全文获取类型
收费全文 | 1075521篇 |
免费 | 73340篇 |
国内免费 | 1389篇 |
专业分类
耳鼻咽喉 | 15063篇 |
儿科学 | 34658篇 |
妇产科学 | 28764篇 |
基础医学 | 153579篇 |
口腔科学 | 29667篇 |
临床医学 | 95050篇 |
内科学 | 204087篇 |
皮肤病学 | 24460篇 |
神经病学 | 81569篇 |
特种医学 | 43061篇 |
外国民族医学 | 201篇 |
外科学 | 163672篇 |
综合类 | 21739篇 |
现状与发展 | 1篇 |
一般理论 | 263篇 |
预防医学 | 74592篇 |
眼科学 | 24586篇 |
药学 | 86226篇 |
7篇 | |
中国医学 | 2810篇 |
肿瘤学 | 66195篇 |
出版年
2019年 | 7808篇 |
2018年 | 11372篇 |
2017年 | 8960篇 |
2016年 | 10170篇 |
2015年 | 11355篇 |
2014年 | 15379篇 |
2013年 | 22365篇 |
2012年 | 30752篇 |
2011年 | 32513篇 |
2010年 | 19058篇 |
2009年 | 17918篇 |
2008年 | 30160篇 |
2007年 | 32323篇 |
2006年 | 32932篇 |
2005年 | 31256篇 |
2004年 | 29900篇 |
2003年 | 28697篇 |
2002年 | 27643篇 |
2001年 | 60092篇 |
2000年 | 61522篇 |
1999年 | 50978篇 |
1998年 | 12452篇 |
1997年 | 11010篇 |
1996年 | 11021篇 |
1995年 | 10331篇 |
1994年 | 9341篇 |
1993年 | 8863篇 |
1992年 | 37801篇 |
1991年 | 36284篇 |
1990年 | 35753篇 |
1989年 | 34294篇 |
1988年 | 30871篇 |
1987年 | 29988篇 |
1986年 | 28216篇 |
1985年 | 26448篇 |
1984年 | 19185篇 |
1983年 | 16114篇 |
1982年 | 8822篇 |
1979年 | 17030篇 |
1978年 | 11406篇 |
1977年 | 10229篇 |
1976年 | 8837篇 |
1975年 | 10068篇 |
1974年 | 11651篇 |
1973年 | 11273篇 |
1972年 | 10754篇 |
1971年 | 10092篇 |
1970年 | 9252篇 |
1969年 | 8938篇 |
1968年 | 7917篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
Martin R. Späth Malte P. Bartram Nicolàs Palacio-Escat K. Johanna R. Hoyer Cedric Debes Fatih Demir Christina B. Schroeter Amrei M. Mandel Franziska Grundmann Giuliano Ciarimboli Andreas Beyer Jayachandran N. Kizhakkedathu Susanne Brodesser Heike Göbel Jan U. Becker Thomas Benzing Bernhard Schermer Martin Höhne Markus M. Rinschen 《Kidney international》2019,95(2):333-349
25.
Senem Maral Muradiye Acar Ozlem Sahin Balcik Eyyup Uctepe Omer Faruk Hatipoglu Derya Akdeniz Hatice Uludag Altun Ali Kosar Mehmet Gunduz Esra Gunduz 《Medicine》2015,94(16)
Chronic myeloproliferative disorders such as polycythemia vera (PV), essential thrombocytosis (ET), and idiopathic myelofibrosis arise from clonal proliferation of neoplastic stem cells in the bone marrow. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that have potential to degrade all types of extracellular matrix (ECM) and also play a role in remodeling of the ECM. It is known that MMPs play a role in bone marrow remodeling.The primary goal of our study is to explore the relationship between chronic myeloproliferative diseases and some of MMP gene polymorphisms. The demonstration of a relationship will help to understand whether these polymorphisms may be a potential early diagnosis marker of the diseases.Patients were selected from outpatient clinics of Turgut Ozal University Hospital, Ankara, Turkey, between December 2010 and May 2011. Twenty-eight patients that previously diagnosed and followed-up with PV, 17 with secondary polycythemia (SP), and 12 with ET were enrolled in the study, along with a control group of 22 healthy people.DNA was isolated from peripheral blood. Using polymerase chain reaction–restriction fragment length polymorphism method, MMP2 and MMP9 gene polymorphisms were analyzed with agarose gel electrophoresis. There was a statistically significant difference between the study groups and the control group in terms of Gln279Arg polymorphisms rates of MMP9. The highest MMP9 Gln279Arg polymorphism rate was observed in the ET group. But nobody from the control group had polymorphic MMP9. There was no statistically significant difference between the groups in terms of MMP2-735 C > T polymorphism rates.In conclusion, MMP9 gene Gln279Arg polymorphism was associated with ET, SP, and PV diseases. Hence, we believe that these gene polymorphisms may play a role in the mechanism of bone marrow fibrosis and may be a factor that increases the risk of thrombosis. Illumination of the molecular basis of the relationship between MMP-thrombosis and MMP-fibrosis provides a better understanding of the pathophysiology of PV and ET diseases and will allow new approaches to diagnosis and treatment. 相似文献
26.
Pradeep Balasubramanian M.D. C. R. Srinivas M.D. Pavai Arunachalam M.S. M.Ch. K. S. Thirumurthy M.S. M.Ch. P. R. Rajkumar M.S. M.Ch. H. Manuvidhya M.B.B.S. 《Pediatric dermatology》2015,32(3):e78-e81
We report on a child with several café au lait spots in association with a lumbar lipomeningomyelocele as an apparently new association. Cutaneous markers, the identification of which plays a crucial role in the early diagnosis and management of spinal malformations, can accompany occult spinal dysraphism. Herein we report a case of lumbar lipomeningomyelocele associated with an overlying café au lait spot that served as a marker of occult spinal dysraphism. The patient also had segmental café au lait spots on the face, making the association unique. 相似文献
27.
28.
29.
30.
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