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排序方式: 共有250条查询结果,搜索用时 9 毫秒
71.
Ignacio E. Grossmann Jose Antonio Caballero Hector Yeomans 《Journal of Global Optimization》2004,30(4):459-515
Authors Index
List of Contributors 相似文献72.
Ma. Joaquina Caballero Inmaculada Suarez Baudilio Coto Rafael Van Grieken Benjamín Monrabal 《Macromolecular Symposia》2007,257(1):122-130
Summary: The incorporation of comonomer molecules in the backbone of a homopolymer can influence the final properties of the material, decreasing its crystallinity and the melting and glass transition temperatures, and increasing its impact resistance and transparency. In the present work, ten ethylene/propylene copolymers have been synthesized using a supported metallocene catalytic system covering the whole composition range. Any desired composition was obtained by controlling the feed composition during the reaction. These synthesized copolymers have been characterized by different techniques in order to study the effect of the comonomer incorporation onto their final properties. When the comonomer content is low, the behaviour of the copolymer is similar to that of the corresponding homopolymer. Nevertheless, if the comonomer content increases, the copolymer becomes more amorphous (low crystallization temperature and soft XRD signals) and easily deformable, reaching a behaviour close to that corresponding to an elastomeric material. In order to corroborate these results the samples have been characterized by TREF and GPC-MALS. TREF analysis showed that copolymers containing less than 10% and more than 80% of ethylene are semicrystalline, with elution temperatures typical of this kind of polymers. Molecular weights are higher for homopolymers and they decrease as the comonomer concentration increases, whereas the polydispersity index keeps almost constant at the expected value for this kind of samples. 相似文献
73.
Manuel Rubio‐Arroyo Federico Jimnez‐Cruz Guadalupe Prez‐Caballero Simn Hernndez‐Ortega 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1028-1029
The crystal structure of the title compound, C19H16N2O2, displays a trans configuration of the azo moiety, which forms an intramolecular O—H?N=N hydrogen bond. The H?N and O?N distances are 1.81 (3) and 2.581 (4) Å, respectively. The azobenzene moiety is approximately planar, and has a dihedral angle of ca 23° with the substituted phenyl group. 相似文献
74.
75.
Encarnación Caballero‐Díaz Christian Pfeiffer Lena Kastl Pilar Rivera‐Gil Bartolome Simonet Miguel Valcárcel Javier Jiménez‐Lamana Francisco Laborda Wolfgang J. Parak 《Particle & Particle Systems Characterization》2013,30(12):1079-1085
A set of three types of silver nanoparticles (Ag NPs) are prepared, which have the same Ag cores, but different surface chemistry. Ag cores are stabilized with mercaptoundecanoic acid (MUA) or with a polymer shell [poly(isobutylene‐alt‐maleic anhydride) (PMA)]. In order to reduce cellular uptake, the polymer‐coated Ag NPs are additionally modified with polyethylene glycol (PEG). Corrosion (oxidation) of the NPs is quantified and their colloidal stability is investigated. MUA‐coated NPs have a much lower colloidal stability than PMA‐coated NPs and are largely agglomerated. All Ag NPs corrode faster in an acidic environment and thus more Ag(I) ions are released inside endosomal/lysosomal compartments. PMA coating does not reduce leaching of Ag(I) ions compared with MUA coating. PEGylation reduces NP cellular uptake and also the toxicity. PMA‐coated NPs have reduced toxicity compared with MUA‐coated NPs. All studied Ag NPs were less toxic than free Ag(I) ions. All in all, the cytotoxicity of Ag NPs is correlated on their uptake by cells and agglomeration behavior. 相似文献
76.
77.
78.
We have designed, grown and fabricated InAs/InP quantum dot (QD) waveguides as the gain materials of mode-locked lasers (MLLs). Passive InAs/InP QD MLLs based on single-section Fabry-Perot (F-P) cavities with repetition rates from 10 GHz to 100 GHz have been demonstrated in the C- and L-band. Femtosecond (fs) pulses with pulse duration of 295 fs have been achieved. The average output power is up to 50 mW at the room temperature of 18 °C. By using the external fiber mixed cavities fs pulse train with a repetition rate of 437 GHz has been generated. We have also discussed the working principles of the developed QD MLLs. 相似文献
79.
Jesus F. Almeida Manuel Grande Joaquín R. Moran Josefa Anaya Ma Luisa Mussons Ma Cruz Caballero 《Tetrahedron: Asymmetry》1993,4(12):2483-2494
The enantioselective synthesis of the potentially nootropic compounds 3–6 is reported. Derivative 3 was obtained from the readily available L-tartaric acid, by reduction of the imide 8 prepared with methyl glycinate. The other derivatives 4–6 were obtained from the dihydroxylactam 11. Protection of one of the hydroxyl groups and a Mitsunobu reaction or triflate displacement of the other group produces the remaining stereoisomers. Aminoderivatives 25 and 27 were obtained by displacement with sodium azide and reduction. 相似文献
80.
M Arenas A Bilbao R Caballero T Gómez M V Rodríguez F Ruiz 《The Journal of the Operational Research Society》2002,53(4):387-396
In this paper, a Goal Programming model is developed in order to study the possibility of decreasing the length of stay on the waiting list of a hospital that belongs to the Spanish Health Service. First, a problem is solved to determine the optimal planning for one year, so as to make the maximum waiting time decrease to six months (at present, some operations have a waiting list of more than a year). Afterwards, two other problems are solved in order to determine the impact that a further reduction of the waiting time (four months) would have on the requirements of extra resources for the hospital. The particular problem for the Trauma service is described in detail, but global results are shown and commented. 相似文献