无样地法在暖温带落叶阔叶林群落调查中的应用

本文以秦岭太白山自然保护区内锐齿栎(Quercus atiena var. acuteserrota)为优势的暖温带落叶阔叶林为对象,采用与大样地(0.5公顷)实测结果的比较,研究了无样地法中的中点四分法取样技术在暖温带落叶阔叶林中的应用。认为中点四分法取样技术,具有较高的精度和效率,可适用于暖温带落叶阔叶林。并用种点数曲线确定了暖温带落叶阔叶林的最小点数为15个。     

Biological responses to overload training in endurance sports

Five subjects undertook 10 days of twice daily interval training sessions on a treadmill followed by 5 days of active recovery. On days 1, 6, 11, and 16 the subjects were required to undertake a test of submaximal and maximal work capacity on a treadmill combined with a performance test consisting of a run to exhaustion with the treadmill set at 18 km.h-1 and 1% gradient. Also on these days a pre-exercise blood sample was collected and analysed for a range of haematological, biochemical and immunological parameters. The subjects experienced a significant fall in performance on day 11 which had returned to pretraining levels on day 16. Serum ferritin concentrations were depressed significantly from pretraining concentrations at the conclusion of the recovery period while the expression of lymphocyte activation antigens (CD25+ and HLA-DR+) was increased both after the training phase and the recovery phase. The number of CD56+ cells in the peripheral circulation was depressed at the conclusion of the recovery period. Several parameters previously reported to change in association with overload training failing to reflect the decrease in performance experienced by subjects in this study, suggesting that overtraining may best be diagnosed through a multifactorial approach to the recognition of symptoms. The most important factor to consider may be a decrease in the level of performance following a regeneration period. The magnitude of this decreased performance necessary for the diagnosis of overtraining and the nature of an "appropriate" regeneration period are, however, difficult to define and may vary depending upon the training background of the subjects and the nature of the preceding training. It may or may not be associated with biochemical, haematological, physiological and immunological indicators. Individual cases may present a different range of symptoms and diagnosis of overtraining should not be excluded based on the failure of blood parameters to demonstrate variation. However, blood parameters may be useful to identify possible aetiology in each separate case report of over-training. An outstanding factor to emerge from this study was the difficulty associated with an objective diagnosis of overtraining and this is a possible reason why there have been new accounts of overtraining research in the literature.     

水稻染色体标本制备的风油精法

水稻的染色体较小,不同的染色体在形态上较难区分。常规的压片技术由于很难使染色体分散,且也不能完全排除细胞质的干扰,因而很不适用于水稻染色体核型分析及显带。Kurata 等(1978)采用酶解与火焰干燥技术制备水稻染色体标本,获得清晰的染色体图象,从而成功地进行了水稻染色体的核型分析。陈瑞阳等(1982)参照人类染色体     

An inflatable minirhizotron system for root observations with improved soil/tube contact

Commonly used minirhizotrons consisting of a transparent tube inserted into the soil seldom attain good contact between the tube and the soil, which leads to root growth occurring in a gap rather than in the soil. A new system is described involving an inflatable flexible rubber wall, made from a modified motorcycle tube. Pressure ensures a proper tube/soil contact so that the environmental circumstances for root growth along the tube more closely correspond to those in the undisturbed soil. Before the endoscope slide is introduced into the minirhizotron for taking pictures, the inflatable tube is removed, so that there is no-often opaque-wall between the endoscope and the roots. This improves the picture quality and facilitates the analysis of root images.     

Kinetic and molecular orbital studies on the rate of oxidation of monosubstituted phenols and anilines by lactoperoxidase compound II in comparison with the case of horseradish peroxidase

The second-order rate constant (k4) for the oxidation of monosubstituted phenols and anilines by lactoperoxidase compound II was examined by Chance's method [B. Chance, Arch. Biochem. Biophys. 71 (1957), 130–136]. When the electronic states of these substrates were calculated by an ab initio molecular orbital method, it was found that the log k4 value correlates well with the highest occupied molecular orbital (HOMO) energy level but not with the net charge or frontier electron density. These results are essentially similar to those reported previously in the case of horseradish peroxidase [J. Sakurada, R. Sekiguchi, K. Sato, and T. Hosoya, Biochemistry 29 (1990), 4093–4098], showing some dissimilar features which are considered to reflect the structural difference between the two enzymes.Abbreviations HOMO highest occupied molecular orbital - HRP horseradish peroxidase - LPO lactoperoxidase (EC 1.11.1.7) - LUMO lowest unoccupied molecular orbital     

Neutralizing effect of zinc oxide on dehydroabietic acid-induced toxicity on human polymorphonuclear leukocytes

The cytotoxic effect of dehydroabietic acid (DHAA), a resin acid found in rosin, was studied on human polymorphonuclear leukocytes using leakage of 51Cr from prelabeled cells, supravital staining, and transmission electron microscopy. DHAA caused a strong dose-related release of 51Cr, a high uptake of trypan blue, and total cell necrosis, as seen in transmission electron microscopy. Albumin slightly reduced the toxic effects, whereas the addition of zinc in various forms strongly inhibited these toxic effects of DHAA in the concentration range of 10-500 micrograms/mL. In the presence of albumin, zinc oxide as a suspension inhibited the damage of the cell membranes more than a filtrate of zinc oxide, indicating a subsequent slow release of zinc from the zinc oxide.     

Metabolism of a subtropical Brazilian lagoon

Total community, planktonic and benthic metabolisms were measured by using the carbon dioxide production and consumption, the diurnal curve' method and the in situ bottle incubation technique over an annual cycle in two sublagoons of the Saquarema Lagoon, Brazil. Metabolic rates of the phytoplankton-based lagoon were characterized by considerable daytime and daily variability in production and respiration, by a seasonal shift between net autotrophy and heterotrophy and by an annual balance of production (P = 105 ± 65 mmoles/m²/dayn = 25) and respiration (R = 102 ± 50 mmoles/m²/dayn = 25). Total community metabolism was similar throughout the lagoon, but phytoplankton assimilation rates and benthic respiration showed spatial differences. Bottle incubations compared to total community free water respiration suggested that the pelagic community was 2–5 times more active than the benthos     

Modelling of formation processes of inclusion complexes of coumarin laser dyes and β-cyclodextrin by the MM2 force field method. I. 7-Amino-4-methylcoumarins

In order to improve the generating and photochemical properties of coumarin laser dyes, the following active media were synthesized: inclusion complexes of -cyclodextrin (-CD) and 7-amino-4-methylcoumarins (COU1, COU102, COU120). Complex formation processes were studied, and the structure of the inclusion complexes was estimated using the method of MM2 molecular mechanics. The data obtained suggest the reasons underlying the complex structure effects on their spectral, luminescent and generating characteristics.     

用TOPSIS方法评价黄土丘陵区草场质量的研究

一、自然概况黄土高原位于我国西北部,西起青海日月山,东抵山西太行山,北至晋陕长城,南达甘陕秦岭,构成一个独具特色的、比较完整的自然区域,其地理范围大致是北纬34°—41°,东经103°—113°之间。高原到处有起伏的黄     

树干径流过程的动态响应模型

本文用实验测试法测量了干流过程。结果表明,干流过程曲线与R-L-C电路瞬态响应过程(包括输入、输出曲线)极为相似。据此,可用R-L-C电路瞬态响应过程曲线拟合干流过程,求出解析解。在计算机上调试参数,讨论其水文学意义,定性分析参数与影响干流因子的关系,取得了满意的结果。