全文获取类型
收费全文 | 39805篇 |
免费 | 2867篇 |
国内免费 | 1087篇 |
专业分类
耳鼻咽喉 | 680篇 |
儿科学 | 471篇 |
妇产科学 | 156篇 |
基础医学 | 1940篇 |
口腔科学 | 2167篇 |
临床医学 | 4850篇 |
内科学 | 5546篇 |
皮肤病学 | 191篇 |
神经病学 | 2800篇 |
特种医学 | 9280篇 |
外国民族医学 | 26篇 |
外科学 | 3972篇 |
综合类 | 4401篇 |
现状与发展 | 4篇 |
预防医学 | 664篇 |
眼科学 | 3043篇 |
药学 | 966篇 |
8篇 | |
中国医学 | 132篇 |
肿瘤学 | 2462篇 |
出版年
2024年 | 72篇 |
2023年 | 1020篇 |
2022年 | 1370篇 |
2021年 | 2251篇 |
2020年 | 1820篇 |
2019年 | 1744篇 |
2018年 | 1604篇 |
2017年 | 1480篇 |
2016年 | 1408篇 |
2015年 | 1489篇 |
2014年 | 2730篇 |
2013年 | 2187篇 |
2012年 | 1996篇 |
2011年 | 2154篇 |
2010年 | 1807篇 |
2009年 | 1877篇 |
2008年 | 1908篇 |
2007年 | 2024篇 |
2006年 | 1766篇 |
2005年 | 1500篇 |
2004年 | 1253篇 |
2003年 | 1008篇 |
2002年 | 861篇 |
2001年 | 731篇 |
2000年 | 637篇 |
1999年 | 527篇 |
1998年 | 414篇 |
1997年 | 465篇 |
1996年 | 433篇 |
1995年 | 386篇 |
1994年 | 365篇 |
1993年 | 282篇 |
1992年 | 230篇 |
1991年 | 207篇 |
1990年 | 190篇 |
1989年 | 186篇 |
1988年 | 157篇 |
1987年 | 171篇 |
1986年 | 121篇 |
1985年 | 157篇 |
1984年 | 159篇 |
1983年 | 98篇 |
1982年 | 146篇 |
1981年 | 116篇 |
1980年 | 80篇 |
1979年 | 66篇 |
1978年 | 36篇 |
1977年 | 40篇 |
1976年 | 25篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
《Radiologia》2022,64(3):245-255
ObjectiveTo review the main findings for anisakiasis in the different imaging tests that can be used to diagnose it, based on studies done at our center.ConclusionThe presence of Anisakis species in food consumed in Western countries is becoming more common. Patients with anisakiasis present with acute abdomen; there are no specific clinical signs or laboratory findings. Careful history taking is key to discovering exposure to Anisakis-contaminated food, but this task is hindered by unfamiliarity with the condition and lack of suspicion and is also confounded by the variable latency period after ingestion of Anisakis-contaminated food. Give the nonspecific presentation, patients with anisakiasis often undergo imaging tests to rule out other processes. Thus, radiologists need to be familiar with the spectrum of imaging findings that should lead to the inclusion of anisakiasis in the differential diagnosis, so they can guide clinicians toward directed history taking and specific tests. 相似文献
82.
83.
84.
《Journal of endodontics》2020,46(11):1712-1718
IntroductionThe preparation of flattened root canals using reciprocating or rotary nickel-titanium instruments associated with the Flatsonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, SP, Brazil) was evaluated by micro–computed tomographic imaging.MethodsTwenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were randomly divided into 2 experimental groups for preparation: a Reciproc Blue (RB; VDW GmbH, Munich, Germany) 40/.06 file in reciprocating motion or ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 40/.01 and 40/.05 files in rotary motion (n = 12). A complementary preparation was performed with the Flatsonic ultrasonic tip for both preparations. Micro–computed tomographic scanning at a resolution of 8.74 μm was performed before and after preparation with the nickel-titanium instruments and after the use of the Flatsonic tip. The percentages of increase in volume, debris, and uninstrumented surface were analyzed. The data obtained were submitted to the paired and unpaired t test, analysis of variance, and the Tukey test (α = 5%).ResultsThe percentage increase in volume, debris, and uninstrumented surface was similar between RB and PDL in the entire root canal (P > .05). The PDL promoted a lower percentage of debris in the cervical third and a lower percentage of increase in volume in the apical third in comparison with RB (P < .05). The Flatsonic decreased debris and uninstrumented surface after PDL preparation in all thirds (P < .05). After preparation with RB, the Flatsonic decreases the debris in the cervical third and the uninstrumented surface in the cervical and middle thirds (P < .05).ConclusionsThe preparation of flattened root canals using RB or PDL produced a high percentage of debris and uninstrumented surface. The Flatsonic ultrasonic tip significantly improved the cleaning of flattened root canals. 相似文献
85.
86.
87.
《Journal of Cardiovascular Computed Tomography》2020,14(6):478-482
BackgroundMultiple appropriate use criteria (AUC) exist for the evaluation of coronary artery disease (CAD), but there is little data on the agreement between AUC from different professional medical societies. The aim of this study is to compare the appropriateness of coronary computed tomography angiography (CCTA) exams assessed using multimodality AUC from the American College of Cardiology Foundation (ACCF) versus the American College of Radiology (ACR).MethodsIn a single-center prospective cohort study from June 2014 to 2016, 1005 consecutive subjects referred for evaluation of known or suspected CAD received a contrast-enhanced CCTA. The primary outcome was the agreement of appropriateness ratings using ACCF and ACR guidelines, measured by the kappa statistic. A secondary outcome was the rate of obstructive CAD by appropriateness rating.ResultsAmong 1005 subjects, the median (5–95th percentile) age was 59 (37–76) years with 59.0% male. The ACCF criteria classified 39.6% (n = 398) appropriate, 24.2% (n = 243) maybe appropriate, and 36.2% (n = 364) rarely appropriate. The ACR guidelines classified 72.3% (n = 727) appropriate, 2.6% (n = 26) maybe appropriate, and 25.1% (n = 252) rarely appropriate. ACCF and ACR appropriateness ratings were in agreement for 55.0% (n = 553). Overall, there was poor agreement (kappa 0.27 [95% confidence interval 0.23–0.31]). By both AUC methods, a low rate of obstructive CAD was observed in the rarely appropriate exams (ACCF 7.1% [n = 26 of 364] and ACR 13.5% [n = 34 of 252]).ConclusionsCompared to ACCF criteria, the ACR guidelines of appropriateness were broader and classified significantly more CCTA exams as appropriate. The poor agreement between appropriateness ratings from the ACCF and ACR AUC guidelines evokes implications for reimbursement and future test utilization. 相似文献
88.
《Diagnostic and interventional imaging》2020,101(9):565-575
PurposeTo report the computed tomography (CT) features of pancreatic acinar cell carcinoma (ACC) and identify CT features that may help discriminate between pancreatic ACC and pancreatic ductal adenocarcinoma (PDA).Materials and methodsThe CT examinations of 20 patients (13 men, 7 women; mean age, 66.5 ± 10.7 [SD] years; range: 51–88 years) with 20 histopathologically proven pancreatic ACC were reviewed. CT images were analyzed qualitatively and quantitatively and compared to those obtained in 20 patients with PDA. Comparisons were performed using univariate analysis with a conditional logistic regression model.ResultsPancreatic ACC presented as an enhancing (20/20; 100%), oval (15/20; 75%), well-delineated (14/20; 70%) and purely solid (13/20; 65%) pancreatic mass with a mean diameter of 52.6 ± 28.0 (SD) mm (range: 24–120 mm) in association with visible lymph nodes (14/20; 70%). At univariate analysis, well-defined margins (Odds ratio [OR], 7.00; P = 0.005), nondilated bile ducts (OR, 9.00; P = 0.007), visible lymph nodes (OR, 4.33; P = 0.028) and adjacent organ involvement (OR, 5.67; P = 0.02) were the most discriminating CT features to differentiate pancreatic ACC from PDA. When present, lymph nodes were larger in patients with pancreatic ACC (14 ± 4.8 [SD]; range: 7–25 mm) than in those with PDA (8.8 ± 4.1 [SD]; range: 5–15 mm) (P = 0.039).ConclusionOn CT, pancreatic ACC presents as an enhancing, predominantly oval and purely solid pancreatic mass that most frequently present with no bile duct dilatation, no visible lymph nodes, no adjacent organ involvement and larger visible lymph nodes compared to PDA. 相似文献
89.
Camilo Brando-de-Resende Helena Hollanda Santos Angel Alessio Rojas Lagos Camila Munayert Lara Jacqueline Souza Dutra Arruda Ana Paula Maia Peixoto Marino Lis Ribeiro do Valle Antonelli Ricardo Tostes Gazzinelli Ricardo Wagner de Almeida Vitor Daniel Vitor Vasconcelos-Santos 《Emerging infectious diseases》2020,26(12):2922
In 2015, an outbreak of presumed waterborne toxoplasmosis occurred in Gouveia, Brazil. We conducted a 3-year prospective study on a cohort of 52 patients from this outbreak, collected clinical and multimodal imaging findings, and determined risk factors for ocular involvement. At baseline examination, 12 (23%) patients had retinochoroiditis; 4 patients had bilateral and 2 had macular lesions. Multimodal imaging revealed 2 distinct retinochoroiditis patterns: necrotizing focal retinochoroiditis and punctate retinochoroiditis. Older age, worse visual acuity, self-reported recent reduction of visual acuity, and presence of floaters were associated with retinochoroiditis. Among patients, persons >40 years of age had 5 times the risk for ocular involvement. Five patients had recurrences during follow-up, a rate of 22% per person-year. Recurrences were associated with binocular involvement. Two patients had late ocular involvement that occurred >34 months after initial diagnosis. Patients with acquired toxoplasmosis should have long-term ophthalmic follow-up, regardless of initial ocular involvement. 相似文献
90.