全文获取类型
收费全文 | 143009篇 |
免费 | 8205篇 |
国内免费 | 756篇 |
专业分类
耳鼻咽喉 | 1382篇 |
儿科学 | 4642篇 |
妇产科学 | 3457篇 |
基础医学 | 20292篇 |
口腔科学 | 4491篇 |
临床医学 | 15622篇 |
内科学 | 30544篇 |
皮肤病学 | 3449篇 |
神经病学 | 13860篇 |
特种医学 | 3122篇 |
外国民族医学 | 2篇 |
外科学 | 12722篇 |
综合类 | 797篇 |
一般理论 | 103篇 |
预防医学 | 15122篇 |
眼科学 | 2192篇 |
药学 | 9557篇 |
中国医学 | 472篇 |
肿瘤学 | 10142篇 |
出版年
2024年 | 136篇 |
2023年 | 1215篇 |
2022年 | 2567篇 |
2021年 | 4371篇 |
2020年 | 2727篇 |
2019年 | 3818篇 |
2018年 | 4350篇 |
2017年 | 3261篇 |
2016年 | 3731篇 |
2015年 | 4228篇 |
2014年 | 5629篇 |
2013年 | 7611篇 |
2012年 | 11491篇 |
2011年 | 12016篇 |
2010年 | 6547篇 |
2009年 | 5528篇 |
2008年 | 9852篇 |
2007年 | 9869篇 |
2006年 | 9320篇 |
2005年 | 8669篇 |
2004年 | 7980篇 |
2003年 | 7231篇 |
2002年 | 6586篇 |
2001年 | 804篇 |
2000年 | 570篇 |
1999年 | 913篇 |
1998年 | 1213篇 |
1997年 | 1021篇 |
1996年 | 881篇 |
1995年 | 736篇 |
1994年 | 703篇 |
1993年 | 611篇 |
1992年 | 484篇 |
1991年 | 356篇 |
1990年 | 353篇 |
1989年 | 327篇 |
1988年 | 310篇 |
1987年 | 281篇 |
1986年 | 271篇 |
1985年 | 239篇 |
1984年 | 305篇 |
1983年 | 304篇 |
1982年 | 355篇 |
1981年 | 291篇 |
1980年 | 296篇 |
1979年 | 180篇 |
1978年 | 162篇 |
1977年 | 158篇 |
1976年 | 127篇 |
1974年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
11.
12.
Zinc sulfate addition to glass-ionomer-based cements: influence on physical and antibacterial properties, zinc and fluoride release. 总被引:5,自引:0,他引:5
Prudencio W R Osinaga Rosa Helena M Grande Rafael Y Ballester Maria Regina L Simionato Célia Regina M Delgado Rodrigues Antonio Muench 《Dental materials》2003,19(3):212-217
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility. 相似文献
13.
Patricia A Wilkosz Sachiko Miyahara Oscar L Lopez Steven T Dekosky Robert A Sweet 《The American journal of geriatric psychiatry》2006,14(4):352-360
BACKGROUND: Psychotic symptoms in Alzheimer disease (AD+P) identify a heritable phenotype associated with more rapid cognitive decline. The authors have proposed that AD+P is itself a composite of a misidentification and a paranoid subtype with increased cognitive impairment restricted to the misidentification type. Most prior studies of the clinical correlates of AD+P have been limited, however, by the inclusion of prevalent cases. METHODS: Subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis at study entry were assessed at the time of initial presentation and then annually. Psychotic symptoms were assessed using the CERAD Behavioral Rating Scale. Survival analyses used Cox proportional hazard models with time-dependent covariates to examine the predictors of psychosis onset. RESULTS: A total of 288 subjects completed at least one follow-up examination. Mean duration of follow-up was 22.1 months. The incidence of psychosis was 0.19 per person-year. Cognitive impairment was associated with onset of psychosis, largely as a result of its association with onset of the misidentification, but not the paranoid, subtype. Including psychotropic medication use in the model revealed an association of antidepressant use with the onset of psychosis. This latter association appeared to arise from an underlying association between depression and the risk of psychosis onset rather than from antidepressant treatment. CONCLUSION: These findings are consistent with the hypothesis that the misidentification and the paranoid subtypes each define a more biologically homogeneous group than AD+P as a whole. Further exploration of the relationship between depressive symptoms and psychosis in patients with AD is warranted. 相似文献
14.
Access to good-quality health services is crucial for the improvement of many health outcomes, such as those targeted by the
Millennium Development Goals (MDGs) adopted by the international community in 2000. The health-related MDGs cannot be achieved
if vulnerable populations do not have access to skilled personnel and to other necessary inputs. This paper focuses on the
geographical dimension of access and on one of its critical determinants: the availability of qualified personnel. The objective
of this paper is to offer a better understanding of the determinants of geographical imbalances in the distribution of health
personnel, and to identify and assess the strategies developed to correct them. It reviews the recent literature on determinants,
barriers and the effects of strategies that attempted to correct geographical imbalances, with a focus on empirical studies
from developing and developed countries. An analysis of determinants of success and failures of strategies implemented, and
a summary of lessons learnt, is included. 相似文献
15.
Maria Stella Aniello Davide Martino Gianluca Masi Paolo Livrea Giovanni Defazio 《Movement disorders》2006,21(4):571-575
We developed a self-administered questionnaire for screening the most common adult-onset dystonias. It was tested in 90 first-degree relatives of 22 adult-onset dystonia patients, yielding 79% sensitivity and 94% specificity. Simulation of a case-finding procedure based on serial application of the questionnaire and clinical examination of both subjects screening positive and subjects screening negative who had < 8 years of schooling increased sensitivity to 95% and specificity to 100%. This questionnaire may be an important screening resource for familial aggregation studies to be used in the context of a complex case-finding procedure. 相似文献
16.
Anna Maria Lavezzi Giulia Ottaviani Lorella Terni Luigi Matturri 《International journal of developmental neuroscience》2006,24(6):365-371
The aim of this study was to investigate the histological and biological features of the human cerebellar cortex development and differentiation. We analyzed 52 brains of fetal and infant death victims, aged from 17 gestational weeks to 12th postnatal month. In particular, in the cerebellar cortex at different ages we evaluated, besides the structural aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, PCNA and apoptosis). We observed morphological patterns progressively evolving every month, from the indefinite structure of the second gestational trimester to the four-layered structure (external granular layer, molecular layer, Purkinje cell layer, internal granular layer) of the late fetal cortex and subsequently to the three-layered postnatal definitive morphology, due to involution of the external granular layer. The evaluation of the biological features of the cerebellar cortex showed high proliferative activity mainly confined to the transient external granular layer in prenatal life, and high apoptotic index after birth. Thus, the histological examination, better with the support of biomarker investigations, allows with accuracy to describe the dynamic sequence of steps that occur in human cerebellar cortex development and to establish in each case the age, namely the pre- or postnatal month of life. Consequently, we can diagnose delayed or altered processes of differentiation during the development of the human cerebellar cortex. 相似文献
17.
Paul C. Willems Leon Elmans Patricia G. Anderson Wilco C. H. Jacobs Dick B. van der Schaaf Marinus de Kleuver 《European spine journal》2006,15(10):1487-1494
The results of lumbar fusion in chronic low back pain (LBP) patients vary considerably, and there is a need for proper patient selection. Lumbosacral orthoses have been widely used to predict outcome, however, with little scientific support. The aim of the present study was to determine the value of a pantaloon cast test in selecting chronic LBP patients for lumbar fusion or conservative management. First, a systematic review of the literature was carried out in which two independent reviewers identified studies in Medline, Cochrane and Current Contents databases. Three papers met the selection criteria. In the only study with a control group, a significantly better outcome after fusion compared to conservative treatment was found in patients who reported significant pain relief while in a cast (i.e. a positive cast test). The results of lumbar fusion, however, were not significantly different for patients with a positive and those with a negative cast test. In addition to the review, a clinical cohort study of 257 LBP patients, who had been allocated to either lumbar fusion or conservative management by a temporary external transpedicular fixation trial, was performed. Prior to allocation, all had undergone a pantaloon cast test. Patients with no history of prior spine surgery and with a positive pantaloon cast test had a better outcome after lumbar fusion than those treated conservatively (P = 0.002, χ
2 test). In patients with previous spine operations the outcomes were poor and the test was of no value. From the literature and the present patient cohort, it was concluded that only in chronic LBP patients without prior spine surgery, a pantaloon cast test with substantial pain relief suggests a favorable outcome of lumbar fusion compared to conservative management. The test has no value in patients who have had previous spine surgery. 相似文献
18.
The molecular and clinical impact of hepatocyte growth factor, its receptor, activators, and inhibitors in wound healing 总被引:1,自引:0,他引:1
Kevin Conway MRCS ; Patricia Price PhD ; Keith G. Harding FRCS ; Wen G. Jiang MD 《Wound repair and regeneration》2006,14(1):2-10
Wound healing involves a number of cellular and molecular events, many of which are controlled by soluble growth factors. In the process of healing, hepatocyte growth factor, a cytokine known to act as mitogen, motogen, and morphogen, has been postulated to play multiple roles during several stages of this complex biological process. Produced primarily by stromal fibroblasts, hepatocyte growth factor regulates angiogenesis, vascular permeability, cell migration, matrix deposition and degradation, and other biological processes. The current article discusses recent progress in understanding the multiple roles played by this growth factor in tissue repair. 相似文献
19.
Marcondes C Fran?a Maria E Calcagnotto Jaderson C da Costa Iscia Lopes-Cendes 《Movement disorders》2006,21(7):1051-1053
Spinocerebellar ataxia (SCA) types 2 and 3 are autosomal-dominant neurodegenerative disorders caused by mutations in two different genes. We identified mutations for SCA2 and SCA3 segregating simultaneously in a single Brazilian family. The index patient had SCA2, whereas her two second-degree cousins had SCA3. Disease was more rapidly progressive in the SCA2 patient, who presented severe brainstem and pancerebellar atrophy, as opposed to the two SCA3 patients, who had only mild cerebellar vermian atrophy. In such situations, molecular confirmation of all patients may avoid misdiagnosis of SCA subtypes and eventual errors in predictive testing of unaffected family members. 相似文献