全文获取类型
收费全文 | 940篇 |
免费 | 86篇 |
国内免费 | 2篇 |
出版年
2021年 | 21篇 |
2019年 | 7篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 22篇 |
2015年 | 45篇 |
2014年 | 46篇 |
2013年 | 44篇 |
2012年 | 45篇 |
2011年 | 53篇 |
2010年 | 33篇 |
2009年 | 28篇 |
2008年 | 56篇 |
2007年 | 48篇 |
2006年 | 39篇 |
2005年 | 49篇 |
2004年 | 35篇 |
2003年 | 43篇 |
2002年 | 31篇 |
2001年 | 27篇 |
2000年 | 36篇 |
1999年 | 20篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1995年 | 5篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1974年 | 6篇 |
1971年 | 4篇 |
1960年 | 4篇 |
1938年 | 4篇 |
1936年 | 9篇 |
1935年 | 5篇 |
1933年 | 8篇 |
1932年 | 9篇 |
1931年 | 9篇 |
1929年 | 7篇 |
排序方式: 共有1028条查询结果,搜索用时 15 毫秒
71.
Tegument-specific, virus-reactive CD4 T cells localize to the cornea in herpes simplex virus interstitial keratitis in humans 总被引:1,自引:0,他引:1 下载免费PDF全文
Koelle DM Reymond SN Chen H Kwok WW McClurkan C Gyaltsong T Petersdorf EW Rotkis W Talley AR Harrison DA 《Journal of virology》2000,74(23):10930-10938
Herpes stromal keratitis (HSK) is a prevalent and frequently vision-threatening disease associated with herpes simplex virus type 1 (HSV-1) infection. In mice, HSK progression occurs after viral clearance and requires T cells and neutrophils. One model implicates Th1-like CD4 T cells with cross-reactivity between the HSV-1 protein UL6 and a corneal autoantigen. HSK can be prevented by establishing specific immunological tolerance. However, HSK can also occur in T-cell receptor-transgenic X SCID mice lacking HSV-specific T cells. To study the pathogenesis of HSK in the natural host species, we measured local HSV-specific T-cell responses in HSK corneas removed at transplant surgery (n = 5) or control corneas (n = 2). HSV-1 DNA was detected by PCR in two specimens. HSV-specific CD4 T cells were enriched in three of the five HSK specimens and were not detectable in the control specimens. Reactivity with peptide epitopes within the tegument proteins UL21 and UL49 was documented. Responses to HSV-1 UL6 were not detected. Diverse HLA DR and DP alleles restricted these local responses. Most clones secreted gamma interferon, but not interleukin-5, in response to antigen. HSV-specific CD8 cells were also recovered. Some clones had cytotoxic-T-lymphocyte activity. The diverse specificities and HLA-restricting alleles of local virus-specific T cells in HSK are consistent with their contribution to HSK by a proinflammatory effect. 相似文献
72.
The co-incubation of morin hydrate with either doxorubicin or mitomycin C could minimize the toxicity of these anti-tumor drugs on cardiovascular cells, such as red blood cells, human umbilical vein endothelial cells (ECV304) and primary mouse cardiomyocytes, whereas morin hydrate did not lower the cytotoxicity of the drugs on human hepatocellular carcinoma cells (HepG2). Morin hydrate may not exert its antioxidant effect by enhancing the antioxidant enzymatic activity because it did not cause any induction on the mRNA levels of manganese superoxide dismutase expression in ECV304 cells and HepG2 cells. 相似文献
73.
Orexin A and B, also known as hypocretin 1 and 2, are two recently isolated hypothalamic peptides. As orexin-containing neurons are strategically located in the lateral hypothalamus, which has long been suspected to play an important role in feeding behaviors, initial studies were focused on the involvement of orexins in positive food intake and energy metabolism. Recent studies implicate a more diverse biological role of orexins, which can be manifested at different level of the neuraxis. For example, canine narcolepsy, a disorder with close phenotypic similarity to human narcolepsy, is caused by a mutation of hypocretin receptor 2 gene. Results from our immunohistochemical and functional studies, which will be summarized here, suggest that the peptide acting on neurons in the rostral ventrolateral medulla augment sympathoexcitatory outflow to the spinal cord. This finding is discussed in the context of increased sympathetic activity frequently associated with obesity. 相似文献
74.
75.
76.
Cheuk-Chun Szeto Bonnie Ching-Ha Kwan Kai-Ming Chow Jeffrey Sung-Shing Kwok Ka-Bik Lai Phyllis Mei-Shan Cheng Wing-Fai Pang Jack Kit-Chung Ng Michael Ho-Ming Chan Lydia Choi-Wan Lit Chi-Bon Leung Philip Kam-Tao Li 《PloS one》2015,10(5)
BackgroundCirculating bacterial DNA fragment is related to systemic inflammatory state in peritoneal dialysis (PD) patients. We hypothesize that plasma bacterial DNA level predicts cardiovascular events in new PD patients.MethodsWe measured plasma bacterial DNA level in 191 new PD patients, who were then followed for at least a year for the development of cardiovascular event, hospitalization, and patient survival.ResultsThe average age was 59.3 ± 11.8 years; plasma bacterial DNA level 34.9 ± 1.5 cycles; average follow up 23.2 ± 9.7 months. At 24 months, the event-free survival was 86.1%, 69.8%, 55.4% and 30.8% for plasma bacterial DNA level quartiles I, II, III and IV, respectively (p < 0.0001). After adjusting for confounders, plasma bacterial DNA level, baseline residual renal function and malnutrition-inflammation score were independent predictors of composite cardiovascular end-point; each doubling in plasma bacterial DNA level confers a 26.9% (95% confidence interval, 13.0 – 42.5%) excess in risk. Plasma bacterial DNA also correlated with the number of hospital admission (r = -0.379, p < 0.0001) and duration of hospitalization for cardiovascular reasons (r = -0.386, p < 0.0001). Plasma bacterial DNA level did not correlate with baseline arterial pulse wave velocity (PWV), but with the change in carotid-radial PWV in one year (r = -0.238, p = 0.005).ConclusionsCirculating bacterial DNA fragment level is a strong predictor of cardiovascular event, need of hospitalization, as well as the progressive change in arterial stiffness in new PD patients. 相似文献
77.
78.
A Comparison of ToxCast Test Results with In Vivo and Other In Vitro Endpoints for Neuro,Endocrine, and Developmental Toxicities: A Case Study Using Endosulfan and Methidathion 下载免费PDF全文
79.
80.
Zhihong Sun Wenyi Zhang Chenyi Guo Xianwei Yang Wenjun Liu Yarong Wu Yuqin Song Lai Yu Kwok Yujun Cui Bilige Menghe Ruifu Yang Liangping Hu Heping Zhang 《PloS one》2015,10(2)
Bifidobacteria are well known for their human health-promoting effects and are therefore widely applied in the food industry. Members of the Bifidobacterium genus were first identified from the human gastrointestinal tract and were then found to be widely distributed across various ecological niches. Although the genetic diversity of Bifidobacterium has been determined based on several marker genes or a few genomes, the global diversity and evolution scenario for the entire genus remain unresolved. The present study comparatively analyzed the genomes of 45 type strains. We built a robust genealogy for Bifidobacterium based on 402 core genes and defined its root according to the phylogeny of the tree of bacteria. Our results support that all human isolates are of younger lineages, and although species isolated from bees dominate the more ancient lineages, the bee was not necessarily the original host for bifidobacteria. Moreover, the species isolated from different hosts are enriched with specific gene sets, suggesting host-specific adaptation. Notably, bee-specific genes are strongly associated with respiratory metabolism and are potential in helping those bacteria adapt to the oxygen-rich gut environment in bees. This study provides a snapshot of the genetic diversity and evolution of Bifidobacterium, paving the way for future studies on the taxonomy and functional genomics of the genus. 相似文献