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   133890篇
  免费   11397篇
  国内免费   3302篇
耳鼻咽喉   1503篇
儿科学   7563篇
妇产科学   4133篇
基础医学   13583篇
口腔科学   1722篇
临床医学   14650篇
内科学   23782篇
皮肤病学   2585篇
神经病学   11726篇
特种医学   2936篇
外国民族医学   5篇
外科学   14840篇
综合类   18771篇
现状与发展   12篇
预防医学   7364篇
眼科学   2481篇
药学   7370篇
  59篇
中国医学   11479篇
肿瘤学   2025篇
  2024年   120篇
  2023年   2430篇
  2022年   3697篇
  2021年   6323篇
  2020年   6245篇
  2019年   5071篇
  2018年   5081篇
  2017年   5200篇
  2016年   5290篇
  2015年   5035篇
  2014年   9610篇
  2013年   9957篇
  2012年   7643篇
  2011年   8865篇
  2010年   6848篇
  2009年   6697篇
  2008年   6539篇
  2007年   6531篇
  2006年   6003篇
  2005年   4984篇
  2004年   4192篇
  2003年   3716篇
  2002年   2569篇
  2001年   2295篇
  2000年   1923篇
  1999年   1711篇
  1998年   1226篇
  1997年   1127篇
  1996年   1093篇
  1995年   1271篇
  1994年   1110篇
  1993年   974篇
  1992年   891篇
  1991年   693篇
  1990年   640篇
  1989年   545篇
  1988年   536篇
  1987年   472篇
  1986年   424篇
  1985年   531篇
  1984年   458篇
  1983年   289篇
  1982年   370篇
  1981年   331篇
  1980年   276篇
  1979年   219篇
  1978年   143篇
  1977年   109篇
  1976年   92篇
  1975年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ObjectiveThe use of mechanical circulatory support (MCS) in lung transplantation has been steadily increasing over the prior decade, with evolving strategies for incorporating support in the preoperative, intraoperative, and postoperative settings. There is significant practice variability in the use of these techniques, however, and relatively limited data to help establish institutional protocols. The objective of the AATS Clinical Practice Standards Committee (CPSC) expert panel was to review the existing literature and establish recommendations about the use of MCS before, during, and after lung transplantation.MethodsThe AATS CPSC assembled an expert panel of 16 lung transplantation physicians who developed a consensus document of recommendations. The panel was broken into subgroups focused on preoperative, intraoperative, and postoperative support, and each subgroup performed a focused literature review. These subgroups formulated recommendation statements for each subtopic, which were evaluated by the entire group. The statements were then developed via discussion among the panel and refined until consensus was achieved on each statement.ResultsThe expert panel achieved consensus on 36 recommendations for how and when to use MCS in lung transplantation. These recommendations included the use of veno-venous extracorporeal membrane oxygenation (ECMO) as a bridging strategy in the preoperative setting, a preference for central veno-arterial ECMO over traditional cardiopulmonary bypass during the transplantation procedure, and the benefit of supporting selected patients with MCS postoperatively.ConclusionsAchieving optimal results in lung transplantation requires the use of a wide range of strategies. MCS provides an important mechanism for helping these critically ill patients through the peritransplantation period. Despite the complex nature of the decision making process in the treatment of these patients, the expert panel was able to achieve consensus on 36 recommendations. These recommendations should provide guidance for professionals involved in the care of end-stage lung disease patients considered for transplantation.  相似文献   
2.
3.
Toxicity resulting from off-target effects, beyond acetylcholine esterase inhibition, for the commonly used organophosphate (OP) insecticides chlorpyrifos (CPS) and malathion (MA) was investigated using Saccharomyces cerevisiae and Caenorhabditis elegans model systems. Mitochondrial damage and dysfunction were observed in yeast following exposure to CPS and MA, suggesting this organelle is a major target. In the C. elegans model, the mitochondrial unfolded protein response pathway showed the most robust induction from CPS and MA treatment among stress responses examined. GABAergic neurodegeneration was observed with CPS and MA exposure. Impaired movement observed in C. elegans exposed to CPS and MA may be the result of motor neuron damage. Our analysis suggests that stress from CPS and MA results in mitochondrial dysfunction, with GABAergic neurons sensitized to these effects. These findings may aid in the understanding of toxicity from CPS and MA from high concentration exposure leading to insecticide poisoning.  相似文献   
4.
特纳综合征(TS)是女性常见的性染色体异常疾病,与多种疾病共存。越来越多的证据表明TS患者有较高的骨质疏松患病率,本文就近年来TS中骨质疏松的危险因素及管理治疗的相关研究进展做一综述。  相似文献   
5.
6.
7.
ObjectiveDeterioration of the native aortic valve function by a late progression of rheumatic disease is not infrequent in patients who underwent rheumatic mitral valve surgery; however, this phenomenon has not been clearly quantified.MethodsA total of 1155 consecutive patients (age 52.0 ± 12.9 years; 807 female) who underwent rheumatic mitral valve surgery without concomitant aortic valve surgery from 1997 to 2015 were enrolled. The primary end point was the composite of progression to severe aortic valve dysfunction or a requirement of subsequent aortic valve replacements during follow-up. To determine the risk factors of the primary outcome, we performed the generalized linear mixed model.ResultsThe baseline severities of aortic valve were none to trivial in 880 patients (76.2%), mild in 256 patients (22.2%), and moderate in 19 patients (1.6%). The latest 1062 echocardiographic assessments (91.9%; median, 81.2 postoperative months; interquartile range, 37.3-132.1 months) demonstrated 26 cases (0.33%/patient-year) meeting the primary end point during follow-up. Cumulative incidence of the primary end point at 10 years was 0.4% ± 0.3% and 7.4% ± 2.5% depending on the presence of mild or greater aortic valve dysfunction at baseline (P < .01). In multivariable analyses, aortic valve peak pressure gradient (odds ratio, 1.14; 95% confidence interval, 1.10-1.20), aortic regurgitation degree (mild over none: odds ratio, 3.26; 95% confidence interval, 1.15-9.23), and time (odds ratio, 1.30; 95% confidence interval 1.19-1.41) were significantly associated with the occurrence of the primary end point.ConclusionsProgression of severe aortic valve dysfunction and the need for aortic valve replacement are uncommon in patients undergoing rheumatic mitral valve surgery. However, such events were relatively common among those with mild or greater aortic valve dysfunction at the time of mitral valve surgery.  相似文献   
8.
9.
目的 探讨血清微小RNA-210(mircoRNA-210,miR-210)与新生儿呼吸窘迫综合征(neonatalrespiratory distress syndrome,NRDS)严重程度和预后的关系。 方法 收集NRDS患儿104例,根据预后分为生存组与死亡组。所有新生儿根据首次胸部X线片结果与病情严重程度分为轻度组(Ⅰ级、Ⅱ级)与重度组(Ⅲ级、Ⅳ级)。比较死亡组与生存组患儿一般资料,轻度组与重度组血清miR-210水平与新生儿急性生理学评分围生期补充Ⅱ(perinatal supplement of acute physiological score for neonates Ⅱ,SNAPPE-Ⅱ)评分。绘制ROC曲线分析血清miR-210水平对NRDS患儿死亡的预测价值。采用Spearman相关性分析NRDS发生与血清miR-210的相关性。 结果 根据预后分组,104例患儿中预后较好81例(77.88%),死亡23例(22.12%)。生存组miR-210水平、SNAPPE-Ⅱ评分低于死亡组(P<0.05);2组性别、胎龄、出生体重、母亲年龄、病因、剖宫产、双胎、羊水异常差异无统计学意义(P>0.05)。按照胸部X线片表现分组,104例患儿轻度患儿73例,重度患儿31例。轻度组miR-210水平、SNAPPE-Ⅱ评分低于重度组(P<0.05)。NRDS发生与血清miR-210水平呈正相关(r=0.638,P<0.001)。血清miR-210与SNAPPE-Ⅱ评分呈正相关(r=0.513,P<0.05)。血清miR-210的最佳分界值为16.71 ng/L时,曲线下面积为0.763,OR=0.846,95%CI:0.892~1.064,敏感度为82.61%,特异度为86.42%。结论 血清miR-210水平升高与NRDS病情严重程度以及预后密切相关,血清miR-210水平与NRDS病情程度呈正相关性,当血清miR-210临界值为16.71 ng/L时对评估NRDS患儿预后具有较高价值。  相似文献   
10.
Irritable bowel syndrome (IBS) is an important health care concern. Alterations in the microbiota of the gut-brain axis may be linked to the pathophysiology of IBS. Some dietary intake could contribute to produce various metabolites including D-amino acids by the fermentation by the gut microbiota. D-amino acids are the enantiomeric counterparts of L-amino acids, in general, which could play key roles in cellular physiological processes against various oxidative stresses. Therefore, the presence of D-amino acids has been shown to be linked to the protection of several organs in the body. In particular, the gut microbiota could play significant roles in the stability of emotion via the action of D-amino acids. Here, we would like to shed light on the roles of D-amino acids, which could be used for the treatment of IBS.  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