全文获取类型
收费全文 | 688篇 |
免费 | 44篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 19篇 |
2015年 | 36篇 |
2014年 | 21篇 |
2013年 | 43篇 |
2012年 | 53篇 |
2011年 | 59篇 |
2010年 | 33篇 |
2009年 | 28篇 |
2008年 | 42篇 |
2007年 | 60篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 35篇 |
2003年 | 38篇 |
2002年 | 25篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有732条查询结果,搜索用时 15 毫秒
81.
The sphingolipid ceramides are known to influence lipid lateral organization in biological membranes. In particular, ceramide-induced alterations of microdomains can be involved in several cell functions, ranging from apoptosis to immune response. We used a combined approach of atomic force microscopy, fluorescence correlation spectroscopy, and confocal fluorescence imaging to investigate the effects of ceramides in model membranes of biological relevance. Our results show that physiological quantities of ceramide in sphingomyelin/dioleoylphosphatidylcholine/cholesterol supported bilayers lead to a significant rearrangement of lipid lateral organization. Our experimental setup allowed a simultaneous characterization of both structural and dynamic modification of membrane microdomains, induced by the presence of ceramide. Formation of similar ceramide-enriched domains and, more general, alterations of lipid-lipid interactions can be of crucial importance for the biological function of cell membranes. 相似文献
82.
Catelani G D'Andrea F Landi M Zuccato C Bianchi N Gambari R 《Carbohydrate research》2006,341(4):538-544
The synthesis and biological evaluation of some new glycose esters bearing the 1,2-O-isopropylidene-d-hexofuranose functionality and belonging to the 3-O-acyl-d-allose and 6-O-acyl-d-glucose series are reported. When the results concerning cell growth inhibition are compared, it appears that the 6-O-acyl-d-glucose derivatives are more active than the 3-O-acyl-d-allose compounds. Within both 6-O-acyl-d-glucose and 3-O-acyl-d-allose derivatives, butyric esters displayed the highest inhibitory effects. Inhibition of cell growth is not associated with high induction levels of erythroid differentiation, despite the fact that pivaloates induce erythroid differentiation to an extent similar to that exhibited by previously reported molecules [Bioorg. Med. Chem. Lett.1999, 9, 3153-3158]. 相似文献
83.
84.
85.
Aureli M Loberto N Bassi R Ferraretto A Perego S Lanteri P Chigorno V Sonnino S Prinetti A 《Neurochemical research》2012,37(6):1296-1307
In this paper, we show that the pH optimum for the plasma membrane (PM)-associated activity of four glycohydrolases (conduritol
B epoxide sensitive β-glucosidase, β-glucosidase GBA2, β-hexosaminidase and β-galactosidase) measured on intact cells is acidic.
Moreover, we show that drugs able to modify the efflux of protons across the PM, thus locally affecting the extracellular
proton concentration close to the PM, are able to modulate the activities of these enzymes. These data strongly suggest that
pH-dependent modulation of PM-associated glycohydrolases activities could be an effective way to locally modulate the cell
surface glycoconjugate composition. 相似文献
86.
Aureli M Gritti A Bassi R Loberto N Ricca A Chigorno V Prinetti A Sonnino S 《Neurochemical research》2012,37(6):1344-1354
The activities of plasma membrane associated sialidase Neu3, total β-glucosidase, CBE-sensitive β-glucosidase, non-lysosomal
β-glucosyl ceramidase GBA2, β-galactosidase, β-hexosaminidase and sphingomyelinase were determined at three different stages
of differentiation of murine neural stem cell cultures, corresponding to precursors, commited progenitors, and differentiated
cells. Cell immunostaining for specific markers of the differentiation process, performed after 7 days in culture in presence
of differentiating agents, clearly showed the presence of oligodendrocytes, astrocytes and neurons. Glial cells were the most
abundant. Sialidase Neu3 after a decrease from progenitors to precursors, showed an increase parallel to the differentiation
process. All the other glycosidases increased their activity along differentiation. The activity of CBE-sensitive β-glucosidase
and GBA2 were very similar at the precursor stage, but CBE-sensitive β-glucosidase increased 7 times while GBA2 only two in
the differentiated cells. In addition, we analysed also sphingomyelinase as enzyme specifically associated to sphingolipids.
The activity of this enzyme increased from precursors to differentiated cells. 相似文献
87.
Drumo R Widmer G Morrison LJ Tait A Grelloni V D'Avino N Pozio E Cacciò SM 《Applied and environmental microbiology》2012,78(10):3523-3529
Recent studies have revealed extensive genetic variation among isolates of Cryptosporidium parvum, an Apicomplexan parasite that causes gastroenteritis in both humans and animals worldwide. The parasite's population structure is influenced by the intensity of transmission, the host-parasite interaction, and husbandry practices. As a result, C. parvum populations can be panmictic, clonal, or even epidemic on both a local scale and a larger geographical scale. To extend the study of C. parvum populations to an unexplored region, 173 isolates of C. parvum collected in Italy from humans and livestock (calf, sheep, and goat) over a 10-year period were genotyped using a multilocus scheme based on 7 mini- and microsatellite loci. In agreement with other studies, extensive polymorphism was observed, with 102 distinct multilocus genotypes (MLGs) identified among 173 isolates. The presence of linkage disequilibrium, the confinement of MLGs to individual farms, and the relationship of many MLGs inferred using network analysis (eBURST) suggest a predominantly clonal population structure, but there is also evidence that part of the diversity can be explained by genetic exchange. MLGs from goats were found to differ from bovine and sheep MLGs, supporting the existence of C. parvum subpopulations. Finally, MLGs from isolates collected between 1997 and 1999 were also identified as a distinct subgroup in principal-component analysis and eBURST analysis, suggesting a continuous introduction of novel genotypes in the parasite population. 相似文献
88.
89.
Michelini L Meggio F La Rocca N Ferro S Ghisi R 《International journal of phytoremediation》2012,14(4):388-402
The application of manure to fertilize arable lands is one of the major means through which veterinary sulfonamides (SAs) enter the environment. Little is known about the capacity of woody plants to phytoremediate this class of antibiotics. To this purpose we performed preliminary studies to evaluate Salix fragilis L. response to sulfadimethoxine (SDM) by investigating both its ability to absorb and tolerate doses of SDM found in fresh faeces of treated calves. Forty cuttings were exposed to either 0, 0.5, 1, or 2 mM of SDM for one month. Decreases in photosynthetic electron transport rate and net CO2 assimilation after 25 days for the higher SDM concentrations were noticed. Moreover, alterations in root morphology of treated plants were observed and further investigated through electron microscopy. However, collected data revealed high root accumulation potential. These preliminary results are promising as they demonstrate that Salix fragilis L. can both absorb and tolerate high concentrations of SAs. 相似文献