基于分散决策的生猪供应链上发展沼气项目的激励机制优化

首先从研究生猪供应链养殖企业发展沼气项目的机制入手,明确了生猪供应链发展沼气项目的动因、模式和结果。其次,通过以一类发展较好的基于分散决策利润共享的生猪供应链模式为例研究,建立了以养殖企业利润最大为目标函数,屠宰加工企业利润最大为约束条件的优化模型,并进行了模型分析,得出了通过基于分散决策实行利润共享发展沼气项目,可以解决产业链上独立经济主体的循环经济目标不一致和行为不协调问题,既达到延长生猪供应链的目的,又有利于增加系统协调和稳定。最后,利用实证分析,证明基于分散决策采取利润共享推进发展沼气项目的激励协调机制是可行的,同时利用线性规划方法为生猪供应链解决粪便污染环境的难题和推进沼气项目提高利润优选出了一个切实可行的激励机制优化方案。     

DNA fragmentation in leukocytes following subacute lowdose nerve agent exposure

The objective of the present study was to determine levels of DNA fragmentation in blood leukocytes from guinea pigs by single-cell gel electrophoresis (comet assay) after exposure to the chemical warfare nerve agent (CWNA), soman, at doses ranging from 0.1 LD₅₀ to 0.4 LD₅₀, once per day for either 5 or 10 days. Post-exposure recovery periods ranged from 0 to 17 days. Leukocytes were imaged from each animal, and the images analyzed by computer. Data obtained for exposure to soman demonstrated significant increases in DNA fragmentation in circulating leukocytes in CWNA-treated guinea pigs compared with saline-injected control animals at all doses and time points examined. Notably, significantly increased DNA fragmentation was observed in leukocytes 17 days after cessation of soman exposure. Our findings demonstrate that leukocyte DNA fragmentation assays may provide a sensitive biomarker for low-dose CWNA exposure.Received 29 July 2003; accepted 14 August 2003     

Identification of the bioactive peptide PEC-60 in brain

PEC-60 is a 60-residue peptide originally isolated from pig intestine. It inhibits glucose-induced insulin secretion from perfused pancreas in a hormonal manner and also has biological activity in the immune system. PEC-60-like immunoreactive material has been reported in catecholamine neurons of the central and peripheral nervous systems, but the peptide has not been identified from that material. We have now isolated PEC-60 from pig and rat brains with a method that combines column purification procedures with the specificity of a radioimmunoassay and the sensitivity of mass spectrometry to directly identify the peptide. The results show that PEC-60, like many other peptides, is expressed in the gastrointestinal tract and the central nervous system. The specific regional brain distribution and interaction with classical neurotransmitters raise the possibility that PEC-60may play a role in the central nervous system disorders involving dopamine dysregulation. Received 6 December 2002; received after revision 10 December 2002; accepted 11 December 2002 RID="*" ID="*"Corresponding author.     

猪血超氧化物歧化酶纯化与分析─—一种铜盐沉淀新工艺

本文建立铜盐沉淀、选择热变性、ＳｅｐｈａｄｅｘＧ—１００层析方法从猪血中提纯超氧化物歧化酶，纯化倍数１８６．５．该酶在聚丙烯酰胺凝胶电泳中呈一蛋白带．纯酶的比活性为９３２５ｕ／ｍｇ—ｐｒ（邻苯三酚—３２５法）．通过ＳＤＳ—ＰＡＧＥ法测出分子量为３００００．该酶对热稳定，纯酶液的最大吸收波长为２６０ｕｍ．     

高速排水型船的运动性能预报

给出一种基于高速细长体理论的预报高速排水型船在波浪上运动性能的数值方法。在高速细长体理论的定解条件中 ,自由面条件是三维的 ,而控制方程和物面条件则是二维的。采用时域自由面 Green函数将定解问题转化为物面上的积分方程 ,进而求解水动力系数和船舶运动方程。对NPL 系列单体船型的运动性能作了理论预报 ,并与实验结果和用切片法的理论预报结果作了比较。结果表明 ,高速细长体理论的预报结果与试验结果更为接近 ,而切片理论由于受到纯二维假定的限制 ,在高航速情况下 ,预报精度较差。     

薄壁圆柱壳的边缘变形

对不同方位的壳体承受不同方向的边缘力和边缘力矩时的边缘变形的解法进行了探讨；给出了方便工程应用的求解边缘变形的方法和公式，并计算了相同材料、中径和壁厚情况下，工程上常见的压力容器组合壳体的边缘变形和边缘载荷。所得结果简化了边缘变形的求解过程，深化和充实了压力容器理论，并且可为工程计算直接引用。     

3-甲基组氨酸三室模型在研究猪骨骼肌蛋白质降解中的应用

3-甲基组氨酸(3MH)主要是动物骨胳肌蛋白分解代谢产物，它不能再用于合成蛋白，因而3MH是研究动物骨胳肌蛋白降解率的一个可行示踪物．将标记的3MH经颈静脉注射，对血液中的同位素丰度进行观测，再根据猪体内3MH代谢特点，构建出猪骨胳肌蛋白降解的三分域模型．本文着重对该模型的的理论基础进行了讨论。     

The effect of ascorbic acid on cadmium accumulation in guinea pig tissues

Accumulation of cadmium in organs of guinea pigs after subchronic oral cadmium treatment (1 mg Cd/animal/24 h) was in the following order: kidneys > liver > heart > testes > brain. The preventive effects of high doses of ascorbic acid (AA) against cadmium deposition were more pronounced in the testes, heart and brain, and in the kidney only after short-term cadmium treatment. Ascorbic acid had no protective effect on cadmium accumulation in the liver.     

Circulatory physiology ofNautilus

Summary Present information places the circulatory performance ofNautilus at the bottom of the cephalopod scale but shows it to be distinctly different from that of gastropods and bivalves. The feature which clearly places it closer to its coleoid relatives than to other groups of molluscs is the enhancement of the branchial circulation by the beating pericardial glands and renal appendages. These organs have their homologues in the coleoid pericardial chamber. Recently, studies of living embryos show that the development of a functional circulatory system is an early event during ontogeny and that this information may have important implications for our understanding of the evolution of a branchial circulation.     

Effects of methylene blue on electrical behavior of myenteric neurons

Summary Intracellular recording methods were used to investigate the action of methylene blue on electrical behavior of myenteric neurons in guinea pig small intestine. The neurophysiological studies were done in parallel with studies on contractile activity of the intestinal musculature. Methylene blue depolarized the membranes, increased the input resistance, augmented excitability and reduced postspike hyperpolarizing potentials in AH/Type 2 myenteric neurons. These effects, with the exception of suppression of postspike hyperpolarization, were reversed by exposure to elevated calcium. The mechanism of action of methylene blue appeared to be suppression of calcium-dependent potassium conductance in the neuronal membranes. The neuronal action of methylene blue was manifest as a release of excitatory neurontransmitter substances with evoked contraction of the small intestinal longitudinal muscle.