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排序方式: 共有2143条查询结果,搜索用时 15 毫秒
971.
A simple way to prepare tri-O-(alkyl)cellulose from cellulose acetate (CA) in dimethylsulfoxide (DMSO) using the appropriate alkyl iodide and NaOH has been developed. In this procedure, the addition of a small amount of water to the DMSO solution improved the efficiency of etherification. The substitution pattern of (methyl)cellulose (MC) was investigated to determine the effect of added water on the relative reactivities of the glucose ring substituents. This etherification method can be applied to alkylate other polymers with acetate-functional groups that are soluble in DMSO. 相似文献
972.
973.
Yoshikazu Suzuki Naoki Kondo Tatsuki Ohji 《Journal of the American Ceramic Society》2003,86(7):1128-1131
Porous CaZrO3 /MgAl2 O4 composites were synthesized in air by pressureless reactive sintering of an equimolar mixture of dolomite (CaMg(CO3 )2 ), monoclinic zirconia ( m -ZrO2 ), and α-alumina powders, with a 0.5 wt% lithium fluoride additive. The reaction behavior of the mixed powders (with/without LiF additive) was studied using high-temperature X-ray diffraction. A bulk porous composite resulted from sintering at 1300°C for 2 h (in a nearly closed container, so as to increase the LiF-doping effect), which consisted of fine grains (CaZrO3 and MgAl2 O4 , ∼0.5–1 μm) and well-grown idiomorphic ones (MgAl2 O4 octahedra ∼ 2–4 μm). The idiomorphic spinel grains were located around the inner walls of relatively large pores. The composite showed appreciably high bending strength (σf = 110 ± 8 MPa for a porosity of 31%). The porous CaZrO3 /MgAl2 O4 composites can be applied as high-temperature filters and lightweight structural components. 相似文献
974.
975.
Yoko Nakajima Judith Meijer Chunhua Zhang Xu Wang Tomomi Kondo Tetsuya Ito Doreen Dobritzsch André B. P. Van Kuilenburg 《International journal of molecular sciences》2016,17(1)
Dihydropyrimidinase (DHP) deficiency is an autosomal recessive disease caused by mutations in the DPYS gene. Patients present with highly elevated levels of dihydrouracil and dihydrothymine in their urine, blood and cerebrospinal fluid. The analysis of the effect of mutations in DPYS on pre-mRNA splicing is hampered by the fact that DHP is primarily expressed in liver and kidney cells. The minigene approach can detect mRNA splicing aberrations using cells that do not express the endogenous mRNA. We have used a minigene-based approach to analyze the effects of a presumptive pre-mRNA splicing mutation in two newly identified Chinese pediatric patients with DHP deficiency. Mutation analysis of DPYS showed that both patients were compound heterozygous for a novel intronic mutation c.1443+5G>A in intron 8 and a previously described missense mutation c.1001A>G (p.Q334R) in exon 6. Wild-type and the mutated minigene constructs, containing exons 7, 8 and 9 of DPYS, yielded different splicing products after expression in HEK293 cells. The c.1443+5G>A mutation resulted in altered pre-mRNA splicing of the DPYS minigene construct with full skipping of exon 8. Analysis of the DHP crystal structure showed that the deletion of exon 8 severely affects folding, stability and homooligomerization of the enzyme as well as disruption of the catalytic site. Thus, the analysis suggests that the c.1443+5G>A mutation results in aberrant splicing of the pre-mRNA encoding DHP, underlying the DHP deficiency in two unrelated Chinese patients. 相似文献
976.
Tasuku Sakuma Shunsuke Nishino Masanobu Miyata Mikio Koyano 《Journal of Electronic Materials》2018,47(6):3177-3183
Transition-metal trichalcogenides MX3 (M = Ti, Zr, Nb, Ta; X = S, Se) are well-known inorganic quasi-one-dimensional conductors. Among them, we have investigated the thermoelectric properties of titanium trisulfide TiS3 microribbon. The electrical resistivity ρ, thermal conductivity κ, and thermoelectric power S were measured using 3ω method. The weight mean values were found to be ρ = 5 mω m and κ = 10 W K?1 m?1 along the one-dimensional direction (b-axis) of the TiS3 microribbon. Combined with the thermoelectric power S = ?530 μV K?1, the figure of merit was calculated as ZT = 0.0023. This efficiency is the same as that of randomly oriented bulk TiS3. We also estimated the anisotropy of σ and κ using the present results and those for randomly oriented bulk material. The obtained weak anisotropy for TiS3 is attributable to strong coupling between triangular columns consisting of TiS3 units. These experimental results are consistent with theoretical results obtained using density functional theory (DFT) calculations. 相似文献
977.
Front Cover: Specific Spatial Localization of Actin and DNA in a Water/Water Microdroplet: Self‐Emergence of a Cell‐Like Structure (ChemBioChem 13/2018)
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978.
Hisatake Kondo 《Microscopy research and technique》1990,14(1):63-69
Following the removal of polyethylene glycol (PEG) from thin sections, and viewing through the endothelial fenestrae and/or the interpedicel spaces, the rat renal glomerular basement membrane in situ was revealed to consist of meshworks and to be electron-transparent when examined at right angles to the plane of the membrane. By subsequent platinum replication of the embedment-free sections, the lamina densa of the basement membrane appeared as a veil composed of rather closely packed particles. The architecture of the slit diaphragm and the surface morphology of the endothelial cell membrane were also clearly revealed. The present results indicate that the PEG method, with or without replication, can provide valuable information on basement membrane morphology. 相似文献
979.
The polyethylene glycol (PEG) embedding and subsequent deembedding method was applied to the observation of general tissues in scanning electron microscopy (SEM). Resulting SEM images were of high quality. It was demonstrated that intermicroscopic correlation of images between light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) is easily and reliably done by means of the PEG method. In particular, the exact correlation of immuno-LM with SEM is shown to be of potential value. 相似文献
980.
Murata S Mochizuki K Nakazawa T Kondo T Nakamura N Yamashita H Urata Y Ashihara T Katoh R 《Microscopy research and technique》2003,61(5):457-462
Various morphonuclear studies by digital image analysis have successfully been applied to quantify the nuclear morphology, including chromatin distribution pattern, in cytology of various organs; however, the majority of past reports have not shown correlation between the quantitative data by digital image analysis and cytological findings in practical diagnosis. In this report, we present the usefulness of morphological abstraction to combine the objective data and subjective observation in cytological diagnosis. Randomly selected, 100 cells in each Papanicolaou-stained ABC smear samples of 39 benign and malignant thyroid tumor cases were studied. Gray-level image data provided seven parameters for nuclear size, four parameters for nuclear shape, and 16 parameters showing the nuclear chromatin patterns from high-dimensional texture analysis of using co-occurrence and run-length matrices. To statistically abstract nuclear morphology, factor analysis was used. Factor analysis classified morphological nuclear characters as abstraction parameter into five abstract parameters composed of nuclear size, shape, heterogeneity, and contrast and homogeneity of chromatin pattern. The nuclei of papillary carcinoma showed larger size, more irregular shape, and higher contrast of chromatin pattern than those of the benign group. The follicular carcinomas have larger nucleus in each cell and more monotonous chromatin pattern among cells in each case than those of the benign group. Morphological abstraction by morphometry with factor analysis may provide a practical approach to the detection of the underlying characteristics of nuclear morphology in aspiration biopsy cytology. 相似文献