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   94641篇
  免费   5435篇
  国内免费   2999篇
耳鼻咽喉   291篇
儿科学   1641篇
妇产科学   299篇
基础医学   4580篇
口腔科学   471篇
临床医学   14288篇
内科学   24186篇
皮肤病学   306篇
神经病学   5716篇
特种医学   3691篇
外科学   5969篇
综合类   20013篇
现状与发展   1篇
预防医学   4146篇
眼科学   347篇
药学   10498篇
  98篇
中国医学   4986篇
肿瘤学   1548篇
  2024年   152篇
  2023年   1057篇
  2022年   2413篇
  2021年   3481篇
  2020年   3192篇
  2019年   2512篇
  2018年   2587篇
  2017年   2725篇
  2016年   3221篇
  2015年   3046篇
  2014年   7086篇
  2013年   6682篇
  2012年   6215篇
  2011年   6485篇
  2010年   5291篇
  2009年   4842篇
  2008年   4839篇
  2007年   4919篇
  2006年   4664篇
  2005年   3918篇
  2004年   3099篇
  2003年   2693篇
  2002年   2219篇
  2001年   2148篇
  2000年   1834篇
  1999年   1552篇
  1998年   1282篇
  1997年   1223篇
  1996年   945篇
  1995年   843篇
  1994年   801篇
  1993年   635篇
  1992年   537篇
  1991年   503篇
  1990年   447篇
  1989年   378篇
  1988年   364篇
  1987年   306篇
  1986年   273篇
  1985年   334篇
  1984年   275篇
  1983年   156篇
  1982年   190篇
  1981年   166篇
  1980年   134篇
  1979年   103篇
  1978年   86篇
  1977年   70篇
  1976年   40篇
  1975年   29篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
31.
目前,国内外肝移植学界对肝移植术后急性排斥反应(AR)的机制阐释为T细胞介导的细胞免疫应答,但为获得长期生存仍需长期乃至终身服用免疫抑制剂。即使如此,临床上AR仍时有发生,并导致相当一部分受者移植肝功能丧失,更重要的是受者术后还受到感染、肿瘤和其他一系列不良反应及沉重经济负担的影响。因此,为肝移植AR机制提出新的理论解释,更全面深入阐明肝移植免疫排斥反应的内在机制,进而依据新的机制研制出新型免疫抑制剂已势在必行。本文就B细胞介导的体液免疫应答在肝移植AR中的作用作一综述。  相似文献   
32.
6-Mercaptopurine (6-MP) is commonly used for treatment of acute lymphoblastic leukemia (ALL). The incidence of hematotoxicity caused by this drug is quite high in Asians even using a standard low dosage regimen. The present study was aimed to elucidate the impact of thiopurine S-methyltransferase (TPMT), a nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15), inosine triphosphatase (ITPA) and ATP Binding Cassette Subfamily C Member 4 (ABCC4) polymorphisms on hematotoxicity in pediatric patients who received a standard low starting dose of 6-MP. One hundred and sixty-nine pediatric patients were enrolled and their genotypes were determined. Patients who carried NUDT1513 and NUDT1512 genotypes were at a 10–15 fold higher risk of severe neutropenia than those of the wild-type during the early months of the maintenance phase. Risk of neutropenia was not significantly increased in patients with other NUDT15 variants as well as in patients with TPMT, ITPA or ABCC4 variants. These results suggest that NUDT15 polymorphisms particularly, NUDT1513 and NUDT1512, play major roles in 6-MP-induced severe hematotoxicity even when using a standard low dosage of 6-MP and genotyping of these variants is necessary in order to obtain precise tolerance doses and avoid severe hematotoxicity in pediatric patients.  相似文献   
33.
34.
BackgroundCoronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%).MethodsWe analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively.ResultsIn 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]).ConclusionsHeart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization.  相似文献   
35.

Background

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil–lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

Methods

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

Results

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18–1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50–3.72). Postoperative NLR measurements were not of prognostic significance.

Conclusions

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.  相似文献   
36.
王武 《现代药物与临床》2019,42(11):2218-2221
目的 探究预防性静滴钾离子、镁离子对急性心梗后并发室性心律失常的预防作用。方法 选择2015年1月-2018年1月于西宁市第一人民医院进行治疗的78例急性心肌梗死患者为研究对象,按照随机数字表法将其均分为观察组与对照组,每组各39例患者。对照组患者进行常规急性心梗治疗,观察组患者在对照组基础上加用门冬氨酸钾镁进行治疗,对比两组治疗有效率,对比两组治疗前后血液流变学指标纤维蛋白原(Fib)、凝血酶原时间(PT)、血小板计数(Plt),对比两组治疗期间不良反应发生率及心律失常发生率。结果 治疗后,观察组患者治疗有效率为87.18%,对照组为76.92%,两组对比差异具有统计学意义(P<0.05)。治疗前两组患者Fib、PT以及Plt水平对比差异不具有统计学意义;治疗后,两组患者Plt及Fib水平低于治疗前,PT水平高于治疗前,差异有统计学意义(P<0.05);治疗后观察组患者Plt及Fib水平低于对照组,PT水平高于对照组(P<0.05)。观察组患者不良反应发生率稍高于对照组,但对比差异不具有统计学意义。观察组心律失常发生率为7.69%,对照组为15.38%,两组对比差异具有统计学意义(P<0.05)。结论 预防性静滴钾离子与镁离子能够显著降低急性心梗患者心律失常发生率,同时有利于提高治疗有效率,改善其血流变指标,且安全性较高。  相似文献   
37.
PurposeType B aortic dissection is a rare but life-threatening disease. Thoracic endovascular aortic repair (TEVAR) was widely used for Type B aortic dissection patients in the last decade due to the lower mortality and morbidity compared with open chest surgical repair (OCSR). AKI in type B aortic dissection is a well-recognized complication and indicates poor short-term and long-term outcome. The objective of this concise review was to identify the risk factors and the impact of AKI on type B aortic dissection patients.Methods and resultsA literature search was performed using PubMed, Embase, MEDLINE, and Cochrane Library with the search terms ‘type B aortic dissection’ and ‘acute kidney injury’ (AKI), and all English-language literatures published in print or available online from inception through August 2020 were thoroughly reviewed. Studies that reported relative AKI risks and outcomes in type B aortic dissection patient were included. Major mechanisms of AKI in type B aortic dissection included renal hypoperfusion, inflammation response, and the use of contrast medium. Type B aortic dissection patients with AKI significantly had increased hospital stay duration, need of renal replacement therapy, and 30-d and 1-year mortality.ConclusionsAKI in type B aortic dissection is a well-recognized complication and associated with poor short-term and long-term outcome. Early identification of high-risk patients, early diagnosis of AKI, stabilization of the hemodynamic parameters, avoidance of nephrotoxic drugs, and optimization of the use of contrast agents are the major strategies for the reduction of AKI in type B aortic dissection patients.  相似文献   
38.
39.
Parasitic infections of the intestine are a major health problem, which is found more prevalent in developing countries such as India. They are one of the important causes of morbidity and mortality among people all over the world. Acute amoebic appendicitis is a rare entity. We came across a case of acute appendicitis in a young pregnant woman, which revealed colonies of Entamoeba histolytica trophozoites in the mucosal epithelium and submucosal layer of the appendix with marked evidence of acute appendicitis. This report highlights acute appendicitis of amoebic origin and emphasises the importance of thorough examination of the appendix at various levels during histopathology and about the combined treatment of appendicectomy combined with antimicrobials as the treatment of choice. Appendicectomy removes the focus of infection, and antimicrobials reduce the incidence of septic complications.  相似文献   
40.
目的探讨宝石CT碘-水基图在急性脑梗死介入治疗后的诊断价值。方法 31例急性脑梗死患者介入治疗后即刻宝石CT平扫QC图发现颅内异常高密度影,采用碘-水基图进行重建分析,同时测定高密度影碘基值、水基值,并与术后24 h普通CT复查诊断结果作比较。结果通过采用碘-水基图,17例诊断为碘对比剂渗出,14例诊断为脑出血转化,与术后24 h普通CT复查诊断结果完全一致(Kappa=1,P0.01);术后即刻碘基图之碘基值:碘对比剂渗出(32.09±5.36) g/L,脑出血转化(6.86±2.26) g/L,二者差异有统计学意义(t=53.291,P0.01);术后即刻水基图之水基值:碘对比剂渗出(1 027.93±8.29) g/L,脑出血转化(1 069.68±7.18) g/L,二者差异有统计学意义(t=-8.897,P0.01)。结论宝石CT碘-水基图可以准确诊断急性脑梗死介入治疗后颅内碘对比剂渗出和脑出血转化,值得向临床介绍推广。  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