全文获取类型
收费全文 | 1798篇 |
免费 | 137篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 73篇 |
妇产科学 | 31篇 |
基础医学 | 239篇 |
口腔科学 | 27篇 |
临床医学 | 150篇 |
内科学 | 293篇 |
皮肤病学 | 15篇 |
神经病学 | 248篇 |
特种医学 | 118篇 |
外国民族医学 | 2篇 |
外科学 | 278篇 |
综合类 | 72篇 |
一般理论 | 9篇 |
预防医学 | 116篇 |
眼科学 | 34篇 |
药学 | 93篇 |
中国医学 | 1篇 |
肿瘤学 | 140篇 |
出版年
2021年 | 13篇 |
2020年 | 18篇 |
2019年 | 14篇 |
2018年 | 34篇 |
2017年 | 27篇 |
2016年 | 30篇 |
2015年 | 30篇 |
2014年 | 29篇 |
2013年 | 59篇 |
2012年 | 82篇 |
2011年 | 73篇 |
2010年 | 55篇 |
2009年 | 64篇 |
2008年 | 65篇 |
2007年 | 64篇 |
2006年 | 86篇 |
2005年 | 74篇 |
2004年 | 93篇 |
2003年 | 71篇 |
2002年 | 64篇 |
2001年 | 49篇 |
2000年 | 56篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 36篇 |
1996年 | 38篇 |
1995年 | 41篇 |
1994年 | 32篇 |
1993年 | 16篇 |
1992年 | 29篇 |
1991年 | 38篇 |
1990年 | 38篇 |
1989年 | 46篇 |
1988年 | 38篇 |
1987年 | 31篇 |
1986年 | 39篇 |
1985年 | 30篇 |
1984年 | 21篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 20篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1974年 | 16篇 |
1972年 | 12篇 |
1971年 | 9篇 |
1967年 | 8篇 |
排序方式: 共有1940条查询结果,搜索用时 15 毫秒
61.
Jennifer J. Eddy Mark D. Gideonsen Richard R. McClaflin Peggy O'Halloran Francie A. Peardon Pamela L. Radcliffe Lynnette A. Masters 《Journal of community psychology》2012,40(5):607-620
Although evidence‐based interventions to reduce underage drinking have been identified, dissemination into ‘real‐world’ communities remains challenging. The purpose of this community‐based translational research is to test SAMHSA's Strategic Prevention Framework (SPF) as a model for such dissemination and evaluate its effect on alcohol use by youth aged 12–17. From 2001–2009 in Eau Claire, Wisconsin we used the SPF to assess community needs and implement a comprehensive strategy of evidence‐based programs targeting youth, parents and the community. Over this time, youth alcohol measures from middle and high school surveys showed an 8.6% decline in past‐month alcohol use (p<.05) and a 20.5% decline in ease of obtaining alcohol (p<.05). From 2004 to 2009 there was a 5.8% decrease in binge alcohol use (p<.05) and a 12.0% increase in perceived parental disapproval of alcohol use (p<.05). Based on our findings, the SPF is a promising model for communities seeking to reduce underage drinking. © 2012 Wiley Periodicals, Inc. 相似文献
62.
The sections in the following review cover six main neurodegenerative diseases. The first article on Alzheimer's disease (AD) outlines the major evidence available to date that links Aβ-amyloid peptide as a proximal cause of AD. The article also highlights how an initial finding of the protein content of the amyloid plaque seen in the brains of patients with AD has led to many very significant findings in the neuroscience field. The next section outlines the many and recent advances that have occurred in the field of frontotemporal lobar degeneration (FTLD), including the most recent finding related to the fused sarcoma gene (FUS) and the newest nomenclature whereby the FTLD is subtyped according to the presence of specific proteins seen at a microscopic level. The section on Lewy bodies outlines the latest advances in the relationship between the anatomical distribution of Lewy bodies and disease phenotype. The following section includes an overview of current known genetic links with familial causes of motor neuron disease (MND) and an update on the areas being researched into the causes of sporadic MND. The presence of TDP-43 within inclusions and its new diagnostic role in MND are discussed. The final article on prion diseases gives an overview of human prion diseases, including the phenotypic spectrum, epidemiology and diagnostic investigations relevant to disease. 相似文献
63.
Miklossy J Taddei K Suva D Verdile G Fonte J Fisher C Gnjec A Ghika J Suard F Mehta PD McLean CA Masters CL Brooks WS Martins RN 《Neurobiology of aging》2003,24(5):655-662
Mutations in the gene encoding presenilin 1 (PS-1) account for 50% of early-onset familial Alzheimer's disease (EOFAD) cases. In this study, we identified two missense mutations in the coding sequence of the presenilin (PS-1) gene in two EOFAD pedigrees. AD was confirmed in one pedigree by autopsy. Mutation analysis of PCR products amplified from genomic DNA templates showed two novel PS-1 mutations resulting in Gln222His and Tyr256Ser. The two novel mutations are located within predicted transmembrane domains five (TM-5) and six (TM-6), respectively, and are associated with very early ages of onset. The Tyr256Ser is associated with one of the youngest age of AD onset, 25 years, which is consistent with a drastic change in function of the altered PS-1 protein. A morphometric analysis of the cortical degenerative changes of the Tyr256Ser case, showed severe involvement of the primary motor cortex, which correlated well with the pyramidal changes, including tetraspasticity. Immunoblot analysis showed the Tyr256Ser case had the greatest expression of Abeta(1-40) and Abeta(1-42), which was confirmed by ELISA, compared to other PS-1 mutant FAD cases and age-matched controls and, thus, contributes to the severity of the disease pathology. 相似文献
64.
65.
66.
Human dihydrofolate reductase gene is located in chromosome 5 and is unlinked to the related pseudogenes. 总被引:4,自引:4,他引:4 下载免费PDF全文
B J Maurer P E Barker J N Masters F H Ruddle G Attardi 《Proceedings of the National Academy of Sciences of the United States of America》1984,81(5):1484-1488
The chromosomal location of the human dihydrofolate reductase (DHFR; EC 1.5.1.3) gene that is amplified in a methotrexate-resistant human cell line has been investigated by screening a large number of human-mouse cell hybrids containing overlapping subsets of human chromosomes. A correlation of genomic blotting data with the chromosome constitution of the individual cell hybrids has allowed the assignment of the human DHFR gene to chromosome 5. This chromosome assignment has been confirmed by the observation of a concomitant loss of the human DHFR gene and of sensitivity to diphtheria toxin, a marker associated with chromosome 5, in two human-mouse cell hybrids selected for resistance to the toxin. Six EcoRI fragments of human DNA containing DHFR pseudogenes or other DHFR-related sequences have been assigned to chromosomes other than chromosome 5. 相似文献
67.
Ester Cerin Stephanie R. Rainey-Smith David Ames Nicola T. Lautenschlager S. Lance Macaulay Christopher Fowler Joanne S. Robertson Christopher C. Rowe Paul Maruff Ralph N. Martins Colin L. Masters Kathryn A. Ellis 《Alzheimer's & dementia》2017,13(4):388-398
Introduction
“Walkable” neighborhoods offer older adults opportunities for activities that may benefit cognition-related biological mechanisms. These have not previously been examined in this context.Methods
We objectively assessed neighborhood walkability for participants (n = 146) from the Australian Imaging, Biomarkers and Lifestyle study with apolipoprotein E (APOE) genotype and two 18-month-apart brain volumetric and/or amyloid β burden assessments. Linear mixed models estimated associations of neighborhood walkability with levels and changes in brain imaging outcomes, the moderating effect of APOE ε4 status, and the extent to which associations were explained by physical activity.Results
Cross-sectionally, neighborhood walkability was predictive of better neuroimaging outcomes except for left hippocampal volume. These associations were to a small extent explained by physical activity. APOE ε4 carriers showed slower worsening of outcomes if living in walkable neighborhoods.Discussion
These findings indicate associations between neighborhood walkability and brain imaging measures (especially in APOE ε4 carriers) minimally attributable to physical activity. 相似文献68.
Guillain-Barr啨综合征(GBS)和Miller Fisher综合征(MFS)的诊断标准随着临床研究的深入在不断演变。2011年1月,《疫苗》杂志发表了国际疫苗安全性监测Brighton合作组关于GBS/MFS的诊断定义和研究资料收集规范。此文献中未采用"诊断标准"而采用"诊断定义"是因为其主要目的为评价疫苗安全性而制定,而非用于神经科的GBS/ 相似文献
69.
Spacing devices have been widely advocated for asthmatic patients having difficulty actuating metered aerosols and co-ordinating inspiration. Studies have generally supported the slow inspiration/breath hold technique. This requires conscious respiratory control. Such control is often not possible in young children; consequently panting techniques are widely recommended. The panting technique has not been studied. The aim of this study was to compare the bronchodilator effectiveness of panting and the single breath maneuver, each followed by a breath hold, and each at functional residual capacity (FRC), using a Volumatic Space. The study design was a randomly allocated cross-over assessment of bronchodilator response for each technique. The drug dosage was controlled by limiting the inspired volumes of gas (single and cumulative) to the pretested inspiratory capacity. Two hundred micrograms of salbutamol was delivered into the spacer. Twenty-one patients were entered in the study and 15 (mean age +/- SD = 10.9 +/- 3.3 years) completed the protocol. There was no significant difference in bronchodilator response between the two groups. We conclude that the panting and the single breath techniques are equally effective in children of this age group. 相似文献
70.
Detection of respiratory syncytial virus antigen in nasal washings by Abbott TestPack enzyme immunoassay. 下载免费PDF全文
We compared the new Abbott TestPack (TP) respiratory syncytial virus (RSV) enzyme immunoassay (EIA) with cell culture and two commercial RSV EIAs (from Abbott Diagnostics and Kallestad Laboratories) by using split samples of fresh nasal washings from children with suspected RSV disease. Two tubes of HEp-2 cells were inoculated and observed for cytopathic effect for 14 days, and isolates were confirmed by immunofluorescence. The TP EIA was performed by following the manufacturer's instructions. Specimens positive by TP EIA but negative by culture were examined in a competitive inhibition (blocking) assay using the TP EIA, and rabbit anti-RSV serum. Of 218 specimens, 93 were positive by culture, 105 were positive by TP EIA, 80 were positive by the Abbott Diagnostics EIA, and 87 were positive by the Kallestad Laboratories EIA. The sensitivity, specificity, positive predictive value, and negative predictive value of the TP EIA were 92, 86, 81, and 93%, respectively. Of 20 apparently false-positive TP EIAs, 10 of 14 that were positive when retested were neutralized in the blocking assay, indicating that they were truly positive. The recalculated sensitivity, specificity, positive predictive value, and negative predictive value of the TP EIA were 92, 91, 90, and 93%, respectively. We conclude that the TP EIA is easy to perform, rapid (less than 0.5 h), and accurate. 相似文献