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   16928篇
  免费   759篇
  国内免费   68篇
耳鼻咽喉   84篇
儿科学   204篇
妇产科学   127篇
基础医学   2115篇
口腔科学   503篇
临床医学   1296篇
内科学   4167篇
皮肤病学   240篇
神经病学   1180篇
特种医学   606篇
外科学   3185篇
综合类   43篇
预防医学   397篇
眼科学   253篇
药学   1261篇
中国医学   22篇
肿瘤学   2072篇
  2023年   90篇
  2022年   155篇
  2021年   270篇
  2020年   150篇
  2019年   225篇
  2018年   247篇
  2017年   217篇
  2016年   244篇
  2015年   262篇
  2014年   334篇
  2013年   436篇
  2012年   673篇
  2011年   699篇
  2010年   437篇
  2009年   345篇
  2008年   663篇
  2007年   688篇
  2006年   746篇
  2005年   776篇
  2004年   797篇
  2003年   743篇
  2002年   793篇
  2001年   648篇
  2000年   669篇
  1999年   598篇
  1998年   260篇
  1997年   181篇
  1996年   162篇
  1995年   153篇
  1994年   142篇
  1993年   162篇
  1992年   544篇
  1991年   494篇
  1990年   453篇
  1989年   449篇
  1988年   357篇
  1987年   325篇
  1986年   317篇
  1985年   268篇
  1984年   181篇
  1983年   166篇
  1979年   142篇
  1978年   99篇
  1977年   81篇
  1975年   64篇
  1974年   87篇
  1973年   77篇
  1972年   80篇
  1971年   74篇
  1969年   65篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The colonic mucosa of 30 patients with ulcerative colitis was analyzed by an immunohistochemical technique. A quantitative evaluation for lymphocyte subsets show significantly increased numbers of CD3+, CD4+, CD8+, and CD28+ cells in ulcerative colitis cases of histological grades 3, 4 and 5 by Matts' classification comparing to normal control cases. CD4/CD8 ratio in each histological grade of ulcerative colitis was not significantly different from those in normal controls and disease controls (infectious colitis cases). However, CD28/CD3 ratio was increased significantly in ulcerative colitis cases of histological grades 3, 4 and 5 comparing to control cases. Most of the lymphocytes were positive for lymphocyte function-associated antigen-1 alpha (LFA-1 alpha). There were increased numbers of S100-beta + dendritic cells and CD68+ macrophages in the luminal area of the lamina propria. Moreover double stainings revealed that most of the S100-beta + dendritic cells and CD68+ macrophages were intercellular adhesion molecule-1 (ICAM-1, a ligand for LFA-1) positive. These findings suggested that the expression of ICAM1 on S100-beta + dendritic cells and CD68+ macrophages is important by the interaction with T cells and T cell antigen recognition.  相似文献   
62.
Among 43 men more than 60 years old who complained of urinary irritative symptoms 40 had subclinical lesions in the brain on magnetic resonance imaging (MRI). Of these 40 patients 23 (57.5%) had detrusor hyperreflexia. The mean age of the patients with and without detrusor hyperreflexia was 75.8 and 68.2 years, respectively, which is a statistically significant difference. Patients with detrusor hyperreflexia were more likely to have lesions of the basal ganglia than patients without detrusor hyperreflexia. This study suggests that detrusor hyperreflexia, subclinical MRI lesions in the brain and aging are intimately interrelated.  相似文献   
63.
The glomerular injuries in 129 cases of IgA nephropathy (IgA-N) were examined ultrastructurally with special reference to the glomerular basement membrane (GBM) deposits and capillary loop abnormalities, and the correlation between these findings and the clinicopathological data was analyzed. The following results were obtained. 1) The degree of daily excretion of urine protein (UP) and creatinine clearance (Ccr) revealed a significant correlation with the degree of mesangial hypercellularities and the frequency of segmental lesions. 2) All sites of GBM deposits, and discontinuity and/or splitting among the GBM abnormalities showed a significant relation to the severity of proliferation and segmental lesions. 3) The GBM deposits, discontinuity and splitting showed a significant relation to the degree of UP and Ccr. We speculate therefore that capillary loop deposits and/or capillary loop discontinuity and splitting could represent histological prognostic factors for an unfavorable outcome in IgA nephropathy.  相似文献   
64.
The effect of hypertension on asymmetrical septal hypertrophy was studied by echocardiography to differentiate idiopathic asymmetrical septal hypertrophy (ASH) from ASH with hypertension. One hundred eight patients with ASH proven by echocardiography were categorized in two groups; 53 patients with hypertension (greater than 160 systolic, greater than 95 diastolic) (hypertensive group: HT) and 55 patients with normal blood pressure (normotensive group: NT). Septal hypertrophy was classified as mid-portion (M-type), diffuse (D-type), and basal (B-type) hypertrophy by the long-axis view, and also diffuse (I-type), anterolateral (II-type), anteroseptal (III-type), and anterior septal (IV-type) by the short-axis view, respectively. Endomyocardial biopsy and left ventriculography were performed in 50 patients (18 hypertensives and 32 normotensives). In the hypertensive group, 45%, 30%, and 25% of cases had diffuse, basal and mid-portion hypertrophy, respectively. There was no case in the basal hypertrophy whose biopsy findings were compatible with hypertrophic cardiomyopathy. In the normotensive group, 78% and 22% of patients had midportion and diffuse hypertrophy, respectively, but none of them had the basal hypertrophy. Type IV was seen in only six patients in the normotensive group.  相似文献   
65.
Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by 123I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome.  相似文献   
66.
67.
We analyzed the determinant factors as to whether open heart surgery with non-blood transfusion may be indicated or not, according to the formula based on the quantitative theory (class II). Extracorporeal circulation with non-blood priming were indicated on 106 patients using Cell Saver apparatus in our department, they were divided into two groups; blood transfusion group (group I): 38 patients, and non-blood transfusion group (group II): 68 patients. These two groups were compared for study in terms of age, preoperative body weight (BW), the body surface area (BSA), preoperative Hct value (Hct), calculated Hct value (Hct(C)) at the start of extracorporeal circulation (ECC), the aortic cross-clamping time (AXT), the total extracorporeal circulation time (TECCT) and total bleeding amount. The followings are described in the ranking of importance. 1) The amount of blood loss in ICU: less than 400 ml. 2) Hct(C): more than 30%. 3) The amount of blood loss after ECC: less than 130 ml. 4) Hct: more than 40%. 5) BW: more than 55 kg. 6) The total bleeding amount: less than 600 ml. 7) TECCT: less than 90 min. 8) AXT: less than 50 min. In addition, prospective factors which should be considered preoperatively are determined in the following ranking. 1) Hct. 2) Hct(C). 3) BW. From these results, the amount of blood loss in ICU, Hct and Hct(C) were found to be reliable critical in any case as determinant factors for open heart surgery with non-blood transfusion.  相似文献   
68.
69.
70.
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