全文获取类型
收费全文 | 240篇 |
免费 | 15篇 |
出版年
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 24篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 9篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 3篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1973年 | 2篇 |
1967年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有255条查询结果,搜索用时 15 毫秒
51.
Inhibition of protein N-glycosylation by tunicamycin induced morphological changes characteristic of apoptosis in human promyelocytic HL-60 cells. Internu-cleosomal DMA fragmentation could be detected after short-time incubation (between 6 and 9 h) of HL-60 cells with low doses of tunicamycin (0.05 μg/ml). Under these conditions the synthesis of glycoproteins was reduced to 17% of control values, while no significant changes in the rates of total protein synthesis could be observed. Tunicamycin ability to induce DNA fragmentation was in good correlation with its potency as glycosylation inhibitor in several myeloid cell lines. Tunicamycin-induced apoptosis was potentiated by activation of protein kinease C (PKC) by phorbol esters and partially prevented by the PKC inhibitor staurosporine. Inhibitors of RNA and protein synthesis displayed a protective effect. Treatment of HL-60 cells with tunicamycin did not elicit the expression of cell surface differentiation antigens or their ability to generate superoxide anion. In contrast, tunicamycin significantly inhibited these processes during dimethyl sulfoxide (DMSO)-induced myeloid differentiation. These observations indicate that the main effect of tunicamycin in HL-60 cells is the induction of apoptosis. © 1995 Wiley-Liss, Inc. 相似文献
52.
Monique Gabriela das Chagas Faustino Alves Celina Maria Pinto G. Dore Allisson Jhonatan G. Castro Marília Silva do Nascimento Ana Katarina M. Cruz Eliane M. Soriano Norma M. Barros Benevides Edda Lisboa Leite 《Journal of applied phycology》2012,24(5):1217-1227
Polysaccharides, galactans, obtained from edible red seaweed Hypnea musciformis were characterized by molecular weight and infrared spectroscopy analysis and were evaluated for antioxidant activity in vitro and for their effects on cell viability. The main components were galactose and sulfate presenting low protein contamination. These sulfated galactans (F1.0) showed a polydisperse profile, and signs in infrared analysis were attributed to a sulfate ester S?=?O bond, the presence of a 3,6-anhydrogalactose C–O bond, nonsulfated β-d-galactose, and a C–O–SO4 bond in galactose C4. The NMR analysis showed signals at about 95 and 92 attributed to anomeric carbon of 4-linked 3,6-anhydro-α-d-galactopyranose residue of κ-carrageenans and 4-linked 3,6-anhydro-α-d-galactopyranose2-sulfate of ι-carrageenans. Sulfated galactan F1.0 showed strong antioxidant activity under lipid peroxidation assay where F1.0 at 8 mg mL?1 promoted 57.92% peroxidation inhibition and displayed the scavenging activity on hydroxyl radicals in a dose-dependent manner leading to 32.5% scavenging of these radicals when 5 mg mL?1 of sulfated galactan F1.0 was used. The sulfated galactan fraction also exhibited strong inhibition on the H2O2-induced hemolysis model. Sulfated galactan F1.0 displayed low cytotoxic action in 3 T3 cells and moderate antitumoral action in HeLa cells. These results suggest that sulfated galactan F1.0 from H. musciformis has antioxidant potential, which is a great effect for a compound used as food and in the food industry. 相似文献
53.
54.
Raquel lvarez Concepcin lvarez Faustino Mollinedo Beatriz G. Sierra Manuel Medarde Rafael Pelez 《Bioorganic & medicinal chemistry》2009,17(17):6422-6431
Isocombretastatins A are 1,1-diarylethene isomers of combretastatins A. We have synthesized the isomers of combretastatin A-4, deoxycombretastatin A-4, 3-amino-deoxycombretastatin A-4 (AVE-8063), naphthylcombretastatin and the N-methyl- and N-ethyl-5-indolyl analogues of combretastatin A-4. Analogues with a 2,3,4-trimethoxyphenyl ring instead of the 3,4,5-trimethoxyphenyl ring have also been prepared. The isocombretastatins A strongly inhibit tubulin polymerization and are potent cytotoxic compounds, some of them with IC50s in the nanomolar range. This new family of tubulin inhibitors shows higher or comparable potency when compared to phenstatin or combretastatin analogues. These results suggest that one carbon bridges with a geminal diaryl substitution can successfully replace the two carbon bridge of combretastatins and that the carbonyl group of phenstatins is not essential for high potency. 相似文献
55.
Camila Infantosi Vannucchi Marcelo Faustino Mariana Groke Marques Marcílio Nichi Mayra Elena Ortiz D’Ávila Assumpção José Antonio Visintin 《In vitro cellular & developmental biology. Animal》2009,45(7):328-333
During the process of maturation in the oviduct, canine oocytes in the germinal vesicle stage are exposed to decreasing levels
of estradiol-17β and increasing levels of progesterone. However, hormone concentrations in the microenvironments in which
they act are higher than serum concentrations. Therefore, the aim of the present study was to compare the meiotic competence
of canine oocytes harvested from anestrous bitches in culture medium containing high concentrations (20 μg ml−1) of estradiol-17β and/or progesterone in association to gonadotropins (luteinizing hormone and follicle-stimulating hormone)
using three different maturation periods (48, 72, and 96 h). Oocytes were cultured in tissue culture medium (TCM-199) and
arranged in four experimental groups: group control, group E2 (estradiol-17β), group P4 (progesterone), and group E2 + P4.
Regardless of the maturation period, groups P4 and E2 + P4 presented statistically higher rate of germinal vesicle breakdown
oocytes compared to the group control and group E2. There were no significant differences among groups on germinal vesicle,
metaphase I, metaphase II, and degenerated or unidentifiable oocytes rates. The mean percentage of metaphase II oocytes was
higher at 96 h when compared to 72 h. Results of the present research indicate no influence of estradiol-17β supplementation,
unless in association with progesterone. There is an evidence of the positive effect of progesterone on germinal vesicle breakdown.
Results also showed that extended periods of in vitro maturation affect positively maturation rates to metaphase II of low
competent oocytes harvested from anestrous bitches, independent of the maturation media. In conclusion, high concentrations
of steroids, especially progesterone, have positive effect on in vitro oocyte maturation when the oocytes are derived from
the anestrous status. 相似文献
56.
A. Oliveira A. Almeida C.M.B. Carvalho J.P.C. Tomé M.A.F. Faustino M.G.P.M.S. Neves A.C. Tomé J.A.S. Cavaleiro Â. Cunha 《Journal of applied microbiology》2009,106(6):1986-1995
Aims: In this study, we propose (i) to study the photodynamic inactivation (PDI) efficiency of neutral and cationic porphyrin derivatives, (ii) to characterize the kinetics of the inactivation process using Bacillus cereus as a model endospore-producing bacterium and (iii) to conclude on the applicability of porphyrin derivatives in the inactivation of bacterial endospores.
Methods and Results: The study of PDI of Bacillus cereus endospores, taken as model-endospores, using porphyrin derivatives differing in the number of positive charges and in the meso-substituent groups, showed that neutral, monocationic and dicationic porphyrins are quite ineffective, in contrast with the tri- and tetra-cationic molecules. The most effective porphyrin is a tricationic porphyrin with a meso-pentafluorophenyl group. With this photosensitizer (PS), at 0·5 μ mol l−1 , a reduction of 3·5 log units occurs after only 4 min of irradiation. None of the porphyrin derivatives showed toxicity in the absence of light.
Conclusions: Some porphyrin derivatives are efficient PSs for the inactivation of bacterial endospores and should be considered in further studies. Small modifications in the substituent groups, in addition to charge, significantly improve the effectiveness of the molecule as a PS for endospore inactivation.
Significance and Impact of the Study: Tetrapyrrolic macrocycles should be regarded as worthy to explore for the PDI of spore-producing gram-positive bacteria. The development of molecules, more selective and effective, emerges as a new objective. 相似文献
Methods and Results: The study of PDI of Bacillus cereus endospores, taken as model-endospores, using porphyrin derivatives differing in the number of positive charges and in the meso-substituent groups, showed that neutral, monocationic and dicationic porphyrins are quite ineffective, in contrast with the tri- and tetra-cationic molecules. The most effective porphyrin is a tricationic porphyrin with a meso-pentafluorophenyl group. With this photosensitizer (PS), at 0·5 μ mol l
Conclusions: Some porphyrin derivatives are efficient PSs for the inactivation of bacterial endospores and should be considered in further studies. Small modifications in the substituent groups, in addition to charge, significantly improve the effectiveness of the molecule as a PS for endospore inactivation.
Significance and Impact of the Study: Tetrapyrrolic macrocycles should be regarded as worthy to explore for the PDI of spore-producing gram-positive bacteria. The development of molecules, more selective and effective, emerges as a new objective. 相似文献
57.
Javier D. Breccia Rajni Hatti-Kaul Guillermo R. Castro Faustino Siñeriz 《Bioseparation》1999,8(6):273-280
-1,4-Xylanase, produced extracellularly by Bacillus amyloliquefaciens MIR 32, was isolated directly from the culture broth by adsorption on a cation exchanger, Amberlite IRC-50, in fluidized bed with a low degree of expansion. The enzyme was eluted from the adsorbent by increase in pH, with a recovery of 82.3% and purification of 5.3 fold. About 99.99% of the colony forming units, 82% of the contaminating neutral protease activity, and 100% of the reducing sugars present in the crude feedstock were removed at the end of the purification cycle. 相似文献
58.
M. Alejandra Martinez Carlos Dezar Mario Baigorí Faustino Siñeriz 《Biotechnology Techniques》1999,13(5):337-340
A simple and easy method for the introduction of plasmid DNA into different species of Bacillus was developed. The method involves the suspension in a transformation buffer of nutrient agar grown cells in their late exponential phase and the addition of unpurified plasmid DNA. Transformants were obtained at a frequency of about 103 to 105 stable transformants per g of plasmid DNA. 相似文献
59.
Carlos M. Abate Guillermo R. Castro Faustino Siñeriz Danley A.S. Callieri 《Biotechnology letters》1999,21(3):249-252
Mixed cultures of Bacillus amyloliquefaciens MIR-41 and Zymomonas mobilis Flo-B3 showed a 2.5 fold increase in -amylase production, and a 20 times fold decrease in ethanol production compared with pure cultures. Enhanced -amylase production by B. amyloliquefaciens in mixed cultures after 24 h could be attributed to the lack of repression in the synthesis of -amylase by ethanol and protease inhibition by the pH of the culture medium. 相似文献
60.
Paula Faustino Leonor Osório-Almeida José Barbot Deonilde Espírito-Santo João Gonçalves Luísa Romão M. Carmo Martins M. Maia Marques João Lavinha 《Human genetics》1992,89(5):573-576
Summary In order to delineate the spectrum and the relative abundance of -globin gene defects causing thalassaemia in the Portuguese population, a representative sample was analysed including 51 -thalassaemia carriers along with 26 patients representing different clinical phenotypes. Seven mutations were identified, four of which [codon 39 (CT), 39%; intervening sequence (IVS)1 nucleotide (nt) 1 (GA), 26%; IVS1 nt 110 (GA), 17%; IVS1 nt6 (TC), 15%] account for 97% of 93 -thalassaemia chromosomes. Two previously undescribed mutations, namely a CT substitution at position — 90 in the proximal CACCC box, and the deletion of nucleotides 4 and 5 (AG) in IVS 2 were identified. The uncommon, though ubiquitous, GT transversion at codon 121 was found once upon haplotype V. Direct prenatal diagnosis can be offered to 95% of couples at risk of bearing a thalassaemic child. 相似文献