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   5757篇
  免费   471篇
  国内免费   8篇
耳鼻咽喉   54篇
儿科学   215篇
妇产科学   206篇
基础医学   786篇
口腔科学   61篇
临床医学   561篇
内科学   1153篇
皮肤病学   68篇
神经病学   695篇
特种医学   98篇
外科学   522篇
综合类   65篇
一般理论   9篇
预防医学   818篇
眼科学   148篇
药学   345篇
中国医学   6篇
肿瘤学   426篇
  2024年   21篇
  2023年   172篇
  2022年   249篇
  2021年   503篇
  2020年   274篇
  2019年   335篇
  2018年   312篇
  2017年   217篇
  2016年   229篇
  2015年   243篇
  2014年   284篇
  2013年   335篇
  2012年   476篇
  2011年   390篇
  2010年   199篇
  2009年   153篇
  2008年   252篇
  2007年   291篇
  2006年   228篇
  2005年   201篇
  2004年   170篇
  2003年   136篇
  2002年   115篇
  2001年   29篇
  2000年   20篇
  1999年   31篇
  1998年   25篇
  1997年   20篇
  1996年   19篇
  1995年   17篇
  1994年   9篇
  1993年   7篇
  1992年   14篇
  1991年   23篇
  1990年   20篇
  1989年   15篇
  1988年   18篇
  1987年   20篇
  1986年   11篇
  1985年   19篇
  1984年   8篇
  1983年   8篇
  1982年   7篇
  1980年   8篇
  1977年   8篇
  1976年   10篇
  1975年   7篇
  1974年   7篇
  1972年   7篇
  1968年   7篇
排序方式: 共有6236条查询结果,搜索用时 10 毫秒
71.
72.
Journal of Thrombosis and Thrombolysis - In patients who undergo thrombectomy for acute ischemic stroke, the relationship between pre-admission antithrombotic (anticoagulation or antiplatelet) use...  相似文献   
73.
Clark  Hannah  Rana  Rezwanul  Gow  Jeff  Pearson  Melissa  van der Touw  Tom  Smart  Neil 《Heart failure reviews》2022,27(2):559-572
Heart Failure Reviews - Heart failure with preserved ejection fraction (HFpEF) is problematic to treat, with guidelines for HFpEF management concentrated on treating prevalent comorbidities. The...  相似文献   
74.
Two differentially expressed genes encode isoenzymes of sucrose synthase in Zea mays. A clone of the shrunken 1 (Sh1) locus, the structural gene for the major endosperm form of sucrose synthase, was used to isolate a genomic clone of constitutive sucrose synthase (Css), the structural gene for the isoenzyme expressed in embryo and other tissues. The Css clone was positively identified by RNA blot analysis of RNA from wild type and a sh1 deletion stock and by analysis of the in vitro translation product of hybrid-selected mRNA. Southern blot analysis of DNA from monosomic plants derived from an r-x1 stock, coupled with restriction fragment length polymorphism mapping, placed the Css gene 32 map units from Sh1 on chromosome 9. In seedling tissues, Css mRNA is present at higher levels than Sh1 mRNA. Expression of both Sh1 and Css in root tissue is enhanced by anaerobic conditions, although Css is induced to a lesser extent than is Sh1. Thus, Css appears to be expressed constitutively, whereas Sh1 is expressed at high levels only in response to specific developmental and environmental stimuli.  相似文献   
75.
BackgroundPostural orthostatic tachycardia syndrome (POTS) is a complex, multifaceted disorder that impairs functional status and quality of life. Current pharmacological treatments are limited.ObjectivesThis study investigated the effect of ivabradine (selective blocker of the Ifunny channel in the sinoatrial node) on heart rate, quality of life (QOL), and plasma norepinephrine (NE) levels in patients with hyperadrenergic POTS defined by plasma NE >600 pg/ml and abnormal tilt table test.MethodsIn total, 22 patients with hyperadrenergic POTS as the predominant subtype completed a randomized, double-blinded, placebo-controlled, crossover trial with ivabradine. Patients were randomized to start either ivabradine or placebo for 1 month, and then were crossed over to the other treatment for 1 month. Heart rate, QOL, and plasma NE levels were measured at baseline and at the end of each treatment month.ResultsThe average age was 33.9 ± 11.7 years, 95.5% were women (n = 21), and 86.4% were White (n = 23). There was a significant reduction in heart rate between placebo and ivabradine (p < 0.001). Patients reported significant improvements in QOL with RAND 36-Item Health Survey 1.0 for physical functioning (p = 0.008) and social functioning (p = 0.021). There was a strong trend in reduction of NE levels upon standing with ivabradine (p = 0.056). Patients did not experience any significant side-effects, such as bradycardia or hypotension, with ivabradine.ConclusionIvabradine is safe and effective in significantly improving heart rate and QOL in patients with hyperadrenergic POTS as the predominant subtype.  相似文献   
76.
OBJECTIVE: The stress protein and endoplasmic reticulum chaperone, immunoglobulin binding protein (BiP), is an autoantigen in rheumatoid arthritis (RA). Stress proteins, however, may have extracellular functions, mediated via cell surface receptors, that may include immunomodulatory functions. We sought to determine whether cell-free BiP is present in the synovial fluid (SF) of patients with RA and to further investigate the possible extracellular antiinflammatory and immunomodulatory properties of BiP in peripheral blood mononuclear cells (PBMCs) in vitro. METHODS: The presence of BiP in SF was established by Western blotting. PBMCs were stimulated with exogenous recombinant human BiP, and cytokine production and cell proliferation were measured in the presence and absence of cell signaling inhibitors or neutralizing anti-interleukin-10 (anti-IL-10) monoclonal antibody. Cytokine levels were quantified by enzyme-linked immunosorbent assay, cell proliferation by tritiated thymidine uptake, and cell surface molecule expression by flow cytometry. RESULTS: PBMCs responded to BiP with secretion of an antiinflammatory profile of cytokines. Although BiP stimulated the early production of tumor necrosis factor alpha (TNF alpha), the major cytokine induced was IL-10. Soluble TNF receptor II and IL-1 receptor antagonist secretion was also increased. Addition of SB203580, the MAPK p38 pathway inhibitor, partially inhibited the production of IL-10 and TNF alpha, whereas they were unaffected by the MAPK ERK-1/2 inhibitor PD98059. BiP also inhibited the recall antigen response by PBMCs to tuberculin purified protein derivative. Further investigation showed that incubation of monocytes in the presence of either BiP or IL-10 down-regulated CD86 and HLA-DR expression. The effect observed with IL-10 was transient compared with the long-lasting reduction induced by BiP. CONCLUSION: Extracellular BiP may stimulate immunomodulatory and antiinflammatory pathways, which are only partly due to the production of IL-10. These properties may be of relevance for the treatment of diseases such as RA.  相似文献   
77.
Obesity has been proposed to inflict a variety of stresses on adipose tissue, including inflammatory, metabolic, oxidative and endoplasmic reticulum stress. Through the activation of 'stress-sensing pathways', metabolic and endocrine alterations are produced, which probably contribute to the co-morbidities associated with obesity. Here, we review the evidence supporting the development of various obesity-related stresses and the activation of several stress-sensing pathways, specifically in adipocytes and/or adipose tissue, which manifest metabolic and endocrine dysfunction frequently in obesity. As the central role of adipose tissue in regulating whole-body metabolism is elucidated, understanding adipose tissue stress-sensing pathways might provide potential new therapeutic targets to attenuate obesity-related morbidity.  相似文献   
78.
79.
80.
The primary progressive aphasias (PPA) are a heterogeneous group of language-led neurodegenerative diseases resulting from large-scale brain network degeneration. White matter (WM) pathways bind networks together, and might therefore hold information about PPA pathogenesis. Here we used diffusion tensor imaging and tract-based spatial statistics to compare WM tract changes between PPA syndromes and with respect to Alzheimer's disease and healthy controls in 33 patients with PPA (13 nonfluent/agrammatic PPA); 10 logopenic variant PPA; and 10 semantic variant PPA. Nonfluent/agrammatic PPA was associated with predominantly left-sided and anterior tract alterations including uncinate fasciculus (UF) and subcortical projections; semantic variant PPA with bilateral alterations in inferior longitudinal fasciculus and UF; and logopenic variant PPA with bilateral but predominantly left-sided alterations in inferior longitudinal fasciculus, UF, superior longitudinal fasciculus, and subcortical projections. Tract alterations were more extensive than gray matter alterations, and the extent of alteration across tracts and PPA syndromes varied between diffusivity metrics. These WM signatures of PPA syndromes illustrate the selective vulnerability of brain language networks in these diseases and might have some pathologic specificity.  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