全文获取类型
收费全文 | 3507篇 |
免费 | 233篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 87篇 |
妇产科学 | 89篇 |
基础医学 | 573篇 |
口腔科学 | 267篇 |
临床医学 | 383篇 |
内科学 | 716篇 |
皮肤病学 | 52篇 |
神经病学 | 336篇 |
特种医学 | 37篇 |
外科学 | 264篇 |
综合类 | 51篇 |
一般理论 | 2篇 |
预防医学 | 353篇 |
眼科学 | 52篇 |
药学 | 236篇 |
中国医学 | 14篇 |
肿瘤学 | 197篇 |
出版年
2024年 | 8篇 |
2023年 | 54篇 |
2022年 | 97篇 |
2021年 | 170篇 |
2020年 | 112篇 |
2019年 | 122篇 |
2018年 | 123篇 |
2017年 | 94篇 |
2016年 | 117篇 |
2015年 | 109篇 |
2014年 | 136篇 |
2013年 | 167篇 |
2012年 | 273篇 |
2011年 | 308篇 |
2010年 | 174篇 |
2009年 | 134篇 |
2008年 | 223篇 |
2007年 | 182篇 |
2006年 | 185篇 |
2005年 | 162篇 |
2004年 | 109篇 |
2003年 | 94篇 |
2002年 | 76篇 |
2001年 | 18篇 |
2000年 | 8篇 |
1999年 | 16篇 |
1998年 | 11篇 |
1997年 | 18篇 |
1996年 | 23篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1982年 | 7篇 |
1980年 | 6篇 |
1959年 | 29篇 |
1958年 | 40篇 |
1957年 | 31篇 |
1956年 | 32篇 |
1955年 | 28篇 |
1954年 | 44篇 |
1949年 | 18篇 |
1948年 | 34篇 |
1946年 | 7篇 |
排序方式: 共有3754条查询结果,搜索用时 17 毫秒
41.
42.
43.
Sandra Ovesen Karina Frahm Kirk Hans Linde Nielsen Henrik Nielsen 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2017,125(3):230-235
Campylobacter concisus is an emerging pathogen associated with gastrointestinal disorders such as gastroenteritis and inflammatory bowel diseases (IBD), but the species is also found in healthy subjects. The heterogeneous genome of C. concisus increases the likelihood of varying virulence between strains. Flagella motility is a crucial virulence factor for the well‐recognized Campylobacter jejuni; therefore, this study aimed to analyze the motility of C. concisus isolated from saliva, gut biopsies, and feces of patients with IBD, gastroenteritis, and healthy subjects. The motility zones of 63 isolates from 52 patients were measured after microaerobic growth in soft‐agar plates for 72 hours. The motility of C. concisus was significantly lower than that of Campylobacter jejuni and Campylobacter fetus subsp. fetus. The motility of C. concisus varied between isolates (4–22 mm), but there was no statistical significant difference between isolates from IBD patients and healthy subjects (p = 0.14). A tendency of a larger motility zones was observed for IBD gut mucosa isolates, although it did not reach statistical significance (p = 0.13), and no difference was found between oral or fecal isolates between groups. In conclusion, the varying motility of C. concisus could not be related to disease outcome or colonization sites. 相似文献
44.
45.
Systolic longitudinal strain correlates with visual assessment of regional left ventricular function during dobutamine stress echocardiography and discriminates the segments with induced contractility impairment
下载免费PDF全文
![点击此处可从《Echocardiography (Mount Kisco, N.Y.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
46.
Corentin M. Barbu Alison M. Buttenheim Maria-Luz Hancco Pumahuanca Javier E. Quintanilla Calderón Renzo Salazar Malwina Carrión Andy Catacora Rospigliossi Fernando S. Malaga Chavez Karina Oppe Alvarez Juan Cornejo del Carpio César Náquira Michael Z. Levy 《Emerging infectious diseases》2014,20(12):2055-2063
Chagas disease vector control campaigns are being conducted in Latin America, but little is known about medium-term or long-term effectiveness of these efforts, especially in urban areas. After analyzing entomologic data for 56,491 households during the treatment phase of a Triatoma infestans bug control campaign in Arequipa, Peru, during 2003–2011, we estimated that 97.1% of residual infestations are attributable to untreated households. Multivariate models for the surveillance phase of the campaign obtained during 2009–2012 confirm that nonparticipation in the initial treatment phase is a major risk factor (odds ratio [OR] 21.5, 95% CI 3.35–138). Infestation during surveillance also increased over time (OR 1.55, 95% CI 1.15–2.09 per year). In addition, we observed a negative interaction between nonparticipation and time (OR 0.73, 95% CI 0.53–0.99), suggesting that recolonization by vectors progressively dilutes risk associated with nonparticipation. Although the treatment phase was effective, recolonization in untreated households threatens the long-term success of vector control. 相似文献
47.
Inclusion compounds of Al-quercetin and Al-catechin complexes with β-cyclodextrin (βCD) were investigated. The complex and the inclusion compound of quercetin are more effective DPPH? scavengers than the corresponding catechin compounds and the inclusion does not compromise their scavenging abilities, with only a slight decrease in the EC50 values. This is in accordance with the electrochemical data, which revealed that the inclusion compounds have lower diffusion coefficients in aqueous solution than the non-included compounds. For the quercetin compounds, some spectroscopic properties were also addressed by means of UV–visible and NMR measurements in aqueous media. 相似文献
48.
49.
50.
Sandra Ovesen Juliana Durack Karina Frahm Kirk Hans Linde Nielsen Henrik Nielsen 《Gut microbes》2019,10(1):34-44
Campylobacter concisus has been isolated from patients with gastroenteritis and inflammatory bowel disease (IBD), as well as healthy subjects. While strain differences may plausibly explain virulence differentials, an alternative hypothesis posits that the pathogenic potential of this species may depend on altered ecosystem conditions in the inflamed gut. One potential difference is oxygen availability, which is frequently increased under conditions of inflammation and is known to regulate bacterial virulence. Hence, we hypothesized that oxygen influences C. concisus physiology. We therefore characterized the effect of microaerophilic or anaerobic environments on C. concisus motility and biofilm formation, two important determinants of host colonization and dissemination. C. concisus isolates (n = 46) sourced from saliva, gut mucosal biopsies and feces of patients with IBD (n = 23), gastroenteritis (n = 8) and healthy subjects (n = 13), were used for this study. Capacity to form biofilms was determined using crystal violet assay, while assessment of dispersion through soft agar permitted motility to be assessed. No association existed between GI disease and either motility or biofilm forming capacity. Oral isolates exhibited significantly greater capacity for biofilm formation compared to fecal isolates (p<0.03), and showed a strong negative correlation between motility and biofilm formation (r = -0.7; p = 0.01). Motility significantly increased when strains were cultured under microaerophilic compared to anaerobic conditions (p<0.001). Increased biofilm formation under microaerophillic conditions was also observed for a subset of isolates. Hence, differences in oxygen availability appear to influence key physiological aspects of the opportunistic gastrointestinal pathogen C. concisus. 相似文献