全文获取类型
| 收费全文 | 3388350篇 |
| 免费 | 252766篇 |
| 国内免费 | 4991篇 |
专业分类
| 耳鼻咽喉 | 47290篇 |
| 儿科学 | 111138篇 |
| 妇产科学 | 93834篇 |
| 基础医学 | 491926篇 |
| 口腔科学 | 96890篇 |
| 临床医学 | 306425篇 |
| 内科学 | 650237篇 |
| 皮肤病学 | 74168篇 |
| 神经病学 | 270610篇 |
| 特种医学 | 129267篇 |
| 外国民族医学 | 902篇 |
| 外科学 | 509135篇 |
| 综合类 | 76509篇 |
| 现状与发展 | 13篇 |
| 一般理论 | 1299篇 |
| 预防医学 | 267435篇 |
| 眼科学 | 79477篇 |
| 药学 | 253834篇 |
| 73篇 | |
| 中国医学 | 6365篇 |
| 肿瘤学 | 179280篇 |
出版年
| 2018年 | 35789篇 |
| 2017年 | 27250篇 |
| 2016年 | 30560篇 |
| 2015年 | 34743篇 |
| 2014年 | 48803篇 |
| 2013年 | 73912篇 |
| 2012年 | 101080篇 |
| 2011年 | 107344篇 |
| 2010年 | 63785篇 |
| 2009年 | 60482篇 |
| 2008年 | 101344篇 |
| 2007年 | 107754篇 |
| 2006年 | 108950篇 |
| 2005年 | 106009篇 |
| 2004年 | 102529篇 |
| 2003年 | 98211篇 |
| 2002年 | 95842篇 |
| 2001年 | 151210篇 |
| 2000年 | 155960篇 |
| 1999年 | 131878篇 |
| 1998年 | 38346篇 |
| 1997年 | 33979篇 |
| 1996年 | 33969篇 |
| 1995年 | 32495篇 |
| 1994年 | 30204篇 |
| 1993年 | 28512篇 |
| 1992年 | 105526篇 |
| 1991年 | 103173篇 |
| 1990年 | 100783篇 |
| 1989年 | 97396篇 |
| 1988年 | 90175篇 |
| 1987年 | 88529篇 |
| 1986年 | 83712篇 |
| 1985年 | 80633篇 |
| 1984年 | 60455篇 |
| 1983年 | 51850篇 |
| 1982年 | 30773篇 |
| 1981年 | 27749篇 |
| 1979年 | 56805篇 |
| 1978年 | 40222篇 |
| 1977年 | 33745篇 |
| 1976年 | 32151篇 |
| 1975年 | 34381篇 |
| 1974年 | 41604篇 |
| 1973年 | 39786篇 |
| 1972年 | 37135篇 |
| 1971年 | 35072篇 |
| 1970年 | 32346篇 |
| 1969年 | 30734篇 |
| 1968年 | 28098篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
41.
Umesh Wadgave Mahesh R. Khairnar Tanvi S. Kadu Yogesh Wadgave 《Acta odontologica Scandinavica》2019,77(3):181-183
Introduction: Significance testing for comparison of the baseline differences between the intervention arms has received a strong condemnation. The goal of this study was to assess the prevalence of randomized controlled trials (RCTs) comparing the baseline characteristics between intervention groups using significance tests in top ten impact factor dental journals.Materials and methods: RCTs published in 10 high impact factor dental journals were searched in PubMed database. Literature search was limited to time duration of 5 years from September 2012 to August 2017.Results: We analysed 521 RCTs after excluding 47 non-RCT articles from the total of 568 articles. Baseline demographic characteristics table was not reported in 45.9% of the RCTs and 26.2% of the RCTs did not report table of baseline clinical characteristics. In 38.9% of the studies, significance testing was employed to compare baseline differences between the intervention arms.Conclusions: Many trials published in the reputed dental journals failed to follow the recommendations of CONSORT statement regarding reporting of baseline tables and avoiding comparison of baseline differences with significance test. 相似文献
42.
Devin B. Gillaspie Kimberly A. Davis Kevin M. Schuster 《American journal of surgery》2019,217(1):98-102
Background
We hypothesized that trends in total bilirubin in the context of cholecystitis and symptomatic cholelithiasis could be used to guide testing for the presence of common bile duct stones (CBDS).Methods
A review of adult patients with acute cholecystitis or biliary colic with elevated total bilirubin and at least two levels drawn prior to procedural intervention was performed. Trends of total bilirubin and other serum makers were examined to predict the presence of CBDS.Results
The total bilirubin level at presentation, average over 24?h and average over 48?h (3.74?mg/dl vs. 2.29?mg/dl, p?=?0.005; 3.72?mg/dl vs. 2.40?mg/dl, p?=?0.009; 2.41?mg/dl vs. 1.47?mg/dl, p?<?0.001) respectively, were all higher in those with CBDS. However, prediction was not improved by following levels over time.Conclusion
Patients presenting with elevated serum bilirubin, should undergo immediate imaging or procedural intervention rather than obtaining follow-up bilirubin levels. 相似文献43.
B. Kowall N. Lehmann A.A. Mahabadi S. Moebus R. Erbel K.H. Jöckel A. Stang 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(3):228-235
Background and aims
There is controversy on the potentially benign nature of metabolically healthy obesity (MHO), i.e., obese persons with few or no metabolic abnormalities. So far, associations between MHO and coronary artery calcification (CAC), a measure of subclinical atherosclerosis, have mainly been studied cross-sectionally in Asian populations. We assessed cross-sectional and longitudinal MHO CAC associations in a Caucasian population.Methods and results
In the Heinz Nixdorf Recall Study, a population-based cohort study in Germany, CAC was assessed by electron-beam tomography at baseline and at 5-year follow-up. For cross-sectional and longitudinal analyses, we included 1585 participants free of coronary heart disease at baseline, with CAC measurements at baseline and at follow-up, and with either normal weight (BMI 18.5–24.9 kg/m2) or obesity (BMI ≥30.0 kg/m2) at baseline. We used four definitions of MHO. In our main analysis, we defined obese persons as metabolically healthy if they met ≤1 of the NCEP ATP III criteria for the definition of the metabolic syndrome – waist circumference was not taken into account because of collinearity with BMI.Persons with MHO had a higher prevalence of CAC than metabolically healthy normal weight (MHNW) persons (prevalence ratio = 1.59 (95% confidence interval 1.38–1.84) for the main analysis). Persons with MHO had slightly larger odds of CAC progression than persons with MHNW (odds ratios ranged from 1.17 (0.69–1.99) to 1.48 (1.02–2.13) depending on MHO definition and statistical approach).Conclusion
Our analyses on MHO CAC associations add to the evidence that MHO is not a purely benign health condition. 相似文献44.
45.
46.
M. Corral-Blanco V.C. Prudencio-Ribera M.E. Jarrín-Estupiñán R. Alonso-Moralejo V. Pérez-González J.C. Meneses-Pardo A. Hermira-Anchuelo A. De Pablo-Gafas 《Transplantation proceedings》2019,51(2):380-382
Background
Pulmonary hypertension (PH) is a comorbidity associated with interstitial lung disease (ILD). The purpose of this study was to evaluate the influence of PH on intrahospital mortality in lung transplantation (LT) for ILD.Methods
We conducted a retrospective cohort study of 66 patients who underwent LT for ILD at the 12 de Octubre University Hospital (Madrid, Spain) from October 2008 to June 2014. PH was defined as mean pulmonary arterial pressure (mPAP) ≥25 mmHg on right-sided heart catheterization and intrahospital mortality as any death taken place after the transplantation of patients not being discharged.Results
We retrospectively analyzed data of 66 patients; they were stratified by the presence or absence of PH before LT. Twenty-seven patients (41%) had PH. The PH group had a lower diffusing capacity of carbon monoxide (DLCO), carbon monoxide transfer coefficient (KCO), and 6-minute walk distance test (6MWT) and a higher total lung capacity (TLC), modified medical research council dyspnea scale (mMRC), and lung allocation score (LAS) than the non-PH group. Patients with PH more often underwent double lung transplantation (DLT; 59%) than single lung transplantation (SLT).Intrahospital mortality was 13% (9/66). No significant differences were observed in Kaplan-Meier survival curves for the PH and non-PH groups with a median survival time of 46 days versus 33 days (IQR 26–74; log-rank P = .056); however, the postoperative length of stay in the hospital was greater in the PH group.Conclusions
In our cohort, pulmonary hypertension was not related to early mortality in lung transplantation recipients for interstitial lung diseases. 相似文献47.
Amgad El Mekabaty Monica S. Pearl Bommy Mershon Ivor Berkowitz Philippe Gailloud Thierry A.G.M. Huisman 《Journal of neuroradiology. Journal de neuroradiologie》2019,46(3):214-221
Background and purpose
The vein of Galen aneurysmal malformation (VGAM) is a rare congenital vascular malformation with a higher morbidity and mortality, especially in neonates. Ultrasound, CT and MR are usually used in diagnosis and treatment monitoring of these disorders. In this current study, we aim to examine utility of SWI in evaluation of treatment response in infants with VGAM.Materials and methods
We performed a retrospective chart analysis of children with VGAM in our institution between January 2008 and December 2016. Inclusion criteria included; confirmed VGAM on DSA; available SWI sequence at baseline and at follow up after at least a single embolization session; age at initial MR of 18?years or younger. Signal intensity and Angioarchitecture of VGAM and cerebral veins on SWI, as well as hydrocephalus and clinical outcome were evaluated.Results
Of 11 patients identified with VGAM in our institution, 5 children (3 males and 2 females) satisfied the inclusion criteria. The average age at initial MR was 29?days (range 1–120). Fourteen MRI were available for review. All children had VGAM of mural type. Intramedullary veins were dilated and SWI-hypointense in all children, while subependymal and sulcal veins were dilated and SWI-hypointense in 4 patients on initial MRI. On the first available follow up MRI, cerebral veins have mostly normalized in 4 children and remained mostly dilated and SWI-hypointense in 1 child; even after complete treatment of the VGAM.Conclusion
Our preliminary findings show that SWI seems to offer a beneficial non-invasive tool in evaluating passive venous congestion patterns in pediatric patients with VGAM. It remains to be determined in larger studies, the clinical significance of these SWI changes. 相似文献48.
49.
Anna-Maria Lutz Rüdiger Hampe Malgorzata Roos Nina Lümkemann Marlis Eichberger Bogna Stawarczyk 《The Journal of prosthetic dentistry》2019,121(1):166-172
Statement of problem
Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.Purpose
The purpose of this in vitro study was to investigate the fracture resistance and 2-body wear of 3-dimensional–printed (3DP) (FotoDent splint; Dreve Dentamid GmbH), milled polymethylmethacrylate (CAM) (Temp Basic; Transpa 95H16, Zirkonzahn GmbH), and conventionally fabricated polymethylmethacrylate (CAST) (Castdon; Dreve Dentamid GmbH) occlusal devices.Material and Methods
A total of 96 occlusal devices were prepared according to the 3 different manufacturing techniques 3DP, CAM, and CAST (n=32). For each manufacturing technique, specimens were further divided into initial fracture resistance tests (n=16) and artificial aging in the mastication simulator (50 N, 37°C) with 2-body wear followed by fracture resistance tests (n=16). The fracture resistance was determined using a universal testing machine (1 mm/min). The wear was measured after 20?000 and 120?000 mastication cycles with the replica technique, mapped with a laser scanner, and quantified in R software. Data were analyzed using a 2-way ANOVA followed by a 1-way ANOVA with Scheffé or Games-Howell post hoc tests, repeated measures ANOVA with corrected Greenhouse-Geisser P values, and the Levene, Mann-Whitney, and paired t tests (α=.05).Results
CAM presented higher initial fracture resistance than 3DP or CAST (P<.001). After mastication simulation, CAM followed by 3DP showed higher fracture resistance than CAST (P<.001). Mastication simulation decreased the fracture resistance for CAM and CAST (P<.001) but not for 3DP (P=.78). Three-dimensional–printed occlusal devices showed the highest material volume loss, followed by CAM and the lowest in CAST (P<.001).Conclusions
Three-dimensional–printed occlusal devices showed lower wear resistance and lower fracture resistance than those milled or conventionally fabricated. Therefore, only short-term application in the mouth is recommended. Further developments of occlusal device material for 3-dimensional printing are necessary. 相似文献50.
Chancellor F. Gray Hernan A. Prieto Justin T. Deen Hari K. Parvataneni 《The Journal of arthroplasty》2019,34(2):206-210