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排序方式: 共有211条查询结果,搜索用时 9 毫秒
1.
Teixeira-Neto É Leite CA Cardoso AH Medeiros da Silva MC Braga M Galembeck F 《Journal of colloid and interface science》2000,231(1):182-189
Poly(styrene-co-acrylamide) (PS-AAM) latex was prepared, fractionated by sedimentation under gravity, and characterized by PCS, infrared spectra, secondary and backscattered electron imaging in the scanning electron microscope, and electron spectroscopy imaging in an analytical transmission electron microscope. Three latex fractions were obtained. The lower fraction was opalescent and its particles were the more uniform, concerning size, chemical composition, and topochemical features. This lower fraction was still further fractionated by zonal centrifugation in a density gradient, yielding two fractions with similar macrocrystal-forming abilities but different sizes and chemical compositions. These results confirm those previously obtained for the PS-HEMA latex. Copyright 2000 Academic Press. 相似文献
2.
Anaí Duarte Wilson Cunico Claudio M.P. Pereira Alex F.C. Flores Rogério A. Freitag Geonir M. Siqueira 《Ultrasonics sonochemistry》2010,17(2):281-283
An ultrasound-enhanced method has been developed for the synthesis of a variety of thioesters from benzoyl chlorides and 2-mercaptobenzoxa(thia)zoles. Applying this methodology, 14 compounds were synthesized in excellent yields. 相似文献
3.
Maria Esmeralda C. de Sousa Valria Wanderley-Teixeira lvaro A.C. Teixeira Herbert A.A. de Siqueira Fbio A.B. Santos Luiz C. Alves 《Micron (Oxford, England : 1993)》2009,40(7):743-749
The insect midgut has ultimately been the focus of researches tempting to control insect pests because alterations in the insect gut may affect not only its development, but also physiological events such as nutrient absorption and transformation. The objective of the present work was to describe morphologically, histochemically, and ultrastructurally the larva midgut of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), a cotton key pest in Brazil. Light and electronic transmission microscopy was used to obtain images from midgut sections of late fourth-instar larvae of A. argillacea. In general, the morphology, histochemistry, and ultrastructure characteristics of A. argillacea midgut follow that described in the literature for other lepidopteran species. However, the results showed a mitochondrial polymorphism and branched microvilli, which suggest an ultrastrucutural and physiological modification possibly associated with a high absorption and secretion activity by the columnar cells of this species. This intense activity may favor a faster response related to the action of ingested microbial agents and/or toxins, and can explain the high susceptibility of A. argillacea to the agents of control such as the toxin of Bacillus thuringiensis. 相似文献
4.
Acid-catalyzed cyclization of D-mannitol followed by isopropylidenation furnished 2,5-anhydro-1,3-O-isopropylidene-D-glucitol, conveniently isolated by dry column vacuum chromatography. 相似文献
5.
Siqueira Iolanda Scheibe de Dweck Jo Toledo Filho Romildo Dias 《Journal of Thermal Analysis and Calorimetry》2020,142(4):1413-1428
Journal of Thermal Analysis and Calorimetry - The interest in the use of cellulose fibers of increasingly smaller sizes in cementitious materials has increased in recent years. This paper brings... 相似文献
6.
Summary In this paper we discuss the existence of compact attractor for the abstract semilinear evolution equation u=Au+f(t, u); the results are applied to damped partial differential equations of hyperbolic type. Our approach is a combination of Liapunov method with the theory of -eontractions. 相似文献
7.
Morelos A Albuquerque IF Bondar NF Carrigan RA Chen D Cooper PS Lisheng D Denisov AS Dobrovolsky AV Dubbs T Endler AM Escobar CO Foucher M Golovtsov VL Gottschalk H Gouffon P Grachev VT Khanzadeev AV Kubantsev MA Kuropatkin NP Lach J Lang Pengfei Li Chengze Li Yunshan Luksys M Mahon JR McCliment E Newsom C Pommot Maia MC Samsonov VM Schegelsky VA Shi Huanzhang Smith VJ Tang Fukun Terentyev NK Timm S Tkatch II Uvarov LN Vorobyov AA Yan Jie Zhao Wenheng Shuchen Z Zhong Yuanyuan 《Physical review letters》1993,71(21):3417-3420
8.
de Oliveira CS Falcão-Silva Vdos S Siqueira JP Harding DP Lira BF Lorenzo JG Barbosa-Filho JM de Athayde-Filho PF 《Molecules (Basel, Switzerland)》2011,16(3):2023-2031
Two salts of the mesoionic compounds 1,4-diphenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-thiol chloride (MC-1) and 4-phenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-phenylamine chloride (MC-2) were synthesized utilizing 1,4-diphenyl-thiosemicarbazide and 5-nitro-2-furoyl chloride as starting materials. Their structures were characterized by IR, 1H-NMR, 13C-NMR and elemental analysis. These compounds were analyzed for their influence on the effectiveness of norfloxacin, tetracycline, and erythromycin (standard antibiotics) against resistant strains of Staphylococcus aureus. MC-1 and MC-2, at sub-inhibitory concentrations of 16 μg/mL, favourably modulated the antibiotic activity of tetracycline by 16- and 32-fold, respectively (MIC), and that of erythromycin by 4-fold. 相似文献
9.
Dina L. Kinoshita Luiz G. Ferreira Manoel L. De Siqueira 《International journal of quantum chemistry》1985,28(1):85-101
This is the third paper on the cellular method for polyatomic systems. We show how to deal with nonspherical Coulomb potentials. We also show how to modify the variational expression for the energy eigenvalues so as to obtain a faster convergence in the angular momentum series for the wavefunctions. We apply both techniques to the self-consistent calculation of SF6. Contrary to what we obtained in CH4 and SiH4, the cellular method cannot yield the correct equilibrium interatomic distance in the present case. The calculated ionization potentials are in the correct order but are all shifted by 2–3 eV. This shift is attributed to the wrong expression for exchange correlation. 相似文献
10.
Morelos A Albuquerque IF Bondar NF Carrigan RA Chen D Cooper PS Dai Lisheng Denisov AS Dobrovolsky AV Dubbs T Endler AM Escobar CO Foucher M Golovtsov VL Gottschalk H Gouffon P Grachev VT Khanzadeev AV Kubantsev MA Kuropatkin NP Lach J Lang Pengfei Li Chengze Li Yunshan Luksys M Mahon JR McCliment E Newsom C Pommot Maia MC Samsonov VM Schegelsky VA Shi Huanzhang Smith VJ Tang Fukun Terentyev NK Timm S Tkatch II Uvarov LN Vorobyov AA Yan Jie Zhao Wenheng Zheng Shuchen Zhong Yuanyuan 《Physical review letters》1993,71(14):2172-2175