全文获取类型
收费全文 | 22691篇 |
免费 | 1537篇 |
国内免费 | 691篇 |
专业分类
耳鼻咽喉 | 181篇 |
儿科学 | 475篇 |
妇产科学 | 390篇 |
基础医学 | 4486篇 |
口腔科学 | 379篇 |
临床医学 | 1601篇 |
内科学 | 3832篇 |
皮肤病学 | 636篇 |
神经病学 | 1380篇 |
特种医学 | 287篇 |
外科学 | 2690篇 |
综合类 | 2926篇 |
现状与发展 | 1篇 |
预防医学 | 1397篇 |
眼科学 | 205篇 |
药学 | 2134篇 |
3篇 | |
中国医学 | 657篇 |
肿瘤学 | 1259篇 |
出版年
2024年 | 37篇 |
2023年 | 254篇 |
2022年 | 516篇 |
2021年 | 694篇 |
2020年 | 645篇 |
2019年 | 778篇 |
2018年 | 675篇 |
2017年 | 708篇 |
2016年 | 725篇 |
2015年 | 787篇 |
2014年 | 1341篇 |
2013年 | 1406篇 |
2012年 | 1268篇 |
2011年 | 1572篇 |
2010年 | 1287篇 |
2009年 | 1261篇 |
2008年 | 1141篇 |
2007年 | 1219篇 |
2006年 | 1159篇 |
2005年 | 1005篇 |
2004年 | 904篇 |
2003年 | 694篇 |
2002年 | 503篇 |
2001年 | 369篇 |
2000年 | 398篇 |
1999年 | 289篇 |
1998年 | 241篇 |
1997年 | 262篇 |
1996年 | 343篇 |
1995年 | 299篇 |
1994年 | 247篇 |
1993年 | 199篇 |
1992年 | 109篇 |
1991年 | 105篇 |
1990年 | 65篇 |
1989年 | 57篇 |
1988年 | 41篇 |
1987年 | 38篇 |
1985年 | 130篇 |
1984年 | 175篇 |
1983年 | 134篇 |
1982年 | 169篇 |
1981年 | 134篇 |
1980年 | 104篇 |
1979年 | 115篇 |
1978年 | 70篇 |
1977年 | 53篇 |
1976年 | 45篇 |
1975年 | 53篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Martin Griebe Michael Daffertshofer Mark Stroick Magdalena Syren Parviz Ahmad-Nejad Michael Neumaier Juergen Backhaus Michael G. Hennerici Marc Fatar 《Neuroscience letters》2007
Biological markers play an evolving role in the diagnosis of Alzheimer disease (AD). We compare conventional measurements of cerebrospinal fluid (CSF) tau and β-amyloid1–42 proteins to a novel approach – Fourier transformed infrared (FT-IR) spectroscopy – a simple technique derived from chemical and physical sciences that characterizes intramolecular bonds. For automatic diagnostic analysis, we developed an artificial neural network (ANN). We examined 71 patients with a clinical diagnosis of AD and 66 controls. β-Amyloid1–42 was decreased (sensitivity 80% and specificity 78%); tau was elevated (sensitivity 76% and specificity 88%) in CSF of AD patients. The combined tau/β-amyloid1–42 quotient was able to distinguish healthy from diseased subjects with 99% sensitivity and 86% specificity. The ANN could separate FT-IR spectroscopy data with 88.5% sensitivity and 80% specificity. FT-IR spectroscopy proved to be cost-effective and simple to perform. Diagnostic sensitivity and specificity is in the range of CSF tau and β-amyloid1–42 protein analysis. Larger sample numbers for ANN training and validation could increase diagnostic accuracy and thus prove to be a useful screening tool. 相似文献
62.
人缺血脑组织中IP-10和IFN-γ的表达 总被引:1,自引:0,他引:1
目的:探讨趋化因子IP-10和细胞因子IFN-γ是否参与人缺血脑损伤过程。方法:将21例脑梗死死亡病例按发病持续时间分为〈7天、7~14天和15~21天3组,以非缺血侧半球做对照,用HE染色法观察炎性细胞浸润情况;通过免疫组织化学方法检测缺血半球脑组织与非缺血半球脑组织中趋化因子IP-10和细胞因子IFN-γ的表达。结果:在〈7天组和7~14天组中,缺血脑组织可见大量炎性细胞浸润。在〈7天组、7~14天组和15~2l天组中,趋化因子IP-10在缺血半球脑组织中的表达高于非缺血半球(分别是1.74倍增高,P〈0.01;1.41倍增高,P〈0.05和1.52倍增高,P〈0.01)。在对细胞因子IFN-γ的检测中发现〈7天和7~14天组中,IFN-γ在缺血半球脑组织中的表达高于非缺血半球(分别是1.65倍增高,P〈0.05和1.32倍增高,P〈0.05);在15~21天组中,IFN-γ在缺血半球与非缺血半球中的表达没有显著差异(P〉0.05)。结论:在人缺血脑组织中观察到IP-10和IFN-γ的表达,提示IP-10和IFN-γ参与了炎症反应对脑组织的损伤过程。同时也提示IP-10可能参与后期对损伤脑组织的修复。 相似文献
63.
64.
65.
Probiotics in infancy induce protective immune profiles that are characteristic for chronic low-grade inflammation 总被引:2,自引:0,他引:2
E. Marschan M. Kuitunen K. Kukkonen T. Poussa A. Sarnesto T. Haahtela R. Korpela E. Savilahti O. Vaarala 《Clinical and experimental allergy》2008,38(4):611-618
Background Probiotics are widely studied both in the treatment and prevention of allergic diseases, but their mode of action is poorly known. Objective Our aim was to examine the effect of probiotic bacteria on in vivo cytokine, antibody, and inflammatory responses in allergy‐prone infants. Methods In a randomized double‐blind study, probiotic bacteria or placebo were given for 1 month before delivery to mothers and for 6 months to infants with a family history of allergy. Plasma samples were analysed for C‐reactive protein (CRP), total IgA and IgE, food‐specific IgA, IgG, and IgE, IL‐2, IL‐4, IL‐6, IL‐10, TNF‐α, and IFN‐γ. We analysed the associations of immunological and inflammatory parameters at age 6 months with probiotic treatment and allergic phenotype at 2 years. Results Infants receiving probiotic bacteria had higher plasma levels of CRP (P=0.008), total IgA (P=0.016), total IgE (P=0.047), and IL‐10 (P=0.002) than infants in the placebo group. Increased plasma CRP level at age 6 months was associated with a decreased risk of eczema [odds ratio (OR) 0.41 [95% confidence interval (CI) 0.17–0.99], P=0.046], and with a decreased risk of allergic disease [OR 0.38 (95% CI 0.16–0.87), P=0.023] at age 2 years, when adjusted with probiotic use. Conclusion The association of CRP with a decreased risk of eczema at 2 years of age in allergy‐prone children supports the view that chronic, low‐grade inflammation protects from eczema. Probiotic‐induced low‐grade inflammation was characterized by elevation of IgE, IgA, and IL‐10, the changes typically observed in helminth infection‐associated induction of regulatory mechanisms. The findings emphasize the role of chronic microbial exposure as an immune modulator protecting from allergy. 相似文献
66.
We provide here 29 genetic variations, including 28 novel ones, in five genes that are potentially involved in the excitement
of cardiomyocytes: we found 4 in KCNA10, 2 in KCNK1, 8 in KCNK6, 11 in SLC18A1 (VMAT1), and 4 in SLC6A2 (norepinephrine transporter). We also examined their allelic frequencies in a Japanese population of long QT syndrome-affected
and nonaffected individuals. These data would be useful for genetic association studies designed to investigate acquired arrhythmias.
Received: May 22, 2001 / Accepted: June 8, 2001 相似文献
67.
Cross-regulatory role of interferon-gamma (IFN-gamma), IL-4 and IL-10 in schistosome egg granuloma formation: in vivo regulation of Th activity and inflammation. 总被引:4,自引:0,他引:4 下载免费PDF全文
S W Chensue K S Warmington J Ruth P M Lincoln S L Kunkel 《Clinical and experimental immunology》1994,98(3):395-400
This study examined the relationship of IL-4, IL-10 and IFN-gamma with regard to the local granuloma (GR) and draining lymph node (LN) response to Schistosoma mansoni eggs. Synchronized GR were induced in naive and schistosome-infected mice at the vigorous (8 weeks) and late chronic (20 weeks) stages. In LN cultures, IL-10 and IFN production peaked on day 4 and was greatest for 8 week-infected mice. All GR cultures contained IFN, but compared with naive mice IL-10 production was accelerated at 8 weeks and abrogated at 20 weeks, consistent with expansion and abatement of Th2 activity. Cytokine neutralization was performed in egg-challenged, naive mice that were adoptively sensitized with lymphoid cells from 8 week-infected donors. GR size, GR macrophage tumour necrosis factor (TNF) production and egg antigen-elicited IL-2, IL-4, IL-5, IL-10 and IFN were examined on day 4 of GR formation. Anti-IFN augmented GR area by 40%, increased local IL-4 and IL-10, but decreased IFN and TNF production. In corresponding LN cultures, IFN decreased by about 50%, while IL-2, IL-4, IL-10 and IL-5 increased by nearly two-, four-, five- and six-fold, respectively. Anti-IL-10 did not affect GR size or GR cytokines, but abrogated GR area by 40%, along with a reduction in local IL-4 and TNF production. In LN, IL-4 depletion reduced IL-4 and IL-5 by 60-70% and increased IFN levels. These results support the notion of a cross-regulatory network in which IFN inhibits Th2 and IL-10 inhibits Th1 cells. IL-4 fosters Th2 cells differentiation in LN, but also performs a critical recruitment function in the eosinophil-rich schistosome egg-induced GR, whereas IFN contributes to enhanced GR macrophage function. 相似文献
68.
A low intake of selenium is associated with increased cardiovascular mortality. This could be reduced by supplementation with selenium and coenzyme Q10. D-dimer, a fragment of fibrin mirroring fibrinolysis, is a biomarker of thromboembolism, increased inflammation, endothelial dysfunction and is associated with cardiovascular mortality in ischemic heart disease. The objective was to examine the impact of selenium and coenzyme Q10 on the level of D-dimer, and its relationship to cardiovascular mortality. D-dimer was measured in 213 individuals at the start and after 48 months of a randomised double-blind placebo-controlled trial with selenium yeast (200 µg/day) and coenzyme Q10 (200 mg/day) (n = 106) or placebo (n = 107). The follow-up time was 4.9 years. All included individuals were low in selenium (mean 67 μg/L, SD 16.8). The differences in D-dimer concentration were evaluated by the use of T-tests, repeated measures of variance and ANCOVA analyses. At the end, a significantly lower D-dimer concentration was observed in the active treatment group in comparison with those on placebo (p = 0.006). Although D-dimer values at baseline were weakly associated with high-sensitive CRP, while being more strongly associated with soluble tumour necrosis factor receptor 1 and sP-selectin, controlling for these in the analysis there was an independent effect on D-dimer. In participants with a D-dimer level above median at baseline, the supplementation resulted in significantly lower cardiovascular mortality compared to those on placebo (p = 0.014). All results were validated with a persisting significant difference between the two groups. Therefore, supplementation with selenium and coenzyme Q10 in a group of elderly low in selenium and coenzyme Q10 prevented an increase in D-dimer and reduced the risk of cardiovascular mortality in comparison with the placebo group. The obtained results also illustrate important associations between inflammation, endothelial function and cardiovascular risk. 相似文献
69.
70.