全文获取类型
收费全文 | 237篇 |
免费 | 23篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 21篇 |
2013年 | 16篇 |
2012年 | 21篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 21篇 |
2006年 | 15篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 8篇 |
1999年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1982年 | 2篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 31 毫秒
41.
A faster ribonuclease protection assay. 总被引:6,自引:0,他引:6
42.
43.
P. Locci Tiziano Baroni Furio Pezzetti Cinzia Lilli Lorella Marinucci Domenica Martinese Ennio Becchetti Mario Calvitti Francesco Carinci 《Cell and tissue research》1999,297(3):475-483
The phenotype of Apert osteoblasts differs from that of normal osteoblasts in the accumulation of macromolecules in the extracellular matrix. Apert osteoblasts increase type I collagen, fibronectin and glycosaminoglycans secretion compared with normal osteoblasts. Because the extracellular matrix macromolecule accumulation is greatly modulated by transforming growth factor-beta(1), we examined the ability of normal and Apert osteoblasts to secrete transforming growth factor-beta(1) by CCL-64 assay and to produce transforming growth factor-beta(1 )by analysis of the mRNA expression of transforming growth factor-beta(1). Northern blot analysis revealed an increased amount of transforming growth factor-beta(1) mRNA expression in Apert osteoblasts compared with normal ones. Moreover, the level of the active transforming growth factor-beta(1) isoform was higher in Apert than in normal media. In pathologic cells, the increase in transforming growth factor-beta(1) gene expression was associated with a parallel increase in the factor secreted into the medium. The level of transforming growth factor-beta(1) was decreased by the addition of basic fibroblast growth factor. Transforming growth factor-beta(1) is controlled temporally and spatially during skeletal tissue development and produces complex stimulatory and inhibitory changes in osteoblast functions. We hypothesise that in vitro differences between normal and Apert osteoblasts may be correlated to different transforming growth factor-beta(1) cascade patterns, probably due to an altered balance between transforming growth factor-beta(1) and basic fibroblast growth factor. 相似文献
44.
Domenica Torino Adriano Mollica Francesco Pinnen Gino Lucente Federica Feliciani Peg Davis Josephine Lai Shou-Wu Ma Frank Porreca Victor J. Hruby 《Bioorganic & medicinal chemistry letters》2009,19(15):4115-4118
Six new endomorphin analogues, incorporating constrained amino acids in place of native proline have been synthesized. Residues of (S)-azetidine-2-carboxylic acid (Aze), 3,4-dehydro-(S)-proline (Δ3Pro), azetidine-3-carboxylic acid (3Aze) and dehydro-alanine (ΔAla) have been used to prepare [Δ3Pro2]EM-2 (1), [Aze2]EM-1 (2), [Aze2]EM-2 (3), [3Aze2]EM-1 (4), [3Aze2]EM-2 (5) and [ΔAla2]EM-2 (6). Binding assays and functional bioactivities for μ- and δ-receptors are reported. The highest affinity, bioactivity and selectivity are shown by peptides 2 and 3 containing the Aze residue. 相似文献
45.
Allison N. Steele Marie A. Simovich Domenica Pepino Kathleen McNamara Schroeder Amy G. Vandergast Andrew J. Bohonak 《Conservation Genetics》2009,10(6):1777-1781
The San Diego fairy shrimp Branchinecta sandiegonensis is a federally endangered species endemic to vernal pools in southern California, USA. Filling events in these habitats are highly variable, with some pools failing to hold water long enough for reproduction over many successive years. Studies of this species are thus hindered by the relatively rare appearance of aquatically active life history phases. Because diapausing cysts are abundant and present at all times, they provide an underutilized opportunity for both species identification and genetic studies. However, methods for extracting DNA from cysts are technically challenging because of their structure and size. Here we present a protocol for extracting DNA from B. sandiegonensis cysts in sufficient quantities for “DNA Barcoding”, microsatellite analysis and other genotyping and sequencing applications. The technique will aid in population genetic studies and species identification (since taxonomic keys only distinguish among adults), and will be applicable to other crustaceans with similar diapausing cysts. 相似文献
46.
47.
Brigotti M Carnicelli D Arfilli V Rocchi L Ricci F Pagliaro P Tazzari PL Vara AG Amelia M Manoli F Monti S 《The Journal of biological chemistry》2011,286(40):34514-34521
Shiga toxins (Stx) play an important role in the pathogenesis of hemolytic uremic syndrome, a life-threatening renal sequela of human intestinal infection caused by specific Escherichia coli strains. Stx target a restricted subset of human endothelial cells that possess the globotriaosylceramide receptor, like that in renal glomeruli. The toxins, composed of five B chains and a single enzymatic A chain, by removing adenines from ribosomes and DNA, trigger apoptosis and the production of pro-inflammatory cytokines in target cells. Because bacteria are confined to the gut, the toxins move to the kidney through the circulation. Polymorphonuclear leukocytes (PMN) have been indicated as the carriers that "piggyback" shuttle toxins to the kidney. However, there is no consensus on this topic, because not all laboratories have been able to reproduce the Stx/PMN interaction. Here, we demonstrate that conformational changes of Shiga toxin 1, with reduction of α-helix content and exposition to solvent of hydrophobic tryptophan residues, cause a loss of PMN binding activity. The partially unfolded toxin was found to express both enzymatic and globotriaosylceramide binding activities being fully active in intoxicating human endothelial cells; this suggests the presence of a distinct PMN-binding domain. By reviewing functional and structural data, we suggest that A chain moieties close to Trp-203 are recognized by PMN. Our findings could help explain the conflicting results regarding Stx/PMN interactions, especially as the groups reporting positive results obtained Stx by single-step affinity chromatography, which could have preserved the correct folding of Stx with respect to more complicated multi-step purification methods. 相似文献
48.
49.
Dörte Randewig Domenica Hamisch Monika Eiblmeier Christian Boedecker Jürgen Kreuzwieser Ralf R. Mendel Robert Hänsch Cornelia Herschbach Heinz Rennenberg 《Trees - Structure and Function》2014,28(2):399-411
Key Message
The critical level for SO 2 susceptibility of Populus × canescens is approximately 1.2 μL L ?1 SO 2 . Both sulfite oxidation and sulfite reduction and assimilation contribute to SO 2 detoxification.Abstract
In the present study, uptake, susceptibility and metabolism of SO2 were analyzed in the deciduous tree species poplar (Populus × canescens). A particular focus was on the significance of sulfite oxidase (SO) for sulfite detoxification, as SO has been characterized as a safety valve for SO2 detoxification in herbaceous plants. For this purpose, poplar plants were exposed to different levels of SO2 (0.65, 0.8, 1.0, 1.2 μL L?1) and were characterized by visible injuries and at the physiological level. Gas exchange parameters (stomatal conductance for water vapor, CO2 assimilation, SO2 uptake) of the shoots were compared with metabolite levels (sulfate, thiols) and enzyme activities [SO, adenosine 5′-phosphosulfate reductase (APR)] in expanding leaves (80–90 % expanded). The critical dosage of SO2 that confers injury to the leaves was 1.2 μL L?1 SO2. The observed increase in sulfur containing compounds (sulfate and thiols) in the expanding leaves strongly correlated with total SO2 uptake of the plant shoot, whereas SO2 uptake rate was strongly correlated with stomatal conductance for water vapor. Furthermore, exposure to high concentration of SO2 revealed channeling of sulfite through assimilatory sulfate reduction that contributes in addition to SO-mediated sulfite oxidation to sulfite detoxification in expanding leaves of this woody plant species. 相似文献50.
Johannes Freitag Julia Ast Uwe Linne Thorsten Stehlik Domenica Martorana Michael Bölker Björn Sandrock 《Molecular microbiology》2014,93(1):24-36
Many microorganisms secrete surface‐active glycolipids. The basidiomycetous fungus Ustilago maydis produces two different classes of glycolipids, mannosylerythritol lipids (MEL) and ustilagic acids (UAs). Here we report that biosynthesis of MELs is partially localized in peroxisomes and coupled to peroxisomal fatty acid degradation. The acyltransferases, Mac1 and Mac2, which acylate mannosylerythritol with fatty acids of different length, contain a type 1 peroxisomal targeting signal (PTS1). We demonstrate that Mac1 and Mac2 are targeted to peroxisomes, while other enzymes involved in MEL production reside in different compartments. Mis‐targeting of Mac1 and Mac2 to the cytosol did not block MEL synthesis but promoted production of MEL species with altered acylation pattern. This is in contrast to peroxisome deficient mutants that produced MELs similar to the wild type. We could show that cytosolic targeting of Mac1 and Mac2 reduces the amount of UA presumably due to competition for overlapping substrates. Interestingly, hydroxylated fatty acids characteristic for UAs appear in MELs corroborating cross‐talk between both biosynthesis pathways. Therefore, peroxisomal localization of MEL biosynthesis is not only prerequisite for generation of the natural spectrum of MELs, but also facilitates simultaneous assembly of different glycolipids in a single cell. 相似文献