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   1878篇
  免费   157篇
  国内免费   6篇
耳鼻咽喉   24篇
儿科学   75篇
妇产科学   17篇
基础医学   245篇
口腔科学   53篇
临床医学   171篇
内科学   317篇
皮肤病学   20篇
神经病学   260篇
特种医学   59篇
外科学   321篇
综合类   30篇
预防医学   221篇
眼科学   45篇
药学   119篇
中国医学   3篇
肿瘤学   61篇
  2021年   27篇
  2018年   35篇
  2017年   24篇
  2016年   30篇
  2015年   32篇
  2014年   45篇
  2013年   58篇
  2012年   72篇
  2011年   78篇
  2010年   44篇
  2009年   32篇
  2008年   75篇
  2007年   75篇
  2006年   64篇
  2005年   57篇
  2004年   63篇
  2003年   56篇
  2002年   44篇
  2001年   50篇
  2000年   64篇
  1999年   42篇
  1997年   19篇
  1995年   25篇
  1994年   21篇
  1993年   18篇
  1992年   35篇
  1991年   32篇
  1990年   31篇
  1989年   39篇
  1988年   28篇
  1987年   30篇
  1986年   38篇
  1985年   43篇
  1984年   29篇
  1983年   32篇
  1982年   20篇
  1980年   21篇
  1979年   29篇
  1978年   33篇
  1977年   20篇
  1976年   20篇
  1975年   25篇
  1974年   20篇
  1973年   28篇
  1971年   18篇
  1969年   25篇
  1968年   18篇
  1967年   20篇
  1921年   23篇
  1920年   21篇
排序方式: 共有2041条查询结果,搜索用时 15 毫秒
31.
Phonocardiographic diagnosis of aortic ball variance   总被引:3,自引:0,他引:3  
Fatty infiltration causing changes in the silastic poppet of the Model 1000 series Starr-Edwards aortic valve prostheses (ball variance) has been detected with increasing frequency and can result in sudden death. Phonocardiograms were recorded on 12 patients with ball variance confirmed by operation and of 31 controls. Ten of the 12 patients with ball variance were distinguished from the controls by an aortic opening sound (AO) less than half as intense as the aortic closure sound (AC) at the second right intercostal space (AO/AC ratio less than 0.5). Both AO and AC were decreased in two patients with ball variance, with the loss of the characteristic high frequency and amplitude of these sounds. The only patient having a diminished AO/AC ratio (0.42) without ball variance at reoperation had a clot extending over the aortic valve struts. The phonocardiographic findings have been the most reliable objective evidence of ball variance in patients with Starr-Edwards aortic prosthesis of the Model 1000 series.  相似文献   
32.
Simon  SI; Rochon  YP; Lynam  EB; Smith  CW; Anderson  DC; Sklar  LA 《Blood》1993,82(4):1097-1106
We have recently found that antibodies to L-selectin, the homing receptor on neutrophils, are as effective as those to beta 2-integrin at blocking formyl peptide-stimulated aggregation. Therefore, we investigated the requirements for expression of L-selectin and beta 2- integrin on adjacent cells during aggregation. Fluorescence flow cytometry allowed characterization of aggregates on the basis of size and color, as well as antibody binding to these two adhesive molecules. Formyl peptide-stimulated aggregate formation was measured for individual populations fluorescently labeled red (LDS-751) or green (CD44-FITC), and interpopulation red-green cell conjugates. Blocking either the beta 2-integrin or L-selectin adhesive epitope with monoclonal antibody on individual cell populations resulted in an approximately 50% reduction in two-color aggregation as compared with that in unblocked samples. Shedding the L-selectin on a cell population by preincubation with complexes of lipopolysaccharide and its plasma membrane binding protein also decreased aggregation to a control population by approximately 50%. We examined the aggregation of neutrophils from patients genetically deficient in beta 2-integrin and clinically leukocyte adhesion deficient (LAD). LAD adhesion to normal neutrophils was dependent on the expression of L-selectin on LAD cells and beta 2-integrin on normal cells. Thus, the minimum requirement for adhesion between two mixed populations of neutrophils was that one population expressed the beta 2-integrin and the other expressed the L- selectin adhesive epitope.  相似文献   
33.
Relapsing eosinophilic perimyositis is a rare entity. Only 11 cases have been reported in the literature. We describe a patient with relapsing myopathy, peripheral blood eosinophilia and cutaneous manifestations, who had histopathological features of eosinophilic perimysial inflammation. His disease responded to moderate doses of glucocorticosteroids, and pursued an apparently benign course. Serum levels of eosinophilic cationic protein correlate with disease activity, and may be helpful in monitoring treatment. The features of this case are compared with those of other hypereosinophilic syndromes. It appears to be part of the spectrum of eosinophilic myositis.  相似文献   
34.
We describe an immunocompetent adolescent who presented with exceptionally severe Bordetella holmesii infection, including previously undescribed manifestations. Sequelae included a severe restrictive lung defect due to pulmonary fibrosis.  相似文献   
35.
OBJECTIVE: To assess the clinimetric properties of a new health-related quality of life (HRQOL) instrument, the World Health Organization Disability Assessment Schedule II (WHODAS II), in patients with early inflammatory arthritis. METHODS: Internal consistency as well as criterion, construct, and discriminative validity of the WHODAS II were assessed in 172 patients with early inflammatory arthritis who completed the WHODAS II, the Medical Outcomes Study Short Form 36 (SF-36), and other measures of disease severity, functioning, pain, depression, and resource use. Test-retest reliability of the WHODAS II was assessed by having a subset of 20 patients complete the WHODAS II a second time, 1 week after the first assessment. RESULTS: The WHODAS II had high internal consistency (Cronbach's alpha = 0.96 for patients working or in school and 0.93 for patients not working or in school). Test-retest intraclass correlation coefficients of the WHODAS II total score and subscales ranged from 0.82-0.96. The WHODAS II total score was strongly correlated with the SF-36 physical component score (Kendall's tau-b 0.51, P < 0.001) and moderately correlated with the SF-36 mental component score (tau-b 0.43, P < 0.001). WHODAS II correlations with disease outcomes ranged from Kendall's tau-b 0.15-0.55. The WHODAS II significantly differentiated between every aspect of disease severity assessed with the exception of measures of health resource use. CONCLUSION: The WHODAS II is a valid and reliable measure of HRQOL in cross-sectional studies of patients with early inflammatory arthritis. Research is still required to investigate potential item redundancy and determine its usefulness in longitudinal studies.  相似文献   
36.
OBJECTIVES: We tested the hypothesis that defective interactions between adhesion junctions and the cytoskeleton caused by the plakoglobin mutation in Naxos disease lead to remodeling of gap junctions and altered expression of the major gap junction protein, connexin43. BACKGROUND: Naxos disease, a recessive form of arrhythmogenic right ventricular cardiomyopathy, is associated with a high incidence of arrhythmias and sudden cardiac death. Naxos disease is caused by a mutation in plakoglobin, a protein that links cell-cell adhesion molecules to the cytoskeleton. METHODS: Myocardial expression of connexin43 and other intercellular junction proteins was characterized in 4 patients with Naxos disease. Immunohistochemistry was performed in all 4 patients, and immunoblotting and electron microscopy were performed in 1 patient who died in childhood before overt arrhythmogenic right ventricular cardiomyopathy had developed. RESULTS: Connexin43 expression at intercellular junctions was reduced significantly in both right and left ventricles in all patients with Naxos disease. Electron microscopy revealed smaller and fewer gap junctions interconnecting ventricular myocytes. Mutant plakoglobin was expressed but failed to localize normally at intercellular junctions. Localization of N-cadherin, alpha- and beta-catenins, plakophilin-2, desmoplakin-1, and desmocollin-2 at intercalated disks appeared normal. CONCLUSIONS: Remodeling of gap junctions occurs early in Naxos disease, presumably because of abnormal linkage between mechanical junctions and the cytoskeleton. Gap junction remodeling may produce a coupling defect which, combined with the subsequent development of pathologic changes in myocardium, could contribute to a highly arrhythmogenic substrate and enhance the risk of sudden death in Naxos disease.  相似文献   
37.
38.
Children of mothers infected with human immunodeficiency virus type 1 (HIV-1) were immunized at birth and at 1, 3, and 5 months with 1 of 3 doses of recombinant gp120 vaccines prepared from SF-2 or MN strains of HIV-1. A total of 126 children were not infected; 21 received adjuvant only. Vaccine recipients developed lymphoproliferative responses on >/=2 occasions, responding more often to homologous HIV-1 antigens than did adjuvant recipients (56% vs. 14%; P<.001). Responses were appreciated after 2 immunizations and were maintained for >84 weeks after the last immunization. An accelerated immunization schedule (birth, 2 weeks, 2 months, and 5 months) with the lowest dose of the SF-2 vaccine produced responses in all 11 vaccinees by 4 weeks. Responses to heterologous envelope antigens were also detected. Immune responses to vaccination are achievable at an age when some infection (perinatal or breast milk exposure related) may be prevented.  相似文献   
39.
40.
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