全文获取类型
收费全文 | 180152篇 |
免费 | 10961篇 |
国内免费 | 472篇 |
专业分类
耳鼻咽喉 | 2353篇 |
儿科学 | 5734篇 |
妇产科学 | 3786篇 |
基础医学 | 24832篇 |
口腔科学 | 8317篇 |
临床医学 | 13268篇 |
内科学 | 40362篇 |
皮肤病学 | 4557篇 |
神经病学 | 15037篇 |
特种医学 | 5527篇 |
外国民族医学 | 26篇 |
外科学 | 22401篇 |
综合类 | 1424篇 |
现状与发展 | 1篇 |
一般理论 | 66篇 |
预防医学 | 18505篇 |
眼科学 | 3275篇 |
药学 | 11121篇 |
中国医学 | 762篇 |
肿瘤学 | 10231篇 |
出版年
2023年 | 874篇 |
2022年 | 1676篇 |
2021年 | 3953篇 |
2020年 | 2612篇 |
2019年 | 3720篇 |
2018年 | 5216篇 |
2017年 | 3943篇 |
2016年 | 3680篇 |
2015年 | 4331篇 |
2014年 | 5910篇 |
2013年 | 7367篇 |
2012年 | 11540篇 |
2011年 | 12075篇 |
2010年 | 6137篇 |
2009年 | 5487篇 |
2008年 | 9337篇 |
2007年 | 9850篇 |
2006年 | 9088篇 |
2005年 | 9364篇 |
2004年 | 8755篇 |
2003年 | 8002篇 |
2002年 | 6012篇 |
2001年 | 5160篇 |
2000年 | 5141篇 |
1999年 | 4496篇 |
1998年 | 1605篇 |
1997年 | 1333篇 |
1996年 | 1326篇 |
1995年 | 1120篇 |
1994年 | 1119篇 |
1993年 | 1005篇 |
1992年 | 2721篇 |
1991年 | 2629篇 |
1990年 | 2389篇 |
1989年 | 2382篇 |
1988年 | 2146篇 |
1987年 | 1983篇 |
1986年 | 1864篇 |
1985年 | 1764篇 |
1984年 | 1274篇 |
1983年 | 1036篇 |
1982年 | 582篇 |
1981年 | 525篇 |
1980年 | 520篇 |
1979年 | 939篇 |
1978年 | 617篇 |
1977年 | 490篇 |
1975年 | 551篇 |
1974年 | 551篇 |
1973年 | 558篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Maria C. Chammas Andre C. Oliveira Mario J. D´Ávilla Pedro H. Moraes Marcelo Straus Takahashi 《Ultrasound in medicine & biology》2019,45(1):50-55
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease. 相似文献
82.
Background Context
Long-term follow-up of patient-reported outcome measures (PROM) is essential in both modern spinal care and research. Lack of time and staff are commonly reported barriers to implementing long-term follow-up of PROM. Automated and digital follow-up systems for PROM collection are seeing widespread use, yet their validity and comparative effectiveness have never been evaluated.Purpose
The present study aimed to assess the validity of digital follow-up systems in comparison with the conventional paper-based follow-up (PB-FU).Study Design
This is a retrospective analysis of prospectively collected double follow-up data.Patient Sample
Patients who underwent lumbar spinal fusion for spondylolisthesis or degenerative disc disease between 2013 and 2016 were included in the study.Outcome Measures
The study determined the Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) for back and leg pain severity at baseline, 6 weeks, 12 months, and 24 months.Materials and Methods
After lumbar spinal fusion surgery, a double follow-up of PROM was carried out by conventional PB-FU during clinical visits, while simultaneously completing an automatically dispatched digital follow-up questionnaire. As the primary end point, we assessed the intraindividual discrepancy in PROM between PB-FU and automated digital follow-up (AD-FU).Results
Forty patients completed all parts of the dual follow-up trajectory and were analyzed. We detected no discrepancy in ODI or NRS for back and leg pain severity at any of the baseline, 6-week, 12-month, or 24 month follow-ups (all p>.05). This was confirmed in a sensitivity analysis.Conclusions
In an analysis of dual paper-based and digital follow-up after lumbar fusion surgery, patients report highly similar values using either method of follow-up. It appears that AD-FU without incentives produces lower response rates. To reassess the validity of these systems for data collection in spinal patient care, a prospective validation with higher statistical power is warranted. 相似文献83.
84.
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85.
Luana Lopes Padilha Elcio Oliveira Vianna Andressa Talícia Machado Vale Joelma Ximenes Prado Teixeira Nascimento Antônio Augusto Moura da Silva Cecilia Claudia Costa Ribeiro 《Pediatric allergy and immunology》2020,31(5):480-488
Studies on the exposure of children to sugar-sweetened beverages (SSBs) at an early age may contribute to better understand the common causes and the temporal order of the relationships between obesity and asthma in early childhood. The objective of this study was to estimate the association between SSB and child asthma traits in the 2nd year of life, modeling direct and indirect pathways mediated by the highest BMI-z of the child and allergic inflammation. Data from the BRISA cohort, São Luís-MA, Brazil (n = 1140), were obtained from the baseline and from the follow-up performed at the 2nd year of life. The main explanatory variable was the calories from added sugars in SSBs as a percentage of the total daily energy intake. The outcome child asthma traits was a latent variable deduced from four indicators: medical diagnosis of asthma, wheezing, emergency visit due to intense wheezing, and medical diagnosis of rhinitis. A high percentage of daily calories from sugars added to SSBs was directly associated with higher values of child asthma traits (standardized coefficient (SC = 0.073; P = .030)). High levels of eosinophils were also directly associated with child asthma traits (SC = 0.118; P = .049). No mediation pathways were observed via greater BMI-z or eosinophil counts. Therefore, early exposure of children to SSB may contribute to increased risk of childhood asthma, preceding the link between sugar consumption and overweight/obesity, not yet evident in children in the first 2 years of life. 相似文献
86.
87.
88.
Rubens Souza de OLIVEIRA Lanna Jamile Corrêa da COSTA Fernanda Atanaena Gon?alves de ANDRADE Wilson UIEDA Luzia Fátima Alves MARTORELLI Ana Paula de Arruda Geraldes KATAOKA Elizabeth Salbé Travassos da ROSA Pedro Fernando da Costa VASCONCELOS Armando de Souza PEREIRA Ant?nio Ismael Barros do CARMO Marcus Emanuel Barroncas FERNANDES 《Revista do Instituto de Medicina Tropical de S?o Paulo》2015,57(6):497-503
The outbreaks of rabies in humans transmitted by Desmodus rotundus in 2004 and 2005,
in the northeast of the Brazilian State of Para, eastern Amazon basin, made this a
priority area for studies on this zoonosis. Given this, the present study provides
data on this phenomenon in an urban context, in order to assess the possible
circulation of the classic rabies virus (RABV) among bat species in Capanema, a town
in the Amazon basin. Bats were collected, in 2011, with mist nets during the wet and
dry seasons. Samples of brain tissue and blood were collected for virological and
serological survey, respectively. None of the 153 brain tissue samples analyzed
tested positive for RABV infection, but 50.34% (95% CI: 45.67-55.01%) of the serum
samples analyzed were seropositive. Artibeus planirostris was the most common
species, with a high percentage of seropositive individuals (52.46%, 95% CI: 52.31
52.60%). Statistically, equal proportions of seropositive results were obtained in
the rainy and dry seasons (c2 = 0.057, d.f. = 1, p = 0.88). Significantly
higher proportions of males (55.96%, 95% CI: 48.96-62.96%) and adults (52.37%, 95%
CI: 47.35-57.39%) were seropositive. While none of the brain tissue samples tested
positive for infection, the high proportion of seropositive specimens indicates that
RABV may be widespread in this urban area. 相似文献
89.
S. Natoli V. Oliveira P. Calabresi L. F. Maia A. Pisani 《European journal of neurology》2020,27(9):1764-1773
The current coronavirus disease (COVID‐19) outbreak, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has raised the possibility of potential neurotropic properties of this virus. Indeed, neurological sequelae of SARS‐CoV‐2 infection have already been reported and highlight the relevance of considering the neurological impact of coronavirus (CoV) from a translational perspective. Animal models of SARS and Middle East respiratory syndrome, caused by structurally similar CoVs during the 2002 and 2012 epidemics, have provided valuable data on nervous system involvement by CoVs and the potential for central nervous system spread of SARS‐CoV‐2. One key finding that may unify these pathogens is that all require angiotensin‐converting enzyme 2 as a cell entry receptor. The CoV spike glycoprotein, by which SARS‐CoV‐2 binds to cell membranes, binds angiotensin‐converting enzyme 2 with a higher affinity compared with SARS‐CoV. The expression of this receptor in neurons and endothelial cells hints that SARS‐CoV‐2 may have higher neuroinvasive potential compared with previous CoVs. However, it remains to be determined how such invasiveness might contribute to respiratory failure or cause direct neurological damage. Both direct and indirect mechanisms may be of relevance. Clinical heterogeneity potentially driven by differential host immune‐mediated responses will require extensive investigation. Development of disease models to anticipate emerging neurological complications and to explore mechanisms of direct or immune‐mediated pathogenicity in the short and medium term is therefore of great importance. In this brief review, we describe the current knowledge from models of previous CoV infections and discuss their potential relevance to COVID‐19. 相似文献
90.
Modena Débora Aparecida Oliveira Miranda Ana Carolina Godoy Grecco Clovis Liebano Richard Eloin Cordeiro Raquel Cristina Tancsik Guidi Renata Michelini 《Lasers in medical science》2020,35(4):797-806
Lasers in Medical Science - Using light sources in phototherapy has presented promising results regarding several types of facial and body skin affections for centuries. The neodymium-doped yttrium... 相似文献