全文获取类型
收费全文 | 67138篇 |
免费 | 6201篇 |
国内免费 | 187篇 |
专业分类
耳鼻咽喉 | 942篇 |
儿科学 | 1831篇 |
妇产科学 | 1550篇 |
基础医学 | 8779篇 |
口腔科学 | 1563篇 |
临床医学 | 6685篇 |
内科学 | 14603篇 |
皮肤病学 | 769篇 |
神经病学 | 5591篇 |
特种医学 | 2215篇 |
外国民族医学 | 9篇 |
外科学 | 10106篇 |
综合类 | 1450篇 |
一般理论 | 52篇 |
预防医学 | 6525篇 |
眼科学 | 1626篇 |
药学 | 4614篇 |
中国医学 | 115篇 |
肿瘤学 | 4501篇 |
出版年
2021年 | 1019篇 |
2020年 | 569篇 |
2019年 | 1023篇 |
2018年 | 1178篇 |
2017年 | 988篇 |
2016年 | 955篇 |
2015年 | 1043篇 |
2014年 | 1710篇 |
2013年 | 2520篇 |
2012年 | 3705篇 |
2011年 | 3779篇 |
2010年 | 2058篇 |
2009年 | 1903篇 |
2008年 | 3431篇 |
2007年 | 3713篇 |
2006年 | 3808篇 |
2005年 | 3696篇 |
2004年 | 3426篇 |
2003年 | 3426篇 |
2002年 | 3294篇 |
2001年 | 1516篇 |
2000年 | 1565篇 |
1999年 | 1429篇 |
1998年 | 846篇 |
1997年 | 709篇 |
1996年 | 710篇 |
1995年 | 605篇 |
1994年 | 575篇 |
1993年 | 525篇 |
1992年 | 1215篇 |
1991年 | 1180篇 |
1990年 | 1073篇 |
1989年 | 1000篇 |
1988年 | 892篇 |
1987年 | 886篇 |
1986年 | 893篇 |
1985年 | 864篇 |
1984年 | 771篇 |
1983年 | 615篇 |
1982年 | 541篇 |
1981年 | 483篇 |
1980年 | 409篇 |
1979年 | 674篇 |
1978年 | 471篇 |
1977年 | 394篇 |
1976年 | 382篇 |
1975年 | 416篇 |
1974年 | 473篇 |
1973年 | 408篇 |
1972年 | 376篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable. 相似文献
2.
Danielle E Whittier Elizabeth J Samelson Marian T Hannan Lauren A Burt David A Hanley Emmanuel Biver Pawel Szulc Elisabeth Sornay-Rendu Blandine Merle Roland Chapurlat Eric Lespessailles Andy Kin On Wong David Goltzman Sundeep Khosla Serge Ferrari Mary L Bouxsein Douglas P Kiel Steven K Boyd 《Journal of bone and mineral research》2022,37(3):428-439
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
3.
4.
5.
6.
Sarah E. Sheppard Laura Elizabeth Anderson Cathryn Sibbald Colleen Cotton Elizabeth Bhoj Marissa J. Perman Leslie Castelo‐Soccio 《Pediatric dermatology》2019,36(6):1007-1009
Epidermolysis bullosa simplex (EBS) is a skin fragility disorder resulting from mutations of structural proteins in the epidermis. We provide a brief report of long‐term survival and reproduction in a mother with EBS due to keratin 5 (KRT5) c.1429G > A (p.E477K) mutation, which causes a particularly severe form of the disease. 相似文献
7.
8.
Emile Gogineni Zaker Rana Michael Wotman Jessie Karten Adam Riegel Mihaela Marrero Luis Maduro Dev Kamdar Douglas Frank Doru Paul Nagashree Seetharamu Maged Ghaly 《Journal of Geriatric Oncology》2021,12(1):122-127
PurposeManagement of head and neck cancers (HNC) in older adults is a common but challenging clinical scenario. We assess the impact of Stereotactic Body Radiation Therapy (SBRT) on survival utilizing the Geriatric-8 (G8) questionnaire.Materials and methods171 HNC patients, deemed medically unfit for definitive treatment, were treated with SBRT ± systemic therapy. G8 questionnaires were collected at baseline, at 4–6 weeks, and at 2–3 months post-treatment. Patients were stratified according to their baseline G8 score: <11 as ‘vulnerable’, 11–14 as ‘intermediate’, and >14 as ‘fit’. Overall survival (OS) was assessed through univariate Kaplan Meier analysis. Repeated measures ANOVA was used to determine if baseline characteristics affected G8 score changes.ResultsMedian follow-up was seventeen months. 60% of patients presented with recurrent HNC, 30% with untreated HNC primaries, and 10% with metastatic non-HNC primaries. Median age was 75 years. Median Charlson Comorbidity Index score was 2. 51% of patients were ‘vulnerable’, 37% were ‘intermediate’, and 12% were ‘fit' at baseline, with median survival of 13.2, 24.3, and 41.0 months, respectively (p = .004). Patients who saw a decrease in their follow-up G8 score (n = 69) had significantly lower survival than patients who had stable or increased follow-up G8 scores (n = 102), with median survival of 8.6 vs 36.0 months (p < .001).ConclusionThe G8 questionnaire may be a useful tool in upfront treatment decision-making to predict prognosis and prevent older patients from receiving inappropriate anti-cancer treatment. Decline in follow-up G8 scores may also predict worse survival and aid in goals of care following treatment. 相似文献
9.
Stress Testing Versus CT Angiography in Patients With Diabetes and Suspected Coronary Artery Disease
Abhinav Sharma Adrian Coles Nishant K. Sekaran Neha J. Pagidipati Michael T. Lu Daniel B. Mark Kerry L. Lee Hussein R. Al-Khalidi Udo Hoffmann Pamela S. Douglas 《Journal of the American College of Cardiology》2019,73(8):893-902