排序方式： 共有44条查询结果，搜索用时 984 毫秒
21.
Caballero A Despagnet-Ayoub E Díaz-Requejo MM Díaz-Rodríguez A González-Núñez ME Mello R Muñoz BK Ojo WS Asensio G Etienne M Pérez PJ 《Science (New York, N.Y.)》2011,332(6031):835-838
Even in the context of hydrocarbons' general resistance to selective functionalization, methane's volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH(4)) with ethyl diazoacetate (N(2)CHCO(2)Et) to yield ethyl propionate (CH(3)CH(2)CO(2)Et). The use of supercritical carbon dioxide (scCO(2)) as the solvent is key to the reaction's success. Although the catalyst is only sparingly soluble in CH(4)/CO(2) mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours. 相似文献
22.
Pistocchi R Guerrini F Pezzolesi L Riccardi M Vanucci S Ciminiello P Dell'Aversano C Forino M Fattorusso E Tartaglione L Milandri A Pompei M Cangini M Pigozzi S Riccardi E 《Marine drugs》2012,10(1):140-162
The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication due to shellfish consumption occurred in 1989, nearly 10 years later than other countries in Europe and worldwide that had faced similar problems. Until 1997, Adriatic mollusks had been found to be contaminated mostly by diarrhetic shellfish poisoning toxins (i.e., okadaic acid and dinophysistoxins) that, along with paralytic shellfish poisoning toxins (i.e., saxitoxins), constitute the most common marine biotoxins. Only once, in 1994, a toxic outbreak was related to the occurrence of paralytic shellfish poisoning toxins in the Adriatic coastal waters. Moreover, in the past 15 years, the Adriatic Sea has been characterized by the presence of toxic or potentially toxic algae, not highly widespread outside Europe, such as species producing yessotoxins (i.e., Protoceratium reticulatum, Gonyaulax spinifera and Lingulodinium polyedrum), recurrent blooms of the potentially ichthyotoxic species Fibrocapsa japonica and, recently, by blooms of palytoxin-like producing species of the Ostreopsis genus. This review is aimed at integrating monitoring data on toxin spectra and levels in mussels farmed along the coast of the Emilia-Romagna region with laboratory studies performed on the species involved in the production of those toxins; toxicity studies on toxic or potentially toxic species that have recently appeared in this area are also reviewed. Overall, reviewed data are related to: (i) the yessotoxins producing species P. reticulatum, G. spinifera and L. polyedrum, highlighting genetic and toxic characteristics; (ii) Adriatic strains of Alexandrium minutum, Alexandrium ostenfeldii and Prorocentrum lima whose toxic profiles are compared with those of strains of different geographic origins; (iii) F. japonica and Ostreopsis cf. ovata toxicity. Moreover, new data concerning domoic acid production by a Pseudo-nitzschia multistriata strain, toxicity investigations on a Prorocentrum cf. levis, and on presumably ichthyotoxic species, Heterosigma akashiwo and Chattonella cf. subsalsa, are also reported. 相似文献
23.
Expression levels of the focal adhesion-associated proteins paxillin and p130CAS in canine and feline mammary tumors 总被引：7，自引：0，他引：7
Scibelli A d'Angelo D Pelagalli A Tafuri S Avallone L Della Morte R Staiano N 《Veterinary research》2003,34(2):193-202
Paxillin and p130CAS are two adaptor proteins localized at the focal adhesions which play an important role in cell signaling, cell motility and oncogenic transformation. In this study we evaluated the levels of paxillin and p130CAS in feline and canine mammary tumor tissues at different stages of malignancy. The results obtained by Western blotting analysis showed no significant differences in the amounts of paxillin and p130CAS between normal and non-invasive tumor tissues. By contrast, mammary tumor tissues with the invasive phenotype showed lower levels of paxillin P < 0.01 and higher levels of p130CAS P < 0.001 than normal tissues. The decrease P < 0.001 of the amount of paxillin and the increase P < 0.001 of p130CAS levels were correlated with the progression stage of malignancy. Since paxillin and p130CAS are involved in regulating cell migration, our results suggest that low levels of paxillin together with high levels of p130CAS expression may cause certain breast cancers to be more motile and possibly more aggressive. Thus, both paxillin and p130CAS may represent useful prognosticators of feline and canine breast cancer malignancy. 相似文献
24.
Scibelli A Roperto S Manna L Pavone LM Tafuri S Della Morte R Staiano N 《Veterinary journal (London, England : 1997)》2007,173(3):482-491
Integrins are heterodimeric receptors that mediate important cell functions, including cell adhesion, migration and tissue organisation. These transmembrane receptors regulate the direct association of cells with each other and with extracellular matrix proteins. However, by binding their ligands, integrins provide a transmembrane link for the bidirectional transmission of mechanical forces and biochemical signals across the plasma membrane. Interestingly, several of this family of receptors are exploited by pathogens to establish contact with the host cells. Hence, microbes subvert normal eukaryotic cell processes to create a specialised niche which allows their survival. This review highlights the fundamental role of integrins in bacterial pathogenesis. 相似文献
25.
Manna L Vitale F Reale S Caracappa S Pavone LM Morte RD Cringoli G Staiano N Gravino AE 《Veterinary parasitology》2004,125(3-4):251-262
In this study, different types of tissue sampling for PCR-based diagnosis and follow-up of canine visceral leishmaniosis were compared. Skin, whole blood and lymph node samples were collected from 95 naturally infected dogs living in South Italy, where the disease is endemic. Twenty-nine of these 95 dogs, treated with meglumine administered concurrently with allopurinol for 30 days, and then with allopurinol alone, were monitored during a period of 2 years. The DNA extracted from the clinical specimens was amplified by PCR using as target DNA a 116-bp fragment in the constant region of the kinetoplast DNA minicircle. PCR analysis was more sensitive than indirect immunofluorescence antibody test in detecting Leishmania infection in symptomatic dogs: 99% of lymph node samples resulted positive, whereas 94% of blood samples and 95% of skin samples gave a positive result. PCR analysis of samples from dogs followed up 2 years showed that: (1) all subjects resulted positive in at least one of the three types of samples; (2) all time the dogs had a relapse, PCR resulted positive in all three types of samples; (3) when dogs were apparently healthy, PCR analysis was positive on skin and lymph node samples, but not always on blood samples. Since lymph node sampling is invasive and sometimes difficult in healthy asymptomatic dogs, our results suggest that, independently from the presence or not of cutaneous lesions, skin biopsy represents a good substratum for PCR-based diagnosis and follow-up of canine visceral leishmaniosis. 相似文献
26.
27.
28.
Emma Scurrell Sue Manning Pedro Malho Alex Civello John Mould Rossella Carrozza Bart E. Wagner 《Veterinary ophthalmology》2020,23(2):402-408
A microsporidial keratopathy is described in two dogs. Both dogs presented with a unilateral stromal keratopathy characterized by multifocal coalescing opacities, and the diagnosis was made on histopathologic examination of keratectomy specimens. Transmission electron microscopy (TEM) on formalin‐fixed, paraffin‐embedded corneal tissue was performed in one dog, and the morphologic features were consistent with Nosema species infection. Both dogs were initially diagnosed and treated by superficial keratectomy. One dog received additional antifungal medication and underwent a penetrating keratoplasty following local recurrence two years later. No other systemic lesions attributable to the microsporidial infection were identified clinically. The clinical and diagnostic pathology findings, treatment, and follow‐up are discussed. 相似文献
29.
Fornasaro Silvia Morelli Guia Rimondi Valentina Fagotti Cesare Friani Rossella Lattanzi Pierfranco Costagliola Pilario 《Journal of Soils and Sediments》2022,22(2):656-671
Journal of Soils and Sediments - The extensive Hg contamination in soil and sediments occurring along the Paglia River (Central Italy) is the result of the interplay between the geomorphological... 相似文献
30.
Resource use efficiency of field-grown sunflower, sorghum, wheat and chickpea: I. Radiation use efficiency 总被引：2，自引：0，他引：2
Radiation use efficiency () is a crop parameter widely used in crop simulation models, derived here as the slope of the relationship linking crop carbon gain to cumulative intercepted solar radiation. Our objectives were to: (i) determine of field-grown sunflower, sorghum, wheat and chickpea, at three levels of aggregation—day-time net assimilation (A), daily net carbon gain as difference between A and night-time dark respiration (R) and biomass; (ii) assess the robustness of parameter in terms of ability to discriminate between C3 and C4 species, pre- and post-anthesis and impact of nitrogen status; (iii) evaluate the opportunity to normalize for climate. Field experiments were conducted in 1998 and 1999 in southern Italy. All crops were well watered. Sunflower and sorghum had two nitrogen application treatments, wheat only one and chickpea had no added nitrogen. Daily intercepted solar radiation was derived from measurements of daily incident solar radiation and the percentage of mid-day light interception. Closed-system canopy chambers monitored canopy gas-exchange rates. , expressed in terms of A, A − R or above-ground biomass, was linear over the entire growth cycle of sorghum and wheat, and up to anthesis in sunflower and chickpea, independent of temperature, vapour pressure deficit and radiation regimes. In sunflower, deviation from linearity was observed after anthesis, due to higher carbon cost in yielding oil seeds. No conclusions could be drawn for post-anthesis chickpea due to the interruption of the experiment caused by a thunderstorm. Overall results showed a great variability in values, independently of classes of species (C4 and C3), crops and nitrogen treatments. This indicates that the robustness of to predict biomass productivity in crop simulation models is constrained. Attempts to normalize by vapour pressure deficit (D), for reducing its variability due to climate and overlaps between crops failed. 相似文献