全文获取类型
收费全文 | 8014篇 |
免费 | 910篇 |
国内免费 | 68篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 215篇 |
妇产科学 | 397篇 |
基础医学 | 879篇 |
口腔科学 | 559篇 |
临床医学 | 1516篇 |
内科学 | 1412篇 |
皮肤病学 | 105篇 |
神经病学 | 565篇 |
特种医学 | 446篇 |
外科学 | 1054篇 |
综合类 | 154篇 |
一般理论 | 15篇 |
预防医学 | 669篇 |
眼科学 | 70篇 |
药学 | 483篇 |
中国医学 | 7篇 |
肿瘤学 | 389篇 |
出版年
2023年 | 66篇 |
2021年 | 93篇 |
2020年 | 91篇 |
2019年 | 114篇 |
2018年 | 157篇 |
2017年 | 175篇 |
2016年 | 168篇 |
2015年 | 195篇 |
2014年 | 261篇 |
2013年 | 324篇 |
2012年 | 324篇 |
2011年 | 434篇 |
2010年 | 289篇 |
2009年 | 253篇 |
2008年 | 359篇 |
2007年 | 438篇 |
2006年 | 402篇 |
2005年 | 353篇 |
2004年 | 310篇 |
2003年 | 336篇 |
2002年 | 315篇 |
2001年 | 159篇 |
2000年 | 159篇 |
1999年 | 156篇 |
1998年 | 174篇 |
1997年 | 178篇 |
1996年 | 170篇 |
1995年 | 154篇 |
1994年 | 107篇 |
1993年 | 84篇 |
1992年 | 118篇 |
1991年 | 96篇 |
1990年 | 99篇 |
1989年 | 95篇 |
1988年 | 109篇 |
1987年 | 90篇 |
1986年 | 110篇 |
1985年 | 93篇 |
1984年 | 81篇 |
1983年 | 85篇 |
1982年 | 70篇 |
1981年 | 57篇 |
1980年 | 56篇 |
1979年 | 48篇 |
1978年 | 74篇 |
1977年 | 72篇 |
1976年 | 51篇 |
1975年 | 58篇 |
1974年 | 48篇 |
1972年 | 51篇 |
排序方式: 共有8992条查询结果,搜索用时 46 毫秒
1.
2.
Alan. B. Franklin Sarah N. Bevins Jeremy W. Ellis Ryan S. Miller Susan A. Shriner J. Jeffrey Root Daniel P. Walsh Thomas J. Deliberto 《Transboundary and Emerging Diseases》2019,66(2):705-714
Using data on waterfowl band recoveries, we identified spatially explicit hotspots of concentrated waterfowl movement to predict occurrence and spatial spread of a novel influenza A virus (clade 2.3.4.4) introduced from Asia by waterfowl from an initial outbreak in North America in November 2014. In response to the outbreak, the hotspots of waterfowl movement were used to help guide sampling for clade 2.3.4.4 viruses in waterfowl as an early warning for the US poultry industry during the outbreak . After surveillance sampling of waterfowl, we tested whether there was greater detection of clade 2.3.4.4 viruses inside hotspots. We found that hotspots defined using kernel density estimates of waterfowl band recoveries worked well in predicting areas with higher prevalence of the viruses in waterfowl. This approach exemplifies the value of ecological knowledge in predicting risk to agricultural security. 相似文献
3.
4.
D Van Neste† RM Trüeb‡ 《Journal of the European Academy of Dermatology and Venereology》2006,20(5):578-583
BACKGROUND: Computer-assisted image analysis has been proposed for human hair growth studies. METHODS: The performances of Trichoscan, a commercially available automated system combining epiluminiscence microscopy with digital image analysis, developed for office-based hair growth measurements, have been evaluated comparatively on the same skin sites using standardized photographic equipment and calibrated processing for contrast-enhanced phototrichogram (CE-PTG) analysis. This reference method has been validated with scalp biopsies and histological examination of serial sectioning. RESULTS: Besides edge effects, hair fibres escaped the Trichoscan analysis for various reasons including, but not limited to, thickness, pigmentation, closeness and crossing. CONCLUSION: Most of these problems have been identified in the late 1980s and remain largely unsolved by the processing software that was evaluated in 2004. Therefore claims promoting the Trichoscan method for accurate hair measurements in clinical trials on scalp and body hair are not supported by the present investigation. The speed at which the analysis is performed is outweighed by the errors in signal detection. Therefore we suggest that improvements must be clearly documented before Trichoscan is established for quantified diagnostic purposes and detailed hair cycle monitoring during hair trials. 相似文献
5.
6.
7.
8.
9.
NOS1 polymorphism is associated with atopy but not exhaled nitric oxide levels in healthy children 总被引:1,自引:0,他引:1
May Ali Siew-Kim Khoo Stephen Turner Stephen Stick Peter Le Souëf Peter Franklin 《Pediatric allergy and immunology》2003,14(4):261-265
Exhaled nitric oxide (FENO ) is raised in atopy. The mechanism for this is unclear. The aim of this study was to investigate whether the number of AAT repeats in intron 20 of the NOS1 gene, recently associated with variations in FENO in adults with asthma and cystic fibrosis, was associated with the raised FENO in healthy atopic children. Eighty-seven healthy children (44 girls, 42 atopic, age range 6–18 years) underwent measurements of FENO , spirometry, airway responsiveness and skin prick testing. Genotyping was carried out to determine the number of AAT repeats. There was no association between the number of AAT repeats and FENO in either the whole sample of healthy children (n = 87) or in the subsample of healthy atopics (n = 42). However, a greater number of atopic children had two high repeat alleles compared with non-atopic children (33.3% vs. 13.6%, respectively, p = 0.03). This suggests that variations in the NOS1 gene may contribute to atopy without this relationship being reflected by FENO . 相似文献
10.
J. R. Bernstein B. M. Manzione R. C. Pohland R. B. Franklin 《Biopharmaceutics & drug disposition》1994,15(2):137-150
Tissue distribution studies, utilizing whole-body autoradiography and organ dissection techniques, were conducted in male Fischer 344 rats following the oral administration of 14C-dapoxetine HCl, a potent serotonin reuptake inhibitor. The preliminary study using whole-body autoradiography proved invaluable in locating radioactivity in an organ not usually harvested in a tissue distribution study, namely the preputial gland. Selected organs, based on whole-body autoradiography findings, were dissected from rats and analyzed for radiocarbon content by liquid scintillation counting and for parent drug and N-dealkylated metabolites by extraction and HPLC analysis. Highest concentrations of radiocarbon were observed in the organs of absorption and elimination (ileum, cecum, stomach, duodenum, liver, colon, and kidney) but notable quantities were observed in the lung and preputial and Harderian glands. Most tissues had returned to background radioactive levels 72 h after dosing but persistent concentrations of radiocarbon were present in the preputial gland and liver one week after the single dose of 14C-dapoxetine. Analysis by HPLC demonstrated the presence of parent drug and N-desmethyl metabolite (nor-dapoxetine) in those organs examined; however, the majority of the radioactivity remained unidentified. 相似文献