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   45902篇
  免费   4899篇
  国内免费   106篇
耳鼻咽喉   438篇
儿科学   1203篇
妇产科学   1095篇
基础医学   6905篇
口腔科学   1064篇
临床医学   5673篇
内科学   8423篇
皮肤病学   546篇
神经病学   4453篇
特种医学   1762篇
外国民族医学   57篇
外科学   5924篇
综合类   985篇
一般理论   43篇
预防医学   5141篇
眼科学   1130篇
药学   3443篇
中国医学   26篇
肿瘤学   2596篇
  2021年   655篇
  2020年   409篇
  2019年   645篇
  2018年   716篇
  2017年   552篇
  2016年   606篇
  2015年   643篇
  2014年   966篇
  2013年   1518篇
  2012年   2029篇
  2011年   2072篇
  2010年   1241篇
  2009年   1074篇
  2008年   1967篇
  2007年   1965篇
  2006年   1997篇
  2005年   1910篇
  2004年   1945篇
  2003年   1714篇
  2002年   1693篇
  2001年   1484篇
  2000年   1607篇
  1999年   1364篇
  1998年   583篇
  1997年   508篇
  1996年   467篇
  1995年   470篇
  1994年   432篇
  1993年   397篇
  1992年   1071篇
  1991年   1112篇
  1990年   1022篇
  1989年   1004篇
  1988年   1006篇
  1987年   875篇
  1986年   866篇
  1985年   839篇
  1984年   699篇
  1983年   580篇
  1982年   383篇
  1981年   360篇
  1980年   346篇
  1979年   662篇
  1978年   517篇
  1977年   437篇
  1976年   413篇
  1975年   381篇
  1974年   438篇
  1973年   435篇
  1972年   377篇
排序方式: 共有10000条查询结果,搜索用时 804 毫秒
191.
Extracapsular cataract extraction (ECCE), placement of a posterior chamber intraocular lens (PC IOL), and pars plana vitrectomy were combined in a single operation in 24 patients. Sixteen of these, 11 of whom are diabetic, have had 6 months or more of follow-up. In all cases, excellent visualization of the posterior segment was obtained, and the surgical objectives were achieved. No diabetic patient without preoperative neovascularization of the iris had this complication later. The advantages and disadvantages of alternative techniques are discussed.  相似文献   
192.
193.
Netlines     
  相似文献   
194.
The objective of this study was to investigate the effect of docosahexaenoic acid (DHA) supplementation on blood and intestinal DHA levels and lung function in mild/moderately affected adult CF patients with the DeltaF508 genotype. BACKGROUND: Cystic Fibrosis (CF) patients often present with plasma fatty acid levels indicating low levels of linoleic (18:2n-6) and docosahexaenoic (22:6n-3) acids and an increased level of arachidonic acid (20:4n-6). Improved dietary fat intake or reducing fat malabsorption with pancreatic enzymes has failed to normalize this biochemical deficiency of DHA. METHODS: Five CF patients, aged 18-43, received 70 mg of DHA/kg body weight/d for six weeks. At baseline and at six weeks a physical exam, lung function, 3-day dietary intake, duodenal mucosal biopsy and blood sample were assessed. The blood was analyzed for plasma vitamin A, D and E levels, liver function tests, clinical chemistry (CBC, differential and electrolytes). Plasma and red blood cell fatty acid levels were also analyzed. At three weeks, assessment included a physical exam, lung function test and fasting blood sample (vitamin levels, liver function and clinical chemistry only). RESULTS: Pre- and post-measurements were compared for the four subjects who completed the study. An increase in DHA content (% w/w) was observed in all phospholipid fractions of plasma, red blood cell and mucosal samples. No significant differences in vitamin levels, liver function or lung function were observed. CONCLUSIONS: The study proves the concept that an increase in tissue DHA levels in CF patients can be achieved by supplementing for six weeks with 70 mg/kg/d DHA.  相似文献   
195.
196.
197.
Nonmotor symptoms (NMS) of Parkinson's disease (PD) are not well recognized in clinical practice, either in primary or in secondary care, and are frequently missed during routine consultations. There is no single instrument (questionnaire or scale) that enables a comprehensive assessment of the range of NMS in PD both for the identification of problems and for the measurement of outcome. Against this background, a multidisciplinary group of experts, including patient group representatives, has developed an NMS screening questionnaire comprising 30 items. This instrument does not provide an overall score of disability and is not a graded or rating instrument. Instead, it is a screening tool designed to draw attention to the presence of NMS and initiate further investigation. In this article, we present the results from an international pilot study assessing feasibility, validity, and acceptability of a nonmotor questionnaire (NMSQuest). Data from 123 PD patients and 96 controls were analyzed. NMS were highly significantly more prevalent in PD compared to controls (PD NMS, median = 9.0, mean = 9.5 vs. control NMS, median = 5.5, mean = 4.0; Mann-Whitney, Kruskal-Wallis, and t test, P < 0.0001), with PD patients reporting at least 10 different NMS on average per patient. In PD, NMS were highly significantly more prevalent across all disease stages and the number of symptoms correlated significantly with advancing disease and duration of disease. Furthermore, frequently, problems such as diplopia, dribbling, apathy, blues, taste and smell problems were never previously disclosed to the health professionals.  相似文献   
198.
199.
An open, randomized, cross-over study was performed to compare the efficacy and acceptability of two breath-actuated inhalers, the Turbohaler (T) and Diskhaler (D), for delivery of beta-agonists. Thirty six adults with chronic asthma requiring beta-agonists four times daily were treated with terbutaline 500 micrograms via T and salbutamol 400 micrograms via D four times daily, each period lasting four weeks. Additional bronchodilator via pressurized aerosol was permitted as required. Peak expiratory flow (PEF) was recorded in the morning (before and after beta-agonist) and in the evening. The mean morning PEF was higher during the first two weeks using T (295 l.min-1) than whilst using D (281 l.min-1, p < 0.01), but this difference did not persist during the second two weeks and there were no differences in post-bronchodilator PEF or rescue beta-agonist use. After four weeks, > 90% of patients used both inhaler devices efficiently and they were equally acceptable in terms of ease of use and convenience to carry. The Diskhaler and Turbohaler achieve similar clinical efficacy for delivery of beta-agonists.  相似文献   
200.
Eighteen specific pathogen-free chickens (nine hens older than 1 year and nine 15-week-old males) were inoculated with highly pathogenic avian influenza virus A/Chicken/Pennsylvania/1370/1983 (H5N2). Birds were serially killed and tissues collected for histological and immunohistochemical evaluation. In the group of older hens, disease was acute or peracute. By immunohistochemistry, antigen was abundant in capillary endothelium in multiple organs, and staining for antigen in parenchymal cells was marked in brain and heart. In the group of younger male birds, disease was subacute. Immunohistochemical staining of capillary endothelium was less pronounced and viral antigen staining was evident in the parenchymal cells of the heart, brain and kidney.  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