日本落叶松引种区林地棕壤肥力的多变量分析

本研究从日本落叶松引种区林地棕壤9个主要理化性状及与之配套的17株优势木材料入手,采用多变量分析方法筛选出影响该地区日本落叶松生长的主要肥力因子为氮及磷,並据此将该林地棕壤划分为9个肥力类型。在进行聚类分析时,本研究的创新在于以任意二样本点在各主成份上的坐标值为变量,以各主成份的贡献率为权重,重新定义欧氏距离公式,对主成份坐标值聚类,使其更为合理、直观。同时采用回归分析拟合出理化性状间的多个回归方程。此研究为该林地科学施肥、速生丰产、永续利用提供了可靠的数量依据。     

山楂叶螨种群空间格局及其应用的研究Ⅱ．成螨种群密度综合估计及其抽样技术

本文结合Ｉｗａｏ零频率法和Ｇｅｒｒａｒｄ阈限密度法,提出一种改进的种群密度估计方法──“综合阈限密度估计法”,并由此探讨了苹果树上山楂叶螨成螨的密度估计及其抽样技术．采用零样频率来估计成螨的平均密度,并得到用概率保证的理论抽样数模型．比较结果表明,零频率法所需的理论抽样数少于直接计数法．综合阈限密度估计法的拟合效果更为显著．     

金属离子螯合剂对橙汁中L—抗坏血酸的保护及其机理探讨

本文研究了在加热过程中金属离子螯合剂植酸、聚磷酸钠和EDTANa_2对橙汁和橙汁模拟体系中L—抗坏血酸的稳定作用,并采用红外光谱和紫外差光谱对EDTANa_2的保护机理作了初步探讨。结果表明:植酸和聚磷酸钠均不能降低Cu~(2+)对橙汁模拟体系中L—抗坏血酸氧化降解的催化作用,而EDTANa_2不仅能络合Cu~(2+),减少L—抗坏血酸的催化降解损失,而且红外光谱和紫外差光谱及溶剂微扰研究还揭示出EDTANa_2可与L—抗坏血酸形成氢键保护,这种氢键保护作用受到糖和柠檬酸的不利影响。     

我国红螯蛛属2新记录种（蜘蛛目：管巢蛛科）

记述了我国红螯蛛属2新记录种,即绿红螯蛛Chiracanlhium virescens(Sundevall)和飘红螯蛛Chiracanlhium erralicum(Wallckenaer)。     

三硝基甲苯对大鼠晶状体中可溶性蛋白质、巯基及二硫键含量的影响

我们采用三硝基甲苯（ＴＮＴ）与大鼠晶状体体外培养的方法,动态观察了晶状体中可溶性蛋白质、非蛋白质巯基、蛋白质巯基、蛋白质结合巯基及二硫键含量的变化,发现随着三硝基甲苯作用时间的延长,可溶性蛋白质、非蛋白质巯基及蛋白质巯基均减少,蛋白质结合巯基及二硫键交联的蛋白质含量增加,其中可溶性蛋白质、非蛋白质巯基及二硫键含量的变化皆达到了统计学上显著意义水平（Ｐ＜０．０５）。     

自由基与软骨基质胶原蛋白类型改变

本文利用ＳＤＳ－聚丙烯酰胺凝胶电泳方法,定量研究了体外培养的软骨细胞和软骨组织基质中Ⅱ型胶原蛋白的含量。结果表明氧自由基（·Ｏ－２和·ＯＨ）和具有自由基性质的物质（黄腐酸,镰刀菌毒素）可使软骨细胞合成,分泌异常的非Ⅱ型的胶原蛋白,同时,硒化合物可明显地抑制此种效应。     

Neutrophil priming mechanisms of sulfolipid-I and n-formyl-methionyl-leucyl-phenylalanine

The principal sulfatide of virulentMycobacterium tuberculosis, sulfolipid-I (SL-I), both directly stimulates neutrophil superoxide (O ₂ ^– ) release and, at substimulatory concentrations, primes these cells for markedly enhanced oxidative responsiveness to other stimuli. The present study was undertaken to clarify the priming mechanisms by comparing cellular events following priming doses of SL-I with those following priming with N-formyl-methionyl-leucyl-phenylalanine (FMLP). We compared the involvement of the calcium cation (Ca²⁺), as well as membrane protein kinase C (PKC) activity and the translocation of NADPH oxidase-cytosolic cofactor effected by priming levels of the two agonists. The investigation led to two important conclusions. First, we clearly demonstrate that priming by both SL-I and FMLP results from activation of cellular processes that are not involved in direct oxidative activation. For example, whereas direct induction of O ₂ ^– generation by FMLP and SL-I required increases in intracellular Ca²⁺, an increase in intracellular calcium concentration ([Ca²⁺]_i) above basal levels was not required for priming. Second, we identified key differences in the cellular responses to priming doses of SL-I and FMLP. Whereas increased membrane PKC activity caused by priming doses of FMLP was only partially blocked by chelation of intracellular Ca²⁺, Ca²⁺ chelation completely inhibited the increase in membrane PKC activity caused by SL-I. NADPH oxidase-cytosolic factor translocation to plasma membranes was completely blocked by pertussis toxin when priming doses of SL-I were used. This guanine-nucleotide-binding protein inhibitor had no effect on FMLP-dependent translocation of the oxidase cofactors. The comparative approach introduced in this report provides a valuable and novel method to discern the complex interactions of various cellular processes that regulate the state of activation of stimulated cells.     

Posttranslational regulation of nitrogenase activity by anaerobiosis and ammonium in Azospirillum brasilense.

In the microaerophilic diazotroph Azospirillum brasilense, the addition of fixed nitrogen or a shift to anaerobic conditions leads to a rapid loss of nitrogenase activity due to ADP-ribosylation of dinitrogenase reductase. The product of draT (DRAT) is shown to be necessary for this modification, and the product of draG (DRAG) is shown to be necessary for the removal of the modification upon removal of the stimulus. DRAG and DRAT are themselves subject to posttranslational regulation, and this report identifies features of that regulation. We demonstrate that the activation of DRAT in response to an anaerobic shift is transient but that the duration of DRAT activation in response to added NH4+ varies with the NH4+ concentration. In contrast, DRAG appears to be continuously active under conditions favoring nitrogen fixation. Thus, the activities of DRAG and DRAT are not always coordinately regulated. Finally, our experiments suggest the existence of a temporary period of futile cycling during which DRAT and DRAG are simultaneously adding and removing ADP-ribose from dinitrogenase reductase, immediately following the addition of a negative stimulus.