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排序方式: 共有494条查询结果,搜索用时 15 毫秒
1.
Tominaga Keii Yoshiharu Doi Hiromu Kobayashi 《Journal of polymer science. Part A, Polymer chemistry》1973,11(8):1881-1888
Mass transfer which affects the rate of propylene polymerization with titanium trichloride–triethylaluminum, has been evaluated by use of a new method developed for this heterogeneous reaction. The polymerization was carried out with the usual flask reactor equipped with a paddle stirrer; the rate of gas absorption into the polymerization slurry was proportional to stirring speed and the reciprocal of the total amount of polymers produced. It has been confirmed that the polymerization rate separated from the absorption rate is purely kinetic (propagation), and an effective physical process, such as monomer transfer through a polymer film covering the catalyst surface, no longer exists. 相似文献
2.
J. Itoh Y. Yonekura T. Toriyama H. Miyasaka K. Hisatake 《Hyperfine Interactions》1983,16(1-4):771-774
Bubble garnet films before and after 50 keV H+ implantation have been studied by means of DCEMS. The spintilt angle of the films as grown after etching off 1000 å was measured to be 30±2? relative to the surface normal at the top of the surface. The doses of implanted H+ ions were 2, 4 and 8×1016 ions/cm2. Mössbauer spectra were measured after successive etching of the implanted layer. The magnetic hyperfine field was obtained as a function of depth. The implanted hydrogen distribution was also measured by the1H(15N, αγ)12C reaction. 相似文献
3.
Toshihiro Okajima Hiroyuki Setoyama Marek Brancewicz Masahide Kawamoto Yoshiharu Sakurai 《X射线光谱测定》2020,49(3):390-397
X-ray fluorescence spectra of copper (Cu) metal, copper monoxide (CuO), and potassium chromate (K2CrO4) were recorded as a function of incident X-ray energy near the Cu K-edge and chromium (Cr) K-edge, respectively, using a conventional silicon drift detector. The spectra contained components due to elastic, inelastic, and multiple scattering, in addition to the Kα and Kβ lines. Cu and Cr K-edge X-ray absorption fine structure (XAFS) spectra of Cu, CuO, and K2CrO4 were obtained by an intensity analysis of the Kα and Kβ lines. The intensity of the Kβ line for the different incident photon energies was obtained by numerically removing the additional scattering components using the MUSCAT program. These spectra exhibited a jump near the K absorption edges, which reproduced the spectral features obtained in transmission mode for both Cu, CuO, and K2CrO4. A chemical shift was also clearly identified in the X-ray absorption near edges structure using the X-ray fluorescence Kβ line. In addition, the Cr K-edge extended XAFS spectrum of K2CrO4 was clearly observed using the Cr Kβ fluorescent line. The XAFS measurements on the Kα and Kβ lines are possible, and they carry equally valuable information. 相似文献
4.
Yoshiharu Sato Kazuaki Sugawa Michiaki Kawaguchi 《Reports on Mathematical Physics》1979,16(1):111-119
The differential geometrical consideration of the parameter space, especially as a Riemannian geometry, was initiated by C.R. Rao in 1945. This approach appears to be important for the problem of estimation and test of hypotheses as well as for applications to physical problems. It has been shown that the parameter spaces of univariate normal distribution, univariate exponential distribution and multinomial distribution are Riemannian spaces of constant curvature. In the present paper the discussion is confined to the parameter space of the two-dimensional normal distribution. It has been shown that in general the parameter space is not necessarily of a constant curvature and that, if the correlation coefficient vanishes, the parameter space becomes an Einstein space. In addition, some invariant quantities, as sectional curvature, mean curvature and scalar curvature, have been calculated. 相似文献
5.
Abdominal apparent diffusion coefficient measurements: effect of diffusion-weighted image quality and usefulness of anisotropic images 总被引:1,自引:0,他引:1
Yoshikawa T Ohno Y Kawamitsu H Ku Y Seo Y Zamora CA Aoyama N Sugimura K 《Magnetic resonance imaging》2008,26(10):1415-1420
This study aimed to assess the effect of diffusion-weighted image (DWI) quality on abdominal apparent diffusion coefficient (ADC) measurements and the usefulness of anisotropic images. Twenty-six patients (10 men and 16 women; mean, 58.1 years) who underwent DW imaging and were diagnosed not to have any abdominal diseases were analyzed. Single-shot spin-echo echo-planar DW imaging was performed, and one isotropic and three orthogonal anisotropic images were created. ADCs were calculated for liver (four segments), spleen, pancreas (head, body, tail) and renal parenchyma. Image quality for each organ part was scored visually. We estimated the correlation between ADC and image quality and evaluated the feasibility of using anisotropic images. ADCs and image quality were affected by motion probing gradient directions in the liver and pancreas. A significant inverse correlation was found between ADC and image quality. The r values for isotropic images were −.46, −.48, −.70 and −.28 for the liver, spleen, pancreas and renal parenchyma, respectively. Anisotropic images had the best quality and lowest ADC in at least one organ part in 17 patients. DWIs with the best quality among isotropic and anisotropic images should be used in the liver and pancreas. 相似文献
6.
Kitajima K Yoshikawa T Seo Y Ohno Y Yano Y Miki A Kanda T Kanata N Azuma T Sugimura K 《Magnetic resonance imaging》2011,29(4):579-583
Budd-Chiari syndrome (BCS) is a rare disorder caused by the obstruction of hepatic venous outflow, leading to sinusoidal congestion, ischemic injury to liver cells and portal hypertension. Long-term survival largely depends on whether hepatocellular carcinoma occurs. A recently available liver-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA), reportedly has high diagnostic capability for detection of malignant liver tumors. However, there has been no report of the sue of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for BCS. We present a case of chronic BCS who underwent both gadopentetate dimeglumine (Gd-DTPA) and Gd-EOB-DTPA-enhanced MRI. Hepatic congestion and edema were seen as slightly hypointense areas on Gd-EOB-DTPA-enhanced hepatobiliary-phase images, although these areas were observed as slightly hyperintense on previously obtained Gd-DTPA-enhanced delayed-phase image. Reduced uptake of Gd-EOB-DTPA by hepatocytes in the region of congestion or edema may account for this difference, which should be recognized in image interpretations. 相似文献
7.
Recently, the CDF Collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained. 相似文献
8.
Norihiro?SadatoEmail author Hiroki?Yamada Tomohisa?Okada Masaki?Yoshida Takehiro?Hasegawa Ken-Ichi?Matsuki Yoshiharu?Yonekura Harumi?Itoh 《BMC neuroscience》2004,5(1):56
Background
Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language. 相似文献9.
An experimental study of the damage of Si solar cells due to Q-switched ruby laser radiation has been made. Four kinds of specimen with different surface states were used in order to examine how the damage depends on the surface state: (a) chemically etched to a mirror finish, (b) mechanically polished by a 0.5 m Al2O3 powder, (c) chemically etched, but rough, (d) coated with SiO on the (c) surface. The threshold power densities, at which a change in the photo-current occurs, were for the specimens (a) to (d) respectively 60 MW cm–2, 20 MW cm–2, 30 MW cm–2 and 9 MW cm–2. Attenuations of the photo-current of the specimens, a, c and d were observed over the whole range of wavelength 500 to 1000 nm. For the b cell, however, increase of the photo-current was observed mainly in the short wavelength region. 相似文献
10.
Shigeyoshí Nishino Yasuhiro Nagato Yoshihiro Hasegawa Hisanao Yamamoto Kazuo Kamaike Yoshiharu Ishido 《Heteroatom Chemistry》1991,2(1):187-196
Reagent systems of sodium– and tetrabutylammonium nitrite–acetic anhydride were proved to be extremely efficient for the deanilidation of nucleoside 3′-phosphoranilidates, whose reactions were rapid with the former and instant with the latter. It was further found that the reagent system is applicable to oligonucleotide synthesis provided that the exocyclic amino groups of 2′-deoxyadenosine, 2′-deoxyguanosine, and 2′-deoxycytidine were protected by succinylation. 相似文献