宁夏宁南山区红庄林场甘肃鼢鼠分布密度与危害研究

通过对红庄林场不同立地条件随机抽样调查,结果表明：山间谷地甘肃鼢鼠平均密度为33只/hm^2;草甸山坡甘肃鼢鼠平均密度为13．3只／hm^2;林地甘肃鼢鼠平均密度为6．3只／hm^2。由于鼢鼠破坏活动,幼林受害率轻者为10％～20％,重者达到70％-80％。鼢鼠危害已制约当地造林工程的发展。     

具有Holling-Ⅳ功能反应的周期捕食者非密度制约的捕食食饵模型的持久性和灭绝性（英文）

本文研究了一类具有功能反应周期的捕食食饵模型,其中捕食者是非密度制约的.我们得到使系统持久灭绝,周期解存在的积分形式的充分条件.把一些关于捕食者密度制约的重要的结论推广到了捕食者非密度制约的情形.     

高原鼠兔种群生产量生态学的研究Ⅲ.高原鼠兔生命率非密度制约与密度制约的种群动态趋势

本文以高原鼠兔(Ochotona curzoniae)自然种群生命表的统计参数为基础,根据非密度制约Leslie模型及具有密度制约反馈的标准Leslie修正模型,分别预测了该种群在1982-2001年间的发展趋势。在菲密度制约条件下,该种群呈指数增长。在密度制约存在肘,种群增长趋于平衡状态,且存滔率密度制约较繁殖率密度制约对种群的作用更大。存活率密度制约与非密度制约的年龄结构均为Leslie分布,繁殖率密度制约作用的种群稳定年龄分布更平均,其平衡状态的种群大小则由模型的参数决定。     

海三棱藨草种群的密度与生物量动态

本文研究了上海市南汇县东海农场海堤外侧滩涂上海三棱藨草种群的密度动态、高度生长动态、生物量动态以及它们之间及其与环境之间的相互关系。研究结果表明:在环境条件相对稳定的地带A和B内,海三棱藨草种群的高度、高度生长和生物量在生长期内符合Logisfis增长。种群生物量动态与密度动态可分为3个阶段,其中阶段Ⅱ符合Yoda等提出的-3/2自疏定律。地带B为海三棱藨草种群生长的最适地带。地带C内生境条件极不稳定,种群的数量动态变化亦相当剧烈。在不同环境条件下,密度制约因素和非密度制约因素对种群数量动态的相对作用是不同的。在环境条件较稳定的生境中(地带A和B),密度制约因素是决定种群数量动态的主要因素;在环境条件变化剧烈的生境中(地带C),非密度制约因素是决定种群数量动态的主要因素。     

海三棱蔗草种群的密度与生物量动态

本文研究了上海市南汇县东海农场海堤外侧滩涂上海三棱藨草种群的密度动态,高度生长动态、生物量动态以及它们之间及其与环境之间的相互关系。研究结果表明：在环境条件相对稳定的地带A和B内,海三棱藨草种群的高度、高度生长和生物量在生长期内符合Logisfic增长。种群生物量动态与密度动态可分为3个阶段,其中阶段Ⅱ符合Yoda等提出的-3/2自疏定律。地带B为海三棱藨草种群生长的最适地带。地带C内生境条件极不稳定,种群的数量动态变化亦相当剧烈。在不同环境条件下,密度制约因素和非密度制约因素对种群数量动态的相对作用是不同的。在环境条件较稳定的生境中(地带A和B),密度制约因素是决定种群数量动态的主要因素;在环境条件变化剧烈的生境中(地带C),非密度制约因素是决定种群数量动态的主要因素。     

非自治Lotka-Volterra型捕食扩散系统中有害时滞对该系统持久性的影响

研究了时滞对一类非自治Lotka-Volterra型捕食扩散系统的影响,该系统由n个斑块组成,食饵种群可以在斑块间迁移,而摘食者限制在某一个斑块不能扩散．我们假设密度制约项系数并不总是严格正的．通过运用比较定理及时滞泛函微分方程的基本原理,分两种情况表明了在一定条件下系统是一致持久的．两种情况的结果表明时滞的引入和变化即可能是“有害”,也可能是”无害”．进一步还说明了系统在一致持久性的条件下至少存在一个正周期解．这些结果是对已知的非自治Lotka-Volterra系统的一些结果的推广与改进．     

樟翠尺蛾种群动态与植物群落结构及气候因子的关系

在昆虫种群的研究中,Ｇｉｅｉｒ和Ｃｌａｒｋ等曾经提出生命系统的基本概念[1,2],认为生命系统由一个对象种群和作用于这个种群的环境所组成。控制昆虫种群增长的有密度制约因子(如食源)和非密度制约因子(如气候环境)。昆虫和植物之间的关系,历来是生态学研究的重要领域。通过长期的定点监测,研究某种昆虫种群动态与各种生态因子之间的关系,不仅可揭示动物和植物及环境之间互相影响的关系,对保护生物学理论的某些方面将有所发展,而且可为林业生产和环保工作提供如何应用生态学原理控制虫害,保护生物多样性和维护生态平衡的理论依据。樟翠尺…     

食饵种群具有收获（存放）率的第II类功能性反应模型的定性分析

本文研究了非密度制约的捕食与捕食系统中被捕食者（食饵）种群具有常数收获（存放）率的第Ⅱ类功能性反应模型的定性性质：当该系统具有存放率时,证明了该系统在一定的条件下极限环的存在性、不存在性及唯一性;当该系统具有收获率时,证明了该系统若存在正平衡点,则它是全局不稳定性。     

具Holling第Ⅱ类功能性反应的捕食者--食饵系统的定性分析

考虑捕食者无密度制约,食饵具有非线性密度制约的第二类Holling功能性反应捕食者－食饵系统。对该系统给出了完整的定性分析,证明了该系统至多有一个极限环,存在极限环的充要条件是平衡点不稳定。     

萼花臂尾轮虫有性生殖、种群增长和休眠卵产量间的关系

利用种群指数增长和Logistic增长模型,通过计算机模拟研究了萼花臂尾轮虫有性生殖发生的频率,后代中的混交雌体发率对种群增长和休眠卵产量的影响。在所模拟的参数范围内,随有性生殖发生频率由100％减小到20％,获得了大休眠卵产量所需的混交雌体百分率由9％增大到69％,随密度制约作用的增大（环境容纳量K值由1000减小到100）,该混交雌体百分率由18％增大到69％,休眠卵产量由1072．10降低至133．67,种群的内禀增长率与获得最大休眠卵产量所需的混交雌体百分率间呈曲线相关。当有性生殖发生得越频繁,种群增长所受的密度制约作用较小时,后代中10％－30％的个体为混交雌体时的种群中休眠卵产量较大。     

鲁北滨海盐生草甸獐茅群落生长季动态

作者在1982—1984年度对鲁北滨海盐土区的山东省沾化草场改良实验站的獐茅(Aeluropus littoralis var.sinensis)群落生长季内的群落动态及其与环境因子的关系进行了研究(其中1982—1983年配合草场站工作进行月份观测),认为温度的变化与群落生长季内的节律性有明显的相关性。根据生物量的变化,把一个完整的生长季划分为上升期和下降期两个时期,并讨论了这两个时期中生物量、半月平均气温和时间的关系以及生物量和半月平均气温的关系。     

O2 transport in cerebral microregions (mathematical simulation)

The effects of the circulation rate in capillaries, the intensity of O2 consumption by nerve cells and the capillary network density on the O2 tension distribution in the cerebral cortex have been studied, utilizing a mathematical model simulating actual neuron-capillary relationships. The model has been written as a system of equations in partial derivatives, its solution obtained by the net-point method. Regulatory variations of the capillary circulation rate in certain cerebral microregions have been shown to ensure similar changes in oxygen supply throughout the region. A drop of the pO2 level in a cerebral microregion with a rising O2 consumption by nerve cells is shown to be due, by 75 percent, to the increase of O2 consumption and by 25 percent, to the lower pO2 in the capillaries. Conversely, an increase in pO2 in microregions resulting from a lower O2 consumption by neurons is due by 75 percent, to a pO2 rise in capillaries and by 25 percent, at the expense of an O2 consumption decrease. In cerebral regions differing in capillary network density by 20 percent, changes in the conditions for oxygen supply to tissue are due by 1/3 to pO2 variations in the capillaries and by 2/3 to alterations in the diffusion distances.     

Dynamics of changes in histomorphometric indices of skin following local irradiation

Recovery of the histomorphometric indices of rat skin at the period from 38 to 150 days following local X-irradiation with doses of 2.5-20 Gy has been studied. It is shown that the rate of restitution of the epidermis and dermis thickness is 0.0021 and 0.0037 days-1, respectively. However, the dermis thickness is less than in the control. The hair follicle density not only fails to restore after irradiation with a dose of above 10 Gy but continues decreasing in time.     

Role of cell attachment in leaching of chalcopyrite mineral by Thiobacillus ferrooxidans

Summary Experiments on the leaching of copper from chalcopyrite mineral by the bacterium Thiobacillus ferrooxidans show that, in the presence of adequate amounts of sulphide, iron-grown bacteria preferentially oxidise sulphur in the ore (through direct attachment) rather than ferrous sulphate in solution. At 20% pulp density, the leaching initially takes place by a predominantly direct mechanism. The cell density in the liquid phase increases, but the Fe²⁺ is not oxidised. However, in the later stages when less solid substrate is available and the cell density becomes very high, the bacteria start oxidising Fe²⁺ in the liquid phase, thus contributing to the indirect mechanism of leaching. Contrary to expectations, the rate of leaching increased with increasing particle size in spite of the decreasing specific surface area. This has been found to be due to increasing attachment efficiency with increase in particle size. Offprint requests to: R. Kumar     

Long-term dynamics of density and diversity of ticks (Ixodidae) on the natural and disturbed territories

As result of long-years monitoring of density and diversity of Ixodidae living on Tomsk territory and in suburbs it has been shown that at least two species of ticks (I. persulcatus and I. pavlovskyi) inhabit there simultaneously. It has been studied that percent of I. pavlovskyi increased nearby town buildings. In the natural biotopes I. persulcatus is dominated, while I. pavlovskyi is founded rare. It has been shown, that during last 15 years (since 1996 till 2010) density of ticks increase on the town suburbs. The combination of ecological and chemical methods of tick suppression on the limited territory may leads to significant decreasing of ticks density. There is one biotope only, where non-typical for this region species (Dermacentor reticulatus and Haemaphysalis concinna).     

Hormonal regulation of prolactin storage in a clonal strain of rat pituitary tumor cells

GH4C1 cells (GH cells) are a clonal strain of rat pituitary tumor cells which secrete prolactin. GH cells have been used to study hormone secretion, but they store relatively little prolactin compared to normal prolactin-secreting cells. They are not suitable, therefore, for studying some aspects of pituitary function. We have found that the amount of prolactin GH cells store can be regulated. When GH cells were plated at 10(6) cells/well and treated for six days with 180 nM insulin or 1 nM estradiol, there was a 60 percent increase in prolactin storage compared to control cells. Insulin and estradiol in combination acted synergistically to cause a 190 percent increase in prolactin storage. In contrast, they were additive in increasing extracellular prolactin; there was a 40 percent increase in extracellular prolactin after insulin, a 20 percent increase after estradiol, and a 50 percent increase after insulin plus estradiol. The increases in prolactin storage were always greater than the increases in extracellular prolactin. The increases in prolactin storage were dose-dependent and reached maximal levels after four days of treatment with 180 nM insulin plus 1 nM estradiol. Reducing the plating density to 10(3) cells/well increased the response to insulin and estradiol to nineteenfold. Epidermal growth factor (10 nM) acted synergistically with estradiol and insulin in combination to increase prolactin storage 27-fold. The insulin- and estradiol-induced increase in extracellular prolactin was caused by a specific increase in the rate of prolactin synthesis. The fractional increase in prolactin storage above the increase in prolactin production could not be explained by an increase in prolactin synthesis, an increase in intracellular transit time, or a change in the cell-cycle distribution of the population. Hormone storage can, therefore, be regulated independently from other processes which control hormone production. The prolactin stored in response to insulin and estradiol was releasable by potassium depolarization. Following depletion of intracellular prolactin by depolarization, the cells retained their increased capacity for prolactin storage. The ability to increase prolactin storage will make GH cells a more useful system in which to study pituitary function.     

我国极端干旱天气变化趋势及其对城市水资源压力的影响

随着全球气候变化和水循环的改变,降水不均和持续干旱等极端天气事件的频度和强度增加,对水资源,尤其是人口和社会经济密度高的城市的水资源带来很大的影响和压力。为了探究我国干旱天气的变化趋势、区域特征、及其对城市水资源压力的影响,采用全国917个气象站点1951—2014年的逐日降水量数据集,分析了我国水资源及干旱的变化趋势和空间分布特征,并以我国289个主要地级市为研究对象,构建了气候变化情境下的城市基于区域降水禀赋的水资源压力评估方法,预测并展望了不同时段和不同代表性浓度路径(RCPs)情景下的未来城市水资源压力的情况。结果显示,我国极端干旱情况整体是随着全球气候变化增加的,年最长连续无降水天数变化速度的平均值为2.3d/100a,但是具有区域性,具体表现为南部地区干旱减缓而北部地区干旱严重。我国城市水资源压力受水资源禀赋的影响,呈现北方高而南方低的分布,除此之外水资源消耗大的大城市资源压力也比较大。随着气候变化,近期我国整体城市水资源压力相对现阶段增加了2%左右,具体水资源压力上升的城市有170个,水资源压力减少的城市有110个,剩下的9个城市水资源压力受气候变化的影响比较小。在低应对的RCP8.5情景下的城市水资源压力远远高于在RCP2.6情景,这说明减缓气候变化工作对降低我国城市水资源压力有积极作用;城市水资源压力的变化并不是均匀的,呈现南部减少而北部增加的变化趋势,我国华北地区城市的水资源压力最大,随着气候的变化,该地区的水资源压力也在随着时间不断增加,需要政府积极行动,提出有针对性和前瞻性的水资源规划方案,并依据方案采取措施,以应对气候变化造成的城市干旱增加。     

Evidence for an excess of rDNA in the testis of Drosophila melanogaster during rDNA magnification.

Summary Hybridization of rRNA with DNA extracted from different tissues of different genotypes have been performed. The results show that: 1) in DNA extracted from the testis of premagnified males there exists an excess of rDNA, which is consistent with the model proposed by Ritossa (1972) and by us (1973) to explain the phenomenon of magnification. 2) in DNA extracted from diploid tissues of different genotypes the percent of rDNA is directly proportional to the number of ribosomal genes. 3) in polytene cells the percent of rDNA for all genotypes so far studied is less than that in diploid cells and is not significantly dependant on the genotype. This last result is consistent with those of Spear and Gall (1973).     

Effect of rosuvastatin on obesity-induced cardiac oxidative stress in Wistar rats--a preliminary study

The prevalence of obesity has been rising alarmingly and it has now become a global concern causing an enormous economic burden on the health care system. Obesity is generally linked to complications in lipid metabolism and oxidative stress. The aim of the present study was to investigate the effect of rosuvastatin (10 mg/kg, po) on obesity-induced oxidative stress in high fat-fed Wistar rats. Oral administration of rosuvastatin (10 mg/kg) for 21 days along with high fat diet brought about significant elevation in serum high density lipoprotein and cardiac antioxidant enzymes levels (superoxide dismutase, catalase, glutathione, glutathione peroxidase, glutathione peroxidase-, glutathione reductase- and glutathione-S-transferase) while decreasing in serum lactate dehydrogenase, apolipoprotein-B, lipids (triglycerides, total cholesterol, low density lipoprotein-cholesterol, very low density lipoprotein-cholesterol and atherogenic index) and cardiac thiobarbituric acid reactive substances levels. The results were comparable with orlistat, a standard antiobesity drug. These preliminary results for the first time demonstrate that administration of rosuvastatin can be beneficial for the suppression of obesity-induced oxidative stress and dyslipidemia in high fat-fed Wistar rats.     

东洞庭湖丁字堤苔草群落特征及其影响因子

近20年来,洞庭湖湿地的湖草面积大幅度减少,退化严重.为寻求湖草的恢复途径,本文以位于洞庭湖丁字堤的短尖苔草为对象,依高程差划分成7条样带,调查了63个样方的植被特征(株高、盖度、密度、生物量、多样性指数)和土壤理化特征(土壤有机碳、全氮、全磷、土壤容重、土壤含水量).结果表明: 除多样性指数先下降后升高外,其余生物学指标均随高程增加呈现倒“U”型分布,即靠近水域(低海拔区)和堤岸(高海拔区)的苔草长势较差,而位于中间的苔草长势较好;土壤容重随高程增加而增加,土壤含水量的变化则相反,土壤有机碳和全氮含量均呈中海拔区高、低和高海拔区低的分布规律.主成分分析表明,影响苔草生物量的关键因子依次为土壤有机碳含量、氮含量、含水量和土壤容重.可见,提高土壤肥力和保持适当的土壤含水量可能是短尖苔草恢复的有效途径.