均匀设计法优化双环戊二烯基铁电化学合成的条件     

潘献晓  蔡铎昌 《商丘师范学院学报》2006,22(5):126-127,130

运用均匀设计法研究双环戊二烯基铁电化学合成的条件.试验表明:在槽电压为1.5 V、反应温度为40℃、无水乙醇与环戊二烯的体积比为5.46的条件下,获得了品质良好的产品,收率达90%以上.  相似文献   

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes     

Cheng-Shiun He  William D. Fraser  Jonathan Tang  Kirsty Brown  Stephen Renwick  Jay Rudland-Thomas 《Journal of sports sciences》2016,34(1):67-74

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D₃ supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D₃ supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D₃ group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D₃ group was higher than in the placebo group (P = 0.025). Only in the vitamin D₃ group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D₃ supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.  相似文献   

冬泳运动对中老年人身体成分的影响分析     

姜燕  武俸羽 《辽宁体育科技》2016,(1):75-77

对齐齐哈尔市冬泳协会的116名冬泳爱好者进行身体成分测试。结果显示：长期进行冬泳运动,可以改善中老年人的身体成分,降低体脂百分比和肥胖发生率,提高身体素质,对预防心血管疾病及老年性骨质疏松具有积极意义。  相似文献   

广义马氏过程及其熵率     

张景晓  连秀国  李光芹  姜曰华 《临沂师范学院学报》2004,26(3):26-28

讨论了k步广义马氏过程及其时间不变性和平稳性，给出了熵率的两种定义，说明了其等价性，还给出了平稳的广义马氏链熵率的计算公式．  相似文献   

食物浓度及低浓度镉对水螅种群动态的影响     

鲍官柢  胡好远 《安徽教育学院学报》2005,23(3):91-93

在温度为20士1℃、自然光照(光照强度约为301x,L : D=14 : 10)条件下,分别以浓度为0.25ind/ml、0.5ind/ml、1.0ind/ml、2.0ind/ml枝角类(Cladocemans)为食物及在1.0ind/ml食物浓度下,应用单个体培养法及群体累积培养法研究了食物浓度及低浓度镉离子(0mg/l(对照组)、0.01mg/l、0.05mg/1)对水螅种群动态的影响.实验表明,食物浓度对水螅种群增长有一定影响,在较高食物浓度下水螅的种群增长率、净增长率普遍提高,而镉子浓度对水螅种群增长有显著影响.在较高离子浓度下,水螅种群增长率、净增长率较大,而世代时间相对缩短.  相似文献   

直接序列扩频系统抗干扰性能研究   总被引：2，自引：0，他引：2  

康丽  邵玉斌 《赣南师范学院学报》2006,27(6):55-57

本文从直接序列扩烦的处理增益及误码率方面,借助Matlab仿真算法,分析了其在几种主要干扰下的抗干扰性能,并指出了几种有利于提高系统抗干扰能力的方法．  相似文献   

用稳态近似法推导反应速度方程时应注意的一个问题     

胡跃华 《赣南师范学院学报》1990,(Z1)

用稳态近似法推导反应的速度方程时,最后所导出的速度方程有时会出现由不不同数值而组成的系数。针对这个问题,本文指出了两种避免出现该问题的方法。  相似文献   

低温胁迫下镧对水稻种子萌发的影响   总被引：3，自引：0，他引：3  

刘惠娜  钟东方  许良政 《嘉应学院学报》2007,25(3):72-76

以水稻(Oryza sativa)种子为实验材料,研究了不同浓度稀土元素镧浸种对水稻种子低温萌发的影响。结果表明:15℃低温胁迫抑制水稻种子的萌发,浸种期用硝酸镧处理能够提高种子的抗逆性。低浓度((50~250)×10-6mol/L)硝酸镧浸种能提高水稻种子发芽率、发芽势、呼吸速率和过氧化氢酶活性,提高种子抗寒能力,实验发现用硝酸镧处理种子萌发以250×10-6mol/L浓度为最佳,低温胁迫下,发芽率提高9.67%,呼吸速率提高56.25%,过氧化氢酶活性提高1.73%。350×10-6mol/L以上高浓度对水稻种子的萌发无明显影响。  相似文献   

Alterations in autonomic cardiac modulation in response to normobaric hypoxia     

David Giles  John Kelly 《European Journal of Sport Science》2016,16(8):1023-1031

Purpose: The present study aimed to determine if autonomic cardiac modulation was influenced by acute exposure to normobaric hypoxia. Method: Ten healthy male lowland dwellers completed five block-randomised single-blinded, crossed-over acute exposures to a normobaric hypoxic environment, each separated by 24 hours’ recovery (20.3%, 17.4%, 14.5%, 12.0% and 9.8% F_IO₂). Supine recordings were made of arterial oxygen saturation and electrocardiogram (ECG). RR intervals from the ECG trace were analysed for time (SDNN, lnrMSSD), frequency (lnVLF, lnLF, lnHF, lnTP, LFnu, and HFnu), and nonlinear (DFA-α1 and SampEn) heart rate variability components. Results: A significant reduction in arterial SaO₂ occurred with reduced F_IO₂, along with a rise in heart rate (Cohen’s d?=?1.16, 95% Confidence Interval [2.64–6.46]), significant at 9.8% F_IO₂. A decrease in autonomic cardiac modulation was also found as shown by a statistically significant (at 9.8% F_IO₂) decrease in lnTP (d?=?1.84 [1.74–1.94]), and SampEn (d?=?0.98 [0.83–1.12]) and an increase in DFA-α₁ (d?=?0.72 [0.60–0.84]) from normoxia at 9.8% F_IO₂. Conclusion: The decrease in variability indicated a reduction in autonomic cardiac modulation. There appears to be a threshold ～9.8% F_IO₂ (～6000?m equiv.), below which significant alterations in autonomic control occur.  相似文献   

关于提高高职高专学生就业率的思考     

崔红 《辽宁高职学报》2007,9(4):89-90

针对当前高职院校毕业生就业率偏低的现象进行了剖析,就业率低的原因,主要由于学校缺少深入细致市场调研,用人单位片面追求高学历所至,还有其他一些因素,为此,提出三个方面的建议。  相似文献