全文获取类型
收费全文 | 969篇 |
免费 | 80篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 23篇 |
2020年 | 11篇 |
2019年 | 22篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 36篇 |
2015年 | 56篇 |
2014年 | 69篇 |
2013年 | 72篇 |
2012年 | 91篇 |
2011年 | 83篇 |
2010年 | 66篇 |
2009年 | 61篇 |
2008年 | 49篇 |
2007年 | 55篇 |
2006年 | 55篇 |
2005年 | 34篇 |
2004年 | 34篇 |
2003年 | 35篇 |
2002年 | 43篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有1049条查询结果,搜索用时 15 毫秒
141.
142.
Ester Fonsatti Elda Lamaj Sandra Coral Luca Sigalotti Gianpaolo Nardi Aldo Gasparollo Mario P. Colombo Maresa Altomonte Michele Maio 《Cancer immunology, immunotherapy : CII》1999,48(2-3):132-138
Melanoma cells constitutively release intercellular adhesion molecule 1 (ICAM-1) as soluble ICAM-1 (sICAM-1), and its levels
are elevated in melanoma patients and correlate with disease progression. However, this correlation is not absolute, suggesting
that specific characteristics of neoplastic cells and/or ICAM-1-positive non-neoplastic cells may influence the amounts of
circulating sICAM-1. In this study, we found a weak correlation (r = 0.55; r
2 = 0.3) between sICAM-1 release by 40 metastatic melanomas (36 primary cultures and 4 cell lines), and ICAM-1 expression on
neoplastic cells. In addition, melanoma-secreted interleukin-1α (IL-1α) (1/40) but not vascular endothelial growth factor
(VEGF) (29/40), significantly (P < 0.05) up-regulated the shedding of sICAM-1 by human umbilical vein endothelial cells (HUVEC). This was completely abolished
by IL-1α/β neutralizing antibodies both at the protein and mRNA level. Altogether, our results suggest that (i) the extent
of sICAM-1 release is distinctive for individual melanomas and can be independent of ICAM-1 expression; (ii) tumor endothelia
may sustain levels of sICAM-1 in selected melanomas; (iii) melanoma-released VEGF does not affect ICAM-1 expression and sICAM-1
release by HUVEC. Melanoma-derived sICAM-1 inhibits cell-mediated cytotoxicity of melanoma cells; therefore, constitutive
levels of sICAM-1 release and IL-1α secretion by individual melanomas can differentially influence tumor progression and the
clinical effectiveness of cytotoxic-cell-based vaccines.
Received: 15 October 1998 / Accepted: 17 February 1999 相似文献
143.
Phagocytic and macropinocytic activity in MARCKS-deficient macrophages and fibroblasts 总被引:3,自引:0,他引:3
Carballo Ester; Pitterle Diana M.; Stumpo Deborah J.; Sperling Robert T.; Blackshear Perry J. 《American journal of physiology. Cell physiology》1999,277(1):C163
Macrophages express high levels of the myristoylated,alanine-rich, C kinase substrate (MARCKS), an actin cross-linkingprotein. To investigate a possible role of MARCKS in macrophagefunction, fetal liver-derived macrophages were generated from wild-type and MARCKS knockout mouse embryos. No differences between the wild-typeand MARCKS-deficient macrophages with respect to morphology (Wright'sstain) or actin distribution (staining with rhodamine-phalloidin, underbasal conditions or after treatment with phorbol esters, lipopolysaccharide, or both) were observed. We then evaluated phagocytosis mediated by different receptors: Fc receptors tested withIgG-coated sheep red blood cells, complement C3b receptors tested withC3b-coated yeast, mannose receptors tested with unopsonized zymosan,and nonspecific phagocytosis tested with latex beads. We also studiedfluid phase endocytosis in macrophages and mouse embryo fibroblasts byusing FITC-dextran to quantitate this process. In most cases, therewere no differences between the cells derived from wild-type andMARCKS-deficient mice. However, a minor but significant andreproducible difference in rates of zymosan phagocytosis at 45-60min was observed, with lower rates of phagocytosis in theMARCKS-deficient cells. Our data indicate that MARCKS deficiency maylead to slightly decreased rates of zymosan phagocytosis. 相似文献
144.
Daniella Schatz Guy Schleyer Marius R. Saltvedt Ruth-Anne Sandaa Ester Feldmesser Assaf Vardi 《The ISME journal》2021,15(12):3714
Extracellular vesicles are produced by organisms from all kingdoms and serve a myriad of functions, many of which involve cell-cell signaling, especially during stress conditions and host-pathogen interactions. In the marine environment, communication between microorganisms can shape trophic level interactions and population succession, yet we know very little about the involvement of vesicles in these processes. In a previous study, we showed that vesicles produced during viral infection by the ecologically important model alga Emiliania huxleyi, could act as a pro-viral signal, by expediting infection and enhancing the half-life of the virus in the extracellular milieu. Here, we expand our laboratory findings and show the effect of vesicles on natural populations of E. huxleyi in a mesocosm setting. We profile the small-RNA (sRNA) cargo of vesicles that were produced by E. huxleyi during bloom succession, and show that vesicles applied to natural assemblages expedite viral infection and prolong the half-life of this major mortality agent of E. huxleyi. We subsequently reveal that exposure of the natural assemblage to E. huxleyi-derived vesicles modulates not only host-virus dynamics, but also other components of the microbial food webs, thus emphasizing the importance of extracellular vesicles to microbial interactions in the marine environment.Subject terms: Virus-host interactions, Microbial ecology, Water microbiology 相似文献
145.
146.
147.
Taíse F. Pedroso Cláudia S. Oliveira Mariana M. Fonseca Vitor A. Oliveira Maria Ester Pereira 《Biological trace element research》2017,180(2):275-284
This study investigated the toxicity of rats exposed to lead acetate (AcPb) during the second phase of brain development (8–12 days postnatal) in hematological and cerebral parameters. Moreover, the preventive effect of zinc chloride (ZnCl2) and N-acetylcysteine (NAC) was investigated. Pups were injected subcutaneously with saline (0.9% NaCl solution), ZnCl2 (27 mg/kg/day), NAC (5 mg/kg/day) or ZnCl2 plus NAC for 5 days (3rd–7th postnatal days), and with saline (0.9% NaCl solution) or AcPb (7 mg/kg/day) in the five subsequent days (8th–12th postnatal days). Animals were sacrificed 21 days after the last AcPb exposure. Pups exposed to AcPb presented inhibition of blood porphobilinogen-synthase (PBG-synthase) activity without changes in hemoglobin content. ZnCl2 pre-exposure partially prevented PBG-synthase inhibition. Regarding neurotoxicity biomarkers, animals exposed to AcPb presented a decrease in cerebrum acetylcholinesterase (AChE) activity and an increase in Pb accumulation in blood and cerebrum. These changes were prevented by pre-treatment with ZnCl2, NAC, and ZnCl2 plus NAC. AcPb exposure caused no alteration in behavioral tasks. In short, results show that AcPb inhibited the activity of two important enzymatic biomarkers up to 21 days after the end of the exposure. Moreover, ZnCl2 and NAC prevented the alterations induced by AcPb. 相似文献
148.
David R Arahal Ester Sánchez M Carmen Macián Esperanza Garay 《International microbiology》2008,11(1):33-39
The genera Leuconostoc, Oenococcus, and Weissella (family "Leuconostocaceae") constitute a group of lactic acid bacteria of great interest in food microbiology. From the taxonomic point of view, they are considered phylogenetically coherent according to their 16S rRNA gene sequences and other macromolecules. These three genera were the focus of the present study; specifically, the resolution and discriminatory power of recN (encoding a DNA repair and genetic recombination protein) as a molecular marker at the species level were investigated. For this purpose, partial sequences (about 1200 nt) were obtained from 23 type strains and from several additional strains following direct amplification of recN and subsequent sequencing. Phylogeny was evaluated according to different treeing methods (neighbor joining, maximum likelihood, and maximum parsimony) and the inclusion of variability filters. The results showed that recN, used either alone or in combination with 16S rRNA data, can serve as a phylogenetic marker as well as a tool for species identification. 相似文献
149.
Maria Carmen Collado Ester Donat Carmen Ribes-Koninckx Miguel Calabuig Yolanda Sanz 《BMC microbiology》2008,8(1):232
Background
Gut bifidobacteria are believed to influence immune-related diseases. The objective of this study was to assess the possible relationships between the gut bifidobacteria composition and coeliac disease (CD) in children. 相似文献150.
Biasutto L Mattarei A Marotta E Bradaschia A Sassi N Garbisa S Zoratti M Paradisi C 《Bioorganic & medicinal chemistry letters》2008,18(20):5594-5597
To target natural polyphenols to the subcellular site where their redox properties might be exploited at best, that is, mitochondria, we have synthesised new proof-of-principle derivatives by linking resveratrol (3,4',5-trihydroxy-trans-stilbene) to the membrane-permeable lipophilic triphenylphosphonium cation. The new compounds, (4-triphenylphosphoniumbutyl)-4'-O-resveratrol iodide and its bis-acetylated derivative, the latter intended to provide transient protection against metabolic conjugation, accumulate into energized mitochondria as expected and are cytotoxic for fast-growing but not for slower-growing cells. They provide a powerful potential tool to intervene on mitochondrial and cellular redox processes of pathophysiological relevance. 相似文献