全文获取类型
收费全文 | 2967篇 |
免费 | 231篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 96篇 |
妇产科学 | 75篇 |
基础医学 | 493篇 |
口腔科学 | 67篇 |
临床医学 | 245篇 |
内科学 | 622篇 |
皮肤病学 | 128篇 |
神经病学 | 399篇 |
特种医学 | 58篇 |
外科学 | 222篇 |
综合类 | 11篇 |
一般理论 | 1篇 |
预防医学 | 255篇 |
眼科学 | 38篇 |
药学 | 221篇 |
中国医学 | 4篇 |
肿瘤学 | 244篇 |
出版年
2024年 | 6篇 |
2023年 | 60篇 |
2022年 | 87篇 |
2021年 | 179篇 |
2020年 | 96篇 |
2019年 | 138篇 |
2018年 | 121篇 |
2017年 | 92篇 |
2016年 | 101篇 |
2015年 | 130篇 |
2014年 | 154篇 |
2013年 | 153篇 |
2012年 | 266篇 |
2011年 | 263篇 |
2010年 | 132篇 |
2009年 | 111篇 |
2008年 | 173篇 |
2007年 | 152篇 |
2006年 | 142篇 |
2005年 | 159篇 |
2004年 | 99篇 |
2003年 | 127篇 |
2002年 | 95篇 |
2001年 | 25篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1971年 | 1篇 |
1964年 | 1篇 |
1932年 | 1篇 |
1931年 | 2篇 |
1930年 | 2篇 |
1929年 | 5篇 |
1903年 | 1篇 |
排序方式: 共有3209条查询结果,搜索用时 296 毫秒
71.
72.
73.
Expert testimony is being used increasingly in child sexual assault cases. This study extended a prior study that examined factors related to expert testimony (evidence strength, coherence and credentials of the expert) on ratings of guilt and overall verdict. Specifically, we replicated our prior study but with two modifications: we used community samples as opposed to university students, and participants made their decisions in groups of 12 (as in the case of juries where one decision represents the overall group) rather than having participants decide and submit their verdicts and guilt ratings individually. Consistent with the prior (less ecologically valid) study, credentials of the expert had negligible impact. Evidence that was high in strength elicited a relatively high guilt rating even when the testimony was low in coherence. Further, it appears that when participants deliberate in a group (as in the case of juries) they are more conservative in their judgements (i.e., they are less likely to give a guilty verdict) compared to individual jurors who make their decisions alone. These findings suggest that caution must be exercised when drawing conclusions about the generalisability of prior research findings where participants did not engage in group deliberation. 相似文献
74.
Monica Pires Ribeiro Sergio Augusto Lopes de Souza Flavia Paiva Proen?a Lobo Lopes Paulo Henrique Rosado-de-Castro Lea Mirian Barbosa da Fonseca Bianca Gutfilen 《Clinics (S?o Paulo, Brazil)》2013,68(3):283-289
OBJECTIVE:
Mammography has been established as the gold standard for the detection of breast cancer, and imaging techniques such as ultrasonography, magnetic resonance imaging, scintigraphy and positron emission tomography may be useful to improve its sensitivity and specificity. The objective of this study with breast scintigraphy was to evaluate the uptake of 99mTc-thymine in mammary lesions.METHODS:
A total of 45 patients were included in this study. Thirty-three patients (73%) were subjected to surgery or percutaneous biopsy, providing histopathological data. The other 12 patients who remained under surveillance received clinical examinations and biannual mammography with a normal follow-up of at least three years, the data from which were used for comparison with the scintimammography results.RESULTS:
The majority of patients (64.4%) had clinically impalpable lesions with a mammogram diagnosis of microcalcifications, impalpable nodules, or focal asymmetry. Of the studied lesions, 87% were smaller or equal to 20 mm in diameter, and 22% had malignant histopathological findings. Scintigraphy with 99mTc-thymine had a sensitivity of 70%, a specificity of 85.7%, positive and negative predictive values of 58.3% and 90.9%, respectively, and an accuracy of 82.2%.CONCLUSIONS:
The results of this study are consistent with those previously reported by other authors. The good specificity and high negative predictive value of this technique and the absence of uptake in the heart indicate that it may be a promising complementary method in clinical practice and that it may contribute to reducing unnecessary benign biopsies. 相似文献75.
76.
77.
Carolina Maso Viegas Anelise Miotti Tonin ?ngela Zanatta Bianca Seminotti Estela Natacha Brandt Busanello Carolina Gon?alves Fernandes Alana Pimentel Moura Guilhian Leipnitz Moacir Wajner 《Metabolic brain disease》2012,27(4):521-530
Ornithine, ammonia and homocitrulline are the major metabolites accumulating in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, a genetic disorder characterized by neurological regression whose pathogenesis is still not understood. The present work investigated the in vivo effects of intracerebroventricular administration of ornithine and homocitrulline in the presence or absence of hyperammonemia induced by intraperitoneal urease treatment on a large spectrum of oxidative stress parameters in cerebral cortex from young rats in order to better understand the role of these metabolites on brain damage. Ornithine increased thiobarbituric acid-reactive substances (TBA-RS) levels and carbonyl formation and decreased total antioxidant status (TAS) levels. We also observed that the combination of hyperammonemia with ornithine resulted in significant decreases of sulfhydryl levels, reduced glutathione (GSH) concentrations and the activities of catalase (CAT) and glutathione peroxidase (GPx), highlighting a synergistic effect of ornithine and ammonia. Furthermore, homocitrulline caused increases of TBA-RS values and carbonyl formation, as well as decreases of GSH concentrations and GPx activity. Hcit with hyperammonemia (urease treatment) decreased TAS and CAT activity. We also showed that urease treatment per se was able to enhance TBA-RS levels. Finally, nitric oxide production was not altered by Orn and Hcit alone or in combination with hyperammonemia. Our data indicate that the major metabolites accumulating in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome provoke lipid and protein oxidative damage and a reduction of the antioxidant defenses in the brain. Therefore, it is presumed that oxidative stress may represent a relevant pathomechanism involved in the brain damage found in patients affected by this disease. 相似文献
78.
Rosso R Di Biagio A Maggiolo F Nulvesu L Callegaro AP Taramasso L Bruzzone B Viscoli C 《AIDS care》2012,24(1):54-58
The choice of an antiretroviral regimen can often impact on adherence, treatment satisfaction and therefore influence on clinical outcome. These concerns are particularly true in adolescents. In this setting, adherence is usually affected by multifactor events and biopsychosocial factors, which connect and changeover time. We evaluated the effect of a switch to a single-pill fixed-dose regimen on patient-reported outcomes, virologic and immunologic outcomes, and safety in a cohort of adolescents with perinatal HIV-1 infection. In addition, we evaluated the effect on low-level residual HIV-RNA. An open-label, non-randomised study was performed: 12 adolescents with a confirmed viremia <50 copies/mL treated with lamivudine or emtricitabine, tenofovir and efavirenz were switched to one-pill fixed-dose regimen of emtricitabine/tenofovir/efavirenz. At the end of follow-up, the new regimen was associated with improvements in treatment satisfaction, HIV-symptoms, whereas adherence remained high. No immunological or virological significative changes were observed. No side-effects were registered. Moreover, the low-level residual HIV-RNA was <3 copie/mL in all patients. One-pill fixed-dose regimen is an added value that favours adherence, reduces HIV-symptoms, improves patients' satisfaction and could better control of HIV-RNA in adolescents, too. 相似文献
79.
80.
Attention deficit hyperactivity disorder (ADHD) is often associated with symptoms of aggression in children and adolescents. Clinically, this is complex because aggression can be from hyperactivity and impulsivity, or could be a distinct symptom from a comorbid diagnosis. Past research has recommended first treating the primary disorder of ADHD. Stimulants are the most common treatment for pediatric ADHD, which can be helpful in decreasing aggressive behaviors. Alpha-adrenergic agonists and atomoxetine (ATX) are non-stimulant medications for ADHD and aggression, but more research is necessary to compare these drugs to stimulants. If aggressive symptoms do not improve from treating the primary disorder, aggression can be treated separately. Risperidone, lithium, valproic acid, clonidine, and guanfacine have shown positive results in reducing aggression, but studies including children with aggression and ADHD are limited. The variability in treatment tolerability in patients has stimulated research in pharmacogenetics for ADHD. Although this field is still emerging, research has found evidence supporting a link between the response rate of methylphenidate and the dopamine transporter (DAT1) and a link between the metabolism rate of atomoxetine and hepatic cytochrome 450 isozymes. Pharmacogenetics may be relevant to ADHD and associated aggression. Further research in pharmacogenetics will strive to identify patterns of genetic variations that can tailor individual treatments. 相似文献