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991.
The cardioprotective effects of EGb 761 on the release of nitric oxide (NO), the concentration of serum thiobarbituric acid reaction substance (TBARS), the activity of creatine kinase (CK) and the incidence of ventricular arrhythmias were investigated in myocardial ischemia-reperfusion injury in vivo. Using sodium nitrite (NaNO2) as standard source of nitric oxide (NO), we compared the correlation coefficients of the three measuring methods used currently in the determination of NOFe2+(DETC)2 complex with that of the measuring method suggested in this study. The result showed that measuring the whole height of three splitting signals is the best linear correlation to the concentration of NO comparing with other methods in this system. Using this method, we observed the effects of EGb 761 on NOFe2+(DETC)2 complex in myocardial ischemia-reperfusion injury in vivo. The hearts of the Wistar rats were subjected to 30 min of ischemia and 10 min of reperfusion in vivo. Different doses of EGb 761 (25, 50, 100, 200 mg/kg i.p.), superoxide dismutase (SOD, 10(4) U/kg), l-arginine (50 mg/kg i.p.) and nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine (NNA, 50 mg/kg i.p.) were administered to the ischemia-reperfusion rats. EGb 761 under the dose of 100 mg/kg increased the signal intensity of NOFe2+(DETC)2 complex, while EGb 761 at 200 mg/kg showed an effect of decreasing the signal intensity of NOFe2+(DETC)2 complex. EGb 761 inhibited the formation of TBARS, the release of CK, and mitigated the incidence of ventricular arrhythmias in a dose dependent way. Both l-arginine and SOD increased the signal intensity of NOFe2+(DETC)2 complex and inhibited the formation of TBARS, the leakage of CK and the incidence of ventricular arrhythmia. NNA not only had no protective effects on myocardial injury, but also increased the incidence of reperfusion-induced arrhythmia. In conclusion, EGb 761 has cardiovascular protective effects by means of adjusting the level of NO and inhibiting oxygen free radicals induced lipid peroxidation in myocardial ischemia-reperfusion injury in vivo. 相似文献
992.
在30CrMnSiA钢中加入不同量的As,Sb,Sn元素,研究了这些元素单独存在及复合存在时对钢的强度,塑性,冲击韧度及韧脆转变温度的影响规律,并用扫描电镜及俄歇能谱分析了As,Sb,Sn导致晶界脆化的机理。 相似文献
993.
A FISH technique for simultaneous detection of fluorescent R-band and in situ hybridization signals]
BACKGROUND: Because of serious adverse effects of centrally acting antitussive agents, is necessary to find new drugs with cough-suppressing activity. Medicinal herbs are a potential source of polysaccharides with high antitussive efficiency and on the other with minimal side effects. AIM: The study was to assess the antitussive action of mixture of a polysaccharides (RL) and polysaccharide-xylan (XY), both isolated from above-ground parts of Rudbeckie fulgida var. sullivantii. The observed activity was compared to those of narcotic and nonnarcotic antitussive substances used in clinical practice. METHODS: Cough was evoked by mechanical irritation of the airways in nonanaesthetized cats with chronic tracheal cannuly. The plant substances were administered perorally in the dose of 50 mg per kg body weight. RESULTS: Results indicate, that administration of RL induced a suppression of the followed cough parameters from both areas of airways (total fall in cough parameters by 46.6%). Administration of xylan induced the fall in the followed cough parameters with more significant influence on the laryngopharyngeal area of the airways (total fall in cough parameters 48.2%). CONCLUSION: Administration of RL and xylan did not achieve the effect of codeine, but had a more intensive antitussive effect than the peripherally acting droprozine and prenoxdiazine. (Fig. 3, Ref. 11.) 相似文献
994.
Jian Song Chongcheng Fan 《Lightwave Technology, Journal of》1995,13(3):546-550
A simplified formula for the dispersion limit of single-mode-fiber intensity modulation/direct detection (IM/DD) systems is derived for arbitrary given normalized pulse width U, eye opening penalty X and source linewidth enhancement factor α. From the comparison with published theoretical analyses, computer simulation and experimental data, its validity and the limits of existing formulae are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems 相似文献
995.
解析扩展X射线吸收精细结构谱(TheExtendedX-rayAbsorptionFineStructureEXAFS)的一种方法是曲线拟合,在曲线拟合中,能量阈值E0的确定有着很重要的意义,同时也有相当的难度,本文应用AKIMA平滑数据点方法达到了对E0在数学意义上的精确求解,数据分析结果表明,这种方处理结果是令人满意的。 相似文献
996.
997.
998.
Sulfur in coal causes problems in coal processing and utilization, therefore the chemical beneficiation of coal has gained widespread attention. Using three coal samples with high sulfur content the effect of desulfurization has been studied. For Nantong coal containing 4.25% total sulfur under the condition sulfur reduction increased from 38.8% upto 62.4% the released sulfur was generally sulfate and pyrite, but the organic sulfur almost remained constant. When alkali treatment was performed at 370°C, organic sulfur removal of Donglin and Yanzhou coal was to 50.6% and 57.3% respectively. 相似文献
999.
飞行器由于采用了××炸药索作为级间分离及壁板减重的火工装置,当火工品引炸时,对周围的仪器支架和脱拔插头产生高达30000g的冲击加速度。为保护仪器支架和脱拔插头,本文,总结了多种隔冲击结构方案的试验结果,选出了一种最佳方案,即二级硅橡胶缓冲器与阻尼复合结构的结合形式。该方案可使冲击加速度衰减至160g以下。测的是周向过载。4结语粘弹阻尼复合结构用于高频响、高过载的冲击衰减系统尚是一种新的尝试。由于本课题所设计的缓冲支架采用了多级隔冲方式,冲击载荷传递的环节多,而且是三维冲击响应,载荷的波形复杂,不确定因素多,无法采用理论分析的方法进行研究。虽然如此,缓冲器的隔冲特性以及粘弹阻尼复合结构的减振性能还是可以估算的。这方面的理论问题有待于进一步研究。从试验角度而言,本次试验已解决了飞行器的仪器盒及脱拔插头的隔冲击振动问题,证明所设计的隔冲击支架满足使用要求。通过对不同支承界面联接方式的研究,选出了较佳的支承结构形式,即文中的标准状态。该结构形式隔冲击性能好,衰减倍数大,安装和更换方便,防热性能好。试验数据表明,仪器架的衰减倍数大于400倍,脱拔插头支架大于290倍;在最大过载约30000g,最大响应频率约22.4 相似文献
1000.
Z. S. Peng Z. Q. Hua Y. N. Li J. Di J. Ma Y. M. Chu W. N. Zhen Y. L. Yang H. J. Wang Z. X. Zhao 《Journal of Superconductivity》1998,11(6):749-754
Bi-based superconductors are of great interest in high-temperature superconductors. We describe what is believed to be the first synthesis of these materials using the Pechini process, a low-temperature synthetic method that often yields inorganic oxide of excellent phase purity and well-controlled stoichiometry. Using this process, it has been possible to synthesize phase-pure Bi-2223 phase by calcining the appropriate polymeric precursors in air at 800°C for several hours. The superconductivity studies show that the Pechini-synthesized materials appear to offer high-quality performance. 相似文献