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        검색결과 571

        381.
        2004.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the effects of backrests of varying degrees (, , ) on three abdominal muscles (upper rectus abdominis, external oblique, internal oblique) and back extensor activation during lower extremity exercise. The three different conditions during bilateral knee extention exercise were: (1) leaning on a chair with a backrest, (2) leaning on a chair with a backrest, (3) leaning on a chair with a backrest. Fifteen healthy muscle subjects (mean age=24.2 years [SD=2.96], mean height=175.6 cm [SD=7.46], mean weight=69.1 kg [SD=7.36]) with no history of neuromusculoskeletal disease voluntarily participated in this study. Electromyography was used to collect muscle activation, and the muscle activation was expressed as a percentage of maximal voluntary isometric contraction (%MVIC). Repeated one-way analysis of variance (ANOVA) was used to determine the statistical significance. The results were as follows: (1) upper rectus abdominis, external oblique, internal oblique activation measured significantly lower. (2) measured significantly lower when lower degree.
        4,000원
        382.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 긍정감성과 부정감성을 각각 유발시키는 음향을 제시할 때에 반응자의 행동활성화체계(BAS)와 행동억제체계(BIS)의 개인차가 심박동변이도(HRV)에 어떤 영향을 미치는지를 조사하기 위하여, BAS와 BIS 민감성의 고저에 따라 네 집단으로 분류된 25명의 대학생(남:14명)에게 명상음악과 소음을 제시하고 심전도를 측정하였다. 심전도로부터 HRV의 전력스펙트럼밀도를 유도하여 3개의 주된 주파수영역에 대한 HRV의 전력을 구하였다[저주파수(LF : low frequency), 중간주파수(MF : medium frequency), 고주파수(HF : high frequency)]. 그 결과, 명상음악을 제시한 경우 BIS와 BAS가 모두 낮은 집단에 비하여 BIS는 낮고 BAS가 높은 집단의 MF/(LF+HF)가 유의하게 높았다. 아울러, 전자의 집단에서 명상음악 청취시가 소음 청취시에 비하여 MF/(LF+HF)가 더 높은 경향을 보였으나, BIS가 높은 경우에는 BAS의 민감성에 관계없이 이러한 경향성을 보이지 않았다. 이 결과는 BIS는 낮고 BAS가 높은 집단은 다른 집단에 비하여 명상음악과 같은 긍정감성에 더 민감하며, MF/(LF+HF)는 긍정 및 부정감성을 평가할 수 있는 지표로 사용될 수 있음을 시사한다.
        4,000원
        383.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The role of KOH in the one-stage KOH-activation of rice straws was studied using FTIR, XPS, TGA, and DTG techniques.It was found that at the impregnation, KOH extracts to some extent the lignin component from rice straw and reacts withhydroxyl groups. On heat-treatment, the impregnated KOH facilitates intermolecular condensation reaction on one hand butretards the thermal degradation of cellulose molecules on the other hand. The oxygen-containing surface functional groupsnewly created by oxidation of KOH may facilitate the bulk, not controlled, consumption of carbon atoms so that the effectiveporosities may not be able to be developed by the one-stage activation process.
        4,000원
        386.
        2003.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 슬관전 신전 직전에 수행된 선행 슬관절 굴곡이 슬관절 신전근의 최대 근력발생 및 근육 활성도(activation)에 미치는 영향을 알아보기 위하여 실시되었다. 16명의 정상인이 Cybex II 등속운동기구에서 3가지 다른 운동 속도(, , )와 2가지 다른 근육 활성 조건(선행부하가 없는 조건과 선행부하 조건)에서 슬관절의 최대 신전을 수행하였다. 연구대상자들에게 선행부하 없는 조건에서는 슬관절 굴곡 상태에서 까지 최대 신전을 수행하도록 하였
        4,800원
        389.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tributyltin (TBT) used world-wide in antifouling paints toy ships is a wide-spread environmental pollutant. At low doses, antiproliferative modes of action have been shown to be involved, whereas at higher doses apoptosis seems to be the mechanism of toxi
        4,000원
        390.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Granular Activated Carbon (GAC) has been proven to be an excellent material for many industrial applications. A systematic study has been carried out of the kinetics of physical as well as chemical activation of phenolic resin chars. Physical activation was carried out using CO2 and chemical activation using KOH as activating agent. There are number of factors which influence the rate of activation. The activation temperature and residence time at HTT varied in the range 550~1000℃ and ½~8 hrs respectively. Kinetic studies show that the rate of chemical activation is 10 times faster than physical activation even at much lower temperature. Above study show that the chemical activation process is suitable to prepare granular activated carbon with very high surface area i.e. 2895 m2/g in short duration of time i.e. 1 to 2 hrs at lower temperature i.e. 750℃ from phenolic resins.
        4,000원
        391.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Repetitive transcranial magnetic stimulation (rTMS) modulates cortical excitability beyond the duration of the rTMS trains themselves. Depending on rTMS parameters, a lasting inhibition or facilitation of cortical excitability can be induced. Therefore, rTMS of high or low frequency over motor cortex may change certain aspects of motor learning performance and cortical activation. This study investigated the effect of high and low frequency subthreshold rTMS applied to the motor cortex on motor learning of sequential finger movements and brain activation using functional MRI (fMRI). Three healthy right-handed subjects (mean age 23.3) were enrolled. All subjects were trained with sequences of seven-digit rapid sequential finger movements, 30 minutes per day for 5 consecutive days using their left hand. 10 Hz (high frequency) and 1 Hz (low frequency) trains of rTMS with 80% of resting motor threshold and sham stimulation were applied for each subject during the period of motor learning. rTMS was delivered on the scalp over the right primary motor cortex using a figure-eight shaped coil and a Rapid(R) stimulator with two Booster Modules (Magstim Co. Ltd, UK). Functional MRI (fMRI) was performed on a 3T ISOL Forte scanner before and after training in all subjects (35 slices per one brain volume TR/TE = 3000/30 ms, Flip angle , FOV 220 mm, matrix, slice thickness 4 mm). Response time (RT) and target scores (TS) of sequential finger movements were monitored during the training period and fMRl scanning. All subjects showed decreased RT and increased TS which reflecting learning effects over the training session. The subject who received high frequency rTMS showed better performance in TS and RT than those of the subjects with low frequency or sham stimulation of rTMS. In fMRI, the subject who received high frequency rTMS showed increased activation of primary motor cortex, premotor, and medial cerebellar areas after the motor sequence learning after the training, but the subject with low frequency rTMS showed decreased activation in above areas. High frequency subthreshold rTMS on the motor cortex may facilitate the excitability of motor cortex and improve the performance of motor sequence learning in normal subject.
        4,200원
        392.
        2003.06 구독 인증기관 무료, 개인회원 유료
        활성화를 통한 수핵란의 대량확보를 위해 44시간동안 체외 성숙된 돼지 난자를 ethanol, Ca/sup 2+/-ionophore, 6-DMAP 및 cycloheximide의 화학물질들을 사용하여 단위발생을 유기한 후 그들의 가장적합한 처리농도 및 노출 시간을 규명하였다. 1. Ethanol은 10%, 10분 처리가 전핵형성율, 난할율 및 배발달율에 있어 각각 약 53.4%, 51.6%, 그리고 39.9%로 가장 적합한 조건으로 판명되었다. 2. Ca/sup 2+/-ionophore 가장 적합한 난활성화 조건은 25μM에서 2분간 처리한 것이며, 전핵형성율, 난할율 및 배발달율은 각각 약 59.7%, 62.2%, 그리고 43.9%를 보였다. 3. 6-DMAP를 처리하여 돼지 난자의 활성화를 유기하였을 경우 2mM의 농도에서 각각 약 57.3%, 58.4% 및 29.0%의 전핵형성율, 난할율, 그리고 배발달율을 보여 가장 적합한 조건을 보였으며 2시간∼4.5시간 사이의 노출에는 영향을 받지 않았다. 4. Cycloheximide는 5㎍/ml의 농도가 전핵형성율 2.1%, 난할율 47.7%, 배발달율 31.8%로 가장 은 효율을 보였고, 노출시간에서는 4시간∼6시간 동안 처리하였을 때 60.5∼65.8%, 63.6∼66.7% 및 39.0∼39.5%로 가장 적합한 조건으로 판명되었다. 이상의 결과들은 돼지 체외 성숙 난자의 활성화에 있어 각 화학물질들의 적합한 조건을 바탕으로한 중복처리 및 병용처리 조건 확립 및 효율적인 수핵란의 확보에 기여할 수 있을 것이다.
        4,200원
        395.
        2003.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 소형 개의 불임 해결과 체외수정란을 생산하기 위한 방안의 하나로써 난자의 형태, 번식주기, 배양시간 및 활성화 처리가 난포란의 체외성숙 및 체외발생에 미치는 영향을 조사하였다. 1. 신선, salt 및 4에 보존한 난소로부터 채취한 난구세포부착 난자와 나화 난자로 각각 체외수정시켰을 때 16세포기로의 발생율은 14.3%, 5.0% 및 7.5%, 2.8%, 5.7% 및 0.0%로써 난구세포 부착난자군의 체외발생율이 나화 난자군에 비해 높게 나타
        4,000원
        397.
        2002.11 구독 인증기관·개인회원 무료
        Further development of reconstructed embryos may be dependent upon the synchronization of donor nucleus and recipient cytoplasm at cell fusion, To control the synchronization of donor and recipient cells, the enucleated MII arrested oocytes are artificially stimulated prior to embryo reconstruction. Destruction of cyclin B results in the exit of cells from M-phase of cell cycle. This study was designed to investigate the effects of single or combined stimulation affected cyclin B1 mRNA and protein levels in mouse oocytes. The oocyte activation was induced by 7% ethanol or 10/ Ca-ionophore without (single) or with (combined) 10/ cycloheximide. Competitive quantitative PCR for cyclin Bl mRNA and western blot analysis for cyclin B1 protein was preformed in mouse oocytes. Cyclin B1 mRNA level was significantly reduced in single (P<0.05) and combined (P<0.05) stimulation groups. However, this level did not change in non-activated group and increased in intact group. Cyclin B1 protein level was also significantly reduced in both single (P<0.05) and combined (P<0.05) stimulation groups. In conclusion, single and combined stimulation induces the degradation of cyclin B1 mRNA and protein after activation in enucleated mouse oocytes.
        399.
        2002.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is well known that the porosity and adsorption capacity in a carbon depends on the nature of precursor, pyrolysis and activation conditions and the ash content. The studies on carbon prepared from the dry and wet babbool wood were under taken to ascertain the effect of initial state of precursor on the development of porosity in the resulting activated carbon. The characterization and adsorption studies carried out shows the presence of mainly mesoporosity in the carbon prepared from dry wood while more of microporosity was observed in the activated carbon prepared from wet wood. The results on porosity in both the cases have been compared and correlated with their processing conditions.
        4,000원
        400.
        2002.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Short pitch fibers were prepared from petroleum based isotropic precursor pitch by melt-blown technology. The pitch fibers were stabilized in oxidizing condition, followed by steam activations at various conditions. The fiber surface and pore structures of the activated carbon fibers (ACFs) were respectively characterized by using SEM and applying BET theory from nitrogen adsorption at 77 K. The weight loss of the oxidized fiber was proportional to activation temperature and activation time, independently. The adsorption isotherms of the nitrogen on the ACFs were constructed and analyzed to be as Type I consisting of micropores mainly. The specific surface area of the ACFs proportionally increased with the weight loss at a given activation temperature. The specific surface area was ranged 850~1900 m2/g with pores of narrow distribution in sizes. The average pore size was ranged 5.8~14.1 a with the larger value from the more severe activation condition.
        4,000원