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排序方式: 共有355条查询结果,搜索用时 31 毫秒
21.
K Nishizawa T Maruyama M Takayama K Iwai Y Furuya 《Canadian Metallurgical Quarterly》1995,55(11):763-768
Tissue or organ doses related to radiological risk were determined for four different types of CT scanners with a spiral scan function. Dose measurements were performed using a Rando phantom and two types of thermoluminescent dosimeters. The effective doses recommended by the International Commission on Radiological Protection in 1990 were evaluated using the tissue or organ doses determined with the phantom measurement. The resultant effective dose per CT examination ranged from 4.6 to 10.8 mSv for chest examination and from 6.7 to 13.3 mSv for upper abdominal examination. It should be noted that the effective dose from CT examination will be increased by increasing in the frequency of CT examinations and technical development of CT scanners. 相似文献
22.
Tadao Tanabe Yuichi Kozawa Ken Suto Jun-ichi Nishizawa Ytaka Oyama 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(6):881-892
Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions. 相似文献
23.
Fujii K Ko S Nako Y Tonari A Nishizawa K Akahane K Takayama M 《Radiation protection dosimetry》2011,144(1-4):459-463
Photoluminescence glass dosemeters (PLDs) and thermoluminescence dosemeters (TLDs) are commonly used as a personal monitoring dosemeter. PLDs and TLDs were used for surface dose monitoring of medical staff involved in (125)I brachytherapy for prostate cancer because these dosemeters have a wide dose-response linearity and high sensitivity for low photon energy. Surface doses measured with PLDs agreed with those with TLDs within ~20 % except for a few cases. Surface doses at a surgeon's left hand and arm were higher than those at the other measuring points. A surgeon received a maximum dose of 650 μGy at the back of left hand. Surface doses to an assistant were <100 μGy. Surface doses to a nurse, a radiologist, an anaesthesiologist and a radiological technologist were <10 μGy. The occupational exposure to a surgeon could be reduced by the adjustment of fluoroscopic parameters and the use of lead gloves. 相似文献
24.
Akada R Hirosawa I Hoshida H Nishizawa Y 《Journal of Bioscience and Bioengineering》2001,92(2):189-192
To identify yeast mutants with a point mutation, detection of the specific mutant alleles is necessary. For this purpose, we applied allele-specific polymerase chain reaction (PCR) to detect the FAS2-1250S dominant mutant allele that encodes an altered fatty acid synthase in Japanese brewer's yeast strains. These strains are known to produce a higher amount of ethyl caproate in Japanese sake. The mutant strains were supposed to be diploid and to contain heterozygous alleles, including wild-type FAS2 and a dominant FAS2-1250S. A set of oligonucleotide primers was designed to contain different nucleotides at their 3' termini: one type was identical to the wild type and the other to the mutant FAS2. Another set of primers was designed to have an additional mismatch at the second nucleotide from their 3' termini. By testing with control strains, we established PCR conditions for specific amplification. Using these conditions and a simple template preparation procedure with SDS, the presence of the allele was detected in commercially used sake yeast strains. The method presented here will be useful for the identification of specific yeast strains. 相似文献
25.
Experimental equipment to investigate multimedia service functions for application to MUSE (multiple sub-Nyquist sampling encoding) HDTV broadcasting has been developed. This system is called the multimedia MUSE system. Programs have also been produced to evaluate service functions of the system taking into account the capacity of the transmission path. This paper describes the configuration of the multimedia MUSE System, service examples, and evaluation of transmission capacity making use of test programs. Our studies reveal that multimedia broadcasting services can be provided when storage memory is installed for achieving interactive viewing and multimedia programs are appropriately configured. In addition, the services described here will provide the basic concept for multimedia broadcasting in future digital broadcasts 相似文献
26.
27.
In this paper, the I-V characteristics of silicon n+-n --n+ diode are investigated as a parameter of the length of the n- region. This diode with shorter n- region than 1 μm has the ohmic characteristics until reaching high electric field in spite of the existence of numerous space-charges in the n- region, for the first time in this report. This conductance of the diode is inversely proportional to the third power of the length of the n- region. The experimental results are in good agreement with an analytical calculation including the diffusion term of carriers injected from the n+ regions to the n- region. However, the diode with longer n- region than 2 μm shows the space-charge-limited conduction which is the same as earlier reports 相似文献
28.
Photocapacitance (PHCAP) measurements have been carried out on GaP crystals grown by the liquid-encapsulated Czochralski (LEC)
method with heat treatment under various phosphorus-vapor pressures at different temperatures. Electron traps of EC−1.1 eV, EC−1.6 eV, EC−1.9 eV, and a hole trap of EV+2.26 eV are mainly detected. The phosphorus-vapor pressure dependence of the EC−1.9 eV trap density and their diffusion behavior indicate that they are interstitial phosphorus atoms. The densities of both
EC−1.1 eV and EC−1.6 eV traps are strongly dependent on the shallow impurity concentrations. Moreover, the density of EC−1.1 eV traps increases with increasing phosphorus-vapor pressure. From these results, we suggest that EC−1.1 eV traps are the complexes of shallow donors and antisite phosphorus atoms. Deep-level densities in GaP crystals after
annealing at 860°C or 960°C for 60 min are decreased almost one order of magnitude lower than those in untreated substrate
crystals, which should have occurred via out-diffusion of interstitial phosphorus atoms. However, such an effect is not prominent
for 800°C treatment for 60 min. 相似文献
29.
Wataru Tamura Arata Yasuda Ken Suto Masasuke Hosokawa Osamu Itoh Jun-Ichi Nishizawa 《Journal of Electronic Materials》2003,32(10):1079-1084
Effects of Bi doping in PbTe liquid-phase epitaxial layers grown by the temperature difference method under controlled vapor
pressure (TDM-CVP) are investigated. For Bi concentrations in the solution, xBi, lower than 0.2 at.%, an excess deep-donor level (activation energy Ed≈0.03–0.04 eV) appears, and Hall mobility is low. In contrast, for xBi>0.2 at.%, Hall mobility becomes very high, while carrier concentration is in the range of 1017 cm−3. Inductive coupled plasma (ICP) emission analysis shows that, for xBi=1 at.%, Bi concentration in the epitaxial layer is as high as NBi=2.3–2.7 × 1019 cm−3. These results indicate that Bi behaves not only as a donor but also as an acceptor, and the nearest neighbor or very near
donor-acceptor (D-A) pairs are formed, so that strong self-compensation of Bi takes place. Carrier concentration for highly
Bi-doped layers shows a minimum at a Te vapor pressure of 2.2 × 10−5 torr for growth temperature 470°C, which is coincident with that of the undoped PbTe. 相似文献
30.
Specimens collected in several localities from Salta and Tucumán provinces (north-western Argentina) Liolaemus quilmes and L. ornatus (oviparous population), and L. alticolor (viviparous population) were dissected. The specimens of lizards examinated have nematodes, in stomach, fore-gut and cloaca, identified as Physaloptera lutzi Guimaraes, Cristófaro and Rodrigues, 1976. This represents the first record for this parasite from Liolaemus species in Argentina. Morphologic and morphometric parasitological studies were done. The specimens were drawn and photographed. Also, the following parasitic infection indexes were calculated: prevalence, mean and maximum intensity. 相似文献