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   2039篇
  免费   325篇
  国内免费   40篇
耳鼻咽喉   59篇
儿科学   103篇
妇产科学   24篇
基础医学   142篇
口腔科学   26篇
临床医学   303篇
内科学   665篇
皮肤病学   61篇
神经病学   183篇
特种医学   291篇
外科学   218篇
综合类   36篇
预防医学   73篇
眼科学   18篇
药学   75篇
中国医学   1篇
肿瘤学   126篇
  2023年   54篇
  2022年   13篇
  2021年   29篇
  2020年   92篇
  2019年   14篇
  2018年   90篇
  2017年   72篇
  2016年   70篇
  2015年   67篇
  2014年   98篇
  2013年   119篇
  2012年   61篇
  2011年   64篇
  2010年   87篇
  2009年   115篇
  2008年   50篇
  2007年   62篇
  2006年   67篇
  2005年   45篇
  2004年   29篇
  2003年   26篇
  2002年   27篇
  2001年   41篇
  2000年   24篇
  1999年   41篇
  1998年   85篇
  1997年   101篇
  1996年   80篇
  1995年   72篇
  1994年   53篇
  1993年   54篇
  1992年   35篇
  1991年   29篇
  1990年   37篇
  1989年   68篇
  1988年   47篇
  1987年   32篇
  1986年   26篇
  1985年   24篇
  1984年   19篇
  1983年   10篇
  1982年   21篇
  1981年   19篇
  1980年   14篇
  1979年   14篇
  1978年   11篇
  1977年   10篇
  1976年   16篇
  1975年   7篇
  1971年   9篇
排序方式: 共有2404条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
The Medical Research Council UKALL V trial for children with standard-risk acute lymphoblastic leukemia (ALL) (aged 1 to 14 years, leucocyte count less than 20 X 10(9)/L) was designed to determine whether the immunosuppressive effects of treatment could be reduced without sacrifice of antileukemic effect by alterations in the type of continuing therapy or in fractionation of cranial irradiation. Remission was achieved in 496 children on standard induction therapy, and 309 children received 24 Gy of cranial irradiation in ten to 16 fractions over 21 days, and 174 received 21 Gy in five to nine fractions over 21 days. The type of radiotherapy administered had no influence on relapse at any site or rate of death in remission. All 496 children were randomized to receive chemotherapy for 2 or 3 years with 6-mercaptopurine and methotrexate either as a continuous (group C) or a semicontinuous (group G) regimen or as a five-day pulse every 3 weeks (group I). All groups also received vincristine and prednisolone every 6 weeks. With a minimum follow-up of almost 7 years, patients in group I had significantly fewer remission deaths (P = .025) but a much higher rate of bone marrow relapse than those in group C or G (P = .002). There was an overall benefit for 3 years of chemotherapy compared with 2 years, which in contrast to previous studies, was more apparent in girls and in patients in groups C and G. Testicular relapse occurred in 37 boys, including 19 patients off therapy, with a previously negative biopsy. The overall results confirmed the prognostic significance of initial leucocyte count, even among these standard-risk patients, while girls had a superior rate of disease-free survival, but not of hematologic remission. It is concluded that, even among standard-risk patients, the prognosis is influenced by the height of the initial leukocyte count. While alterations in the fractionation of cranial irradiation do not appear to have influenced disease-free survival, intermittent continuing chemotherapy, although less immunosuppressive, is less effective than conventional continuous therapy in the treatment of ALL. In this study, 3 years of chemotherapy appeared superior to 2 years.  相似文献   
6.
7.
8.
9.
筛检对肝癌死亡率影响的研究   总被引:5,自引:0,他引:5  
5581名HBsAg阳性的男性随机分入周期性筛检组(A组,3712人)及对照组(B组,1869人)。A组(19155.4人年)共发生肝癌257例,B组(9785.5人年)为117例,两组的肝癌发生率分别为1342/10万与1196/10万;两组肝癌死亡分别为218与109例,肝癌死亡率分别为1138/10万与1114/10万。两组中Ⅰ期肝癌病例分别为29.6%与6.0%,差异有非常显著性意义。1、3、5年相对生存率A组为23.7%、7.0%、4.0%,B组为9.7%、4.0%、4.1%。用Poisson回归模型拟合显示,在调正年龄、初筛AFP及入列年份后,筛检对于肝癌的相对危险度为0.83,95%CI为0.68~1.03,有较弱的“保护”作用,Cox回归模型拟合结果显示当临床分期未引入模型时,筛检对于肝癌有显著的“保护”作用:危险率为0.6617,95%CI为0.5234~0.8365;而模型经调整后,危险率即接近“1”,95%CI为0.74~1.26。  相似文献   
10.
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.  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