全文获取类型
收费全文 | 1351953篇 |
免费 | 100633篇 |
国内免费 | 4362篇 |
专业分类
耳鼻咽喉 | 16995篇 |
儿科学 | 43962篇 |
妇产科学 | 36615篇 |
基础医学 | 199793篇 |
口腔科学 | 36411篇 |
临床医学 | 130735篇 |
内科学 | 262508篇 |
皮肤病学 | 26726篇 |
神经病学 | 113242篇 |
特种医学 | 48475篇 |
外国民族医学 | 366篇 |
外科学 | 186542篇 |
综合类 | 28871篇 |
现状与发展 | 1篇 |
一般理论 | 466篇 |
预防医学 | 115718篇 |
眼科学 | 29371篇 |
药学 | 99761篇 |
7篇 | |
中国医学 | 3209篇 |
肿瘤学 | 77174篇 |
出版年
2021年 | 11526篇 |
2019年 | 12188篇 |
2018年 | 16933篇 |
2017年 | 12621篇 |
2016年 | 13606篇 |
2015年 | 15643篇 |
2014年 | 21429篇 |
2013年 | 32845篇 |
2012年 | 45541篇 |
2011年 | 48268篇 |
2010年 | 27837篇 |
2009年 | 25645篇 |
2008年 | 43818篇 |
2007年 | 46155篇 |
2006年 | 46224篇 |
2005年 | 44560篇 |
2004年 | 42433篇 |
2003年 | 40274篇 |
2002年 | 38993篇 |
2001年 | 60969篇 |
2000年 | 62628篇 |
1999年 | 52413篇 |
1998年 | 14703篇 |
1997年 | 13381篇 |
1996年 | 13200篇 |
1995年 | 12524篇 |
1994年 | 11697篇 |
1993年 | 10971篇 |
1992年 | 41634篇 |
1991年 | 40812篇 |
1990年 | 39497篇 |
1989年 | 37367篇 |
1988年 | 34608篇 |
1987年 | 33724篇 |
1986年 | 32179篇 |
1985年 | 30658篇 |
1984年 | 23059篇 |
1983年 | 19604篇 |
1982年 | 11784篇 |
1979年 | 20811篇 |
1978年 | 14822篇 |
1977年 | 12075篇 |
1976年 | 11882篇 |
1975年 | 12117篇 |
1974年 | 14818篇 |
1973年 | 14476篇 |
1972年 | 13361篇 |
1971年 | 12423篇 |
1970年 | 11488篇 |
1969年 | 10413篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Erin L. Sutfin Jennifer Cornacchione Ross Allison J. Lazard Elizabeth Orlan Cynthia K. Suerken Kimberly D. Wiseman 《Health communication》2019,34(3):343-351
ABSTRACTAdolescents and young adults smoke waterpipe tobacco (WT) and cigarillos, at least in part, based on erroneous beliefs that these products are safer than cigarettes. To address this challenge, we used a systematic, three-phase process to develop a health communication campaign to discourage WT and cigarillo smoking among at-risk (tobacco users and susceptible non-users) 16- to 25-year-olds. In Phase 1, we used a national phone survey (N = 896) to determine salient message beliefs. Participants reported constituents (i.e., harmful chemicals) emitted by the products were worrisome. In Phase 2, we developed and evaluated four message executions, with varying imagery, tone, and unappealing products with the same constituents, using focus groups (N = 38). Participants rated one execution highly, resulting in our development of a campaign where each message: (1) identified a tobacco product and constituent in the smoke; (2) included an image of an unappealing product containing the constituent (e.g., pesticides, gasoline) to grab attention; and (3) used a humorous sarcastic tone. In Phase 3, we tested the campaign messages (17 intervention and six control) with a nationally representative online survey (N = 1,636). Participants rated intervention and control messages highly with few differences between them. Exposure to messages resulted in significant increases in all risk beliefs from pre to post (p < 0.05). For WT, intervention messages increased beliefs about addiction more than control messages (p < 0.05). This systematic, iterative approach resulted in messages that show promise for discouraging WT and cigarillo use. 相似文献
72.
Carlos A. ávila-Orta Zoe V. Qui?ones-Jurado Miguel A. Waldo-Mendoza Erika A. Rivera-Paz Víctor J. Cruz-Delgado José M. Mata-Padilla Pablo González-Morones Ronald F. Ziolo 《Materials》2015,8(11):7900-7912
Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods. 相似文献
73.
74.
75.
76.
77.
Jeroen M. van de Pol Jurjen G. Geljon Svetlana V. Belitser Geert W.J. Frederix Anke M. Hövels Marcel L. Bouvy 《Research in social & administrative pharmacy》2019,15(1):70-76
Introduction
The nature of community pharmacy is changing, shifting from the preparation and distribution of medicines to the provision of cognitive pharmaceutical services (CPS); however, often the provision of traditional services leaves little time for innovative services. This study investigated the time community pharmacists spend on the tasks and activities of daily practice and to what extent they are able to implement CPS-related services in daily practice.Methods
Self-reporting work sampling was used to register the activities of community pharmacists. A smartphone application, designed specifically for this purpose, alerted participants to register their current activity five times per working day for 6 weeks. Participants also completed an online survey about baseline characteristics.Results
Ninety-one Dutch community pharmacists provided work-sampling data (7848 registered activities). Overall, 51.5% of their time was spent on professional activities, 35.4% on semi-professional activities, and 13.1% on non-professional activities. The proportion of time devoted to CPS decreased during the workweek, whereas the time spent on traditional task increased.Discussion and conclusion
This study shows it is feasible to collect work-sampling data using smartphone technology. Community pharmacists spent almost half of their time on semi-professional and non-professional activities, activities that could be delegated to other staff members. In practice, the transition to CPS is hampered by competing traditional tasks, which prevents community pharmacists from profiling themselves as pharmaceutical experts in daily practice. 相似文献78.
79.
J. Rodríguez-Carrio A. Martínez-Zapico I. Cabezas-Rodríguez L. Benavente Á.I. Pérez-Álvarez P. López J.B. Cannata-Andía M. Naves-Díaz A. Suárez 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(2):135-143
Background and aims
Since accelerated atherosclerosis has been reported in systemic lupus erythematosus (SLE), predictive biomarkers of cardiovascular disease (CVD) are needed. Among non-traditional risk factors, bone mineral density (BMD) has been related to CVD. However, its role in SLE remains controversial. This study aims to analyze the associations of subclinical atherosclerosis with traditional and non-traditional CV risk factors.Methods and results
In a cross-sectional study, atherosclerosis burden was compared between 112 female SLE patients and 31 controls. Plaque number and carotid intima-media wall thickness (cIMT) were assessed by ultrasonography. In a retrospective study, BMD determinations obtained 5-years before the ultrasonography assessment were analyzed in a subgroup of 62 patients. Plaque frequency was increased in SLE, even in patients without CV events or carotid wall thickening. cIMT was increased in patients with CVD, positively correlated with body mass index (BMI). Interestingly, a paradoxical effect of BMI on carotid parameters was observed. Whereas underweight patients (BMI < 20) showed increased prevalence of carotid plaques with low cIMT, those with BMI > 30 showed higher cIMT and plaque burden. Overweight patients (25 < BMI<30) exhibited both elevated cIMT and plaque number. BMI was an independent predictor of BMD. In our retrospective study, patients with either clinical or subclinical CVD exhibited lower BMD levels than their CV-free counterparts. A low lumbar spine BMD independently predicted CVD development after adjusting for confounders.Conclusion
SLE was associated with a higher subclinical atherosclerosis burden, a bimodal effect being observed for BMI. Decreased BMD can be a CV risk biomarker in SLE. 相似文献80.
Maggie L. Westfal David C. Chang Cassandra M. Kelleher 《Journal of pediatric surgery》2019,54(1):140-144