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21.
利用2009年1月~2010年12月河间自动气象站和人工观测的气压、气温、相对湿度资料,对其资料进行统计对比分析并探讨两者差值的形成原因。结果表明,自动站与人工观测值月平均气压差值为-0.2~0.3 hPa,月平均最高气压差值为0~0.5 hPa,月平均最低气压差值为-0.4~0.3 hPa,月极端最高气压差值为-0.2~0.9 hPa,月极端最低气压差值为-0.6~0.6 hPa;月平均气温差值为0~0.2℃,月平均最高气温差值为0~0.2℃,月平均最低气温差值为-0.1~0.4℃,月极端最高气温差值为-0.2~0.6℃,月极端最低气温差值为-0.3~0.6℃;月平均相对湿度差值为-3%~3%,月最小相对湿度差值为-9%~3%。气象要素对比观测差值产生的原因主要有观测仪器和观测原理的差异、数据采集时间与方法不同、感应器安装位置及所处环境不同以及人工干预与观测误差等主观因素。 相似文献
22.
我国森林生物多样性变化的评价研究 总被引:11,自引:0,他引:11
应用控制论中“黑箱”理论的原理 ,参考经济合作与发展组织 (OECD)对环境政策影响的评价和芬兰森林资源核算的研究 ,创造性地使用压力 -状态响应评价法 ,设计了森林生物多样性变化评价的框架、指标和计算公式 ,并使用该方法对我国 1973年 - 1998年的森林生物多样性的变化进行了评价。评价结果表明 :1973年 -1998年 ,我国森林生物多样性的压力越来越大 ;森林生态系统多样性先逐渐上升 ,尔后又逐渐下降 ;森林物种多样性和森林生物多样性总体趋势增加 ,但第四次资源清查之后有所下降 相似文献
23.
Wang Li-Ping 《园艺学报》2014,30(10):1760-1764
AIM:To explore the effect of erythropoietin (EPO) on the expression of myocardial NADPH oxidase (Nox) in the pressure overload rats. METHODS:Male SD rats (n=36) were used to establish a pressure overload myocardial hypertrophy model by abdominal aorta ligation. The animals were divided into model group, control group (sham, without narrowing abdominal aorta, the rest of the operation was the same as the model) and recombinant human erythropoietin (rhEPO) treatment group (intraperitoneal injection of rhEPO postoperatively, 4 000 U/kg, twice a week). After 8 weeks, the cardiac ultrasound imaging and hemodynamic evaluation were conducted to determine the cardiac functions. Masson staining was used to observe the degree of myocardial fibrosis. The expression of Nox2 and Nox4 at mRNA and protein levels was detected by real-time quantitative PCR and Western blotting. The protein levels of myocardial inflammatory factors CD45, F4/80 and TGF-β were determined by Western blotting. RESULTS:Compared with model group, the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular end-systolic pressure (LVESP) and left ventricular pressure maximum rising and falling rates (±dp/dtmax) increased significantly in EPO treatment group (P<0.01). At the same time, left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD) and left ventricular end-diastolic pressure (LVEDP) were decreased in EPO treatment group (P<0.01). EPO reduced the degree of myocardial fibrosis caused by pressure overload (P<0.01) and decreased the expression of Nox2 and Nox4 at mRNA and protein levels in the myocardium (P<0.05 or P<0.01), and reduced the protein expression of myocardial inflammatory factors CD45, F4/80 and TGF-β. CONCLUSION: EPO inhibits rat myocar-dial fibrosis induced by pressure overload, improves heart functions by decreasing NADPH oxidase activity and inhibiting myocardial oxidative stress levels and myocardial inflammatory reaction. 相似文献
24.
Jessica D. Briley Morika D. Williams Mila Freire Emily H. Griffith B. Duncan X. Lascelles 《Veterinary journal (London, England : 1997)》2014,199(2):245-250
Feasibility and inter-session repeatability of cold and mechanical quantitative sensory testing (QST) were assessed in 24 normal dogs. Cold thermal latencies were evaluated using a thermal probe (0 °C) applied to three pelvic limb sites. Mechanical thresholds were measured using an electronic von Frey anesthesiometer (EVF) and a blunt-probed pressure algometer (PA) applied to the dorsal aspect of the metatarsus. All QST trials were performed with dogs in lateral recumbency. Collection of cold QST data was easy (feasible) in 19/24 (79%) dogs. However, only 18.4%, 18.9% and 13.2% of cold QST trials elicited a response at the medial tibia, third digital pad and plantar metatarsal regions, respectively. Collection of mechanical QST data was easy (feasible) in 20/24 (83%) dogs for both EVF and PA.At consecutive sampling times, approximately 2 weeks apart, the average EVF sensory thresholds were 414 ± 186 g and 379 ± 166 g, respectively, and the average PA sensory thresholds were 1089 ± 414 g and 1028 ± 331 g, respectively. There was no significant difference in inter-session or inter-limb threshold values for either mechanical QST device. The cold QST protocol in this study was achievable, but did not provide consistently quantifiable results. Both mechanical QST devices tested provided repeatable, reliable sensory threshold measurements in normal, client-owned dogs. These findings contribute to the validation of the EVF and PA as tools to obtain repeated QST data over time in dogs to assess somatosensory processing changes. 相似文献
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目前,UV淋幕式平面涂装机在我国尚处研制阶段,其成幕原理各说不一。就成幕而言,既可因重力自流而成,也可靠施加压力动压而成。本文根据分析计算和实例认为,适合竹木板材的UV油漆必须加压成幕。 相似文献
27.
就流体技术领域中的压力传感器标定和测量方法进行了讨论,提出了工业现场情况下的采样技术,还对测量参数的非线性处理和计算机规范化进行了表述。 相似文献
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29.
散装黑木耳容积林,重量轻,易破碎,是贮运的难题。本研究确定了黑木耳块的精加工工艺。通过软化,加压,干燥等项试验,分析了黑木耳的含水率,设备系统压力,环境温度等因素对黑木耳块加工的影响,确定了温度为10-25℃,含水率为20%-22%,压力为11MPa是工艺最佳参数,根据此工艺,又确定了液压专用设备。 相似文献
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