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   1195篇
  免费   36篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   38篇
妇产科学   11篇
基础医学   104篇
口腔科学   16篇
临床医学   120篇
内科学   246篇
皮肤病学   15篇
神经病学   32篇
特种医学   257篇
外科学   216篇
综合类   16篇
预防医学   24篇
眼科学   4篇
药学   64篇
  1篇
中国医学   9篇
肿瘤学   63篇
  2021年   3篇
  2018年   5篇
  2017年   5篇
  2016年   6篇
  2015年   13篇
  2014年   9篇
  2013年   18篇
  2012年   35篇
  2011年   37篇
  2010年   34篇
  2009年   32篇
  2008年   27篇
  2007年   35篇
  2006年   35篇
  2005年   41篇
  2004年   30篇
  2003年   24篇
  2002年   33篇
  2001年   30篇
  2000年   42篇
  1999年   36篇
  1998年   49篇
  1997年   42篇
  1996年   41篇
  1995年   50篇
  1994年   42篇
  1993年   40篇
  1992年   15篇
  1991年   13篇
  1990年   17篇
  1989年   45篇
  1988年   32篇
  1987年   40篇
  1986年   46篇
  1985年   26篇
  1984年   22篇
  1983年   23篇
  1982年   17篇
  1981年   21篇
  1980年   20篇
  1979年   15篇
  1978年   15篇
  1977年   15篇
  1976年   17篇
  1975年   12篇
  1971年   4篇
  1969年   3篇
  1958年   4篇
  1957年   6篇
  1954年   2篇
排序方式: 共有1238条查询结果,搜索用时 12 毫秒
51.
52.
Data on body composition in conjunction with reference centiles are helpful in identifying the severity of growth and nutritional disorders in infancy and for evaluating the adequacy of treatment given during this important period of rapid growth. Total body fat (TBF) and fat-free mass (FFM) were estimated from total body electrical conductivity (TBEC) measurements in 423 healthy term Caucasian infants, aged 14-379 days. Cross sectional age, weight, and length related centile standards are presented for TBF and FFM. Centiles were calculated using Altman's method, based on polynomial regression and modelling of the residual variation. The TBF percentage steeply increased during the first half year of life, and slowly declined beyond this age. Various simple TBEC derived anthropometric prediction equations for TBF and FFM are available to be used in conjunction with these standards. Regression equations for the P50 and the residual SD, depending on age, weight, or length, are provided for constructing centile charts and calculating standard deviation scores.  相似文献   
53.
This study of etoposide in thyroid cancer was designed to determine the activity and toxicity of etoposide in a variety of inoperable, thyroid hormone insensitive, and radio-iodine resistant primary cancers of the thyroid. The patients were required to have an ECOG performance status of at least 3 and no previous exposure to chemotherapy. The etoposide was given at a dose of 140 mg/m2 daily for 3 days and every 3 weeks until progression. The study was closed after 18 months because of poor accrual. There were no responses seen among the 10 patients accrued. The toxicity was primarily hematologic. There was no evidence of activity of etoposide in thyroid carcinoma, although this study lacked significant power because of the poor accrual.  相似文献   
54.
55.
Background : There has been a great deal of discussion regarding the necessity of the prophylactic use of antibiotics in transurethral procedures. In order to clarify this complicated issue, a randomized prospective study was performed for patients undergoing urethrocystoscopy or urethrocystography.
Patients and Methods : Patients who underwent urethrocystoscopy or urethrocystography and did not have pyuria and bacteriuria were included and divided randomly into 2 groups, either receiving a prophylactic antibiotic or no antibiotic. For antibiotic prophylaxis, 200 mg of sparfloxacin or fleroxacin were administered within a 1-hour period before the urethrocystoscopic or urethrocystographic examination, respectively. Analyses were performed on patients who were seen within 1 month after the examination, using the appearance of pyuria, bacteriuria, or a febrile infection as the endpoint.
Results : Of47 patients undergoing urethrocystoscopy, 45 were eligible for analysis, and of these, sparfloxacin was administered to 21 patients. Thirty-three of 37 patients undergoing urethrocystography were eligible for analysis with fleroxacin administered to 16 patients. There were no significant differences in the background factors between the 2 groups undergoing either transurethral examination. None of the patients in either group developed pyuria, bacteriuria or a febrile infection after the examination.
Conclusions : Prophylactic administration of antibiotics is not necessarily essential in urethrocystoscopy or urethrocystography in patients with sterile urine.  相似文献   
56.
57.
In 63 teenagers the proximal surfaces of premolars to be extracted for orthodontic reasons and the adjacent surfaces of neighboring teeth, 598 surfaces in all, were examined radiographically and by probing. Direct inspection after extraction revealed that 51% of the surfaces had incipient carious lesions and 5% lesions with cavities. Of the surfaces with cavities 82.1% were correctly diagnosed radiographically if any radiolucency, regardless of its extent, was used as a diagnostic criterion. However, this yielded a false positive rate of 19.6%. If only radioluccncies extending at least into the inner third of the enamel were called positive the true positive rate was 36.7% and the associated false positive rate 1.6%. At a 5% cavity frequency the predictive positive values were 17% and 53%, respectively. Probing yielded a true positive rate of about 29% and a false positive rate of 1.1% with a predictive positive value of 50-57%. All radiolucencies extending into the dentin were associated with cavities. When the most liberal radiographic criterion was used 37.5% of all carious lesions, whether associated with a cavity or not, were detected and 3.8% of sound surfaces were falsely called carious. The corresponding predictive positive value at the actual rate of incipient lesions and lesions with cavities was 92.6%.  相似文献   
58.
59.
60.
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