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   20110篇
  免费   1497篇
  国内免费   815篇
耳鼻咽喉   29篇
儿科学   582篇
妇产科学   179篇
基础医学   1040篇
口腔科学   51篇
临床医学   4213篇
内科学   3995篇
皮肤病学   113篇
神经病学   918篇
特种医学   1435篇
外国民族医学   1篇
外科学   3676篇
综合类   3199篇
现状与发展   4篇
预防医学   653篇
眼科学   167篇
药学   1196篇
  20篇
中国医学   428篇
肿瘤学   523篇
  2024年   36篇
  2023年   324篇
  2022年   563篇
  2021年   788篇
  2020年   808篇
  2019年   724篇
  2018年   674篇
  2017年   692篇
  2016年   720篇
  2015年   690篇
  2014年   1328篇
  2013年   1300篇
  2012年   1124篇
  2011年   1133篇
  2010年   1030篇
  2009年   1000篇
  2008年   947篇
  2007年   959篇
  2006年   939篇
  2005年   801篇
  2004年   642篇
  2003年   581篇
  2002年   530篇
  2001年   497篇
  2000年   422篇
  1999年   331篇
  1998年   324篇
  1997年   300篇
  1996年   258篇
  1995年   243篇
  1994年   219篇
  1993年   163篇
  1992年   171篇
  1991年   129篇
  1990年   133篇
  1989年   93篇
  1988年   112篇
  1987年   98篇
  1986年   87篇
  1985年   110篇
  1984年   73篇
  1983年   43篇
  1982年   65篇
  1981年   48篇
  1980年   29篇
  1979年   31篇
  1978年   28篇
  1977年   21篇
  1976年   23篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous‐wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end‐hole catheter was required to determine the subvalvular and valvular components of the obstruction.  相似文献   
4.
易栓症是外科围手术期静脉血栓栓塞症(VTE)的防治重点。对于接受手术的止凝血障碍病人,需要谨慎评估VTE的个体风险,同时兼顾手术和麻醉的性质、出血障碍类型和严重程度、年龄、体重指数(BMI)、血栓形成史、恶性肿瘤和其他高危共患病。VTE风险应与已知出血障碍病人使用抗凝相关的出血风险平衡。实验室检查有助于发现和判断血栓与出血的病因,对病人的止凝血代偿能力作出评估,并对抗凝药物的合理使用提供依据。对上述病人,建议术后不常规使用药物预防血栓,尤其是血友病病人,但围手术期因子替代和止血药物的过度应用仍存在导致血栓的风险。使用低分子肝素(LMWH)和直接口服抗凝剂前应评估肾小球滤过率。当血小板计数<50×109/L,LMWH短期减量应用可能相对安全,监测抗Хa水平可用于调整中重度血小板减少症病人LMWH的剂量。主要消化道出血停止和重新使用华法林应至少相隔7 d。对于高血栓栓塞风险和术后高出血风险病人,术后当晚和术后第1天减量应用直接口服抗凝剂是一种可取的做法。  相似文献   
5.
6.
Purpose: To describe how central venous access devices (CVADs) are utilized for ambulatory oncology patients and to evaluate the rate of complications. Method: Single institution retrospective study of oncology patients with CVADs who received systemic treatment at the Walker Family Cancer Centre (WFCC) between 1 January and 31 December 2018. Results: A total of 480 CVADS were placed in 305 patients, of which 408 (85%) were peripherally inserted central catheters (PICCs) and 72 (15%) were implanted vascular access devices (PORTs). The incidence of early and late complications was 9% and 24%, respectively. For the entire cohort, the rate of venous thromboembolism (VTE) was 16%, of which 9% were CVAD-related thrombosis (CRTs) and 7% were distant VTE. The CRT rates were similar for PICCs and PORTs (9% vs. 7%). A total of 6% of CVADs were complicated by infection (i.e., localized infections and bacteremia), with a total infection rate of 0.43 and 0.26 per 1000 indwelling days for PICCs and PORTs, respectively. The incidence of central line associated bloodstream infections (CLABSI) was greater for PICCs than PORTs, at a rate of 0.22 compared with 0.08 per 1000 indwelling days, respectively. The premature catheter removal rate was 26% for PICCs and 18% for PORTs. PORTs required more additional hospital visits. Conclusions: PICCs were utilized more frequently than PORTs and had a higher rate of premature removal. The rates of VTE and CRT were similar for both CVAD types. PORTs had a lower rate of infection per 1000 indwelling days. However, the management of PORT related complications required more visits to the hospital and oncology clinic.  相似文献   
7.
ObjectiveThe objective of this study was to investigate the association between morphological variation and postsurgical pulmonary vein (PV) stenosis (PPVS) in patients with cardiac total anomalous pulmonary venous connection (TAPVC).MethodsThis single-center, retrospective study included 168 pediatric patients who underwent surgical repair of cardiac TAPVC from 2013 to 2019 (connection to the coronary sinus [CS], n = 136; connection directly to the right atrium [RA], n = 32). Three-dimensional computed tomography modeling and geometric analysis were performed to investigate the morphological features; their relevance to the PPVS was examined.ResultsThe connection type had no association with PPVS (CS type: 18% vs right atrial type: 19%; P = .89) but there was a higher incidence of PPVS in patients with a single PV orifice than > 1 orifice (P < .001). Confluence-to-total PV area ratio (hazard ratio, 4.78, 95% CI, 1.86-12.32; P = .001) and length of drainage route (hazard ratio, 1.22; 95% CI, 1.14-1.31; P < .001) had a 4- and 1-fold increase in the risk for PPVS in the CS type after adjustment for age and preoperative pulmonary venous obstruction. In the right atrial type, those with anomalous PV return to the RA roof were more likely to develop PPVS than to the posterior wall of the RA (P < .001).ConclusionsThe number of inter-junction PV orifice correlated with PPVS development in cardiac TAPVC. The confluence-to-total PV ratio, length of drainage route, and anomalous PV return to the RA roof are important predictors for PPVS. Morphological subcategorization in this clinical setting can potentially assist in surgical decision-making.  相似文献   
8.
Rifamycins (rifampin, rifabutin, and rifapentine) play an essential role in the treatment of mycobacterial and some nonmycobacterial infections. They also induce the activity of various drug transporting and metabolizing enzymes, which can impact the concentrations and efficacy of substrates. Many anticoagulant and antiplatelet (AC/AP) agents are substrates of these enzymes and have narrow therapeutic indices, leading to risks of thrombosis or bleeding when coadministered with rifamycins. The objective of this systematic review was to evaluate the effects on AC/AP pharmacokinetics, laboratory markers, and clinical safety and efficacy of combined use with rifamycins. A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidance was performed. The PubMed, Embase, and Web of Science databases were queried for English-language reports on combination use of rifamycins and AC/AP agents from database inception through August 2021. The 29 studies identified examined warfarin (n = 17), direct oral anticoagulants (DOACs) (n = 8), and antiplatelet agents (n = 4) combined with rifampin (n = 28) or rifabutin (n = 1). Eleven studies were case reports or small case series; 14 reported on pharmacokinetic or laboratory markers in healthy volunteers. Rifampin-warfarin combinations led to reductions in warfarin area under the curve (AUC) of 15%–74%, with variability by warfarin isomer and study. Warfarin dose increases of up to 3–5 times prerifampin doses were required to maintain coagulation parameters in the therapeutic range. DOAC AUCs were decreased by 20%–67%, with variability by individual agent and with rifampin versus rifabutin. The active metabolite of clopidogrel increased substantially with rifampin coadministration, whereas prasugrel was largely unaffected and ticagrelor saw decreases. Our review suggests most combinations of AC/AP agents and rifampin are problematic. Further studies are required to determine whether rifabutin or rifapentine could be safe alternatives for coadministration with AC/AP drugs.  相似文献   
9.
Patients with active cancer are at an increased risk of arterial and venous thromboembolism (VTE) and bleeding events. Historically, in patients with cancer, low molecular weight heparins have been preferred for treatment of VTE, whereas warfarin has been the standard anticoagulant for stroke prevention in patients with atrial fibrillation (AF). More recently, direct oral anticoagulants (DOACs) have been demonstrated to reduce the risk of venous and arterial thromboembolism in large randomized clinical trials of patients with VTE and AF, respectively, thus providing an attractive oral dosing option that does not require routine laboratory monitoring. In this review, we summarize available clinical trial data and guideline recommendations, and outline a practical approach to anticoagulation management of VTE and AF in cancer.  相似文献   
10.
The Impella 5.0, a percutaneously inserted left ventricular assist device, has been used to support patients who have severe heart failure or who are undergoing high-risk percutaneous coronary intervention. We report our surgical placement of the Impella 5.0, through a graft sewn to the aorta, to unload the left ventricle of a 59-year-old man who was undergoing venoarterial extracorporeal membrane oxygenation for postcardiotomy shock. The patient underwent successful placement of a long-term left ventricular assist device before his discharge from the hospital. The versatility of the Impella 5.0 is exemplified in this patient who was successfully bridged to long-term support.  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