反例在高等数学教学中的重要性

在高等数学教学中,恰当地使用反例可加深学生对基本概念的理解和对基础知识的掌握,发现并纠正学习中的错误,培养学生的创新能力和良好的思维品质。     

高新技术在国内外公路养护中的应用

随现代科学技术的不断进步和发展，高新技术在公路管理和养护方面的应用也日益广泛。本文介绍了国外公路管理与养护的新技术和新方法，并对公路管理情况进行了阐述。     

Experiment on Interplanting Corn Yield and Cultivate Density，Application Rates of Nitrogen Phosphorus Potassium

采用二次回归通用旋转组合设计方法试验，以马铃薯套作玉米产量为目标，以套作的玉米密度、氮、磷、钾肥施用量为探讨对象，建立了套作玉米产量与密度、氮、磷、钾肥施用量间关系的数学模型（y=7396.05-536.7x1+129.0x2+135.6x3+104.7x4-19.65x1x2-5.4x1x3+147.75x1x4+165.15x2x3-86.55x2x4+113.7x3x4-478.8x12-407.7x22-446.25x32-450.3x42），通过模拟寻优，提出了玉米产量≥6750.00kg/hm2     

吉林省西部盐碱地水稻综合农艺数学模型及优化方案的研究

根据“最佳模拟配合法”原理 ,利用吉优 1号在盐碱地高产栽培技术体系中几个关键性农艺因素 ,采用五元二次回归正交旋转组合设计法 ,进行多因素、多水平的试验研究 ,建立了 6 0 0kg/ 6 6 7m2 以上的综合农艺数学模型及优化方案 ,为西部盐碱地大面积水稻高产优质栽培技术提供了理论依据     

Apoptosis in diabetic foot ulcers and human fibroblast cells treated with AGEs

AIM：To investigate cell apoptosis in diabetic foot ulcers and the effect of advanced glycosylation end products (AGEs) on apoptosis in human fibroblast cells. METHODS：Diabetic foot patients (n=18) and 18 age-matched non-diabetic controls were recruited. The clinical and biochemical features were compared by statistics methods. Skin biopsies were obtained from foot. Cleaved caspase-3 was measured by immunohistochemistry using the technique of streptavidin-biotin complex (SABC) staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique was used to detect apoptosis of the skin tissues. Human primary foreskin fibroblasts were isolated and cultured in the presence of 5.6 mmo/L glucose, 25 mmo/L glucose, fluctuant glucose (changing the glucose from 5.6 mmo/L to 25 mmo/L every 8 h) or AGEs (150 mg/L, containing 5.6 mmo/L glucose). After 72 h treatment, Western blotting was used to determine the levels of the apoptotic protein cleaved-caspase-3. Other cells were trypsinized, washed with cold PBS and incubated with PI and Annexin V-FITC, then analyzed by flow cytometry to detect cell apoptosis. RESULTS：Diabetic patients had higher levels of fasting blood glucose (FBG), 2-hour postprandial blood glucose (2 h PBG) and glycosylated hemoglobin A1c (HbA1c), and longer wound duration. The protein level of cleaved caspase-3 was significantly higher in diabetic group, suggesting that apoptosis was increased in diabetic skin tissues. TUNEL analysis showed that apoptotic index was higher in diabetic group compared with that in non-diabetic group (8.4%±1.5% vs 3.8%±08%), which further confirmed that cell apoptosis was increased in diabetic foot tissues. In human fibroblasts, the levels of cleaved caspase-3 in normal group, sustained high glucose group, fluctuant high glucose group and AGEs group were 080±0.13, 1.22±0.18, 1.46±0.32 and 1.83±0.25, respectively. The apoptotic rates detected by flow cytometry were 2.43%±0.19%, 2.89%±0.51%, 3.99%±0.24% and 6.83%±0.36%, respectively. Both the level of cleaved caspase-3 and the apoptotic rate in AGEs group were higher than those in normal glucose group and sustained high glucose group. CONCLUSION：Increased apoptosis in diabetic foot ulcers is one of the most important reasons for impaired wound healing. As compared to sustained high glucose and glucose fluctuations, AGEs induce greater apoptosis in human fibroblast cells.     

付里叶变换近红外漫反射光谱定量分析数学模型的建立与评价

本文在I的研究基础上,根据近红外漫反射光谱定量分析的原理,以谷子、玉米、小麦样品为实验材料,选用近代回归分析的方法,研究了谷子、玉米蛋白质及小麦沉淀值品质分析近红外光谱定量数学模型的建立与评价。     

小麦幼苗吸收H_2PO_4~-动态的室内试验与数学模拟

 在不同磷营养液培养的基础上,对耗竭48 h后的CA9325和晋麦2号(JM2)小麦幼苗吸收H2PO4-动态过程进行了室内试验及数学模拟。结果表明,缺磷时,2个品种小麦的根冠比高于供磷植株;CA9325的生物量和含磷量均高于JM2。吸收H2PO4-的动力学参数表明,缺磷的CA9325根系对H2PO4-的亲合力大,最大吸收速率也高。与缺磷小麦相比,供磷后2品种小麦植株的生物量和含磷量均显著提高,根冠比均显著降低,但各供磷水平间差异不明显。在生物试验的基础上,对小麦根系吸收H2PO4-动态的结果进行了数学模拟,表     

食盐、蔗糖及果汁与牛肉干风味数学模型的建立及分析

本文应用二次正交旋转组合设计建立调味料：食盐、蔗糖及浓缩汁添加量与牛肉干风味评价的数学模型，通过模型分析初步揭示了牛肉干的风味与各调味料的内在规律。得出调味料优化添加范围，即风味最好的调味料添加量在食盐为１．９％左右、蔗糖为１４．０％左右、果汁为０．５％左右。并进行了检验。     

传统农业技术向现代农业技术的转变-继承、改造和提升

根据中国传统农业技术的特点,通过分析其历史演变过程,对比传统农业技术与现代农业技术的不同特征,提出在实现农业现代化的过程中,要正确对待传统农业技术,继承其优良传统,改造其落后和不完善的地方,最终将传统农业技术提升为现代农业技术的组成部分,是实现传统农业现代农业技术转变的有效途径和必由之路。     

春大豆高产栽培与数学模型研究

[目的]探讨春大豆优化施肥方案。[方法]采用二次回归正交旋转组合设计试验,分析N、P2O5、K2O对大豆产量的影响效应,并建立产量优化模型,提出N、P、K肥的适宜取值区间。[结果]产量优化模型为Y(kg/hm2)=3 671.36-107.58X1+160.64X2+144.90X3-276.50X21-140.14X22-183.15X23-184.33X1X3,该模型对试验点的拟合程度较好。当N、P2O5、K2O施用量分别小于36.11、61.46和35.93 kg/hm2时,大豆产量随施用量增加而逐渐提高,反之,产量逐渐降低。在大豆生产过程中,应适当增施N、P、K肥。由于N肥的负效应较大,须严格控制施用量。获得产量大于3 600 kg/hm2的施肥方案为:纯N 25.78~40.88 kg/hm2,P2O552.0~68.0 kg/hm2,K2O34.34~45.66 kg/hm2。[结论]该研究可为建立春大豆高产栽培技术体系提供参考。