全文获取类型
收费全文 | 4375篇 |
免费 | 347篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 136篇 |
妇产科学 | 81篇 |
基础医学 | 619篇 |
口腔科学 | 68篇 |
临床医学 | 499篇 |
内科学 | 822篇 |
皮肤病学 | 84篇 |
神经病学 | 558篇 |
特种医学 | 169篇 |
外科学 | 584篇 |
综合类 | 15篇 |
预防医学 | 516篇 |
眼科学 | 40篇 |
药学 | 256篇 |
中国医学 | 12篇 |
肿瘤学 | 208篇 |
出版年
2024年 | 8篇 |
2023年 | 79篇 |
2022年 | 99篇 |
2021年 | 222篇 |
2020年 | 130篇 |
2019年 | 167篇 |
2018年 | 237篇 |
2017年 | 161篇 |
2016年 | 170篇 |
2015年 | 184篇 |
2014年 | 230篇 |
2013年 | 269篇 |
2012年 | 420篇 |
2011年 | 379篇 |
2010年 | 178篇 |
2009年 | 167篇 |
2008年 | 253篇 |
2007年 | 221篇 |
2006年 | 234篇 |
2005年 | 209篇 |
2004年 | 146篇 |
2003年 | 149篇 |
2002年 | 109篇 |
2001年 | 21篇 |
2000年 | 22篇 |
1999年 | 29篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 18篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1985年 | 5篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1976年 | 4篇 |
1942年 | 5篇 |
1928年 | 5篇 |
1926年 | 7篇 |
1923年 | 8篇 |
1922年 | 6篇 |
1921年 | 5篇 |
1912年 | 6篇 |
1911年 | 7篇 |
排序方式: 共有4734条查询结果,搜索用时 10 毫秒
71.
Daniel Zúiga-Núez Pablo Barrias Gloria Crdenas-Jirn M. Soledad Ureta-Zaartu Camilo Lopez-Alarcn F. Eduardo Morn Vieyra Claudio D. Borsarelli Emilio I. Alarcon Alexis Aspe 《RSC advances》2018,8(4):1927
Coumarin compounds have been described as anti-inflammatories, and chemotherapeutic agents as well as antioxidants. However, the origin of the antioxidant activity of non phenolic coumarins remains obscure. In the present report, we demonstrate that non-phenolic 7-dialkyl-aminocoumarins may also have significant antioxidant properties against free radicals derived from 2,2′-azobis(2-amidinopropane) dihydrochloride under aerobic conditions. This atypical behaviour is due to the presence of traces of very reactive hydroxycinnamic acid-type compounds. Changing functional groups at the C-3 and C-4 positions shifts the reactivity of the compounds from peroxyl to alkoxyl free radicals. Kinetic and theoretical studies based on Density Functional Theory support the formation of reactive hydroxycinnamic acid and directly link the antioxidant behaviour of the compounds to hydrogen atom transfer.Relevant antioxidant properties of non-phenolic 7-dialkyl-aminocoumarins against free radicals derived from 2,2′-azobis(2-amidinopropane) dihydrochloride under aerobic conditions have been experimentally and theoretically demonstrated. 相似文献
72.
Julien Frandon Stéphanie Bricq Zakarya Bentatou Laetitia Marcadet Pierre Antoine Barral Mathieu Finas Daniel Fagret Frank Kober Gilbert Habib Monique Bernard Alain Lalande Lucile Miquerol Alexis Jacquier 《Journal of cardiovascular magnetic resonance》2018,20(1):70
Background
The definition of left ventricular (LV) non-compaction is controversial, and discriminating between normal and excessive LV trabeculation remains challenging. Our goal was to quantify LV trabeculation on cardiovascular magnetic resonance (CMR) images in a genetic mouse model of non-compaction using a dedicated semi-automatic software package and to compare our results to the histology used as a gold standard.Methods
Adult mice with ventricular non-compaction were generated by conditional trabecular deletion of Nkx2–5. Thirteen mice (5 controls, 8 Nkx2–5 mutants) were included in the study. Cine CMR series were acquired in the mid LV short axis plane (resolution 0.086?×?0.086x1mm3) (11.75 T). In a sub set of 6 mice, 5 to 7 cine CMR were acquired in LV short axis to cover the whole LV with a lower resolution (0.172?×?0.172x1mm3). We used semi-automatic software to quantify the compacted mass (Mc), the trabeculated mass (Mt) and the percentage of trabeculation (Mt/Mc) on all cine acquisitions. After CMR all hearts were sliced along the short axis and stained with eosin, and histological LV contouring was performed manually, blinded from the CMR results, and Mt, Mc and Mt/Mc were quantified. Intra and interobserver reproducibility was evaluated by computing the intra class correlation coefficient (ICC).Results
Whole heart acquisition showed no statistical significant difference between trabeculation measured at the basal, midventricular and apical parts of the LV. On the mid-LV cine CMR slice, the median Mt was 0.92 mg (range 0.07–2.56 mg), Mc was 12.24 mg (9.58–17.51 mg), Mt/Mc was 6.74% (0.66–17.33%). There was a strong correlation between CMR and the histology for Mt, Mc and Mt/ Mc with respectively: r2?=?0.94 (p?<?0.001), r2?=?0.91 (p?<?0.001), r2?=?0.83 (p?<?0.001). Intra- and interobserver reproducibility was 0.97 and 0.8 for Mt; 0.98 and 0.97 for Mc; 0.96 and 0.72 for Mt/Mc, respectively and significantly more trabeculation was observed in the Mc Mutant mice than the controls.Conclusion
The proposed semi-automatic quantification software is accurate in comparison to the histology and reproducible in evaluating Mc, Mt and Mt/ Mc on cine CMR.73.
74.
Are there common familial influences for major depressive disorder and an overeating–binge eating dimension in both European American and African American Female twins? 下载免费PDF全文
75.
Alexis J. Hure Catherine L. Chojenta Jennifer R. Powers Julie E. Byles Deborah Loxton 《Journal of epidemiology / Japan Epidemiological Association》2015,25(1):30-37
Background
A high rate of stillbirth was previously observed in the Australian Longitudinal Study of Women’s Health (ALSWH). Our primary objective was to test the validity and reliability of self-reported stillbirth data linked to state-based administrative datasets.Methods
Self-reported data, collected as part of the ALSWH cohort born in 1973–1978, were linked to three administrative datasets for women in New South Wales, Australia (n = 4374): the Midwives Data Collection; Admitted Patient Data Collection; and Perinatal Death Review Database. Linkages were obtained from the Centre for Health Record Linkage for the period 1996–2009. True cases of stillbirth were defined by being consistently recorded in two or more independent data sources. Sensitivity, specificity, positive predictive value, negative predictive value, percent agreement, and kappa statistics were calculated for each dataset.Results
Forty-nine women reported 53 stillbirths. No dataset was 100% accurate. The administrative datasets performed better than self-reported data, with high accuracy and agreement. Self-reported data showed high sensitivity (100%) but low specificity (30%), meaning women who had a stillbirth always reported it, but there was also over-reporting of stillbirths. About half of the misreported cases in the ALSWH were able to be removed by identifying inconsistencies in longitudinal data.Conclusions
Data linkage provides great opportunity to assess the validity and reliability of self-reported study data. Conversely, self-reported study data can help to resolve inconsistencies in administrative datasets. Quantifying the strengths and limitations of both self-reported and administrative data can improve epidemiological research, especially by guiding methods and interpretation of findings.Key words: data, kappa, linkage, reliability, self-report, sensitivity, specificity, stillbirth, validity 相似文献76.
77.
Richard F. Armenta Alexis M. Roth Karla D. Wagner Steffanie A. Strathdee Stephanie K. Brodine Jazmine Cuevas-Mota Fatima A. Munoz Richard S. Garfein 《Journal of urban health》2015,92(6):1081-1091
Persons who inject drugs (PWID) are at increased risk for blood-borne virus (BBV) infections and overdose resulting from high-risk injecting practices. Studies of prefilled syringe use ([PFSU] using a syringe that already contained drug solution when it was obtained by the user), an injection practice previously described in Eastern Europe, suggest that it increases susceptibility to BBV. However, little is known about this practice in the USA. Data were obtained from an ongoing cohort study of PWID to determine the prevalence and assess correlates of PFSU in San Diego, CA. Baseline interviews assessed socio-demographics and drug use behaviors. Logistic regression was used to identify factors independently associated with ever using a prefilled syringe (yes/no). Participants (n = 574) were predominately males (73.9 %) and white (50.9 %) with a mean age of 43.4 years (range 18–80); 33.3 % reported ever using prefilled syringes, although only 4.9 % reported use in the past 6 months. In multivariable analyses, PFSU was independently associated with ever having a rushed injection due to police presence [adjusted odds ratio (AOR) = 2.51, 95 % CI 1.66, 3.79], ever being in prison (AOR = 1.80, 95 % CI 1.23, 2.63), injecting most often in public versus private places in the past 6 months (AOR = 1.66, 95 % CI 1.11, 2.48), and injecting drugs in Mexico (AOR = 1.70, 95 % CI 1.16, 2.49). Results indicate that a history of PFSU is common and associated with environmental factors that may also increase risk for adverse health outcomes. Studies are needed to better understand PFSU in order to develop interventions to prevent adverse outcomes associated with their use. 相似文献
78.
Lynne Moore Brahim Cisse Brice Lionel Batomen Kuimi Henry T. Stelfox Alexis F. Turgeon François Lauzier Julien Clément Gilles Bourgeois 《BMC health services research》2015,15(1):285
Background
Injury is second only to cardiovascular disease in terms of acute care costs in North America. One key to improving injury care efficiency is to generate knowledge on the determinants of resource use. Socio-economic status (SES) is a documented risk factor for injury severity and mortality but its impact on length of stay (LOS) for injury admissions is unknown. This study aimed to examine the relationship between SES and LOS following injury.This multicenter retrospective cohort study was based on adults discharged alive from any trauma center (2007–2012; 57 hospitals; 65,486 patients) in a Canadian integrated provincial trauma system. SES was determined using ecological indices of material and social deprivation. Mean differences in LOS adjusted for age, gender, comorbidities, and injury severity were generated using multivariate linear regression.Results
Mean LOS was 13.5 days. Patients in the highest quintile of material/social deprivation had a mean LOS 0.5 days (95 % CI 0.1-0.9)/1.4 days (1.1-1.8) longer than those in the lowest quintile. Patients in the highest quintiles of both social and material deprivation had a mean LOS 2.6 days (1.8-3.5) longer than those in the lowest quintiles.Conclusions
Results suggest that patients admitted for traumatic injury who suffer from high social and/or material deprivation have longer acute care LOS in a universal-access health care system. The reasons behind observed differences need to be further explored but may indicate that discharge planning should take patient SES into consideration.79.
Johnson Laura M. Green Harold D. Lu Minggen Stockman Jamila K. Felsher Marisa Roth Alexis M. Wagner Karla D. 《AIDS and behavior》2022,26(9):2866-2880
AIDS and Behavior - Pre-Exposure Prophylaxis (PrEP) health campaigns invite women to talk with their provider, partner, and peers about PrEP, though they do not offer specific guidance about who... 相似文献