可移动模型校准航空γ能谱仪剥离系数的修正方法研究

为解决可移动模型与现有大型航空模型校准结果之间的量值统一的关键问题,首先在现有校准方法的基础上,建立了可移动模型校准航空/车载γ能谱仪的方法;再通过专门研制的可移动模型开展试验,经可移动模型校准直升机载、固定翼载、车载等多种大型γ能谱仪试验,证明了可移动模型校准结果满足国家计量标准的基本要求,校准航空/车载γ能谱仪的方法可行。进一步总结剥离系数随模型摆放距离变化规律的基础上,提出了采用可移动模型校准航空γ能谱仪时,应对校准结果进行剥离系数修正,得到的结果证明,在现有航空混合模型上的示值误差更小,修正后的剥离系数更加接近于现有航空模型的校准结果,并给出了可移动模型校准结果的修正方法和修正因子。

Effect of 1, 25-Dihydroxyvitamin D_3 on Gastric Carcinogenesis Induced by N-Methyl-N'-nitro-N-nitrosoguanidine in Rats

The effect of 1, 25-dihydroxyvitamin D3 (1, 25 (OH)2D3) given in the post-initiation stage of gastric carcinogenesis induced by N-methyl-N-nitro-N-nitrosoguanidine (MNNG) was investigated in male Wistar rats. Gastric carcinogenesis in rats was induced by administration of MNNG (150 mg·L-1) in drinking water. Four weeks after MNNG exposure, the rats were switched to the diet containing 1, 25 (OH)2D3 (2. 5 μg·kg-1 and 5. 0 μg·kg-1) and maintained on the diet. Animals were killed at week 16 and week 32 for immunohistochemical and histopathological studies. At week 16, the proliferating cell nuclear antingen (PCNA) labeling index in epithelium from the glandular stomach of rats that received 1, 25 (OH)2D3 (5.0 μg·kg-1) in combination with MNNG (150 mg·L-1) were significantly higher when compared with the rats receiving MNNG alone. Supplementation of 1, 25 (OH)2D3 (5. 0 μg·kg-1) in the rats' diet caused a dramatic increase in carcinoma incidence, and the number of individual cancer foci in the glandular stomach of rats receiving MNNG at week 32. It was concluded that certain dose of 1, 25 (OH)2D3 enhanced gastric carcinogenesis induced by MNNG in rats.

延长油田的采油工艺技术措施探讨

针对延长油田的生产实际情况,优选最佳的采油工艺技术措施,不断提高油田的开采效果,降低油田生产的成本,达到预期的采油生产指标。延长油田多数的油井在野外生产,需要合理设计采油工艺技术措施,才能满足延长油田的生产要求。因此,有必要研究延长油田的采油工艺技术措施,使其达到最佳的生产效率。