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   4855395篇
  免费   393655篇
  国内免费   15776篇
耳鼻咽喉   69470篇
儿科学   153374篇
妇产科学   129644篇
基础医学   731248篇
口腔科学   137950篇
临床医学   448279篇
内科学   882654篇
皮肤病学   114312篇
神经病学   410084篇
特种医学   191997篇
外国民族医学   1128篇
外科学   730328篇
综合类   140211篇
现状与发展   24篇
一般理论   2882篇
预防医学   413540篇
眼科学   115689篇
药学   345110篇
  24篇
中国医学   12407篇
肿瘤学   234471篇
  2021年   56296篇
  2019年   59025篇
  2018年   75092篇
  2017年   57144篇
  2016年   63509篇
  2015年   76228篇
  2014年   111124篇
  2013年   176642篇
  2012年   136165篇
  2011年   143120篇
  2010年   128770篇
  2009年   129747篇
  2008年   129679篇
  2007年   139140篇
  2006年   146531篇
  2005年   141930篇
  2004年   142091篇
  2003年   132217篇
  2002年   122512篇
  2001年   181294篇
  2000年   178389篇
  1999年   162112篇
  1998年   74484篇
  1997年   69933篇
  1996年   68059篇
  1995年   63726篇
  1994年   57937篇
  1993年   53687篇
  1992年   122055篇
  1991年   117717篇
  1990年   112697篇
  1989年   109514篇
  1988年   101979篇
  1987年   100129篇
  1986年   95258篇
  1985年   92738篇
  1984年   76494篇
  1983年   67913篇
  1982年   51763篇
  1981年   48074篇
  1980年   45184篇
  1979年   68999篇
  1978年   54525篇
  1977年   47636篇
  1976年   44413篇
  1975年   44737篇
  1974年   51260篇
  1973年   49438篇
  1972年   46627篇
  1971年   43035篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
Major depressive disorder and other neuropsychiatric disorders are often managed with long-term use of antidepressant medication. Fluoxetine, an SSRI antidepressant, is widely used as a first-line treatment for neuropsychiatric disorders. However, fluoxetine has also been shown to increase the risk of metabolic diseases such as non-alcoholic fatty liver disease. Fluoxetine has been shown to increase hepatic lipid accumulation in vivo and in vitro. In addition, fluoxetine has been shown to alter the production of prostaglandins which have also been implicated in the development of non-alcoholic fatty liver disease. The goal of this study was to assess the effect of fluoxetine exposure on the prostaglandin biosynthetic pathway and lipid accumulation in a hepatic cell line (H4-II-E-C3 cells). Fluoxetine treatment increased mRNA expression of prostaglandin biosynthetic enzymes (Ptgs1, Ptgs2, and Ptgds), PPAR gamma (Pparg), and PPAR gamma downstream targets involved in fatty acid uptake (Cd36, Fatp2, and Fatp5) as well as production of 15-deoxy-Δ12,14PGJ2 a PPAR gamma ligand. The effects of fluoxetine to induce lipid accumulation were attenuated with a PTGS1 specific inhibitor (SC-560), whereas inhibition of PTGS2 had no effect. Moreover, SC-560 attenuated 15-deoxy-Δ12,14PGJ2 production and expression of PPAR gamma downstream target genes. Taken together these results suggest that fluoxetine-induced lipid abnormalities appear to be mediated via PTGS1 and its downstream product 15d-PGJ2 and suggest a novel therapeutic target to prevent some of the adverse effects of fluoxetine treatment.  相似文献   
64.
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   
65.
66.
67.
68.
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   
69.
Heart Failure Reviews - The nitric oxide (NO)–guanylate cyclase (GC)–cyclic guanosine monophosphate (cGMP) pathway plays an important role in cardiovascular, pulmonary and renal...  相似文献   
70.
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   
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