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   46462篇
  免费   1815篇
  国内免费   1349篇
耳鼻咽喉   1650篇
儿科学   986篇
妇产科学   685篇
基础医学   1306篇
口腔科学   926篇
临床医学   4646篇
内科学   3142篇
皮肤病学   283篇
神经病学   1577篇
特种医学   1391篇
外国民族医学   7篇
外科学   15319篇
综合类   8431篇
现状与发展   1篇
预防医学   2638篇
眼科学   821篇
药学   3037篇
  70篇
中国医学   624篇
肿瘤学   2086篇
  2024年   59篇
  2023年   570篇
  2022年   1120篇
  2021年   1352篇
  2020年   1267篇
  2019年   1225篇
  2018年   1242篇
  2017年   1106篇
  2016年   1387篇
  2015年   1498篇
  2014年   3137篇
  2013年   2796篇
  2012年   3077篇
  2011年   3282篇
  2010年   2966篇
  2009年   2916篇
  2008年   2730篇
  2007年   2921篇
  2006年   2560篇
  2005年   2302篇
  2004年   1846篇
  2003年   1493篇
  2002年   1286篇
  2001年   1067篇
  2000年   770篇
  1999年   523篇
  1998年   435篇
  1997年   393篇
  1996年   327篇
  1995年   258篇
  1994年   210篇
  1993年   168篇
  1992年   134篇
  1991年   112篇
  1990年   108篇
  1989年   65篇
  1988年   74篇
  1987年   80篇
  1986年   62篇
  1985年   101篇
  1984年   87篇
  1983年   60篇
  1982年   62篇
  1981年   55篇
  1980年   56篇
  1979年   59篇
  1978年   60篇
  1976年   32篇
  1975年   36篇
  1974年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
IntroductionTranssphenoidal surgical removal is the preferred treatment of most pituitary adenomas. Postoperative cerebrospinal fluid (CSF) leakage is the leading cause of morbidity after this procedure, with an incidence rate that varies from 0,5-15% in the main published series.ObjectivesThe primary objective of this study was to establish the incidence of postoperative CSF leakage in a sample of surgeries performed at the University Hospital of La Ribera by the same surgical team. The secondary objectives were to: ascertain the distinctive features between patients with and without postoperative CSF leakage, identify risk factors for their development, evaluate the relationship between the surgical technique for closing the sella turcica and the onset of postoperative CSF leakage and evaluate different treatment regimens for this complication.MethodsThe data of 302 consecutive transsphenoidal surgical procedures for pituitary adenoma removal which were performed between 1999 and 2017 were retrospectively reviewed.Results and conclusionsThe incidence of postoperative CSF leakage in our series was 2,3% (in accordance with similar published studies). It was possible to correlate intraoperative CSF leakage with two variables: pituitary macroadenoma and tumors with suprasellar extension (P < .005). This correlation did not exist for postoperative CSF leakage. We found a statistically significant correlation between intraoperative and postoperative CSF leakage (P < .005). Due to the low incidence of postoperative CSF leakage in our series, it was not possible to identify risk factors for its development.  相似文献   
32.
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   
33.
目的 前瞻性评估T1~T2期乳腺癌保乳术后化疗后程大分割放疗的不良反应和耐受性,以及在缩短治疗时间、减轻患者经济负担等方面的价值。方法 共入组20例T1~T2期乳腺癌保乳术后患者,所有患者于末次多西他赛化疗前开始大分割放疗。观察急性放射反应、治疗完成率及无病生存率、住院时间及住院费用等。结果 治疗完成率100%。主要不良反应为血液学毒性(白细胞减少)及皮肤反应,患者均可耐受。中位随访时间为30.1个月,随访率100%。美容效果良好率100%。平均总治疗时间为4周,总住院治疗费用节省约1万元。21个月无病生存率为100%。结论 T1~T2期乳腺癌保乳术后可耐受同步大分割放化疗,局部控制好,美容效果佳,且具有较高的卫生经济学价值。  相似文献   
34.
Background and Study AimsIn developing countries, endemic indications, blood shortages, and the scarcity of liver surgeons and intensive care providers can affect liver resection (LR) outcomes, but these have been rarely addressed in the literature. Therefore, in this study we determined risk factors for major complications after LR in a North African general surgery and teaching department.Patients and MethodsFrom January 2010 to December 2015, 213 consecutive LRs were performed on 203 patients. All patients underwent a postoperative follow-up of >90 days. Postoperative complications were assessed according to the Clavien–Dindo (CD) classification of surgical complications. A score of CD ≥III is considered as major postoperative complications. In this study, we analyzed the variables assumed to affect these complications.ResultsThe overall 90-day complication rate was 35.7% (n = 76), including a CD ≥III of 14% (n = 30) and a mortality rate of 6.1% (n = 14). According to the multivariate analysis, a preoperative performance status (PS) of ≥2 (P = 0.011; odds ratios [OR], 6.8; 95% confidence intervals [CI], 1.55–29.8), an estimated intraoperative blood loss of >500 ml (P = 0.002; OR, 3.71; 95% CI, 1.23–11.20), and bilioenteric anastomosis (P < 0.004; OR, 7.76; 95% CI, 1.5–3.89) were independent risk factors for major complications after LR.ConclusionWe recommend that, in the setting of a non-Eastern/non-Western general surgery and teaching department, patients with a PS of ≥2 should undergo a specific selection and preoperative optimization protocol; intermittent clamping indications should be extended; and special attention should paid to patients undergoing LR associated with biliary reconstruction, such as for perihilar cholangiocarcinoma.  相似文献   
35.
室管膜瘤是一种原发于神经上皮的中枢神经系统肿瘤,病变累及脑和脊髓,多发于儿童。基因分型的新分类方法,为室管膜瘤的治疗和预后评估提供了更为可靠的依据。室管膜瘤对辅助治疗的敏感性低是造成患儿预后较差的重要原因之一。该文对近年来儿童室管膜瘤的分型、诊断、治疗策略等进行综述。  相似文献   
36.
目的探讨预见习在精神病教学中的作用。方法选取120名本科学生,随机分为预见习组(n=60)和对照组(n=60)。预见习组在学习精神病学理论课程前一学期开始实施带教老师带领学生预见习、见习、实习全程教学,对比两组学生实践操作、理论知识成绩和学生满意度。结果干预后,导师制预见习组实践操作和理论知识成绩显著高于对照组(P<0.05)。导师制预见习组学生满意度显著高于对照组(P<0.05)。结论预见习教学有助于学生全面发展,提高精神病学教学水平。  相似文献   
37.
《Clinical neurophysiology》2019,130(9):1562-1569
ObjectiveConventional deep brain stimulation (DBS) systems with ring-shaped leads generate spherical electrical fields. In contrast, novel directional leads use segmented electrodes. Aim of this study was to quantify the impedance variations over time in subjects with the directional Cartesia-Boston® system.MethodsImpedance records, programming settings, and clinical data of 11 consecutive Parkinsonian patients implanted with DBS directional leads in two Italian centers (Udine and Vicenza) were retrospectively evaluated. Data were collected before starting stimulation (in the operating room and at days 5 and 40) and after switching stimulation on at the successive follow-up visits (1, 6 and 12 months).ResultsDirectional leads have significantly higher impedance than ring leads. Stimulated contacts had always lower impedance compared to non-stimulated contacts. Before DBS-on, all contacts had higher impedance in the operating room, with an initial decrease five days post-surgery and a subsequent increase at day 40, more evident for directional contacts. The impedance of directional leads increased post-implantation at 1 and 6 months with a plateau at 12 months.ConclusionsThere was a significant difference between the directional and ring leads at baseline (before activation of DBS) and during follow-up (chronic DBS).SignificanceOur study reveals new information about the impedance of segmented electrodes that is useful for patient management during the initial test period, as well as during long-term DBS follow-up.  相似文献   
38.
目的:探究原发性肝癌患者手术切除术后早期复发影响因素分析。方法:对广州市番禺区中医院2017年2月-2019年2月收治的原发性肝癌患者98例进行回顾性分析,依据各项临床指标分析手术切除术后早期复发的影响因素。结果:原发性肝癌患者经由手术切除后出现复发的可能性较高,同时手术切缘有残留、包膜不完整、肿瘤结节、心理因素、甲胎蛋白、血管侵犯、肝硬化及肿瘤直径等均是影响原发性肝癌手术期后再复发的高危因素。结论:原发性肝癌通常具有术后复发的生物学特性,依据对手术切除术之后早期复发因素的分析,对手术风险与治疗方案进行充分评估,同时要求患者进行定期复查及随访等工作,可对患者手术成功以及并发症的防治等均具有积极意义。  相似文献   
39.
Background and objectivesThe ideal timing of tranexamic acid administration in total knee arthroplasty with tourniquet remains unclear. Our primary objective was to prove if administering it before surgical incision, instead of before releasing the tourniquet, reduces postoperative bleeding. A second objective was to determine whether a second dose reduces post-operative bleeding.Material and methodsA prospective, double-blind clinical trial was performed on 212 patients scheduled for total knee arthroplasty. They were randomised into 4 groups. Tranexamic acid was administered before the surgical incision in “pre-induction groups” (1 and 2), and just before the tourniquet release in “pre-release groups” (3 and 4). Groups 2 and 4 received a second dose 3 hours post-surgery. Main outcome was postoperative bleeding (visible blood loss and calculated total bleeding). Secondary outcomes were haemoglobin variations, complications and transfusion rate.ResultsThe mean calculated total bleeding was 1563 ml (95%CI: 1445 to 1681) in preinduction groups versus 1576 ml (95%CI: 1439 to 1713) in pre-release groups (P = .9); 1579 ml (95%CI: 1452 to 1706) in single-dose groups versus 1559 ml (95%CI: 1431 to 1686) in double-dose groups (P = .82). One patient was transfused. The mean haemoglobin at discharge was 10.4 g/dl (95%CI: 10.2 to 10.7) in singledose groups versus 10.8 (95%CI: 10.6 to 11.1) in double-dose groups (P = .06).ConclusionsThere were no differences in bleeding or transfusion regarding the time of tranexamic acid administration. The second dose had not impact on outcomes.Trial registration: EudraCT 2016-000071-24.  相似文献   
40.
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