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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
N. Ilayaraja A. Manivel D. Velayutham M. Noel 《Journal of Applied Electrochemistry》2008,38(2):175-186
Electrochemical perfluorination (ECPF) of n-hexanoyl, n-heptanoyl, n-octanoyl, n-nonanoyl and n-decanoyl chlorides was carried out under identical experimental conditions in liquid HF. The product distribution among perfluorinated
carboxylic acids, perfluoro ethers, perfluoroalkanes, isomerised and fragmented products containing less number of carbon
atoms was identified using 19F NMR. The selectivity of C6–C10 perfluoro carboxylic acid varied between 29 and 36%. The alkali insoluble perfluoro cyclic ether and perfluoro alkane fractions
increased with increasing chain length. The increase of perfluoroalkane fractions is mainly due to decarboxylation. Cyclic
ether fractions also decreased slightly with increase in chain length. Among the cyclic ethers α substituted oxolanes were
the predominant products. Six membered cyclic ethers were always found to contain β substitution. The possible pathways for
these products are also indicated.
An erratum to this article can be found at 相似文献
982.
Effect of Li+ ions on structure,properties, and actuation of cellulose electro‐active paper actuator
We have reported an electro‐active paper actuator from regenerated cellulose. After dissolving cellulose fibers with a solution of lithium chloride in N,N‐dimethylacetamide, cellulose was regenerated by combining distillation of cellulose solution along with washing with the mixture of deionized water, isopropyl alcohol, and running water. However, the effect of Li+ ions on structure, properties, and the actuation behavior of the actuator was not studied. This article describes the changes in these parameters when the Li+ ions are removed by subjecting it to different running water exposure time. The structure and properties of cellulose electro‐active paper and its actuation behavior were studied. As Li+ ions content reduced from 4354.17 to 10.26 ppm by increasing the exposure time of running water, crystallinity, Young's modulus, and bending displacement decreased. Details about the investigation have been explained. This elimination of ions is important to increase the piezoelectric effect in EAPap by decreasing the ion migration effect. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
983.
I Beck-Speier N Dayal C Denzlinger C Haberl KL Maier A Ziesenis J Heyder 《Canadian Metallurgical Quarterly》2003,71(3-4):217-234
Recent studies have shown that long-term in vivo exposure of dogs to neutral sulfur(IV)/sulfite aerosols induces mild inflammatory reactions, whereas the combination of neutral sulfite with acidic sulfur(VI)/sulfate aerosols evokes less pronounced effects. To understand underlying mechanisms, we studied in vitro the role of lipid mediators in the responses of alveolar macrophages (AMs) to sulfur-related compounds under neutral (pH 7) or moderate acidic (pH 6) conditions. Canine AMs incubated with sulfite at pH 7 released threefold higher amounts of platelet-activating factor than control (P < 0.005). Generation of arachidonic acid, leukotriene B4, 5-hydroxy-eicosatetraenoic acid, prostaglandin E2, thromboxane B2 and 12-hydroxyheptadecatrienoic acid increased twofold (P < 0.0005). However, these metabolites remained unchanged following incubation of AMs with sulfite at pH 6 or with sulfate at pH 7 or pH 6. Mediator release by sulfite-treated AMs at pH 7 stimulated respiratory burst activity of neutrophils. Inhibition of MAPK pathway by PD 98059, of cytosolic (cPLA2) and secretory phospholipases A2 by AACOCF3 and thioetheramide-PC, respectively, reduced sulfite-induced eicosanoid formation in AMs. Sulfite activated cPLA2 activity twofold at pH 7. This mechanism of sulfite-stimulated responses in phospholipid metabolism predicts that chronic exposure to sulfur(IV)/sulfite is associated with a considerable health risk. 相似文献
984.
985.
V. N. Gurin M. M. Korsukova S. P. Nikanorov A. P. Nechitailov L. I. Derkachenko Z. I. Uspenskaya I. N. Zimkin 《Technical Physics Letters》2003,29(6):464-466
Ionic substances under normal conditions are stoichiometric compounds with phase diagrams featuring no homogeneity regions.
Crystals grown under nonequilibrium conditions, in particular, under significant centrifugal acceleration, are characterized
by nonstoichiometric compositions (e.g., K2−x
Br1.07). In this way, it is possible to obtain nonequilibrium nonstoichiometric ionic compounds possessing certain homogeneity regions.
Nonstoichiometric crystals of KCl, KBr, and KI grown under various accelerations ranging within (1.3–100.0)×103
g exhibit insignificant variations in the lattice constants and a significant increase in micro-hardness with acceleration. 相似文献
986.
Paustovskii Alexander V. Alfintseva Raisa A. Kurinnaya Tatyana V. Pogorelaya Valentina V. Kirilenko Stepan N. 《Powder Metallurgy and Metal Ceramics》2004,43(5-6):251-257
The main parameters of electrospark alloying of steel 45 with anodes made from Ni – Cr – Al – Y alloys have been investigated. The anodes were fabricated by casting and hot pressing. The highest values of the mass transfer coefficient were observed in the case of electrospark alloying with hot-pressed alloys. Microstructure and x-ray phase analyses of electrospark coatings revealed the presence of solid solutions based on nickel, iron, chromium as well as intermetallic compounds. Coatings obtained by electrospark alloying with hot-pressed alloy are more wear-resistant than are coatings obtained by alloying with cast alloys. 相似文献
987.
A study is carried out to describe irreversibilities in one stage refrigerating process for vapour compression cycle with refrigerant mixtures R-404A, R-410A, R-410B and R-507 as working fluids. They are calculated as exergy losses by an algorithm developed on the basis of thermodynamics. The proposed relationships have been derived from exergy balances on the system components. Emphasis is placed on parameters influencing the losses and the related results are presented through Grassmann diagrams (diagrams of exergy fluxes). Furthermore, detailed information on the variation of cycle's exergy efficiency with evaporating and condensing temperatures is given. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
988.
A. N. Ponomarev 《Journal of Engineering Physics and Thermophysics》2007,80(2):237-248
We have analyzed the physical processes in a vacuum chamber in the centrifugal dispersion of blanks of D16 and AMg6 aluminum
blanks rotating at a rate of 10–80 m/sec with local melting under the action of a stationary electron beam of power density
∼109 W/ m2. A method for approximate calculations of melting under flash heating, diffusion, and vapor and gas release into vacuum is
proposed.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 25–35, March–April, 2007. 相似文献
989.
Raab W. Bruels N. Hachmann U. Harnisch J. Ramacher U. Sauer C. Techmer A. 《Design & Test of Computers, IEEE》2003,20(1):8-15
New generations of automobiles will include driver assistance systems requiring powerful, low-cost processors to handle video/camera applications and to enable fast, convenient application development. Shrinking feature sizes on processors already in development will bring substantial increases in system speed and functionality. 相似文献
990.
On-Chip Optical Technology in Future Bus-Based Multicore Designs 总被引:1,自引:0,他引:1
Kirman N. Kirman M. Dokania R.K. Martinez J.F. Apsel A.B. Watkins M.A. Albonesi D.H. 《Micro, IEEE》2007,27(1):56-66
This work investigates the integration of CMOS-compatible optical technology to on-chip coherent buses for future CMPs. The analysis results in a hierarchical optoelectrical bus that exploits the advantages of optical technology while abiding by projected limitations. This bus achieves significant performance improvement for high-bandwidth applications relative to a state-of-the-art fully electrical bus 相似文献