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   1912166篇
  免费   130441篇
  国内免费   5187篇
耳鼻咽喉   24862篇
儿科学   61440篇
妇产科学   50623篇
基础医学   290962篇
口腔科学   52865篇
临床医学   177965篇
内科学   368749篇
皮肤病学   40927篇
神经病学   152544篇
特种医学   67693篇
外国民族医学   422篇
外科学   266009篇
综合类   36157篇
现状与发展   4篇
一般理论   602篇
预防医学   161784篇
眼科学   42898篇
药学   142501篇
  7篇
中国医学   4736篇
肿瘤学   104044篇
  2021年   17815篇
  2019年   18411篇
  2018年   26526篇
  2017年   18978篇
  2016年   20461篇
  2015年   23224篇
  2014年   31213篇
  2013年   47464篇
  2012年   68037篇
  2011年   72791篇
  2010年   41567篇
  2009年   36627篇
  2008年   64772篇
  2007年   69146篇
  2006年   67922篇
  2005年   65652篇
  2004年   62535篇
  2003年   59411篇
  2002年   57346篇
  2001年   81037篇
  2000年   83405篇
  1999年   69503篇
  1998年   19507篇
  1997年   17184篇
  1996年   17008篇
  1995年   16088篇
  1994年   14865篇
  1992年   53878篇
  1991年   53966篇
  1990年   52618篇
  1989年   50285篇
  1988年   46423篇
  1987年   45543篇
  1986年   43209篇
  1985年   41251篇
  1984年   30999篇
  1983年   26387篇
  1982年   15278篇
  1979年   28545篇
  1978年   20291篇
  1977年   16521篇
  1976年   16623篇
  1975年   17911篇
  1974年   21486篇
  1973年   20815篇
  1972年   19231篇
  1971年   18161篇
  1970年   16876篇
  1969年   15472篇
  1968年   14725篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
Cognitive Therapy and Research - Despite interest in psychological inflexibility as a marker of suicide risk, no measure of psychological inflexibility specific to SI exists. The present study...  相似文献   
26.
Gestational trophoblastic neoplasia (GTN) patients are treated according to the eight-variable International Federation of Gynaecology and Obstetrics (FIGO) scoring system, that aims to predict first-line single-agent chemotherapy resistance. FIGO is imperfect with one-third of low-risk patients developing disease resistance to first-line single-agent chemotherapy. We aimed to generate simplified models that improve upon FIGO. Logistic regression (LR) and multilayer perceptron (MLP) modelling (n = 4191) generated six models (M1-6). M1, all eight FIGO variables (scored data); M2, all eight FIGO variables (scored and raw data); M3, nonimaging variables (scored data); M4, nonimaging variables (scored and raw data); M5, imaging variables (scored data); and M6, pretreatment hCG (raw data) + imaging variables (scored data). Performance was compared to FIGO using true and false positive rates, positive and negative predictive values, diagnostic odds ratio, receiver operating characteristic (ROC) curves, Bland-Altman calibration plots, decision curve analysis and contingency tables. M1-6 were calibrated and outperformed FIGO on true positive rate and positive predictive value. Using LR and MLP, M1, M2 and M4 generated small improvements to the ROC curve and decision curve analysis. M3, M5 and M6 matched FIGO or performed less well. Compared to FIGO, most (excluding LR M4 and MLP M5) had significant discordance in patient classification (McNemar's test P < .05); 55-112 undertreated, 46-206 overtreated. Statistical modelling yielded only small gains over FIGO performance, arising through recategorisation of treatment-resistant patients, with a significant proportion of under/overtreatment as the available data have been used a priori to allocate primary chemotherapy. Streamlining FIGO should now be the focus.  相似文献   
27.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.  相似文献   
28.
Journal of Immigrant and Minority Health - COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to...  相似文献   
29.
30.
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