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排序方式: 共有141条查询结果,搜索用时 15 毫秒
71.
Araújo HC Cavalcanti MG Santos SS Alves LC Brayner FA 《Micron (Oxford, England : 1993)》2008,39(2):184-189
Mosquitoes have an efficient defence system against infection. Insect blood cells (hemocytes) play an essential role in defense against parasites and other pathogenic organisms that infect insects. We have identified by light and transmission electron microscopy six hemocytes cell types from the hemolymph of Aedes aegypti. They were: prohemocytes (20%), adipohemocytes (29%), granulocytes (16%), plasmatocytes (27%), oenocytoids (7%) and thrombocytoids (0.9%). The prohemocytes were the smallest hemocytes found in the hemolymph. Its cytoplasm occupies only a narrow area around the nucleus. The adipohemocytes were the most abundant cell type presented. These hemocytes exhibited a large lipid like vesicle and mitochondria. In electron micrographs, the granulocytes showed cytoplasm containing dilated rough endoplasmic reticulum (RER) and a round or elongated mitochondria. Electron-dense granules with a proteinaceous material were also present. The plasmatocytes were polymorphic and exhibited plasma membrane with irregular processes, philopodia and pseudopodia. Ultrastructural investigation revealed that the reticular cytoplasm showed a well-developed RER, a Golgi and vacuoles. Oenocytoids showed homogeneous cytoplasm with many mitochondria and ribosomes are scattered throughout the cytoplasm, abundant RER and a small smooth endoplasmic reticulum (SER) present at the cell poles. Thrombocytoids were very fragile and few in number. Similar characteristics were found in oenocytoids, possessing a homogeneous cytoplasm with poorly developed organelles, few mitochondria and granules. 相似文献
72.
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74.
Michaela Wilhelm Michael Jeske Roland Marschall Welchy Leite Cavalcanti Pia Tlle Christof Khler Dietmar Koch Thomas Frauenheim Georg Grathwohl Jürgen Caro Michael Wark 《Journal of membrane science》2008,316(1-2):164-175
For increased efficiency of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC), new types of membranes have to be developed. This approach has been realized by preparing hybrid membranes containing SO3H-functionalized mesoporous Si-MCM-41 as hydrophilic inorganic modifier in a polysiloxane matrix exhibiting sulfonic acid groups and basic heterocyclic groups like benzimidazole. The proton conductivity of sulfonated particles was modelled on the atomic scale in order to understand the influence of the density of sulfonic acid groups and of the presence of water molecules. The different hybrid membranes are characterized concerning their thermal stability, water uptake, and proton conductivity. Whereas the proton conductivity of well-established, but expensive and at >120 °C not long-time stable Nafion membranes continuously decreases with increasing temperature, the polysiloxane membranes, which suffer from a low-proton conductivity at around 100 °C, recover at about 120 °C due to intrinsic proton transport. At 180 °C the pure polysiloxane shows a proton conductivity which is only one order of magnitude lower than that of Nafion. Moreover, if the polysiloxane membrane contains additionally 10 wt.% of an SO3H-modified Si-MCM-41, the proton conductivity of such hybrid membrane at temperatures >180 °C and low relative humidity <10% is higher than that of Nafion membranes by a factor of 10. 相似文献
75.
Osório Luizangela Reis Meneguin Andréia Bagliotti da Silva Hernane Barud Barreto Humberto Medeiros Osajima Josy Anteveli da Silva Filho Edson Cavalcanti 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1629-1637
The aim of this work was to study the effect of tris(3-nitrophenyl) phosphine (NPPh3), which showed a good thermal stability and carbon-forming ability, on the flame retardancy and thermal degradation mechanism of epoxy resins. A series of diglycidyl ether of bisphenol A (DGEBA) loaded with tris(3-nitrophenyl) phosphine (NPPh3) were prepared. It was found that NPPh3 can effectively improve the flame retardancy and thermal stability of the composites. When the loading amount of NPPh3 was 14%, the LOI value of the DGEBA composites was 29.2% (about 1.53 times the corresponding value of the original DGEBA resin). Thermal stability was studied by thermogravimetric analysis, and the results showed that the addition of NPPh3 can improve char formation of this system both in nitrogen and in air atmosphere. Specifically, its combustion residue at 800 °C in nitrogen atmosphere was about 4.26 times of the original resin. Differential scanning calorimetry indicated that NPPh3 slightly decreased the glass transition temperature of epoxy resins. Additionally, the gaseous degradation products were analyzed by thermogravimetric analysis/infrared spectrometry, providing insight into the thermal degradation mechanism. Scanning electron microscopy and Fourier transform infrared were brought together to evaluate the morphology and structure of the residual char obtained after combustion. 相似文献
76.
77.
The action modes of Lippia sidoides (Cham) essential oil as penetration enhancers on snake skin 总被引:1,自引:0,他引:1
M. B. Brito Gabriela B. Barin A. A. S. Araújo D. P. de Sousa S. C. H. Cavalcanti Ana Amélia M. Lira Rogéria S. Nunes 《Journal of Thermal Analysis and Calorimetry》2009,97(1):323-327
The aim of this work was to study the effect of Lippia sidoides essential oil (LSEO) on stratum corneum lipids and the permeation of salicylic acid. DSC and FTIR spectroscopy were applied.
LSEO 1% (v/v) significantly enhanced salicylic acid flux through snake skin. According to the DSC curves changes in the transition
temperature of the lipids were observed indicating that LSEO can interact with stratum corneum. The IR spectrum of skin treated
with LSEO showed a decrease in the peak intensity for CH2 stretchings (2920–2850 cm–1) however the peak positions did not alter suggesting the extraction of the lipids. 相似文献
78.
da Silva CD Coriolano MC da Silva Lino MA de Melo CM de Souza Bezerra R de Carvalho EV Dos Santos AJ Pereira VR Coelho LC 《Applied biochemistry and biotechnology》2012,166(2):424-435
The aim of this work was to purify and partially characterize a mannose recognition lectin from Nile tilapia (Oreochromis niloticus) serum, named OniL. OniL was isolated through precipitation with ammonium sulfate and affinity chromatography (Concanavalin
A–Sepharose 4B). In addition, we evaluated carbohydrate specificity, sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS–PAGE) profiles, and in vitro immunomodulatory activity on mice splenocyte experimental cultures through cytotoxic assays
and cytokine production. The ammonium sulfate fraction F2 showed the highest specific hemagglutinating activity (331) and
was applied to affinity matrix. Adsorbed proteins (OniL) were eluted with methyl-α-d-mannopyranoside. OniL, a 17-kDa protein by SDS–PAGE constituted by subunits of 11 and 6.6 kDa, showed highest affinity for
methyl-α-d-mannopyranoside and d-mannose. Immunological assays, in vitro, showed that OniL did not show cytotoxicity against splenocytes, induced higher IFN-γ
production and lower IL-10 as well as nitrite release. In conclusion, OniL lectin was successfully purified and showed a preferential
Th1 response in mice splenocytes. 相似文献
79.
Global well-posedness and exponential decay rates for a KdV–Burgers equation with indefinite damping
M.M. Cavalcanti V.N. Domingos Cavalcanti V. Komornik J.H. Rodrigues 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2014
We consider the KdV–Burgers equation ut+uxxx−uxx+λu+uux=0 and its linearized version ut+uxxx−uxx+λu=0 on the whole real line. We investigate their well-posedness their exponential stability when λ is an indefinite damping. 相似文献
80.
Gil Ramos Cavalcanti 《Transactions of the American Mathematical Society》2007,359(1):333-348
In this paper we study the behaviour of the Lefschetz property under the blow-up construction. We show that it is possible to reduce the dimension of the kernel of the Lefschetz map if we blow up along a suitable submanifold satisfying the Lefschetz property. We use this, together with results about Massey products, to construct compact nonformal symplectic manifolds satisfying the Lefschetz property.