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排序方式: 共有859条查询结果,搜索用时 15 毫秒
21.
Single‐Crystal‐Like Organic Thin‐Film Transistors Fabricated from Dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT) Precursor–Polystyrene Blends 下载免费PDF全文
22.
The oxidative degradation of β-cyclodextrin (β-CD) induced by autoxidation of linoleate has been investigated in the solid system composed of β-CD and linoleate. β-CD was oxidized with a propagative oxidation of linoleate to induce the cleavage of its glucosidic linkage and this degradation proceeded proportionally with the moisture content in the solid system. The oxidative cleavage of β-CD gave several kinds of oligosaccharides which were composed of D -erythrose, D -arabinose, D -erythropentosulose, D -xylopentdial-dose, D -glucose and deoxyunsaturated hexose as their reducing terminals. These degradation of β-CD seemed to be initiated by certain radical species formed from the peroxidation of linoleate. 相似文献
23.
The methanolic extract of the marine sponge Ircinia felix has yielded nine novel fatty acid esters, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-22-methyltricosadienoate, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-tetracosadienoate, (7E, 12E, 18R, 20Z)-variabilin hexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 10-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 15-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 14-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 9-octadecenoate, (7E, 12E, 18R, 20Z)-variabilin octadecanoate, and (7E, 12E, 18R, 20Z)-variabilin 2,11-dimethyloctadecanoate, along with the recently described (7E, 12E, 18R, 20Z)-variabilin 11-methyloctadecanoate. The characterization of the new fatty acids (5Z, 9Z)-22-methyltricosadienoic and 2,11-dimethyloctadecanoic acids is also described. The chemical structures were determined by
extensive spectroscopic, chromatographic, and chemical analyses. 相似文献
24.
Ko Ikeda Yoshinori Nakamura Kiyoshi Masumoto Hiromi Shima 《Journal of the American Ceramic Society》1997,80(10):2672-2676
Unpolarized optical spectra were measured in the wavelength range 322–1666 nm by the diffuse reflection technique from spinel powders synthesized in the system MgAl2 O4 –MgCr2 O4 . The spectra were interpreted by the crystal-field theory on the basis of trigonally distorted spinel octahedra with D3d symmetry. For chromium-rich solid solutions, including the MgCr2 O4 end-member, results after peak fittings showed octahedral D3d local symmetry around Cr3+ ions, identical to the crystallographic site symmetry. For chromium-poor solid solutions, however, octahedral C3v local symmetry was suggested around Cr3+ ions, different from the D3d crystallographically expected. 相似文献
25.
Yoshinori Nishiki Koichi Aoki Koichi Tokuda Hiroaki Matsuda 《Journal of Applied Electrochemistry》1987,17(1):67-76
On the basis of the observation of gas bubbles evolved by electrolysis, a two-dimensional vertical model cell composed of electrodes with open parts for releasing gas bubbles to the back side is proposed. The model cell consists of two layers. One layer forms a bubble curtain with a maximum volume fraction of gas bubbles in the vicinity of the working electrode with open parts. The other. being located out of the bubble layer, is a convection layer with a small volume fraction distributed in the vertical direction under forced convection conditions. The cell resistance and the current distribution were computed by the finite element method when resistivity in the back side varied in the vertical direction along the cell. The following three cases for overpotential were considered: no overpotential, overpotential of the linear type and overpotential of the Butler-Volmer type. It was found that the cell resistance was determined not only by the interelectrode gap but also by the percentage of open area and in some cases by the superficial surface area. The cell resistance varied only slightly with the distribution of the bubble layer in the back side.Nomenclature
b
linear overpotential coefficient given byb=/i
-
C
proportionality constant given by Equation 15
-
d
1
distance between front side of working electrode and separator
-
d
2
thickness of separator
-
F
Faraday constant
-
I
total current per half pitch
-
i
current density at working electrode
-
i
0
exchange current density
-
L
length of a real electrolysis cell
-
n
number of electrons transferred in electrode reaction
-
O
p
percentage of open area given by Equation 1
-
p
pitch, i.e. twice the length of the unit cell, defined by 2(BC) in Fig. 4
-
q
thickness of bubble curtain, defined by (AM) in Fig. 4
-
R
gas constant
-
r
t
total cell resistance
-
r
unit-cell resistance defined by (V – V
eq)/I
-
r
rs
residue ofr from sum ofr
0 andr
-
r
0
ohmic resistance of solution when0
p=0
-
r
resistance due to overpotential when0
p=0
-
s
electrode surface ratio or superficial surface area given by Equation 2 for the present model
-
T
absolute temperature
-
t
thickness of working electrode defined by EF in Fig. 4
-
V
cell voltage
-
V
eq
open circuit potential difference between working and counter electrodes
-
solution velocity in cell
- 0
solution velocity at bottom of cell
-
w
width of working electrode, defined by 2(DE) in Fig. 4
-
x
abscissa located on cell model
-
y
ordinate located on cell model
-
anodic transfer coefficient
-
linear overpotential kinetic parameter defined byb/[bc(p/2)]
- d
infinitesimally small length on the boundary
-
volume fraction of gas bubbles in cell
-
dimensionless cell voltage defined bynF(V – V
eq)/RT
-
overpotential at working electrode
-
Butler-Volmer overpotential kinetic parameter defined by [nFi
0bc(p/2)]/RT
-
coordinate perpendicular to boundary of model cell
- 1
resistivity of bubble-free solution
- 2
resistivity of separator
- bc
resistivity of bubble curtain
-
potential in cell 相似文献
26.
Yoshinori Itaya Nobusuke Kobayashi Lianlin Li Akira Suami Masakazu Sawai Hisashi Hamabe 《Drying Technology》2015,33(9):1029-1038
An innovative technology for sewage treatment systems is proposed. A mixture of sewage sludge and char particle is subjected to drying in the progress of composting in an updraft column. Exothermic heat generated during composting is utilized for energy of sludge drying. The char particle in the mixture contributes to enhancement of composting and drying rate. This study presents drying and composting behaviors of sludge to examine the effect of char addition. A fundamental drying experiment was carried out by hot-air heating of the sample in a small vessel. The drying characteristic curve for a mixture of sludge and char was greater than the sample of only sludge over a whole period if the drying rates were compared with the same moisture content. The drying behavior could be analyzed with a reasonable agreement by the water front receding model. The enhancement effect of drying and composting of sludge by char addition was confirmed by examination using a pilot scale of the updraft column whose volume was 50 m3. Sludge with 400% dry base (80% wet base) in moisture content could be dried successfully to lower moisture content than 67% dry base (40% wet base) only by exothermic heat during composting without supplying any auxiliary energy from the outside, and the treatment time was reduced by mixing char in sludge. The behavior was analyzed with a satisfactory agreement by a theoretical model employing moisture diffusion parameters determined from the drying characteristic curve. 相似文献
27.
Titanium bis(2-pyridinethiolate) complexes, Ti(6-R-SPy)2(NMe2)2 (6-R-SPy = 6-R-2-pyridinethiolate, 3a: R = H; 3b: R = Me; 3c: R = Ph; 3d: R = C6H4-4-Me; 3e: R = C6H4-4-t-Bu; 3f: R = C6H3-3,5-Me2), and the titanium bis(2-pyridinolate) complexes, Ti(6-Ph-OPy)2(NMe2)2 (6-Ph-OPy = 6-phenyl-2-pyridinolate, 8) were prepared by treating Ti(NMe2)4 with 2 equiv. of 6-R-2-pyridinethiol or 6-Ph-2-pyridinol. The cis-configuration of the diamido moieties in the pseudo octahedral geometry was elucidated by X-ray crystallography for 3a. Reaction of M(NMe2)4 (M = Ti, Zr) with 4 equiv. of 2-pyridinethiol cleanly gave tetrakis(pyridinethiolate) complexes, M(6-H-SPy)4·THF (6: M = Ti; 7: M = Zr). The triangular dodecahedral geometries of 6 and 7 were also revealed by X-ray crystallography. These complexes catalyzed ethylene polymerization upon activation with MAO (methylaluminoxane) or MMAO (modified MAO). The catalytic activities of titanium bis(6-aryl-pyridinethiolate) systems were found to be remarkably higher than that of titanium bis(6-methyl-pyridinethiolate) system. Among the complexes synthesized in this study, Ti[6-(C6H3-3,5-Me2)-SPy]2(NMe2)2 (3f)/MMAO showed the highest activity (1200 kg/Ti-mol h atm) for ethylene polymerization at 60 °C under atmospheric pressure. In contrast, the activity of the corresponding 6-aryl-pyridinolate system 8/MMAO was rather low (9.3 kg/Ti-mol h atm). Both the N-S chelating structure and the bulky aryl substituents are essential for the high activities of the 6-aryl-pyridinethiolate complexes. 相似文献
28.
Munehisa Yasuniwa Shinsuke Tsubakihara Koji Iura Yoshinori Ono Yusuke Dan Kazuhisa Takahashi 《Polymer》2006,47(21):7554-7563
The crystallization behavior of poly(l-lactic acid) was studied in the range of 80-160 °C. The peak crystallization time (τp) was defined and obtained from the crystallization isotherm measured with a differential scanning calorimeter (DSC). Isothermal crystallization temperature (Tc) dependence of log(τp) discretely changed at 113 °C (= Tb). The linear growth rate of spherulite, G, was measured with a polarizing microscope. The Tc dependence of G and the size of the spherulite also discretely changed at Tb. Crystal structures for samples isothermally crystallized at temperatures which were higher and lower than Tb were orthorhombic (α-form) and trigonal (β-form), respectively. The discrete change of the crystallization behavior was explained by the formation of different crystal. 相似文献
29.
毛细管电泳仪具有灵敏度高、分析速度快等优势,为降低其生产成本,基于电泳原理,以荧光显微镜为基础,设计了一套毛细管电泳系统。以20 bp(base pairs,碱基对)DNA ladder和100 bp DNA ladder为样本,全面分析了系统的稳定性、灵敏度和分离效果。结果表明:该系统在9 min内可以实现1500 bp以内DNA片段的高效分离,系统检测极限为0.1 ng/μL;在优化的电泳条件下,对限制性内切酶φX174-HincⅡ作用过的λ-DNA片段5 min内实现了291 bp与297 bp DNA片段的区分。 相似文献
30.
Qiang Dong Nobuhiro Kumada Yoshinori Yonesaki Takahiro Takei Nobukazu Kinomura Dan Wang 《Journal of Materials Science》2010,45(20):5685-5691
Hollow hematite (α-Fe2O3) microspheres with an average diameter of 3-4 μm and a shell thickness of approximate 150 nm was synthesized by a simple
hydrothermal route using FeCl3·6H2O solution and acetic acid without using any templates. The hollow microspheres were composed of α-Fe2O3 nanoparticles with the diameter range from 20 to 40 nm. The effects of reaction parameters such as reaction time, temperature,
concentration of FeCl3·6H2O solution, and initial pH on the morphology of the final products were investigated. A possible formation mechanism of hollow
α-Fe2O3 microspheres was also proposed, where the acetic acid played a role of etching in the formation of hollow structure. 相似文献