全文获取类型
收费全文 | 54629篇 |
免费 | 4700篇 |
国内免费 | 1230篇 |
专业分类
耳鼻咽喉 | 825篇 |
儿科学 | 496篇 |
妇产科学 | 160篇 |
基础医学 | 1997篇 |
口腔科学 | 2234篇 |
临床医学 | 8611篇 |
内科学 | 6099篇 |
皮肤病学 | 191篇 |
神经病学 | 2895篇 |
特种医学 | 17632篇 |
外国民族医学 | 27篇 |
外科学 | 4851篇 |
综合类 | 6150篇 |
现状与发展 | 4篇 |
预防医学 | 842篇 |
眼科学 | 3084篇 |
药学 | 1390篇 |
8篇 | |
中国医学 | 155篇 |
肿瘤学 | 2908篇 |
出版年
2024年 | 74篇 |
2023年 | 1040篇 |
2022年 | 1503篇 |
2021年 | 2435篇 |
2020年 | 2042篇 |
2019年 | 1816篇 |
2018年 | 1857篇 |
2017年 | 1768篇 |
2016年 | 1879篇 |
2015年 | 1892篇 |
2014年 | 3735篇 |
2013年 | 2976篇 |
2012年 | 3298篇 |
2011年 | 3529篇 |
2010年 | 3098篇 |
2009年 | 3210篇 |
2008年 | 3129篇 |
2007年 | 3152篇 |
2006年 | 2815篇 |
2005年 | 2395篇 |
2004年 | 1945篇 |
2003年 | 1614篇 |
2002年 | 1321篇 |
2001年 | 1189篇 |
2000年 | 934篇 |
1999年 | 797篇 |
1998年 | 607篇 |
1997年 | 625篇 |
1996年 | 491篇 |
1995年 | 468篇 |
1994年 | 417篇 |
1993年 | 304篇 |
1992年 | 245篇 |
1991年 | 207篇 |
1990年 | 195篇 |
1989年 | 190篇 |
1988年 | 164篇 |
1987年 | 177篇 |
1986年 | 125篇 |
1985年 | 155篇 |
1984年 | 161篇 |
1983年 | 94篇 |
1982年 | 140篇 |
1981年 | 114篇 |
1980年 | 78篇 |
1979年 | 61篇 |
1978年 | 34篇 |
1977年 | 39篇 |
1976年 | 23篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
61.
《Journal of Cardiovascular Computed Tomography》2019,13(5):254-260
Invasive coronary plaque imaging such as intravascular ultrasound and optical coherence tomography has been widely used to observe culprit or non-culprit coronary atherosclerosis, as well as optimize stent sizing, apposition and deployment. Coronary computed tomographic angiography (CTA) is non-invasively available to assess coronary artery disease (CAD) and has become an appropriate strategy to evaluate patients with suspected CAD. Given recent technologies, semi-automated plaque software is available to identify coronary plaque stenosis, volume and characteristics and potentially allows to be used for the assessment of more details of plaque information, progression and future risk as a surrogate tool of the invasive imaging modalities. This review article aims to focus on various evidence in coronary plaque imaging by coronary CTA and describes how accurate coronary CTA can classify coronary atherosclerosis. 相似文献
62.
Dominic Gehweiler Teun Teunis Viktor Varjas Dirk Kerstan Boyko Gueorguiev Lukas Kamer Hansrudi Noser 《Clinical anatomy (New York, N.Y.)》2019,32(3):361-368
Distal radius fractures are common and fracture patterns and fixation can be complex. Computerized anatomy evaluation (CAE) might offer non‐invasive and enhanced anatomy assessment that might help with implant selection and placement and screw length determination. Our goal was to test the accuracy of two CAE methods for anatomical volar plate positioning and screw lengths measurement of the distal radius. We included 56 high‐resolution peripheral quantitative computed tomography scans of intact, human distal radii. Plates were placed manually onto 3D printed models (method 1), which was compared with automated computerized plate placement onto the 3D computer models (method 2). Subsequently, screw lengths were determined digitally for both methods. Screw lengths evaluations were compared via Bland–Altman plots. Both CAE methods resulted in identical volar plate selection and in anatomical plate positioning. For screw length the concordance correlation coefficient was ≥0.91, the location shift ≤0.22 mm, and the scale shift ≤0.16. The differences were smaller than ±1 mm in all samples. Both CAE methods allow for comparable plate positioning and subsequent screw length measurement in distal radius volar plating. Both can be used as a non‐invasive teaching environment for volar plate fixation. Method 2 even offers fully computerized assessments. Future studies could compare our models to other anatomical areas, post‐operative volar plate positioning, and model performance in actual distal radius fracture instead of intact radii. Clin. Anat. 32:361–368, 2019. © 2018 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists. 相似文献
63.
Abdol-Mohammad Kajbafzadeh Reza Khorramirouz Seyedeh Maryam Kameli Kiarad Fendereski Seyedeh Sima Daryabari Seyed Mohammad Tavangar Bahram Azizi Garajegayeh 《The Journal of thoracic and cardiovascular surgery》2019,157(4):1494-1502
Background
Various investigations have reported that the internal mammary artery (IMA) is an efficient and functional choice of conduit for vascular graft surgeries, especially for coronary artery bypass grafts; however, the quest to find an ideal vascular substitute remains. We hypothesized that acellular IMA could be an appropriate graft for small-diameter vascular bypasses that could be used in various surgeries including coronary artery bypass grafting.Methods
We decellularized human IMAs and performed histologic evaluations and scanning electron microscopy to confirm the decellularization process and the preservation of the extracellular matrix. Subsequently, we grafted the scaffolds into the superficial femoral arteries of 8 New Zealand rabbits with an end-to-end anastomosis. Computed tomography angiograms were provided at 3, 12, and 36 months postoperatively. Subsequently, the animals were killed, and biopsies were taken for histologic and immunohistochemical assessments.Results
Evaluation of the acellular tissue confirmed the efficacy of the decellularization protocol and the preservation of the extracellular matrix. All 8 animals survived the entire follow-up period. Doppler ultrasonography and computed tomography angiographies verified the conduit's patency. Histologic assessments depicted the recellularization of all 3 layers of the scaffold. Smooth muscle cells were detected in tunica media. Immunohistochemical assessments confirmed these findings.Conclusions
In conclusion, we demonstrated that acellular human IMA could be used as an efficient small-diameter vascular substitute with high patency. These findings could pave the path for future investigations on the clinical application of acellular IMA as a novel vascular graft for small-diameter bypass surgeries. 相似文献64.
《Clinical neurophysiology》2019,130(1):128-137
ObjectiveHigh frequency oscillations (HFO) between 80–500 Hz are markers of epileptic areas in intracranial and maybe also scalp EEG. We investigate simultaneous recordings of scalp and intracranial EEG and hypothesize that scalp HFOs provide important additional clinical information in the presurgical setting.MethodsSpikes and HFOs were visually identified in all intracranial scalp EEG channels. Analysis of correlation of event location between intracranial and scalp EEG as well as relationship between events and the SOZ and zone of surgical removal was performed.Results24 patients could be included, 23 showed spikes and 19 HFOs on scalp recordings. In 15/19 patients highest scalp HFO rate was located over the implantation side, with 13 patients having the highest scalp and intracranial HFO rate over the same region. 17 patients underwent surgery, 7 became seizure free. Patients with poor post-operative outcome showed significantly more regions with HFO than those with seizure free outcome.ConclusionsScalp HFOs are mostly located over the SOZ. Widespread scalp HFOs are indicative of a larger epileptic network and associated with poor postsurgical outcome.SignificanceAnalysis of scalp HFO add clinically important information about the extent of epileptic areas during presurgical simultaneous scalp and intracranial EEG recordings. 相似文献
65.
观察并评估角膜电刺激对糖尿病大鼠前部缺血性视神经病变(AION)模型的影响。方法:实验 研究。健康雄性Sparague-Dawley大鼠40只,随机分组后抽出8只作为正常大鼠组。余下32只先予 以链脲佐菌素腹腔注射建立糖尿病大鼠模型,将造模成功的大鼠随机抽出8只作为糖尿病组,余下 24只糖尿病大鼠采用孟加拉玫瑰红联合532 nm激光方法建立AION大鼠模型。将24只造模成功的 AION大鼠随机分成3组,每组8只,分别为AION模型组,不予任何处理;电刺激组,予以角膜电刺 激(刺激参数为:电流1 mA,频率20 Hz,波宽1 ms/phase,刺激时间1 h,隔日1次,刺激2周);假电 刺激组,电极安放位置与电刺激组相同,仅不接通电源。2周后5组大鼠进行眼底照相、光学相干断 层扫描和视觉诱发电位,然后处死,行视网膜及视神经冰冻切片,苏木精伊红染色观察。数据采用 单因素方差分析和LSD-t检验进行分析。结果:正常大鼠组视盘上半部视网膜厚度为(211±13)μm, 糖尿病大鼠组为(206±16)μm,AION模型组为(240±54)μm,假电刺激组为(216±11)μm,电刺 激组为(198±4)μm,5组视盘上半部视网膜厚度差异有统计学意义(F=2.854,P=0.038)。其中AION 模型组视盘上半部视网膜厚度高于正常组、糖尿病组、电刺激组,差异均有统计学意义(P<0.05); 正常组与糖尿病组差异无统计学意义,AION模型组与假电刺激组未见明显差异。视觉诱发电位示 AION模型组N1潜伏期较电刺激组延长,差异有统计学意义(t=4.1,P<0.001);AION模型组P1潜伏 期较正常组、糖尿病组、假电刺激组、电刺激组延长,差异均有统计学意义(t=4.1、2.5、2.6、3.2, P<0.05);电刺激组N1-P1波幅大于假电刺激组,差异有统计学意义(t=4.0,P<0.001)。结论:角膜电 刺激能促进糖尿病大鼠前部缺血性视神经病变模型肿胀的视盘变薄,加速视盘水肿的消退,同时在 一定程度上改善视功能。 相似文献
66.
Shih-Chuan Chou Justine M. Nagurney Scott G. Weiner Arthur S. Hong J. Frank Wharam 《The American journal of emergency medicine》2019,37(6):1037-1043
ObjectivesTo describe recent trends in advanced imaging and hospitalization of emergency department (ED) syncope patients, both considered “low-value”, and examine trend changes before and after the publication of American College Emergency Physician (ACEP) syncope guidelines in 2007, compared to conditions that had no changes in guideline recommendations.MethodsWe analyzed 2002–2015 National Hospital Ambulatory Medical Care Survey data using an interrupted-time series with comparison series design. The primary outcomes were advanced imaging among ED visits with principal diagnosis of syncope and headache and hospitalization for ED visits with principal diagnosis of syncope, chest pain, dysrhythmia, and pneumonia. We adjusted annual imaging and hospitalization rates using survey-weighted multivariable logistic regression, controlling for demographic and visit characteristics. Using adjusted outcomes as datapoints, we compared linear trends and trend changes of annual imaging and hospitalization rates before and after 2007 with aggregate-level multivariable linear regression.ResultsFrom 2002 to 2007, advanced imaging rates for syncope increased from 27.2% to 42.1% but had no significant trend after 2007 (trend change: ?3.1%; 95%CI ?4.7, ?1.6). Hospitalization rates remained at approximately 37% from 2002 to 2007 but declined to 25.7% by 2015 (trend change: ?2.2%; 95%CI ?3.0, ?1.4). Similar trend changes occurred among control conditions versus syncope, including advanced imaging for headache (difference in trend change: ?0.6%; 95%CI ?2.8, 1.6) and hospitalizations for chest pain, dysrhythmia, and pneumonia (differences in trend changes: 0.1% [95%CI ?1.9, 2.0]; ?0.9% [95%CI ?3.1, 1.3]; and ?1.2% [95%CI ?5.3, 2.9], respectively).ConclusionsBefore and after the release of 2007 ACEP syncope guidelines, trends in advanced imaging and hospitalization for ED syncope visits had similar changes compared to control conditions. Changes in syncope care may, therefore, reflect broader practice shifts rather than a direct association with the 2007 ACEP guideline. Moreover, utilization of advanced imaging remains prevalent. To reduce low-value care, policymakers should augment society guidelines with additional policy changes such as reportable quality measures. 相似文献
67.
68.
Sabin J. Bozso Jeevan Nagendran Roderick G.G. MacArthur Michael W.A. Chu Bob Kiaii Ismail El-Hamamsy Raymond Cartier Ali Shahriari Michael C. Moon 《The Journal of thoracic and cardiovascular surgery》2019,157(5):1763-1771
Objectives
We describe the Canadian results of the Ascyrus Medical Dissection Stent (AMDS), a novel partially uncovered aortic arch hybrid graft implanted antegrade during hypothermic circulatory arrest to promote true lumen expansion and enhance aortic remodeling.Methods
From March 2017 to February 2018, 16 consecutive patients (66 ± 12 years; 38% female) presented with acute type A aortic dissections and underwent emergent surgical aortic repair with AMDS implantation. All patients presented with DeBakey I aortic dissection, with evidence of malperfusion in 50% (n = 8) of patients. All cases were performed under hypothermic circulatory arrest with an additional average duration for AMDS implantation time of 2.1 minutes.Results
All 16 device implantations were successful. Overall 30-day mortality was 6.3% (n = 1) and stroke occurred in 6.3% (n = 1) of cases. There was no incidence of device-related aortic injury or aortic arch branch vessel occlusion. During the follow-up period, 12 patients had completed at least 1 postoperative computed tomography scan. At initial follow-up computed tomography scan, complete or partial thrombosis, and remodeling of the aortic arch occurred in 91.7% of cases (n = 11/12) and in the proximal descending thoracic aorta, complete or partial thrombosis, and remodeling occurred in 91.7% (n = 11/12).Conclusions
Preliminary results suggest that the AMDS is a safe, feasible and reproducible adjunct to current surgical approaches for acute DeBakey I aortic dissection repair. Further, the AMDS manages malperfusion and promotes early positive remodeling in the aortic arch and distal dissected segments, with favorable FL closure rates at follow-up. Ongoing follow-up will provide additional insight into the long-term effects of the AMDS. 相似文献69.
Matthew D. Li Katrina F. Chu Allegra DePietro Vincent Wu Eric Wehrenberg-Klee Omar Zurkiya Raymond W. Liu Suvranu Ganguli 《Journal of vascular and interventional radiology : JVIR》2019,30(3):314-319
Purpose
To evaluate the feasibility of a same-day yttrium-90 (90Y) radioembolization protocol with resin microspheres (including pretreatment angiography, lung shunt fraction [LSF] determination, and radioembolization) for the treatment of hepatocellular carcinoma (HCC) and liver metastases.Materials and Methods
All same-day radioembolization procedures performed over 1 y (February 2017 to January 2018) were included in this single-institutional retrospective analysis, in which 34 procedures were performed in 26 patients (median age, 63 y; 13 women), 19 with liver metastases and 7 with HCC. Yttrium-90 treatment activities were calculated by body surface area method. Tumor imaging response was assessed by Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 for liver metastases and modified RECIST for HCC. Clinical side effects and adverse events were graded per Common Terminology Criteria for Adverse Events version 4.0.Results
All planned cases were technically successful, and no cases were canceled for elevated LSF or vascular anatomic reasons. Pretreatment angiography modified the planned 90Y treatment activity in 1 case in which vascular anatomy required a lobar-dose split into 2 for segmental infusions. In 18% of cases, patients were briefly admitted after the procedure for observation or symptom management. Imaging evaluation of initial efficacy at 1 month demonstrated partial response in 25% and stable disease in 67% of patients with liver metastases and partial/complete response in 43% and stable disease in 14% of patients with HCC. Grade ≥ 3 adverse events occurred in 6% of cases, with no systemic therapy–limiting toxicities. The mean total procedure time was 4.2 hours.Conclusions
A same-day 90Y radioembolization protocol with resin microspheres is feasible in select patients, which can expedite cancer therapy. 相似文献70.