Lotka-Volterra数学模型在草地管理中的应用

介绍了Lotka-Volterra数学模型建立、求解方法,详细讨论了该模型在草地生态系统中的应用特点。通过分析认为可以利用Lotka-Volterra模型调控草地生态系统中载畜量与草地牧草产量间的关系,从而准确指导草地畜牧业生产。     

发展学基本理论与我国当前农村发展问题研究

基于师法自然的理念,提出了发展学基本原理(生态基础原理,民生至上原理,和谐发展原理),社会组织的职能与责任,劳动公平与劳动计量,社会规范的生命周期与进化,社会发展多元化、去货币化、减商化理论,和谐社会评价指标体系,社会系统的分析评价方法与社会系统管理理论与方法,分析了我国农村当前发展障碍并提出了对策。     

Energy requirements of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation

This experiment was conducted to investigate the energy requirement of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation. Fifteen ewes after parturition were randomly assigned to three treatments: ad libitum(100%) feed intake and 80 or 60% ad libitum intake, and another nine non-pregnant ewes were assigned to a blank control group. Digestibility trials were performed in the non-pregnant ewes and in the lactating ewes on the 20 th, 50 th, and 80 th d of lactation. In parallel with the digestibility trial, a respirometry experiment was conducted to determine the methane and carbon dioxide production with an open-circuit respirometry system that was equipped with respiratory chambers. The net energy(NE) and metabolizable energy(ME) requirements for maintenance and growth were calculated using the carbon and nitrogen balance method. The results revealed that the carbon(C) and nitrogen(N) excretions and energy losses at faeces and urine, as well as the output of methane and CO2, increased significantly with decreasing feed intake(P0.01). The apparent digestibilities of C in th e stages of non-pregnancy and early, middle and late lactation were 55.8–58.3%, 62.5–73.8%, 64.8–71.3%, and 61.7–65.0%, respectively, and the apparent digestibilities of N were 45.2–51.3%, 73.7–82.7%, 72.8–80.5%, and 73.6–76.5%, respectively. The corresponding energy apparent digestibilities were 52.0–56.3%, 60.7–76.6%, 61.0–68.8%, and 61.4–67.7%, respectively. The ME/DE(digestible energy) values were 79.5–85.9%, 79.4–83.5%, 81.0%–85.3% and 78.6–82.9%, respectively. The maintenance requirements of NE, ME, and the efficiencies of ME utilisation for maintenance during the stages of non-pregnancy and early, middle and late lactation were 215.5, 253.1, 247.7, and 244.7 k J kg~(–1) BW0.75 d, and 372.4, 327.1, 320.9, and 362.0 k J kg~(–1) BW0.75 d, and 0.58, 0.77, 0.77, and 0.68, respectively. The ME requirement for the growth of non-pregnant ewes was 31.3 MJ kg~(–1) BW gain.     

Stability Contrast of Landslide Disaster After Repeating Control

Xiang-jiapo landslide,which consists of shallow layer,middle layer and deep layer,is a multi-landslide with several layers.Influenced by geological condition and rainfall,it have not obtained good effect even after three-time control.Because the distortion of landslide increase so fast, the government planed to control the landslide for the forth time.Based on monitoring data of the landslide movement,the paper make a constrast analysis of 3D numerical simulation's calculating between the formal control and the forth time control by a non-linear finite elements programm ABAQUS.Both results of numerical simulation and monitoring indicate that the forth time control have achieved good effect.     

慢性冷暴露对小鼠肝脏抗氧化功能的影响

本试验旨在探讨慢性冷暴露对小鼠肝脏抗氧化功能的影响。体内慢性冷暴露模型建立：试验将12只3周龄C57BL/6雄性小鼠饲养1周后随机分为2组（对照组和冷暴露组）,每组6只。冷暴露组小鼠每日随机放置在4℃环境中3 h,连续4周。冷暴露结束后将所有小鼠同时安乐死,并收集其血液和肝脏。体外冷暴露模型建立：将小鼠肝细胞系AML12细胞随机分为4组（对照组、冷暴露1 h组、冷暴露3 h组、冷暴露6 h组）,先在37℃培养箱中培养24 h,然后将冷暴露组细胞置于32℃培养箱中分别亚低温冷刺激0、12、24、36 h,冷刺激结束后将细胞刮取下来进行后续试验。用酶联免疫吸附测定（ELISA）法对小鼠血清中谷胱甘肽（GSH）和丙二醛（MDA）含量进行检测,用Western Blot检测小鼠肝细胞和肝脏组织中抗氧化蛋白硫氧还蛋白-1(Trx-1)和硫氧还蛋白互作蛋白（TXNIP）的表达情况。结果显示：与对照组相比,冷刺激36 h后AML12细胞数量显著下降（P<0.05）。与对照组相比,Trx-1的蛋白表达量在组织和细胞中都显著降低（P<0.05）,TXNIP的蛋白表达量显著增加（P<0....     

Effect of L-carnitine on apoptosis and oxidant damage of cardiomyocytes induced by hypoxia/reoxygenation in vitro

AIM: To examine the effects of L-carnitine on apoptosis and oxidant injury in cultured neonatal rat cardiomyocytes induced by hypoxia/reoxygenation and its possible mechanism. METHODS: The cultured cardiomyocytes were divided into three groups， control， A/R group （anoxia for 120 min, reoxygenation for 240 min） and L-carnitine treatment group, in which cells were exposed to 20 mg/L, 50 mg/L, 100 mg/L, 200 mg/L L-carnitine respectively at 2 h before anoxia. The superoxide dismutase (SOD), succinate dehydrogenase (SDH) activities and malondialdehyde (MDA) content were examined, and the apoptosis was determined by flow of cytometry (FCM). In addition, the ultrastructure was observed by transmission electron microscopy. RESULTS: In A/R group, SOD and SDH activities were lower, the apoptosis rate and MDA content were higher than those in control group (P<0.05). In L-carnitine treatment group, SOD and SDH activities were higher, the apoptosis rate and MDA content were lower than those in A/R group, a L-carnitine concentration-dependent effect was found. Moreover, impairment of myocardial ultrastructure was more severe in A/R group than L-carnitine treatment group. CONCLUSION: L-carnitine can protect cardiomyocytes against hypoxia/reoxygenation-induced injury in a dose-dependent manner.     

In vitro inhibitory effect of CD8+ cells from patients with aplastic anemia on normal CFU-Mk growth is blocked by cimetidine

AIM: To investigate the effect of CD8+ cells from aplastic anemia (AA) patients and its histamine type II (H2) receptors on the growth of normal CFU-Mk. METHODS: The effects of CD8+ cells and/or cimetidine, on normal human CFU-Mk growth were studied by using CFU-Mk assay. RESULTS: The CD8+ cells from the perpheral blood of AA patients significantly suppressed the growth of normal allogeneic CFU-Mk. This inhibitory effect was blocked by cimetidine at concentration of 1.0×10-5 mol/L. 1.0×10-5 mol/L cimitidine alone didn't inhibit the growth of normal CFU-Mk. CONCLUSION: H2 receptor antagonist cimitidine abolishes the suppressive effect of AA patients CD8+ cells on the growth of normal CFU-Mk.