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   630351篇
  免费   47595篇
  国内免费   25565篇
耳鼻咽喉   7041篇
儿科学   14384篇
妇产科学   8724篇
基础医学   52668篇
口腔科学   13396篇
临床医学   67726篇
内科学   72751篇
皮肤病学   9624篇
神经病学   20745篇
特种医学   27366篇
外国民族医学   112篇
外科学   66555篇
综合类   121721篇
现状与发展   109篇
一般理论   6篇
预防医学   66892篇
眼科学   9948篇
药学   67671篇
  701篇
中国医学   44650篇
肿瘤学   30721篇
  2024年   2255篇
  2023年   5826篇
  2022年   14367篇
  2021年   18201篇
  2020年   16028篇
  2019年   8830篇
  2018年   12772篇
  2017年   16455篇
  2016年   12691篇
  2015年   22330篇
  2014年   26611篇
  2013年   31294篇
  2012年   49699篇
  2011年   47321篇
  2010年   40302篇
  2009年   37131篇
  2008年   36370篇
  2007年   35880篇
  2006年   32155篇
  2005年   34258篇
  2004年   29160篇
  2003年   22041篇
  2002年   14144篇
  2001年   13896篇
  2000年   8865篇
  1999年   8832篇
  1992年   7179篇
  1991年   7377篇
  1990年   7565篇
  1989年   7120篇
  1988年   6601篇
  1987年   6393篇
  1986年   6113篇
  1985年   5359篇
  1984年   3665篇
  1983年   2986篇
  1979年   3856篇
  1978年   2373篇
  1977年   1795篇
  1976年   1573篇
  1975年   2479篇
  1974年   3116篇
  1973年   2751篇
  1972年   2767篇
  1971年   2745篇
  1970年   2559篇
  1969年   2472篇
  1968年   2238篇
  1967年   2163篇
  1966年   1904篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The value of ventilation scintigraphy after single lung transplantation.   总被引:1,自引:0,他引:1  
BACKGROUND: A decrease in forced expiratory volume in 1 second (FEV(1)) as a diagnostic criterion for bronchiolitis obliterans syndrome (BOS) after single lung transplantation may be influenced significantly by the presence of the native lung. To quantify and to discriminate between the relative contribution of graft and native lung to the FEV(1), we retrospectively investigated the diagnostic value of combined FEV(1) measurements and ventilation scintigraphy in pulmonary dysfunction after single lung transplantation in 11 recipients with pulmonary vascular disease, 3 with obstructive lung disease, and 3 with restrictive lung disease. METHODS: We assessed function of the native lung and the graft, and subsequently calculated an adjusted grading of BOS by correcting routine FEV(1) measurements using linear interpolation of bi-annual lung ventilation scans. RESULTS: The contribution of the native lung to the total FEV(1) was slight (median, 9%) in recipients with obstructive disease compared with recipients with vascular (38%) or restrictive lung diseases (27%). Adjusted BOS grading was not useful in patients with obstructive disease. In the other patient groups, the onset of adjusted BOS Grade 1 and standard BOS Grade 1 was at a median of 220 days (range, 127-1146 days) and 836 days (184-3065 days), respectively. CONCLUSION: Ventilation scintigraphy is a useful adjunct in the (early) diagnosis of BOS in recipients of single lung transplants who have vascular and restrictive lung diseases.  相似文献   
992.
2型糖尿病患者外周血白细胞iNOSmRNA表达的变化及意义   总被引:1,自引:0,他引:1  
目的研究2型糖尿病DM患者外周血白细胞中iNOSmRNA表达的变化及其与糖尿病肾病DN发生、发展的关系。方法101例2型DM患者,根据尿微量白蛋白排泄率和血肌酐水平分为单纯DM组和不同的DN组,用原位杂交法检测外周血白细胞iNOSmRNA表达的阳性细胞的百分率,并与21例健康体检者进行比较。结果早期DN组白细胞iNOSmRNA表达的百分率明显高于对照组、DM组及晚期DN组(P<0.001)。结论外周血白细胞iNOSmRNA表达的变化参与了DN的发生、发展。  相似文献   
993.
目的:探讨经皮肺活检及支气管肺泡灌洗(BAL)对周围性肺疾病诊断的价值。方法:对以结节或块状阴影为主的52例病人行经皮肺活检;对以弥漫性周围性肺疾病为主的33例病人行BAL检查;对采用两种不同方法的检查结果进行阳性率分析。结果:52例经皮肺活检对肺周围性病变诊断敏感性为88%,特异性100%。33例行BAL检查对结核及恶性弥漫性肺周围性病变诊断敏感性为75%~80%,特异性100%。结论:BAL检查及经皮肺活检对肺周围块状阴影或弥漫性病变的确诊有很高价值。  相似文献   
994.
Sympathetic skin response in scleroderma.   总被引:1,自引:0,他引:1  
Examination of the sympathetic skin response (SSR) was performed in 32 patients with systemic sclerosis, morphea and mixed connective tissue disease displaying scleroderma-like features. The control group consisted of 26 healthy subjects and 12 patients with other skin diseases and asymmetrical cutaneous changes. Right and left median and tibial nerves were stimulated successively and the responses were recorded from the palms and soles simultaneously. SSR abnormalities (delayed latency, decrease and/or asymmetry of amplitude, absent response) were observed in 68.8% of the patients, most frequently in linear scleroderma. An amplitude asymmetry of the responses from upper extremities was the most characteristic pattern of abnormalities. There was no correlation between the SSR and the localization, degree and character (inclurated oedema, atrophy, sclerosis) of skin changes, the duration of the disease, symptoms of the disorder of the autonomic nervous system symptoms (vasomotor and/or sudomotor) and the changes in capillaroscopy. All patients with slow motor conduction and sensor conduction velocities (MCV and SCV) had lower SSR amplitude and the patients with prolonged skin sensory chronaxy had more often delayed latency. The results revealed presence of disturbances of the autonomic nervous system in all varieties of scleroderma, both systemic and localized forms, even without any other signs of autonomic dysfunction.  相似文献   
995.
In Brazil, Public Health specialization courses with the characteristics presently adopted by the National School of Public Health, i.e., short duration and great amplitude, are relatively recent, having started approximately fifteen years ago. In Brasília, nine such courses have been already completed, having, six of them, directive and/or teaching involvement by the authors. Results on a final assessment of one the courses are herewith presented in order to introduce our experience as a contribution to future analogous initiatives. The assessment was applied to a random sample of students, teachers and coordinators, with the objective of identifying positive and negative appreciations about methodological, operational, administrative and institutional aspects. Answers were quite variable, with the highest frequencies scored to field work and to the apprehension on admitting graduates to the Health System. Such aspects deserve final differentiated discussion.  相似文献   
996.
997.
对AF系统整复压缩爆裂骨折椎体高度及椎管横截面的观测   总被引:4,自引:3,他引:1  
目的 :量化评价AF系统恢复胸腰段压缩爆裂椎体高度椎管截面积的效果。方法 :测量AF系统治疗的 72例胸腰段压缩爆裂骨折术前后影像。统计椎体前后缘高度、Cobb角、椎管截面积资料。结果 :术后伤椎前缘高度恢复至 ( 96.5± 2 .3 ) %后缘高度恢复至 ( 98.2± 0 .9) % ,Cobb角恢复至 ( 5 .4± 1.5 )° ,椎管截面积恢复至 ( 97.2± 2 .1% ) ,各项指标与术前比较有非常显著性差异 (P <0 .0 0 1)。术后随访 0 .5~ 3 .5年 ,神经功能按Frankel评定 :60例提高 1~ 3级。结论 :AF系统能恢复或基本恢复胸腰段压缩爆裂骨折椎体的前后缘高度、Cobb角、椎管容积 ,为脊髓神经功能的恢复提供一个良好的环境。是治疗脊柱胸腰段压缩爆裂骨折较好的内固定器。  相似文献   
998.
999.
阻塞性黄疸:PTC下胆管钳夹活检的技术方法学研究   总被引:1,自引:0,他引:1  
目的探索切实可行的胆管病理学检查新途径.资料与方法连续92例阻塞性黄疸患者接受经皮肝穿刺胆管造影(PTC)和经皮肝穿胆管引流(PTCD)治疗.PTCD过程中,影像监测下经皮经肝胆管穿刺,向胆管内引入活检钳对梗阻段钳夹活检,行组织病理学检查.统计学分析用χ2检验或Fisher确切概率计算法,以α=0.05作为检验水准.结果 92例钳夹活检患者90例成功获得组织块,技术成功率97.83%(90/92).钳夹活检敏感性为88.04%,63例胆管癌性恶性肿瘤钳夹活检敏感性较25例非胆管癌性恶性肿瘤高(93.65%比72.00%,P<0.05).结论PTC下胆管钳夹活检操作简单,创伤小,敏感性高,是一种值得推广的胆管病理学诊断新途径.  相似文献   
1000.
目的:研究肺癌放射导向手术中肿瘤及正常组织P糖蛋白(P-gp)、Ki-67抗原表达与放射性核素摄取比(T/NT)的关系.方法:采用免疫组化方法和显微图像分析技术,测定32例接受放射导向手术的肺癌病人P-gp和Ki-67抗原表达,分析P-gp和Ki-67的标记指数(LI)与T/NT之间的相关性.结果:P-gp和Ki-67的LI和肺癌病人T/NT之间均有相关性(r=-0.61,P=0.0002; r=0.75,P=0.0001).结论:Ki-67的LI越高(肿瘤增殖越旺盛),T/NT值越高;P-gp阳性的肿瘤,T/NT值较低.  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