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51.
Abdelhafidh Dhouib Manel Hamza Hela Zouari Tahar Mechichi Rafik Hmidi Marc Labat Maria Jesus Martinez Sami Sayadi 《World journal of microbiology & biotechnology》2005,21(8-9):1415-1423
Summary This work represents the first report on the ability of autochthonous fungi from Tunisia to produce ligninolytic enzymes.
Three hundred and fifteen fungal strains were isolated from different Tunisian biotopes. These fungal strains were firstly
screened on solid media containing Poly R-478 or ABTS as indicator compounds that enabled the detection of lignin-modifying
enzymes as specific color reactions. Of the 315 tested strains, 49 exhibited significant ABTS-oxidation activity expressed
within the first week of incubation and only 18 strains decolorized the Poly R-478. Liquid cultivations and laccase, manganese
peroxidase and lignin peroxidase activity assays of positive strains confirmed that eight efficient enzyme producers were
found in the screening. These strains were attributed to the most closely related species using PCR amplification and sequencing
of the internal transcribed spacer ‘ITS’ regions of the ribosomal DNA. The identification results showed fungal genera such
as Oxyporus, Stereum and Trichoderma which have been only rarely reported as ligninolytic enzyme producers in the literature. Culture conditions and medium composition
were optimized for the laccase producer Trametes trogii CTM 10156. This optimization resulted in high laccase production, 367 times more than in non-optimized conditions and which
reached 110 U ml-1 within 15 days of incubation. 相似文献
52.
The interaction between soil drying and salinity was studied in the perennial halophyte, Sesuvium portulacastrum. Rooted cuttings were individually cultivated for three months in silty-sandy soil under two irrigation modes: 100 and 25% of field capacity (FC). The amount of the evapotranspirated water was replaced by a nutrient solution containing either 0 or 100 mM NaCl. Whole-plant growth, leaf water content, leaf water potential (Psi(w)), and Na+, K+, and proline concentrations in the tissues were measured. When individually applied, both drought and salinity significantly restricted whole-plant growth, with a more marked effect of the former stress. However, the effects of the two stresses were not additive on whole-plant biomass or on leaf expansion. Root growth was more sensitive to salt than to soil drying, the latter being even magnified by the adverse impact of salinity. Leaf water content was significantly reduced following exposure to water-deficit stress, but was less affected in salt-treated plants. When simultaneously submitted to water-deficit stress and salinity, plants displayed higher values of water and potassium use efficiencies, leaf proline and Na+ concentrations, associated with lower leaf water potential (-1.87 MPa), suggesting the ability of S. portulacastrum to use Na+ and proline for osmotic adjustment. 相似文献
53.
Flexible control of plant architecture and yield via switchable expression of Arabidopsis gai 总被引:2,自引:0,他引:2
The growth of plants is repressed by DELLA proteins, nuclear regulators whose activities are opposed by the growth-promoting phytohormone gibberellin (GA). Mutations affecting DELLA protein function were previously used by plant breeders to create the high-yielding semidwarf wheat varieties of the green revolution. gai is an Arabidopsis mutant DELLA protein-encoding orthologue of the wheat semidwarfing genes. Here we describe the development of a transgene that confers ethanol-inducible gai expression. Transient induction of gai causes transient growth repression: growth prior to and after treatment is unaffected. Appropriate ethanol treatments result in dwarf plants that produce the same numbers of seeds as untreated controls. This new technology represents a substantial advance in the applicability of genes encoding mutant DELLA proteins to agricultural and horticultural improvement, enhancing the flexibity with which these genes can be used for the sustainable achievement of increased crop plant yields. 相似文献
54.
Ascorbate oxidase-dependent changes in the redox state of the apoplast modulate gene transcript accumulation leading to modified hormone signaling and orchestration of defense processes in tobacco 总被引:2,自引:0,他引:2 下载免费PDF全文
Pignocchi C Kiddle G Hernández I Foster SJ Asensi A Taybi T Barnes J Foyer CH 《Plant physiology》2006,141(2):423-435
55.
Gibberellin-mediated proteasome-dependent degradation of the barley DELLA protein SLN1 repressor 总被引:24,自引:0,他引:24 下载免费PDF全文
Fu X Richards DE Ait-Ali T Hynes LW Ougham H Peng J Harberd NP 《The Plant cell》2002,14(12):3191-3200
DELLA proteins are nuclear repressors of plant gibberellin (GA) responses. Here, we investigate the properties of SLN1, a DELLA protein from barley that is destabilized by GA treatment. Using specific inhibitors of proteasome function, we show that proteasome-mediated protein degradation is necessary for GA-mediated destabilization of SLN1. We also show that GA responses, such as the aleurone alpha-amylase response and seedling leaf extension growth, require proteasome-dependent GA-mediated SLN1 destabilization. In further experiments with protein kinase and protein phosphatase inhibitors, we identify two additional signaling steps that are necessary for GA response and for GA-mediated destabilization of SLN1. Thus, GA signaling involves protein phosphorylation and dephosphorylation steps and promotes the derepression of GA responses via proteasome-dependent destabilization of DELLA repressors. 相似文献
56.
Imen Ben Tahar Małgorzata Kus-Liśkiewicz Yannick Lara Emmanuelle Javaux Patrick Fickers 《Biotechnology progress》2020,36(2):e2912
In this study, we report on the ability of the yeast Yarrowia lipolytica W29 to produce an extracellular melanin-like brown pigment at high yield (0.5 mg/ml) in culture medium supplemented with L-tyrosine. This pigment has been characterized as pyomelanin and its synthesis was found to occur by the so-called HGA-melanin pathway. The purified pyomelanin was found embedded with antioxidant properties as it exhibited a radical scavenging activity toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 of 230 μg/ml. It was also characterized as noncytotoxic toward two mammalian cell lines, namely the mouse fibroblast NIH3T3 and human keratinocytes HaCaT. When blended with different commercial sunscreens, the purified pyomelanin increased significantly the sun protection factor (SPF) value, highlighting its potential utilization as UV-filter in cosmetic preparations. 相似文献
57.
58.
Marouani N Tebourbi O Mahjoub S Yacoubi MT Sakly M Benkhalifa M Rhouma KB 《Reproductive biology》2012,12(2):119-133
Hexavalent chromium is an environmental contaminant which may be associated with reproductive abnormalities in male rats. In the present study, we examined the effect of hexavalent chromium on male reproductive function of rats. Male Wistar rats received a daily intraperitoneal injection of potassium dichromate (1 or 2 mg/kg body weight) for fifteen consecutive days. A decrease in testis weight and an increase in seminal vesicles and prostate weights were demonstrated after chromium treatment. Moreover, a dose-dependent increase in blood and testis chromium levels as well as an increase in FSH and a decrease in LH and testosterone serum levels were detected in treated rats. Histological analysis revealed pronounced morphological alterations with enlarged intracellular spaces, tissue loosening and dramatic loss of gametes in the lumen of the seminiferous tubules of treated rats. In addition, a decreased sperm motility and number of epididymal spermatozoa together with an increased sperm abnormality rate was found in chromium-treated rats in comparison to controls. In rats receiving the higher chromium dose, histological images presented considerably increased areas filled with seminal vesicle and prostate secretions. The mucosal crypts of seminal vesicles and the typical invaginations of prostate were altered. The results suggest that subacute treatment of potassium dichromate promotes reproductive system toxicity and affects testicular function of adult male rats. 相似文献
59.
S Thomas M Legendre S Saunier B Bessières C Alby M Bonnière A Toutain L Loeuillet K Szymanska F Jossic D Gaillard MT Yacoubi S Mougou-Zerelli A David MA Barthez Y Ville C Bole-Feysot P Nitschke S Lyonnet A Munnich CA Johnson F Encha-Razavi V Cormier-Daire C Thauvin-Robinet M Vekemans T Attié-Bitach 《American journal of human genetics》2012,91(2):372-378
Orofaciodigital syndromes (OFDSs) consist of a group of heterogeneous disorders characterized by abnormalities in the oral cavity, face, and digits and associated phenotypic abnormalities that lead to the delineation of 13 OFDS subtypes. Here, by a combined approach of homozygozity mapping and exome ciliary sequencing, we identified truncating TCTN3 mutations as the cause of an extreme form of OFD associated with bone dysplasia, tibial defect, cystic kidneys, and brain anomalies (OFD IV, Mohr-Majewski syndrome). Analysis of 184 individuals with various ciliopathies (OFD, Meckel, Joubert, and short rib polydactyly syndromes) led us to identify four additional truncating TCTN3 mutations in unrelated fetal cases with overlapping Meckel and OFD IV syndromes and one homozygous missense mutation in a family with Joubert syndrome. By exploring roles of TCTN3 in human ciliary related functions, we found that TCTN3 is necessary for transduction of the sonic hedgehog (SHH) signaling pathway, as revealed by abnormal processing of GLI3 in patient cells. These results are consistent with the suggested role of its murine ortholog, which forms a complex at the ciliary transition zone with TCTN1 and TCTN2, both of which are also implicated in the transduction of SHH signaling. Overall, our data show the involvement of the transition zone protein TCTN3 in the regulation of the key SHH signaling pathway and that its disruption causes a severe form of ciliopathy, combining features of Meckel and OFD IV syndromes. 相似文献
60.
Elisabeth Peltier Cedric Peltier Stephanie Tahar Evelyne Alliot-Lugaz Yves Cazals 《PloS one》2012,7(12)
Over the last three years of hearing aid dispensing, it was observed that among 74 subjects fitted with a linear octave frequency transposition (LOFT) hearing aid, 60 reported partial or complete tinnitus suppression during day and night, an effect still lasting after several months or years of daily use. We report in more details on 38 subjects from whom we obtained quantified measures of tinnitus suppression through visual analog scaling and several additional psychoacoustic and audiometric measures. The long-term suppression seems independent of subject age, and of duration and subjective localization of tinnitus. A small but significant correlation was found with audiogram losses but not with high frequency loss slope. Long-term tinnitus suppression was observed for different etiologies, but with a low success rate for sudden deafness. It should be noted that a majority of subjects (23) had a history of noise exposure. Tinnitus suppression started after a few days of LOFT hearing aid use and reached a maximum after a few weeks of daily use. For nine subjects different amounts of frequency shifting were tried and found more or less successful for long-term tinnitus suppression, no correlation was found with tinnitus pitch. When the use of the LOFT hearing aid was stopped tinnitus reappeared within a day, and after re-using the LOFT aid it disappeared again within a day. For about one third of the 38 subjects a classical amplification or a non linear frequency compression aid was also tried, and no such tinnitus suppression was observed. Besides improvements in audiometric sensitivity to high frequencies and in speech discrimination scores, LOFT can be considered as a remarkable opportunity to suppress tinnitus over a long time scale. From a pathophysiological viewpoint these observations seem to fit with a possible re-attribution of activity to previously deprived cerebral areas corresponding to high frequency coding. 相似文献