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   88177篇
  免费   5483篇
  国内免费   2470篇
耳鼻咽喉   387篇
儿科学   1111篇
妇产科学   825篇
基础医学   4971篇
口腔科学   811篇
临床医学   11715篇
内科学   25932篇
皮肤病学   195篇
神经病学   3618篇
特种医学   5975篇
外国民族医学   3篇
外科学   13079篇
综合类   15471篇
预防医学   2326篇
眼科学   532篇
药学   5781篇
  60篇
中国医学   2601篇
肿瘤学   737篇
  2024年   58篇
  2023年   1289篇
  2022年   1848篇
  2021年   3282篇
  2020年   3284篇
  2019年   2684篇
  2018年   2685篇
  2017年   2494篇
  2016年   2513篇
  2015年   2816篇
  2014年   6149篇
  2013年   5943篇
  2012年   5034篇
  2011年   5573篇
  2010年   4645篇
  2009年   4712篇
  2008年   4781篇
  2007年   5048篇
  2006年   4441篇
  2005年   3760篇
  2004年   3066篇
  2003年   2567篇
  2002年   2134篇
  2001年   2001篇
  2000年   1530篇
  1999年   1272篇
  1998年   1259篇
  1997年   1187篇
  1996年   890篇
  1995年   980篇
  1994年   807篇
  1993年   734篇
  1992年   649篇
  1991年   549篇
  1990年   446篇
  1989年   384篇
  1988年   372篇
  1987年   335篇
  1986年   282篇
  1985年   322篇
  1984年   255篇
  1983年   149篇
  1982年   213篇
  1981年   167篇
  1980年   124篇
  1979年   117篇
  1978年   92篇
  1977年   73篇
  1976年   54篇
  1975年   32篇
排序方式: 共有10000条查询结果,搜索用时 31 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.

Background

Glutamate plays a key role for post-ischaemic recovery of myocardial metabolism. According to post hoc analyses of the two GLUTAMICS trials, patients without diabetes benefit from glutamate with less myocardial dysfunction after coronary artery bypass surgery (CABG). Copeptin reflects activation of the Arginine Vasopressin system and is a reliable marker of heart failure but available studies in cardiac surgery are limited. We investigated whether glutamate infusion is associated with reduced postoperative rises of plasma Copeptin (p-Copeptin) after CABG.

Methods

A prespecified randomised double-blind substudy of GLUTAMICS II. Patients had left ventricular ejection fraction ≤0.30 or EuroSCORE II ≥3.0 and underwent CABG ± valve procedure. Intravenous infusion of 0.125 M L-glutamic acid or saline at 1.65 mL/kg/h was commenced 10–20 min before the release of the aortic cross-clamp and then continued for another 150 min P-Copeptin was measured preoperatively and postoperatively on day one (POD1) and day three. The primary endpoint was an increase in p-Copeptin from the preoperative level to POD1. Postoperative stroke ≤24 h and mortality ≤30 days were safety outcomes.

Results

We included 181 patients of whom 48% had diabetes. The incidence of postoperative mortality ≤30 days (0% vs. 2.1%; p = .50) and stroke ≤24 h (0% vs. 3.2%; p = .25) did not differ between the glutamate group and controls. P-Copeptin increased postoperatively with the highest values recorded on POD1 without significant inter-group differences. Among patients without diabetes, p-Copeptin did not differ preoperatively but postoperative rise from preoperative level to POD1 was significantly reduced in the glutamate group (73 ± 66 vs. 115 ± 102 pmol/L; p = .02). P-Copeptin was significantly lower in the Glutamate group on POD1 (p = .02) and POD 3 (p = .02).

Conclusions

Glutamate did not reduce rises of p-Copeptin significantly after moderate to high-risk CABG. However, glutamate was associated with reduced rises of p-Copeptin among patients without diabetes. These results agree with previous observations suggesting that glutamate mitigates myocardial dysfunction after CABG in patients without diabetes. Given the exploratory nature of these findings, they need to be confirmed in future studies.  相似文献   
3.
4.
ObjectiveNew-onset postoperative atrial fibrillation (POAF) after cardiac surgery is common, with rates up to 60%. POAF has been associated with early and late stroke, but its association with other cardiovascular outcomes is less known. The objective was to perform a meta-analysis of the studies reporting the association of POAF with perioperative and long-term outcomes in patients with cardiac surgery.MethodsWe performed a systematic review and a meta-analysis of studies that presented outcomes for cardiac surgery on the basis of the presence or absence of POAF. MEDLINE, EMBASE, and the Cochrane Library were assessed; 57 studies (246,340 patients) were selected. Perioperative mortality was the primary outcome. Inverse variance method and random model were performed. Leave-one-out analysis, subgroup analyses, and metaregression were conducted.ResultsPOAF was associated with perioperative mortality (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.58-2.33), perioperative stroke (OR, 2.17; 95% CI, 1.90-2.49), perioperative myocardial infarction (OR, 1.28; 95% CI, 1.06-1.54), perioperative acute renal failure (OR, 2.74; 95% CI, 2.42-3.11), hospital (standardized mean difference, 0.80; 95% CI, 0.53-1.07) and intensive care unit stay (standardized mean difference, 0.55; 95% CI, 0.24-0.86), long-term mortality (incidence rate ratio [IRR], 1.54; 95% CI, 1.40-1.69), long-term stroke (IRR, 1.33; 95% CI, 1.21-1.46), and longstanding persistent atrial fibrillation (IRR, 4.73; 95% CI, 3.36-6.66).ConclusionsThe results suggest that POAF after cardiac surgery is associated with an increased occurrence of most short- and long-term cardiovascular adverse events. However, the causality of this association remains to be established.  相似文献   
5.
6.
PurposeTo review and to compare indirectly the outcomes of minimally invasive therapies for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia.Materials and MethodsA literature search via Medline and Cochrane Central databases was completed for randomized control studies published between January 2000 to April 2020 for the following therapies: Rezum, Urolift, Aquablation, and prostatic artery embolization (PAE). Data on the following variables were included: International prostate symptom score (IPSS), maximum urinary flow rate, quality of life, and postvoid residual (PVR). Standard mean differences between treatments were compared through a meta-analysis using transurethral resection of the prostate (TURP) to assess differences in treatment effect.ResultsThere was no significant difference in outcomes between therapies for IPSS at the 3, 6, and 12-month follow ups. Although outcomes for Rezum were only available out to 3 months, there were no consistently significant differences in outcomes when comparing Aquablation versus PAE versus Rezum. TURP PVR was significantly better than Urolift at 3, 6, and 12 months. No significant differences in minor or major adverse events were noted.ConclusionAlthough significant differences in outcomes were limited, Aquablation and PAE were the most durable at 12 months. PAE has been well studied on multiple randomized control trials with minimal adverse events while Aquablation has limited high quality data and has been associated with bleeding-related complications.  相似文献   
7.
目的:评价吸气肌训练在冠状动脉旁路移植术(coronary artery bypass grafting, CABG)术后患者中的应用效果。方法:检索Web of Science、Cochrane Library、EMBASE、PubMed、CINAHL、中国知网、中国生物医学文献数据库、万方和维普国内外数据库中自建库至2022年2月15日内有关CABG术后患者吸气肌训练的随机对照试验,使用RevMan 5.3进行Meta分析。结果:经筛选最终纳入7篇英文文献,3篇中文文献,共410例CABG术后患者。分析结果显示,CABG术后吸气肌训练可有效提高患者术后最大吸气压力[加权均数差值(WMD)=19.36, 95%CI:11.77~26.95, P<0.001]、最大呼气压力(WMD=24.14, 95%CI:4.13~44.16, P=0.02)、第1 s用力呼气容积(WMD=0.31,95%CI:0.19~0.44,P<0.001)、动脉氧分压(WMD=6.75, 95%CI:2.37~11.12, P=0.003)、峰值摄氧量(WMD=-3.31, 95%CI:-4.67~-1.95, P<0.001)以及6分钟步行距离(WMD=79.14, 95%CI:41.97~116.31, P<0.001),缩短机械通气时间(WMD=-5.54, 95%CI:-7.47~-3.62, P<0.001)和住院时间(WMD=-1.26, 95%CI:-1.85~-0.66,P<0.001)。结论:对于CABG患者,术后吸气肌训练为简单且易接受的II期心脏康复方式,可最大限度提高其术后身体机能,降低不良事件风险,改善远期预后。  相似文献   
8.
目的 建立妊娠11~13+6周子宫动脉多普勒参数在低危人群中的正常参考值,同时评估其对不良妊娠结局的预测价值。方法 收集2019年6月至2021年6月于我院行产前超声检查的妊娠11~13+6周孕妇,根据妊娠结局分组。收集两侧子宫动脉多普勒指标,包括搏动指数(PI)、阻力指数(RI)、舒张早期是否有切迹,以及孕妇基本临床资料和胎儿出生信息,将以上相关参数进行统计学分析。结果 最终纳入800例孕妇,包括正常妊娠结局组740例和不良妊娠结局组60例。两组孕妇体质量指数(BMI)、分娩孕周和胎儿出生体质量比较,差异均有统计学意义(均P<0.05)。随着孕周的增加,子宫动脉两侧平均搏动指数(mPI)、平均阻力指数(mRI)和两侧舒张早期切迹检出率均呈逐渐下降的趋势。ROC曲线分析显示,mPI、mRI及两侧舒张早期切迹预测妊娠结局的曲线下面积(AUC)分别为0.542、0.574、0.521,三者联合预测妊娠结局的AUC为0.648;孕妇BMI、年龄mPI、mRI及两侧舒张早期切迹预测妊娠结局的AUC为0.751。结论 建立了低危人群在妊娠11~13+6周子宫动脉多普勒参数的正常参考值范围。在妊娠11~13+6周单纯应用子宫动脉多普勒参数预测妊娠结局的价值有限,将子宫动脉参数与临床相关指标结合可提高对不良妊娠结局的预测价值。  相似文献   
9.
10.
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