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The influences of adrenal corticosteroid on the development and regression of the neurons of hippocampal and dentate were examined in the steroid overloaded neonatal rats. The results obtained were as follows. The regression occurred naturally in numerous dentate granule cells and hippocampal pyramidal cells, which was the apoptotic process. The apoptotic granule cells in dentate gyrus decreased in number with steroid overload, and this change was more prominent at 6 days than at 4 days. The decrease in the number of apoptotic neurons by steroid overload occurred only in the upper limb of dentate gyrus at 6 days. The gradient of regression in dentate gyrus had no relation with the gradient of neurogenesis, and the regression of hippocampal pyramidal cells decreased in the gyrus but not in CA regions. In conclusion, the cell death occurred in neurons of hippocampal formation, which was the process of apoptosis. The adrenal corticosteroid seemed to be influential significantly on the development and regression of the neurons.
1993년 6월부터 7월까지 서울 시내 중학교 2학년과 3학년 여학생 1,089명을 대상으로 설문지를 이용하여 초경 및 월경의 특성과 장애에 대하여 조사, 분석하여 다음과 같은 결과를 얻었다. 1. 대상 학생의 평균 초경연령은 12.6세였으며, 가장 빠른 초경연령은 8.3세, 가장 늦은 초경연령은 15.3세였다. 2. 초경 경험 학생과 비경험 학생의 체중 및 신장을 보면 초경경험 학생의 경우 신장 158 cm, 체중 48.8 kg으로, 초경 비경험 학생의 신장 154 cm, 42.9 kg에 비해 각각 4.0 cm, 5.9 kg차이가 있었다. 3. 월경의 주기는 평균 29.4일이었으며, 월경의 지속기간은 2-10일 사이로 평균 5.8일이었고, 월경의 양은 보통이라고 생각하는 경우가 80.6%로 가장 많았다. 4. 월경의 주기가 22-39일 사이로 정상인 경우가 80.7%로 가장 많았고, 21일이하의 빈발월경은 11.5%, 40일이상 3개월미만의 희발월경은 5.5%, 3개월이상 월경이 없는 경우는 2.1%였다. 5. 계절에 따른 초경시작의 분포를 살펴보면 겨울(29.6%), 여름(27.5%), 봄(23.0%), 가을(20.9%)로 여름과 겨울에 초경의 발생빈도가 높았다. 6. 월경곤란증을 경험한 학생은 응답자 881명중 78%였으며, 이중 견딜만하거나, 중등도인 경우가 91%로 대부분이었으며, 심하거나, 심해서 학교를 결석, 조퇴하는 경우는 6.9%였다. 7. 월경곤란증 때문에 진통제를 복용한 경험이 있는 경우는 45.3%였으며, 이중 매 주기마다 복용하는 경우는 19.6%였으며, 가끔 복용하는 경우는 48.6%로 거의 반수 이상이 진통제를 복용하는 것으로 나타났다. 8. 월경전 증후군은 대상학생 881명중 23.4%에서 경험한 적이 있었으며, 주증상은 불안, 피로, 우울등이 대부분이었다. 9. 초경시의 문제점이나 월경곤란증, 월경전 증후군 등의 청소년기 부인과적 문제 대문에 병원을 내원한 경험이 있는 경우는 5.8%였고, 골반진찰에 동의한 경우는 64.7%였으며, 여의사인 경우에만 진찰하겠다는 경우도 2.1%있었다. 진찰을 거부하는 경우는 33%였는데, 창피하고 무섭다는 반응이 대부분이었다. 10. 부인과적 문제에 대한 학생들의 고민을 보면, 월경에 대해 고민이 있는 경우는 74.6%였으며, 이중 월경곤란증이 46.2%로 가장 많았고, 월경전 증후군이 15.6%, 월경불순이 6.3%, 질분비물 0.8%의 순이었다. This study was designed to obtain the menarche, the factors which influence on menarche and menstual patterns after menarche. For the data smpling, self administered questionaire survey was made in July, 1993. Among the 1089 middle school girls in urban area. 1. The mean age of menarche was 12.6 years old. And menarchel age ranged from 8.5 years old to 15.3 years old. 2. The girls at manarche was taller and heavier than those of the same age who had not experienced menarche. 3. The mean menstrual interval was 29.4 days, the mean duration was 5.8 days. The proportion of normal menstruation, polymenorrhea, oligomenorrhea, and amenorrhea were 80.7%, 11.5%, 5.5% and 2.1%. 4. The summer and winter were highly frequent seasons of the menarche. 5. Seventy eight percent of girls suffered from dysmenorrhea. 6. The percentage of subjects who took analgesia due to dysmenorrhea was 45.3%. 7. The premenstrual syndrome was experienced by 23.4%. 8. Only 5.8% of girls visited hospital with adolescent gynecologic problems. 9. The percentage of students had gynecologic concerns was 74%.
A conventional taped banknotes detecting device in the banknote counting machine have some problems caused by temperature, humidity, dust and other environmental conditions. In order to the improve the detection performance of taped banknote in the banknote counting machine, we developed taped banknotes detecting device that the ultrasonic wave sensor was replaced by mechanical method device. There are many factors for the performance of the taped banknote detecting device of a mechanical method, we considered three main factors that are the amplification ratio of the thickness of banknotes, the pressing force of banknotes and the feeding speed of banknotes. We carried out the experiments with the 27 kinds of combination of these three main factors. As the result, accurate detection was possible to the normal banknotes and taped banknotes regardless of the feeding rate in terms of the amplification rate 27 times and the pressing force 660gf.
In concert with the development of new materials in the last decade, the need for toxicological studies of these materials has been increasing. These new materials include a group of rare earths (RE). The use of RE nanotechnology is being considered in some green applications, to increase their efficiency by using nano-sized RE compounds, and therefore hazard evaluation and risk assessment are highly recommended. This review was conducted through an extensive contemplation of the literatures in toxicology with in vitro and in vivo studies. Major aspects reviewed were the toxicological evaluations of these elements and metallic compounds at the molecular and cellular level, animal and human epidemiological studies and environmental and occupational health impacts on workers. We also discuss the future prospect of industries with appliances using RE together with the significance of preventive efforts for workers' health. To establish a safe and healthy working environment for RE industries, the use of biomarkers is increasing to provide sustainable measure, due to demand for information about the health risks from unfavorable exposures. Given the recent toxicological results on the exposure of cells, animals and workers to RE compounds, it is important to review the toxicological studies to improve the current understanding of the RE compounds in the field of occupational health. This will help to establish a sustainable, safe and healthy working environment for RE industries.
A huge number of chemicals are produced and used in the world, and some of them can have negative effects on the reproductive health of workers. To date, most chemicals and work environments have not been studied for their potential to have damaging effects on the workers' reproductive system. Because of the lack of information, many workers may not be aware that such problems can be related to occupational exposures. Newly industrialized countries such as Republic of Korea have rapidly amassed chemicals and other toxicants that pose health hazards, especially to the reproductive systems of workers. This literature review provides an overview of peer-reviewed literature regarding the teratogenic impact and need for safe handling of chemicals. Literature searches were performed using PubMed, Google Scholar, and ScienceDirect. Search strategies were narrowed based on author expertise and 100 articles were chosen for detailed analysis. A total of 47 articles met prespecified inclusion criteria. The majority of papers contained studies that were descriptive in nature with respect to the Medical Subject Headings (MeSH) terms and keywords: “reproductive and heath or hazard and/or workplace or workers or occupations.” In the absence of complete information about the safe occupational handling of chemicals in Republic of Korea (other than a material safety data sheet), this review serves as a valuable reference for identifying and remedying potential gaps in relevant regulations. The review also proposes other public health actions including hazard surveillance and primary prevention activities such as reduction, substitution, ventilation, as well as protective equipment.
Carbon-doped titanium dioxide (TiO2) nano-powders were synthesized by the aerosol flame deposition (AFD) process using 2-butanol liquid sol containing 20 wt% of titanium isopropoxide (TTIP). They were mesoporous nano-powders with particle size ranging from 20 to 40 nm, the specific surface area of 36 m2/g, and the pore size of 19 nm. They had the anatase structure and showed high photocatalytic activity not only under UV-A light but also under fluorescent light. They reduced the concentration of methylene blue (MB) from 5.0 to 1.5 ppm within 2 h under UV-A light and from 5.0 to 2.0 ppm within 4 h under fluorescent light. And, they killed 99% of Escherichia coli (E. coli) cells within 2 h and bacterial growth of the E. coli was not observed for 12 h under both UV-A and fluorescent lights. 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
We investigated the genotoxicities or mutagenicities of two chemicals (potassium nitrate and 2-methylpentane)that have limited toxicological data in spite of their common usage based on Ames reverse mutation test. In this test, treatment of two chemicals at each five dose did not induce mutagenicity in Salmonella typhimurium TA98, TA100, TA1535, TA 1537, and in Escherichia coli WP2uvrA with and without metabolic activation. These results indicate that two chemicals do not have mutagenic potentials under the conditions of our study
We investigated the genotoxicity of two chemicals, methylcyclopentane and 1,4-dichlorobutane with in vivo micronucleus test. Although these two chemicals have already been tested many times, a micronucleus test has not been conducted and the usage of these chemicals has been recently increased. 7 week male ICR mice were tested at dosages of 500, 1,000, and 2,000 mg/kg for methylcyclopentane and 500, 1,000, and 2,000 mg/kg for 1,4-dichlorobutane, respectively. After 24 hours of oral administration with the two chemicals, the mice were sacrificed and their bone marrow cells were prepared for smearing slides. As a result of counting the micronucleated polychromatic erythrocyte (MNPCE) of 2,000 polychromatic erythrocytes (PCE), all treated groups expressed no statistically significant increase of MNPCE compared to the negative control group. There were no clinical signs related with the oral exposure of these two chemicals. It was concluded that the two chemicals did not induce micronucleus in the bone marrow cells of ICR mice, and there was no direct proportion with dosage. These results indicate that the two chemicals have no mutagenic potential under each study condition.