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   2699606篇
  免费   199975篇
  国内免费   7568篇
耳鼻咽喉   35342篇
儿科学   88626篇
妇产科学   73452篇
基础医学   388124篇
口腔科学   77113篇
临床医学   252225篇
内科学   521697篇
皮肤病学   58321篇
神经病学   215862篇
特种医学   100054篇
外国民族医学   594篇
外科学   395100篇
综合类   62590篇
现状与发展   6篇
一般理论   948篇
预防医学   214527篇
眼科学   62817篇
药学   198817篇
  16篇
中国医学   7164篇
肿瘤学   153754篇
  2021年   21329篇
  2019年   22251篇
  2018年   31827篇
  2017年   24156篇
  2016年   26447篇
  2015年   30183篇
  2014年   41806篇
  2013年   62531篇
  2012年   86201篇
  2011年   91127篇
  2010年   53826篇
  2009年   49923篇
  2008年   84047篇
  2007年   89181篇
  2006年   89762篇
  2005年   86084篇
  2004年   82596篇
  2003年   78598篇
  2002年   76079篇
  2001年   131372篇
  2000年   134680篇
  1999年   112204篇
  1998年   30705篇
  1997年   27139篇
  1996年   27049篇
  1995年   25860篇
  1994年   23961篇
  1993年   22241篇
  1992年   86793篇
  1991年   84221篇
  1990年   81151篇
  1989年   77692篇
  1988年   71317篇
  1987年   69687篇
  1986年   66063篇
  1985年   62852篇
  1984年   46706篇
  1983年   39786篇
  1982年   23029篇
  1979年   41806篇
  1978年   29323篇
  1977年   24534篇
  1976年   23320篇
  1975年   24297篇
  1974年   29578篇
  1973年   28692篇
  1972年   26613篇
  1971年   24688篇
  1970年   22957篇
  1969年   21265篇
排序方式: 共有10000条查询结果,搜索用时 859 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.
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