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   104492篇
  免费   5703篇
  国内免费   1736篇
耳鼻咽喉   578篇
儿科学   1746篇
妇产科学   976篇
基础医学   10895篇
口腔科学   3823篇
临床医学   11021篇
内科学   19464篇
皮肤病学   1699篇
神经病学   9069篇
特种医学   4415篇
外国民族医学   8篇
外科学   17060篇
综合类   8429篇
现状与发展   4篇
一般理论   5篇
预防医学   6462篇
眼科学   1771篇
药学   7246篇
  44篇
中国医学   3619篇
肿瘤学   3597篇
  2023年   1230篇
  2022年   1647篇
  2021年   3467篇
  2020年   2930篇
  2019年   6673篇
  2018年   6871篇
  2017年   4982篇
  2016年   2429篇
  2015年   2399篇
  2014年   4354篇
  2013年   4764篇
  2012年   3535篇
  2011年   4007篇
  2010年   3220篇
  2009年   2998篇
  2008年   2845篇
  2007年   2878篇
  2006年   2529篇
  2005年   2145篇
  2004年   1749篇
  2003年   1675篇
  2002年   1419篇
  2001年   1354篇
  2000年   1047篇
  1999年   922篇
  1998年   686篇
  1997年   634篇
  1996年   601篇
  1995年   634篇
  1994年   575篇
  1993年   486篇
  1992年   498篇
  1991年   430篇
  1990年   335篇
  1989年   345篇
  1988年   290篇
  1987年   267篇
  1985年   3137篇
  1984年   3625篇
  1983年   3019篇
  1982年   3513篇
  1981年   3191篇
  1980年   2641篇
  1979年   2576篇
  1978年   2139篇
  1977年   1600篇
  1976年   2047篇
  1975年   1537篇
  1974年   1350篇
  1973年   1289篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
51.
52.
ObjectivesThe reduction of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery using an oxygen delivery-guided perfusion strategy (oxygen delivery strategy) for cardiopulmonary bypass management compared with a fixed flow perfusion (conventional strategy) remains controversial. The purpose of this study was to determine whether a oxygen delivery strategy would reduce the incidence of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery.MethodsWe randomly enrolled 300 patients undergoing cardiopulmonary bypass surgery. Patients were randomly assigned to a oxygen delivery strategy (maintaining a oxygen delivery index value >300 mL/min/m2 through pump flow adjustments during cardiopulmonary bypass) or a conventional strategy (a target pump flow was determined on the basis of the body surface area). The primary end point was the development of acute kidney injury. Secondary end points were the red blood cell transfusion rate and number of red blood cell units, intubation time, postoperative length of stay in the intensive care unit and the hospital, predischarge estimated glomerular filtration rate, and hospital mortality.ResultsAcute kidney injury occurred in 20 patients (14.6%) receiving the oxygen delivery strategy and in 42 patients (30.4%) receiving the conventional strategy (relative risk, 0.48; 95% confidence interval, 0.30-0.77; P = .002). The secondary end points were not significantly different between strategies. In a prespecified subgroup analysis of patients who had nadir hematocrit less than 23% or body surface area less than 1.40 m2, the oxygen delivery strategy seemed to be superior to the conventional strategy and the existence of quantitative interactions was suggested.ConclusionsAn oxygen delivery strategy for cardiopulmonary bypass management was superior to a conventional strategy with respect to preventing the development of acute kidney injury.  相似文献   
53.
[目的] 探讨研究陈念祖治疗月经病的用药规律及特点。[方法] 收集陈氏《女科要旨》《南雅堂医案》《医学从众录》中治疗月经病的处方81首,构建处方数据库。运用Excel 2010与SPSS Statistics 26.0软件对高频药物进行频数和聚类分析,并结合理论分析,提炼出陈氏治疗月经病的用药规律及特点。[结果] 收集的81首处方中,涉及药物共121味。≥6次的高频药物共32味,使用频数排前3位的是当归、白芍、茯苓。高频药物种类以补血药、补气药为主;四气以温性为首;五味以甘、苦、辛为主;归经以脾经为首,肝经次之,心经再次。聚类分析得出5组核心药组,涉及归脾汤、六君子汤、越鞠丸等方剂。用药特点:使气血化生而调和脾胃,畅气血运行而疏理心肝,守气血循经而调理冲任。[结论] 陈氏治疗月经病以气血为核心,调和脾胃气血、调畅心肝气机、调理冲任气血,多运用补血药、补气药、理气药。  相似文献   
54.
BackgroundWe assessed whether or not covalently closed circular DNA (cccDNA) levels in the background liver influence the recurrence of hepatocellular carcinoma (HCC) in patients with resolved hepatitis B virus (HBV) infection.MethodsAmong 425 patients who underwent initial hepatectomy for HCC between 2010 and 2018, a retrospective review was performed in 44 with resolved HBV infection. The clinicopathologic characteristics were analyzed for correlation with tumor recurrence. The HBV cccDNA levels were tested via a droplet digital polymerase chain reaction assay.ResultsHBV cccDNA was detected in 27 of 44 patients (61%), and the median level was 1.0 copies/1000 ng (range, 0-931.3 copies/1000 ng). Anti-HBc ≥8.9 S/CO was associated with cccDNA detection (odds ratio, 11.08; 95% confidence interval [95% CI], 2.48-49.46; P = 0.002). Twenty-eight patients (64%) developed HCC recurrence after hepatectomy. The overall 3- and 5-year recurrence-free survival rates were 45.7% and 34.3%, respectively.19 HBV cccDNA levels was not significantly associated with HCC recurrence, while the presence of multiple tumors was an independent risk fact or (hazard ratio, 6.53; 95% CI, 2.48-17.19; P < 0.001.ConclusionHBV cccDNA levels did not influence HCC recurrence after hepatectomy. Anti-HBc levels may be used as a surrogate marker for cccDNA.  相似文献   
55.
PurposeTo describe national trends in the utilization of endovascular approaches (including balloon angioplasty, atherectomy, and stent placement) for the management of femoropopliteal peripheral arterial disease (PAD).Materials and MethodsThe Medicare Physician/Supplier Procedure Summary dataset containing 100% of Part B claims was interrogated for years 2011–2019. The Current Procedural Terminology codes specific for femoropopliteal angioplasty, stent placement, and atherectomy were used to create summary statistics for utilization by year, place of service (hospital inpatient, hospital outpatient, and office-based laboratory), and provider specialty (cardiology, radiology, and surgery).ResultsThe use of atherectomy increased from 34,732 (33%) procedures in 2011 to 75,435 (53%) procedures in 2019, and atherectomy became the dominant treatment strategy for femoropopliteal PAD. The relative utilization of stent placement (36,793 [35%] to 28,899 [20%]) and angioplasty only (34,398 [32%] to 38,228 [27%]) decreased concomitantly from 2011 to 2019. By 2019, the use of atherectomy was twofold higher in office-based laboratories than in the outpatient hospital setting (44,767 and 20,901, respectively). Treatment strategy varied by provider specialty in 2011 when cardiologists used atherectomy most frequently (17,925 [43%]), whereas radiologists used angioplasty alone (5,928 [6%]) and surgeons stented (18,009 [37%]) most frequently. By 2019, all specialties utilized atherectomy most frequently (29,564 [59%] for cardiology, 10,912 [58%] radiology, and 33,649 [47%] surgery).ConclusionsThe national approach to endovascular management of femoropopliteal PAD has changed since 2011 toward an implant-free strategy, including a multifold increase in the use of atherectomy. Discordant rates of atherectomy use between the ambulatory hospital and office-based settings highlight the need for comparative effectiveness studies to guide management.  相似文献   
56.
PurposeTo compare the technical success of antegrade uteral stent (AUS) and retrograde ureteral stent (RUS) placements in patients with malignant ureteral obstruction (MUO) and to determine the predictors of technical failure of RUS.Materials and MethodsThis study retrospectively included 61 AUS placements (44 patients) performed under fluoroscopic guidance and 76 RUS placements (55 patients) performed under cystoscopic guidance in patients with MUO from January 2019 to December 2020. Technical success rates of the 2 techniques were compared using inverse probability of treatment weighting (IPTW) analysis. Logistic regression was used to identify predictive factors for technical failures.ResultsTechnical success was achieved in 98.4% of the AUS group and 47.4% of the RUS group. After stabilized IPTW, the technical success rate was higher in the AUS group than in the RUS group (adjusted risk difference, 49.4%; 95% confidence interval [CI], 35.4%–63.1%). The independent predictors for technical failure of the RUS procedure were age of ≥65 years (odds ratio [OR], 5.56; 95% CI, 1.73–21.27), ureteral orifice invasion (OR, 4.21; 95% CI, 1.46–13.46), and extrinsic cancer (OR, 15.58; 95% CI, 2.92–111.81).ConclusionsThe technical success rate of AUS placement was higher than that of RUS placement in patients with MUO. RUS failure was associated with age of ≥65 years, cancer with ureteral orifice invasion, and extrinsic ureteral obstruction.  相似文献   
57.
Neonates with progressive respiratory failure should be referred early for subspecialty evaluation and lung transplantation consideration. ECMO should be considered for patients with severe cardiopulmonary dysfunction and a high likelihood of death while on maximal medical therapy, either in the setting of reversible medical conditions or while awaiting lung transplantation. While ECMO offers hope to neonates that experience clinical deterioration while awaiting transplant, the risks and benefits of this intervention should be considered on an individual basis. Owing to the small number of infant lung transplants performed yearly, large studies examining the outcomes of various bridging techniques in this age group do not exist. Multiple single-centre experiences of transplanted neonates have been described and currently serve as guidance for transplant teams. Future investigation of outcomes specific to neonatal transplant recipients bridged with advanced devices is needed.  相似文献   
58.
《中国现代医生》2020,58(13):39-42
目的观察卡托普利对左向右分流先天性心脏病肺动脉高压患者的血液动力学影响。方法随机选取2018年5月~2019年5月我院左向右分流先天性心脏病患者30例,给予所有患者卡托普利治疗,治疗前、治疗后3~5 d分别采用彩色多普勒超声诊断仪(麦瑞Resona 75型)对患者的血液动力学指标进行检测,然后统计分析30例患者治疗前后的血液动力学。结果 30例患者治疗后的PAMP、AMP、TSR均显著低于治疗前(P0.05)。30例患者中治疗后19例TPR/TSR上升,11例TPR/TSR下降。TPR/TSR上升患者治疗后的AMP、TSR、Qp/Qs均显著低于治疗前(P0.05),TPR/TSR、Qs均显著高于治疗前(P0.05);TPR/TSR下降患者治疗后的PAMP、AMP、PAMP/AMP、TPR、TPR/TSR均显著低于治疗前(P0.05),Qp/Qs显著高于治疗前(P0.05)。治疗前TPR/TSR上升患者的TPR/TSR显著低于TPR/TSR下降患者(P0.05),但二者的PAMP、AMP、PAMP/AMP、TPR、TSR、Qp、Qs、Qp/Qs之间的差异均不显著(P0.05)。结论卡托普利能够有效降低左向右分流先天性心脏病患者的肺动脉高压,但会提升患者的Qp/Qs。  相似文献   
59.
目的建立一测多评法同时测定艾纳香Blumea balsamifera(L.)DC.油中β⁃蒎烯、β⁃石竹烯、樟脑、α⁃石竹烯和龙脑5种成分的含有量。方法艾纳香油乙酸乙酯提取物的分析采用PEG⁃20 M柱(30 m×0.32 mm,1.0μm);程序升温;载气为高纯氮气(99.999%);FID检测器温度240℃,进样口温度240℃。以龙脑为内标,计算其他4种成分的相对校正因子,再测定其含有量。结果蒎烯、β⁃石竹烯、樟脑、α⁃石竹烯和龙脑分别在1.49~59.5μg/mL(r=0.9996)、2.22~88.8μg/mL(r=0.9996)、6.48~259μg/mL(r=0.9997)、3.64~146μg/mL(r=0.9991)和16.4~656μg/mL(r=0.9998)范围内线性关系良好,平均加样回收率(RSD)分别为97.4%(0.9%)、99.0%(1.3%)、98.9%(0.9%)、97.6%(0.9%)和99.7%(1.0%)。一测多评法所得结果接近于外标法。结论该方法准确稳定,重复性好,可用于艾纳香油的质量控制。  相似文献   
60.
赵军  师建平  段迎喜 《河南中医》2020,40(3):344-347
脾胃之气的充足和清气的正常升发对人体生命活动具有决定意义,饮食、劳倦、情志、外感对脾胃的损伤往往影响中焦脾胃清阳的生成及升发,脾胃病以本虚为主,多由虚致实,虚实兼有,病机关键为升降失常,脾气不升。肝对人体气机具有升宣调畅作用,脾气的升清有赖于肝气升发促进。在补中益气的同时,要补肝益气。同时,肾精气充盈,元气方能充沛,肾阳又主气化,肾精不封、肾气不固者必致肾气下陷。治疗须温肾壮阳、升阳举陷。脾胃中气不足,气机郁滞而化火,并脾之清气下流而生泄泻,相火乘其土位更加耗伤中焦清阳之气。段老师特别注重脾气生长、升发,只有清阳升发,脾气上升,元气才能充沛,阴火才会收敛潜藏。治疗时运用辛甘之药以补益中气,借升阳风药以助肝胆之用,补其中而升其阳,升浮变通,使生长之气健旺。段老师善于运用甘温之品,温补中气,升发清阳。  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