalis to serve as a bridge vector of RVFV between livestock and humans in Colorado.  相似文献   
3.
4.
BackgroundAmerican Society of Clinical Oncology guidelines recommend that patients ≥65 years of age starting chemotherapy undergo a geriatric assessment (GA) to inform and guide management; however, little is known about resources available in community oncology practices to implement these guidelines and to facilitate geriatric oncology research.Materials and MethodsOncology practices within the National Cancer Institute Community Oncology Research Program (NCORP) were electronically surveyed in 2017 regarding the availability of specialty providers, supportive services, and practice characteristics, as part of a larger survey of cancer care delivery research capacity.ResultsOf the 943 NCORP practices, 504 (54%) responded to the survey, representing 210 practice groups. The median new cancer cases per year ≥65 years of age was 457 (interquartile range 227–939). Of respondents, only 2.0% of practices had a fellowship‐trained geriatric oncologist on staff. Geriatricians were available for consultation or comanagement at 37% of sites, and of those, only 13% had availability within the oncology clinic (5% of overall). Practice size of ≥1,000 new adult cancer cases (ages ≥18) per year was associated with higher odds (1.81, confidence interval 1.02–3.23) of geriatrician availability. Other multidisciplinary care professionals that could support GA were variably available onsite: social worker (84%), nurse navigator (81%), pharmacist (77%), dietician (71%), rehabilitative medicine (57%), psychologist (42%), and psychiatrist (37%).ConclusionOnly a third of community oncology practices have access to a geriatrician within their group and only 5% of community sites have access within the oncology clinic. Use of primarily self‐administered GA tools that direct referrals to available services may be an effective implementation strategy for guideline‐based care.Implications for PracticeOnly a minority of community oncology practices in the U.S. have access to geriatric specialty care. Developing models of care that use patient‐reported measures and/or other geriatric screening tools to assess and guide interventions in older adults, rather than geriatric consultations, are likely the most practical methods to improve the care of this vulnerable population.  相似文献   
5.
Abstract

Purpose: Cannabis is the most prevalent drug in the world and its consumption is growing. Cannabinoid receptors are present in the human central nervous system. Recent studies show evidence of the effects of cannabinoids on the retina, and synthesising the results of these studies may be relevant for ophthalmologists. Thus, this review adopts standardised, systematic review methodology to investigate the effects of exposure to cannabis and components on the retina.

Methods: We searched five online databases for the combined terms for outcome (“retina”) and exposure (“cannabis”). Eligibility of studies were conducted by two independent reviewers, and risk of bias was assessed.

Results: We retrieved 495 studies, screened 229 studies, assessed 52 studies for eligibility, and included 16 studies for qualitative analysis. The cannabinoids most frequently investigated were delta-9-tetrahydrocannabinol (THC), abnormal cannabidiol, synthetic cannabinoid, and cannabidiol (CDB). The outcomes most studied were neuroretinal dysfunction, followed by vascular effects. The studies also included investigation of neuroprotective and anti-inflammatory effects and teratogenic effects.

Conclusions: This review suggests that cannabinoids may have an important role in retinal processing and function.  相似文献   
6.
7.
This paper is built upon an assumption: that social theory can be generated through a meaningful engagement with a co‐researcher group of disabled young people. Our co‐researchers are theoretical provocateurs and theorists in their own right who, through their activism and writing, are challenging us to reconsider the meaning of life, death and disability. Their work on our funded Economic and Social Research Council (ESRC) project has enabled us to consider the promise and potential of humanist and posthuman epistemologies, theories, methodologies, interventions and activisms. The paper introduces the research, the authors of this paper (academics and co‐researchers) and then explores three layers of analysis that work the edges of posthuman thinking; sovereign and assembled selves; affects and desires; mourning and affirmation. We conclude by asserting that as a research team we are engaging with a DisHuman approach to theory and activism: one that blends the pragmatics of humanism with posthuman possibilities.  相似文献   
8.
Asthma is a chronic, recurrent and incurable allergy‐related respiratory disease characterized by inflammation, bronchial hyperresponsiveness and narrowing of the airways. Extracellular vesicles (EVs) are a universal feature of cellular function and can be detected in different bodily fluids. Recent evidence has shown the possibility of using EVs in understanding the pathogenesis of asthma, including their potential as diagnostic and therapeutic tools. Studies have reported that EVs released from key cells involved in asthma can induce priming and activation of other asthma‐associated cells. A literature review was conducted on all current research regarding the role and function of EVs in the pathogenesis of asthma via the PRISMA statement method. An electronic search was performed using EMBASE and PubMed through to November 2018. The EMBASE search returned 76 papers, while the PubMed search returned 211 papers. Following duplicate removal, titles and abstracts were screened for eligibility with a total of 34 studies included in the final qualitative analysis. The review found evidence of association between the presence of EVs and physiological changes characteristic of asthma, suggesting that EVs are involved in the pathogenesis, with the weight of evidence presently favouring deleterious effects of EVs in asthma. Numerous studies highlighted differences in exosomal contents between EVs of healthy and asthmatic individuals, which could be employed as potential diagnostic markers. In some circumstances, EVs were also found to be suppressive to disease, but more often promote inflammation and airway remodelling. In conclusion, EVs hold immense potential in understanding the pathophysiology of asthma, and as diagnostic and therapeutic markers. While more research is needed for definitive conclusions and their application in medical practice, the literature presented in this review should encourage further research and discovery within the field of EVs and asthma.  相似文献   
9.
There has been a significant increase in the past few decades in the number of children receiving noninvasive positive airway pressure (PAP) therapy at home. At present, PAP therapy can be successfully used in children of all ages, for a variety of indications. Data acquired from PAP devices is clinically useful, providing objective information regarding adherence, leak, and efficacy of PAP therapy. However, guidelines outlining a standardized approach to interpretation of PAP device data in pediatrics is currently lacking. Given the rapidly expanding use of PAP therapy in pediatric practice, we aim to provide an overview of the interpretation of data reports, otherwise called “data downloads,” from PAP devices and illustrate how they can be used to guide clinical care.  相似文献   
10.
Purpose

Internet use is common among people with suicidal feelings and a considerable amount of suicide help material is available online. Despite attempts to promote formal help sites (e.g. governmental and charity sector) in internet search results, users’ evaluation of these sites is lacking. This study, therefore, aimed to explore distressed users’ perceptions of formal online help and their experiences of using this in times of crisis.

Methods

In-depth interview study of 53 adults reporting suicide-related internet use.

Results

While highly valued in relation to general mental health problems, formal sites were not perceived to meet the different needs of those experiencing suicidal thoughts, and did not engage individuals in crisis. Sites were criticised for being impersonal, dispassionate, too focused on information-giving, and lacking solutions that were novel or sensitive to reasons why an individual may choose to seek help online. Most participants criticised the tendency for sites to signpost to offline services as their primary response. Participants desired immediacy and responsive online help incorporating ‘live chat’, self-help tools, opportunities to interact with others and lived-experience content. Positive accounts of seeking online help described sites incorporating these features.

Conclusions

Formal online help services should be reappraised to ensure they meet users’ needs for immediacy and responsive help to capitalise upon the opportunity available for suicide prevention.

  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