全文获取类型
收费全文 | 6227篇 |
免费 | 380篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 95篇 |
儿科学 | 185篇 |
妇产科学 | 135篇 |
基础医学 | 885篇 |
口腔科学 | 376篇 |
临床医学 | 547篇 |
内科学 | 1447篇 |
皮肤病学 | 150篇 |
神经病学 | 659篇 |
特种医学 | 79篇 |
外科学 | 558篇 |
综合类 | 25篇 |
一般理论 | 2篇 |
预防医学 | 612篇 |
眼科学 | 72篇 |
药学 | 416篇 |
中国医学 | 40篇 |
肿瘤学 | 359篇 |
出版年
2024年 | 5篇 |
2023年 | 64篇 |
2022年 | 160篇 |
2021年 | 303篇 |
2020年 | 165篇 |
2019年 | 274篇 |
2018年 | 310篇 |
2017年 | 159篇 |
2016年 | 180篇 |
2015年 | 228篇 |
2014年 | 304篇 |
2013年 | 335篇 |
2012年 | 571篇 |
2011年 | 629篇 |
2010年 | 309篇 |
2009年 | 280篇 |
2008年 | 416篇 |
2007年 | 365篇 |
2006年 | 342篇 |
2005年 | 268篇 |
2004年 | 252篇 |
2003年 | 231篇 |
2002年 | 214篇 |
2001年 | 36篇 |
2000年 | 34篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 22篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 3篇 |
排序方式: 共有6642条查询结果,搜索用时 20 毫秒
1.
Caio Henrique de Carvalho Assuno Júlio Csar Trabanco Raquel Fornaziero Gomes Renata Rodrigues Moreira Alessandra Giannella Samelli 《La Medicina del lavoro》2019,110(4):304
Objective:The present study evaluates a training program for fitting different hearing protection devices (HPDs) based on personal attenuation rating (PAR) before, immediately after, and six months after training.Methods:A total of 67 workers from a public university in the city of São Paulo, Brazil, were invited to participate in the measurement of PARs for foam and silicone protectors through the 3M™ E-A-Rfit Validation System. Two evaluations were performed for each protector at each sampling date: one after reading printed material (the package instructions) and another after being trained by an audiologist. The same procedures were repeated after six months. The final sample consisted of 30 individuals. ANOVA was used for statistical analysis.Results:Larger PAR values were observed after training by the audiologist, and smaller values were observed after six months. Then, after re-training, the values increased again. There were no statistically significant differences in PAR among the HPDs tested. Even after the two training sessions, 23 to 27% of the subjects did not obtain adequate PAR values.Conclusion:These findings emphasize the need for continual worker training in the correct fit of earplug HPDs and the importance of longitudinal PAR monitoring. In addition, some workers, despite the training provided, did not adapt to the HPDs used. Therefore, it is essential that other protection methods and/or other HPD types are made available to these individuals.Key words: Hearing, noise-induced hearing loss, occupational health, personal protective equipment, hearing protection devices 相似文献
2.
3.
Del Lama Rafael Silva Candido Raquel Mariana Chiari-Correia Natália Santana Nogueira-Barbosa Marcello Henrique de Azevedo-Marques Paulo Mazzoncini Tinós Renato 《Journal of digital imaging》2022,35(3):446-458
Journal of Digital Imaging - Vertebral Compression Fracture (VCF) occurs when the vertebral body partially collapses under the action of compressive forces. Non-traumatic VCFs can be secondary to... 相似文献
4.
Samira Marín-Romero Teresa Elías-Hernández María Isabel Asensio-Cruz Rocío Ortega-Rivera Raquel Morillo-Guerrero Javier Toral Emilio Montero Verónica Sánchez Elena Arellano José María Sánchez-Díaz Macarena Real-Domínguez Remedios Otero-Candelera Luis Jara-Palomares 《Archivos de bronconeumología》2019,55(12):619-626
IntroductionScales for predicting venous thromboembolism (VTE) recurrence are useful for deciding the duration of the anticoagulant treatment. Although there are several scales, the most appropriate for our setting has not been identified. For this reason, we aimed to validate the DASH prediction score and the Vienna nomogram at 12 months.MethodsThis was a retrospective study of unselected consecutive VTE patients seen between 2006 and 2014. We compared the ability of the DASH score and the Vienna nomogram to predict recurrences of VTE. The validation was performed by stratifying patients as low-risk or high-risk, according to each scale (discrimination) and comparing the observed recurrence with the expected rate (calibration).ResultsOf 353 patients evaluated, 195 were analyzed, with an average age of 53.5 ± 19 years. There were 21 recurrences in 1 year (10.8%, 95% CI: 6.8%-16%). According to the DASH score, 42% were classified as low risk, and the rate of VTE recurrence in this group was 4.9% (95% CI: 1.3%-12%) vs. the high-risk group that was 15% (95% CI: 9%-23%) (p <.05). According to the Vienna nomogram, 30% were classified as low risk, and the rate of VTE recurrence in the low risk group vs. the high risk group was 4.2% (95% CI:0.5%-14%) vs. 16.2% (95% CI: 9.9%-24.4%) (p <.05).ConclusionsOur study validates the DASH score and the Vienna nomogram in our population. The DASH prediction score may be the most advisable, both because of its simplicity and its ability to identify more low-risk patients than the Vienna nomogram (42% vs. 30%). 相似文献
5.
6.
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
7.
8.
Effect of leptin on the regulation of placental hormone secretion in cultured human placental cells.
Raquel Coya Pedro Martul Jaime Algorta Ma Angeles Aniel-Quiroga Ma Angeles Busturia Rosa Se?arís 《Gynecological endocrinology》2006,22(11):620-626
Placenta is an important source of leptin during pregnancy that contributes to the high plasma leptin levels in pregnant women. Leptin and its functional receptors are synthesized in trophoblast cells that, in turn, secrete gestational hormones supporting a paracrine or autocrine role for leptin in the endocrine activity of the placenta. In the present study we examined the effect of leptin on in vitro release of gestational hormones (human chorionic gonadotropin (hCG), human placental lactogen (hPL), progesterone, estrogens and testosterone) by human term placental cells in culture. Placentas at term were obtained immediately after delivery from mothers with uncomplicated pregnancies. Progesterone, hCG, hPL, estradiol, estrone, estriol and testosterone levels were measured by different assays in culture media of cells maintained in monolayer culture after incubation for 12, 24, 48 or 72 h with leptin or placebo. Incubation with leptin did not modify hCG, hPL, progesterone, estriol and estrone secretion for any of the doses and times assayed. However, leptin led to a dose-dependent decrease in estradiol release. This effect was observed when treatment with recombinant human leptin spanned from 12 to 72 h. At this time an increase in testosterone levels was observed in leptin-treated cells versus placebo. These results indicate that leptin can be considered a gestational hormone implied in the endocrine function of the placenta, with an important role in control of the production of steroid reproductive hormones in placental cells in vitro. 相似文献
9.
José Abal Arca Isaura Parente Lamelas Raquel Almazán Ortega José Blanco Pérez María Elena Toubes Navarro Pedro Marcos Velázquez 《Archivos de bronconeumologia》2009,45(10):502-507
Background and objectiveTo analyse frequency, characteristics and patient survival with lung cancer (LC) and Common Obstructive Pulmonary Disease (COPD), comparing them with patients that do not have COPD.Material and methodsA retrospective study, of patients diagnosed by means of cytohistology. Survival was estimated by the Kaplan-Meier method. Statistical analysis was carried out using SPSS 15.0.ResultsA total of 996 patients were diagnosed, 39.8% with COPD. Mean age70±9.19 years. GOLD stages: I 18.2%, II 53.6%, III 24%, IV 4.2%. The histological types: squamous cell carcinoma 48.2%, adenocarcinoma 22%, and small cell carcinoma 22.5%. Survival was longer in the COPD group.ConclusionsLC and COPD are combined in 39.8%. Squamous cell type is more frequent and survival was longer in the COPD group. 相似文献
10.
A sexually dimorphic ratio of orbitofrontal to amygdala volume is altered in schizophrenia. 总被引:3,自引:0,他引:3
Raquel E Gur Christian Kohler Bruce I Turetsky Steven J Siegel Stephen J Kanes Warren B Bilker Avis R Brennan Ruben C Gur 《Neuropsychopharmacology》2004,55(5):512-517
BACKGROUND: Neuroanatomic sexual dimorphisms have been correlated with behavioral differences between healthy men and women. We have reported higher orbitofrontal cortex to amygdala ratio (OAR) in women than men. Although gender differences in schizophrenia are evident clinically and correlate with neuroanatomic measures, their relationship to OAR has not been examined. METHODS: Magnetic resonance imaging was performed in 31 neuroleptic-na?ve schizophrenic patients (16 men) and 80 healthy volunteers (34 men), aged less than 50 years. An automated tissue segmentation procedure was combined with expert-guided parcellation of orbitofrontal and amygdala volumes. RESULTS: Men with schizophrenia had increased OAR relative to healthy men, whereas women had decreased OAR. Increased OAR in men with schizophrenia reflected abnormally low amygdala volumes, whereas decreased OAR in women reflected abnormally low orbitofrontal volumes. Less severe negative symptoms were associated with increased OAR in men but with decreased OAR in women. In men, increased amygdala volume was associated with greater symptom severity, whereas in women higher volumes of both amygdala and orbitofrontal regions were associated with lesser severity of negative symptoms. CONCLUSIONS: These opposite OAR abnormalities, whereby men show feminization and women masculinization, suggest gender-mediated effects of the underlying neuropathologic processes. The correlations with symptom severity suggest that neuroanatomic abnormalities in OAR reflect compensatory brain changes. 相似文献