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排序方式: 共有333条查询结果,搜索用时 437 毫秒
71.
72.
Nataliya Hearn 《Materials and Structures》1998,31(8):563-567
It is well known that as concrete hydrates its permeability decreases. Continued hydration, however, is not the only mechanism which causes such reduction. Self-sealing, which is largely attributed to the dissolution and redeposition of hydrates, and autogenous healing of cracks, can also significantly reduce the flow. This paper reviews the relative effects of self-sealing, autogenous healing and hydration. 相似文献
73.
74.
Effects of Oleic Acid and Phospholipids on the Formation of Lecithin Organogel and Microemulsion 下载免费PDF全文
Nataliya M. Murashova Liliya A. Prokopova Ekaterina S. Trofimova Eugeny V. Yurtov 《Journal of surfactants and detergents》2018,21(5):635-645
The formation of organogels and microemulsions of lecithin in the presence of a biocompatible cosurfactant, oleic acid, was studied. Low content of oleic acid ([oleic acid]/[lecithin] < 0.1) in the lecithin–oleic acid–dodecane–water system leads to an expansion of the region of existence and to a decrease in the viscosity of lecithin organogels. At high contents of oleic acid ([oleic acid]/[lecithin] > 0.6), low‐viscosity microemulsion exists in the system. Phosphatidylethanolamine, lysophosphatidylcholine, and other phospholipids that are present as impurities in the commercial samples of soybean lecithin can act as cosurfactants. For the first time, the formation of lecithin organogels in the systems containing commercial samples of soybean lecithin with phosphatidylcholine concentrations of 69.3 wt% (Lipoid S75) and 52.9 wt% (Lipoid S45) and saturated aliphatic hydrocarbons is demonstrated. The gelation is observed at T =25 °C in octane, decane, dodecane, and hexadecane for Lipoid S75 and in dodecane and hexadecane for Lipoid S45. A decrease in the degree of purification of lecithin leads to an expansion of the regions of existence of the organogels and to a reduction of their viscosity. 相似文献
75.
Development of a Sensitive Microarray Platform for the Ranking of Galectin Inhibitors: Identification of a Selective Galectin‐3 Inhibitor 下载免费PDF全文
Dr. Johann Dion Tamara Advedissian Nataliya Storozhylova Dr. Samir Dahbi Dr. Annie Lambert Dr. Frédérique Deshayes Dr. Mireille Viguier Prof. Dr. Charles Tellier Dr. Françoise Poirier Dr. Stéphane Téletchéa Dr. Christophe Dussouy Dr. Hiroaki Tateno Prof. Dr. Jun Hirabayashi Dr. Cyrille Grandjean 《Chembiochem : a European journal of chemical biology》2017,18(24):2428-2440
Glycan microarrays are useful tools for lectin glycan profiling. The use of a glycan microarray based on evanescent‐field fluorescence detection was herein further extended to the screening of lectin inhibitors in competitive experiments. The efficacy of this approach was tested with 2/3′‐mono‐ and 2,3′‐diaromatic type II lactosamine derivatives and galectins as targets and was validated by comparison with fluorescence anisotropy proposed as an orthogonal protein interaction measurement technique. We showed that subtle differences in the architecture of the inhibitor could be sensed that pointed out the preference of galectin‐3 for 2′‐arylamido derivatives over ureas, thioureas, and amines and that of galectin‐7 for derivatives bearing an α substituent at the anomeric position of glucosamine. We eventually identified a diaromatic oxazoline as a highly specific inhibitor of galectin‐3 versus galectin‐1 and galectin‐7. 相似文献
76.
José A. Rodriguez Jae Y. Kim Jonathan C. Hanson Manuel Pérez Anatoly I. Frenkel 《Catalysis Letters》2003,85(3-4):247-254
CuO is used as a catalyst or catalyst precursor in many chemical reactions that involve hydrogen as a reactant or product. A systematic study of the reaction of H2 with pure powders and films of CuO was carried out using in situ time-resolved X-ray diffraction (XRD) and surface science techniques. Oxide reduction was observed at atmospheric H2 pressures and elevated temperatures (150-300 °C), but only after an induction period. High temperature or H2 pressure and a large concentration of defects in the oxide substrate lead to a decrease in the magnitude of the induction time. Under normal process conditions, in situ time-resolved XRD shows that Cu1+ is not a stable intermediate in the reduction of CuO. Instead of a sequential reduction (CuO Cu4O3 Cu2O Cu), a direct CuO Cu transformation occurs. To facilitate the generation of Cu1+ in a catalytic process one can limit the supply of H2 or mix this molecule with molecules that can act as oxidant agents (O2, H2O). The behavior of CuO-based catalysts in the synthesis of methanol and methanol steam reforming is discussed in the light of these results. 相似文献
77.
Andrey O. Baranov Nataliya A. Erina Sergey A. Kuptsov Tatiyana I. Medintseva Eduard V. Prut 《应用聚合物科学杂志》2003,89(1):249-257
The influence of the interphase layer, formed by the introduction of an oil in ethylene–propylene rubber (EPR), on the structure and properties of isotactic polypropylene (iPP)/EPR blends was studied. The dispersity of the rubber phase in the iPP matrix did not depend on presence of oil. The melting temperature of iPP decreased with increasing content of oil‐extended EPR, and it did not change if the oil was absent. The compatibility parameter was determined from the dependency of the iPP melting point on the rubber content with the Nishi–Wang equation. A negative value of the parameter indicated a limited compatibility of iPP with oil‐extended EPR. The latter also reduced the temperature and heat of crystallization of iPP. The mechanical properties of iPP/EPR blends were investigated as functions of temperature and elongation rate. It appeared that elastic modulus and yield stress of the blends linearly depended on the logarithm of the elongation rate. Activation volumes, calculated with the Eyring equation, increased with increasing content of elastomer; moreover, this increase was more pronounced for the oil‐extended elastomer. It is suggested that the oil influenced the structure of the interphase layer and, accordingly, the characteristics of the iPP/EPR blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 249–257, 2003 相似文献
78.
With the aim to synthesize water‐dispersible superparamagnetic nanoparticles, iron oxide was precipitated in aqueous solution of dextran, (carboxymethyl) dextran (CM‐dextran), (DEAE‐dextran), or D ‐mannose. Glycidyl methacrylate (GMA) was emulsion‐polymerized in the presence of the nanoparticles and the effect of iron oxide modification on the product properties was investigated. The main factors affecting the morphology, size, and size distribution of the latex particles are the type and concentration of emulsifier (Disponil AES 60, Tween 20, Triton X‐100) and initiator [ammonium persulfate (APS) and 4,4′‐azobis(4‐cyanovaleric acid) (ACVA)]. Disponil AES 60 and ACVA are the preferred emulsifier and initiator, respectively, because oxirane groups hydrolyzed during the APS‐initiated polymerization. Up to some 5 wt % of iron was found in poly(glycidyl methacrylate) (PGMA) microspheres obtained by emulsion polymerization in the presence of dextran‐coated iron oxide and emulsified with Disponil AES 60. The size of magnetic PGMA microspheres could be controlled in the range ? 70–400 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4348–4357, 2006 相似文献
79.
Using survey data from Irish and Israeli firms we examine the influence of public policy on the characteristics, location
and innovation capability of high-tech firms. The innovation activities of Israeli firms in Israel are found to be much more
locationally sensitive than that of Irish companies. Regional policy incentives, involving the dispersal of high-tech firms
to peripheral areas of Ireland are therefore likely to have had little negative effect on firms' innovation capabilities.
In Israel, however, inducing highly R&D intensive firms to locate away from the main metropolitan areas may be counter-productive.
Received: 28 November 2000 / Accepted: 26 September 2002 相似文献
80.
V. F. Ochkov K. A. Orlov M. L. Frenkel A. V. Ochkov V. E. Znamenskiy 《Thermal Engineering》2012,59(7):566-572
A technology of thermal engineering calculations that uses references to Internet-functions (??cloud?? functions) on the properties of working media used in steam-gas cycles is described. 相似文献