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   1711300篇
  免费   141321篇
  国内免费   3086篇
耳鼻咽喉   23062篇
儿科学   55809篇
妇产科学   48294篇
基础医学   241866篇
口腔科学   49600篇
临床医学   151947篇
内科学   337277篇
皮肤病学   35549篇
神经病学   140017篇
特种医学   69005篇
外国民族医学   474篇
外科学   261595篇
综合类   41351篇
现状与发展   4篇
一般理论   713篇
预防医学   133706篇
眼科学   38890篇
药学   129201篇
  5篇
中国医学   3127篇
肿瘤学   94215篇
  2018年   17206篇
  2016年   14802篇
  2015年   17230篇
  2014年   23891篇
  2013年   36419篇
  2012年   49808篇
  2011年   52472篇
  2010年   30729篇
  2009年   29367篇
  2008年   49977篇
  2007年   52739篇
  2006年   53078篇
  2005年   51893篇
  2004年   50938篇
  2003年   48706篇
  2002年   47646篇
  2001年   76700篇
  2000年   79163篇
  1999年   67488篇
  1998年   19064篇
  1997年   17349篇
  1996年   17320篇
  1995年   16995篇
  1994年   15889篇
  1993年   15026篇
  1992年   56055篇
  1991年   54443篇
  1990年   53144篇
  1989年   51400篇
  1988年   47785篇
  1987年   47122篇
  1986年   44864篇
  1985年   43522篇
  1984年   32769篇
  1983年   28244篇
  1982年   17058篇
  1981年   15365篇
  1980年   14343篇
  1979年   30932篇
  1978年   21584篇
  1977年   18257篇
  1976年   17099篇
  1975年   17942篇
  1974年   21858篇
  1973年   21037篇
  1972年   19088篇
  1971年   18009篇
  1970年   16513篇
  1969年   15435篇
  1968年   14107篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
51.
52.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
53.
54.
55.

Background

Resistin is an immunometabolic mediator that is elevated in several inflammatory disorders. A ligand for Toll-like receptor 4, resistin modulates the recruitment and activation of myeloid cells, notably neutrophils. Neutrophils are major drivers of cystic fibrosis (CF) lung disease, in part due to the release of human neutrophil elastase- and myeloperoxidase-rich primary granules, leading to tissue damage. Here we assessed the relationship of resistin to CF lung disease.

Methods

Resistin levels were measured in plasma and sputum from three retrospective CF cohorts spanning a wide range of disease. We also assessed the ability of neutrophils to secrete resistin upon activation in vitro. Finally, we constructed a multivariate model assessing the relationship between resistin levels and lung function.

Results

Plasma resistin levels were only marginally higher in CF than in healthy control subjects. By contrast, sputum resistin levels were very high in CF, reaching 50–100 fold higher levels than in plasma. Among CF patients, higher plasma resistin levels were associated with allergic bronchopulmonary aspergillosis, and higher sputum resistin levels were associated with CF-related diabetes. Mechanistically, in vitro release of neutrophil primary granules was concomitant with resistin secretion. Overall, sputum resistin levels were negatively correlated with CF lung function, independently of other variables (age, sex, and genotype).

Conclusions

Our data establish relationships between resistin levels in the plasma and sputum of CF patients that correlate with disease status, and identify resistin as a novel mechanistic link between neutrophilic inflammation and lung disease in CF.  相似文献   
56.
57.
58.
59.
60.
Context: Persons with spinal cord injury (SCI) experience significant challenges when they access primary care and community services.

Design: A provincial summit was held to direct research, education, and innovation for primary and community care for SCI.

Setting: Toronto, Ontario, Canada.

Participants: Key stakeholders (N?=?95) including persons with SCI and caregivers, clinicians from primary care, rehabilitation, and specialized care, researchers, advocacy groups, and policy makers.

Methods: A one-day facilitated meeting that included guest speakers, panel discussions and small group discussions was held to generate potential solutions to current issues related to SCI care and to foster collaborative relationships to advance care for SCI. Perspectives on SCI management were shared by primary care, neurosurgery, rehabilitation, and members of the SCI community

Outcome Measures: Discussions were focused on five domains: knowledge translation and dissemination, application of best practices, communication, research, and patient service accessibility.

Results: Summit participants identified issues and prioritized solutions to improve primary and community care including the creation of a network of key stakeholders to enable knowledge creation and dissemination; an online repository of SCI resources, integrated health records, and a clinical network for SCI care; development and implementation of strategies to improve care transitions across sectors; implementation of effective care models and improved access to services; and utilization of empowerment frameworks to support self-management.

Conclusions: This summit identified priorities for further collaborative efforts to advance SCI primary and community care and will inform the development of a provincial SCI strategy aimed at improving the system of care for SCI.  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