“民工荒”视角下的农民工工资决定机制及其影响研究

"民工荒"背景下,识别农民工工资决定机制的新特征,将有助于把握农村剩余劳动力城镇化进程的新趋势。基于"进城务工人员生存状况调查"数据,分析人力资本和社交网络在农民工工资决定机制的作用,探讨其对农村人口转移决策和教育投资的影响。结果表明,人力资本和社交网络对农民工工资具有显著正向影响。但初、中等教育投资回报率明显偏低,初中教育不会对工资产生显著影响,高中教育仅能引起工资落入2 000元以下工资区间的概率减少7.0%;接受初、中等教育给带来的工资增幅低于其通过工作经验增加所带来的增幅,并将促使农村初中等教育适龄人口提前做出转移决策;社交网络则通过提高实现高工资就业的机会,进一步强化上述倾向。研究揭示了农民工工资决定机制的调整,存在着抑制农村人口教育投资、鼓励农村人口提前做出转移决策的消极影响,并据此提出相关对策建议。     

北太平洋鱿鱼肌肉蛋白质凝胶特性的研究

以北太平洋鱿鱼为原料,从擂溃工艺、弹性补强剂、品质改良剂以及加热方式对鱿鱼肌肉蛋白质凝胶特性进行了较为系统的研究.先利用正交试验设计分别确定擂溃参数,淀粉、植物蛋白和水的添加量,并在此基础上通过单因素试验确定转谷氨酰胺酶、柠檬酸钠、多磷酸盐的添加量及加热方式.研究结果表明,在试验范围内,擂溃温度3 ℃,空溃5 min,盐溃10 min;添加8%植物蛋白,10%淀粉,20%水分,凝胶弹性较好.采用二段加热,柠檬酸钠、转谷氨酰胺酶、多磷酸盐的添加量分别为0.2%、0.2%、0.3%,鱼糜的凝胶性能较好.     

参考文献著引的编辑精练与修正

结合编辑实践,通过实例分析,探讨了科技论文参考文献引、著中的信息冗余的多种表现形式,提出编辑在加工时应采取的防范措施与精简对策,以真正体现参考文献引用与著录的内在价值,最大限度地实现参考文献资源的共享。     

复合菌制剂及其在断奶仔猪生产上的应用

复合菌制剂是一种新型的安全、无毒、无残留的绿色饲料添加剂,可维持断奶仔猪胃肠道微生态环境的平衡,具有促进断奶仔猪生长、控制肠道致病性菌的繁殖、增强动物免疫性能、降低仔猪患病几率等作用,是理想的抗生素替代品.     

数字化测图实践与认识

随着测绘科学技术的发展，传统的模拟法测图方法已被数字化测图方法所替代。本文从数字化测图工作的外业、内业以及测量成果表现形式上，对数字化测图与模拟法测图的特点进行了对比分析；分析了数字化测图质量评价的内容和特点；结合数字化测图的工作实践，对数字化测图工作提出了几点有益的认识。     

农村土地承包经营权流转的法律问题分析

《中华人民共和国农村土地承包法》对农村土地承包经营权的流转作出了较为全面的规定,但随着农村土地承包经营权流转的进一步深入,该法逐渐显示出某些不适应性。参考相关专家学者在此问题上所持观点,简要地分析了目前我国农村土地承包经营权流转在立法上存在的问题。     

山羊毛虱的形态结构和分子标志研究

为了解山羊毛虱形态结构和分子标志,用电子显微镜和三维立体显微镜观察了采自山羊的山羊毛虱形态结构,测定了其18SrDNA和cox1基因序列,并基于比对,揭示其序列特点。形态观察发现,触角3节,第1节短粗,第2、3节细长;中胸气门1对,位于前胸两侧;腹部有气门6对;跗节3节。序列分析显示,本样虱、山羊毛虱、具边毛虱和牛毛虱四者的18SrDNA基因序列高度相似,不适于做种间鉴定。cox1序列极不保守。     

Effects of atorvastatin on expression of PAPP-A induced by TNF-α and IL-1β in rat aortic endothelial cells

AIM: To investigate the effects of atorvastatin on the expression of pregnancy-associated plasma protein A(PAPP-A)induced by TNF-α and IL-1β in endothelial cells. METHODS: The rat aortic endothelial cells were isolated from thoracic aortas and cultured by the tissue explant method. The cells in passage 3-4 were used in the experiment and were randomly divided into 4 groups: blank control group: the cells were treated without any intervention; atorvastatin concentration groups: the cells were incubated with atorvastatin at the concentrations of 0.1, 1 and 10 μmol/L for 24 h; atorvastatin time groups: the cells were incubated with atorvastatin at the concentration of 10 μmol/L for 6 h,12 h and 24 h; atorvastatin+inflammatory factors groups: the cells were pre-incubated with 60 μg/L TNF-α or 20 μg/L IL-1β for 1 h, then different concentrations of atorvastatin (0.1, 1.0, 10 μmol/L) were added for 6 h,12 h and 24 h. MTT reduction assay was used to observe the cell proliferation. The mRNA expression of PAPP-A was detected by RT-PCR. The protein level of PAPP-A in the supernatants of cultured cells was measured by ELISA. RESULTS: Compared with blank control group, no significant change of cell proliferation was observed after the intervention of atorvastatin and TNF-α/IL-1β for 3 h, 6 h, 12 h, 24 h and 48 h, indicating that the drugs had no toxic effects on the cells. No significant difference of PAPP-A expression between atorvastatin groups and blank control groups was found. Compared with TNF-α groups and IL-1β groups, PAPP-A expressions in atorvastatin intervention groups significantly decreased. The protein level of PAPP-A was gradually decreased with the raised concentration of atorvastatin and the prolonged time in a concentration- and time-dependent manner. CONCLUSION: Atorvastatin doesn't influence the PAPP-A expression, but inhibits the expression of PAPP-A activated by inflammatory factors in a concentration- and time-dependent manner in primary cultured rat aortic endothelial cells.     

纳豆菌发酵对豆粕脲酶活性的影响

微生物发酵可一定程度降低豆粕抗营养因子活性，提高豆粕作为蛋白源的利用率。采用2株纳豆菌发酵研究豆粕中脲酶的失活情况。首先测定了其生长曲线，用以指导其发酵条件的优化研究。研究了水／豆粕比例、培养温度、pH、接种量等发酵参数对脲酶活性的影响，结果表明：降低脲酶活性的最优发酵条件为：彬豆粕比例为5：1，pH4．5、温度30℃、接种量5％、种龄为8h，发酵60h，豆粕脲酶活性降低93％。