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   2388330篇
  免费   199285篇
  国内免费   4237篇
耳鼻咽喉   34481篇
儿科学   73272篇
妇产科学   63472篇
基础医学   336974篇
口腔科学   67720篇
临床医学   218132篇
内科学   471599篇
皮肤病学   48150篇
神经病学   202418篇
特种医学   96290篇
外国民族医学   886篇
外科学   362012篇
综合类   56508篇
现状与发展   1篇
一般理论   1007篇
预防医学   192656篇
眼科学   55720篇
药学   178616篇
  4篇
中国医学   4379篇
肿瘤学   127555篇
  2018年   24713篇
  2017年   19156篇
  2016年   20972篇
  2015年   23682篇
  2014年   34147篇
  2013年   51625篇
  2012年   69926篇
  2011年   73546篇
  2010年   43154篇
  2009年   41422篇
  2008年   69784篇
  2007年   74129篇
  2006年   75043篇
  2005年   73095篇
  2004年   70187篇
  2003年   67797篇
  2002年   66956篇
  2001年   112668篇
  2000年   116748篇
  1999年   98551篇
  1998年   28001篇
  1997年   25632篇
  1996年   25561篇
  1995年   24710篇
  1994年   23279篇
  1993年   21633篇
  1992年   79562篇
  1991年   76539篇
  1990年   73709篇
  1989年   70988篇
  1988年   65960篇
  1987年   64917篇
  1986年   61442篇
  1985年   58502篇
  1984年   44299篇
  1983年   37731篇
  1982年   22951篇
  1981年   20369篇
  1979年   41375篇
  1978年   29050篇
  1977年   24384篇
  1976年   22870篇
  1975年   24014篇
  1974年   29685篇
  1973年   28082篇
  1972年   26276篇
  1971年   24194篇
  1970年   22778篇
  1969年   21108篇
  1968年   19152篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Continuity of relationship between physician and patient is a fundamental aspect of the health care provided by family physicians. Measurement of continuity has proved difficult, however. Commonly applied measures, usual provider of care (UPC), continuity of care (COC), and the modified continuity index (MCI), either ignore key aspects of continuity or provide misleading results. Consequently, a new measure of continuity, the modified, modified continuity index (MMCI), with a possible range of 0 to 1, was developed to overcome these problems. It was applied to a residency model practice, in which mean MMCI was found to be 0.59 (range 0.3 to 1.0). Mean COC was .41 and a mean MCI was .44. Thus, unlike COC and MCI, MMCI suggests fairly good continuity of care in this practice while still implying possible improvement. The MMCI should be useful for enhancing training and practice of family medicine.  相似文献   
992.
993.
994.
In order to prevent essential fatty acid (EFA) deficiency induced by fat-free total parenteral nutrition (TPN), 10 infants on TPN were rubbed three times daily for 20 days using oenethera oil (80% EFA). Total EFA amount provided cutaneously was 1900 mg/kg/d. Plasma and red blood cells phospholipids were determined on days 1 and 20 in these 10 treated and six untreated infants on TPN and compared with those of normal control infants. On day 1, plasma nonessential FA including 20:3 n-9(p less than 0.01) were increased in both TPN groups while 18:2 n-6 and 18:3 n-3 (p less than 0.001 and p less than 0.01) were decreased. On the 20th day, EFA deficiency had worsened with a decrease in plasma level of 20:4 n-6 (p less than 0.02) and a higher than normal triene/tetraene ratio : 3.4 +/- 1.1 and 2.3 +/- 0.6 vs 0.1 +/- 0.1 (p less than 0.02). As for red blood cells phospholipids, 16:0 was increased and 18:2 n-6 and 20:3 n-6 were decreased (p less than 0.05) on day 1. On day 20, these FA were more abnormal while 20:3 n-9 became significantly increased (p less than 0.05). No difference was observed between the TPN groups at any time. These results show that cutaneous application of large amounts of EFA-rich oil is unable to prevent or cure TPN induced EFA deficiency.  相似文献   
995.
996.
997.
998.
The simultaneous determination of cerebrospinal fluid (CSF) and plasma adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in tuberculous meningitis (TBM). CSF and plasma ADA activity were determined in four groups of patients: (i) a 'no meningitis' group of 174 children investigated for possible meningitis, but found to be uninfected; (ii) an aseptic meningitis group of 40 children; (iii) a bacterial meningitis group of 31 children; and (iv) a TBM group of 27 patients (24 children and 3 adults). CSF ADA alone was determined in a further 23 children with aseptic meningitis, 19 with bacterial meningitis and 13 children and 7 adults with TBM. Both the CSF/plasma ADA ratio and the absolute CSF ADA activity were raised in TBM (mean values 0,24 and 12,61 U/I respectively) and bacterial meningitis (mean values 0,59 and 15,43 U/I respectively), but not in the aseptic meningitis group (mean values 0,06 and 2,00 U/I) or the 'no meningitis' group (mean values 0,04 and 1,51 U/I). Both values will distinguish TBM from aseptic meningitis, but do not appear to hold any marked advantages over conventional CSF criteria in the diagnosis of TBM.  相似文献   
999.
Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.  相似文献   
1000.
Traumatic infarction of the spinal cord in children   总被引:2,自引:0,他引:2  
Infarction of the spinal cord in childhood is rarely due to trauma. During a 15-year period (1971 to 1985), eight children were admitted to The Hospital for Sick Children, Toronto, with a diagnosis of traumatic infarction of the spinal cord. All of these patients had delayed onset of neurological signs varying between 2 hours and 4 days after their initial trauma. No bone abnormalities were seen on plain spine x-ray films. Myelography was carried out in seven of these children and found to be normal in all seven. Six patients who were paraplegic at the time of admission remained permanently paraplegic, but two with incomplete cord signs did show some improvement.  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