贮存老化对某弹药射程的影响研究

目的 研究长期贮存老化对某弹药射程的影响,确定其有效增程射角范围。方法 对130 mm某弹药在不同贮存老化时间下的射程进行数值仿真分析,揭示其射程和有效增程射角范围随贮存时间的变化规律。结合射程与贮存老化时间和射角之间的函数关系,提出以剩余推力比为表征参数的射程变化模型。结果 在相同贮存老化时间下,随着射角的增大,该弹药的射程呈现出先增大、后减小的趋势。相同射角下,射程随贮存老化时间呈线性下降趋势,有效增程射角范围逐渐减小。使用三次多项式拟合有效增程比与射角之间的函数关系,拟合方程的相关系数超过了0.997 0。该弹药射程变化模型的拟合结果与仿真计算结果的相关系数大于0.998 5,表明其可以准确描述该弹药的射程变化规律。结论 贮存老化会显著影响某弹药的射程和有效增程射角范围,在实际贮存和使用过程中,不能忽略其贮存老化因素。     

不同种类片岩耐崩解特性试验研究*

为研究不同种类片岩耐崩解特性,以曼家寨东帮边坡3种片岩为研究对象,通过室内耐崩解性试验和薄片鉴定分析,研究3种片岩崩解物形态特征、破坏模式和耐崩解性指数的变化规律,同时探讨3种片岩崩解差异产生的机理。研究结果表明:3种片岩的崩解差异特性与其物质组成成分密切相关;在相同循环次数下,3种片岩的耐崩解性指数有如下关系,绿泥石化片岩＞云母石英片岩＞石英云母片岩;片岩的崩解模式分为表层剥落、顺节理面劈裂、次生劈裂3个类型;从崩解微观机制上分析,岩石内部孔隙度这一微观结构的损伤是引起片岩崩解的内在因素,孔隙度的高低影响着损伤因子的大小,从而导致3种片岩崩解特性呈现差异性。     

广东省崩岗侵蚀规律和防治的研究

花岗岩风化壳的侵蚀是华南地区最严重的水土流失类型,而崩岗侵蚀则是其中最重要的侵蚀过程。本文主要通过调查、分析,论述了崩岗形成与演变的基本特点,剖析了崩岗侵蚀的内在机理及外部营力,从而揭示了广东省崩岗侵蚀的基本规律,并提出了相应的防治途径。     

Estimating Extinction Risk with Metapopulation Models of Large‐Scale Fragmentation

Habitat loss is the principal threat to species. How much habitat remains—and how quickly it is shrinking—are implicitly included in the way the International Union for Conservation of Nature determines a species’ risk of extinction. Many endangered species have habitats that are also fragmented to different extents. Thus, ideally, fragmentation should be quantified in a standard way in risk assessments. Although mapping fragmentation from satellite imagery is easy, efficient techniques for relating maps of remaining habitat to extinction risk are few. Purely spatial metrics from landscape ecology are hard to interpret and do not address extinction directly. Spatially explicit metapopulation models link fragmentation to extinction risk, but standard models work only at small scales. Counterintuitively, these models predict that a species in a large, contiguous habitat will fare worse than one in 2 tiny patches. This occurs because although the species in the large, contiguous habitat has a low probability of extinction, recolonization cannot occur if there are no other patches to provide colonists for a rescue effect. For 4 ecologically comparable bird species of the North Central American highland forests, we devised metapopulation models with area‐weighted self‐colonization terms; this reflected repopulation of a patch from a remnant of individuals that survived an adverse event. Use of this term gives extra weight to a patch in its own rescue effect. Species assigned least risk status were comparable in long‐term extinction risk with those ranked as threatened. This finding suggests that fragmentation has had a substantial negative effect on them that is not accounted for in their Red List category. Estimación del Riesgo de Extinción Mediante Modelos Metapoblacionales de Fragmentación a Gran Escala     

Ecological Determinants of Distribution Decline and Risk of Extinction in Moths

Abstract:  For successful conservation of species it is important to identify traits that predispose species to the risk of extinction. By identifying such traits conservation efforts can be directed toward species that are most at risk of becoming threatened. We used data derived from the literature to determine ecological traits that affect distribution, distribution change, and the risk of extinction in Finnish noctuid moths (Lepidoptera, Noctuidae). The ecological traits we examined included body size, larval specificity, length of the flight period, and overwintering stage. In addition, in monophagous species we examined the effects of resource distribution. Larval specificity, length of the flight period, and the overwintering stage each had an independent effect on the risk of extinction when the effects of other traits were controlled by entering all traits into the same regression model. Not a single trait predicted the risk of extinction when analysis was conducted without controlling for the other traits. This discrepancy among the results suggests that a single trait may not be enough to allow prediction of the risk of extinction. Instead, it seems that for successful, predictive conservation science data on several ecological characteristics are needed.     

Types of Ontogeny and Territorial Distribution of Small Rodents

In small rodents, differences in the average home range size, depending on the type of ontogeny and animal sex, have been revealed. The dynamics of changes in the spatial structure of populations during the breeding season are described.     

赣东北地区不同构造单元内微古化石及其地质意义

赣东北地区构造复杂 ,可以划分为扬子地块、浙西地块和南华造山带等三个不同类型的构造单元 ;通过对该区微古化石资料的系统整理 ,发现不同构造单元中所产微古化石类型存在较大的差别 ,从一个侧面佐证了三个不同类型的构造单元具有各不相同的演化历史及特点 ;同时通过对扬子地块中发育的大面积浅变质岩系中微古化石资料的整理 ,其微古组合时代主要为蓟县纪—青白口纪 ,结合岩石地层及其它相关资料综合分析与对比研究 ,认为扬子地块中大面积出露的浅变质岩系时代为中元古代 ;这一结果对研究赣东北地区不同构造单元的构造演化历史具有较为重要的意义     

组织蛋白酶L在非小细胞肺癌组织中的表达

通过免疫组化检测组织蛋白酶L(CL)在40例非小细胞肺癌标本中的表达情况.结果Ⅲ~Ⅳ期肺癌组织CL阳性表达率高于Ⅰ~Ⅱ期,随着分化程度由高分化、中分化至低分化,CL阳性表达率亦明显增加.伴有淋巴结转移者,CL阳性表达率显著高于无淋巴结转移者.提示CL在非小细胞肺癌中明显表达,其表达与非小细胞肺癌的转移及预后相关.     

Magnetic-activated cell sorting (MACS) significantly decreases the hybridization efficiency of fluorescence in situ hybridization (FISH)

Fetal cells were enriched from maternal blood using density gradient centrifugation of Histopaque followed by magnetic-activated cell sorting (MACS) to select CD71-positive cells. For each specimen, cells partially purified by Histopaque were split into equal portions, and each portion was subjected to purification by MACS in parallel. Cells before and after MACS were subjected to dual-color fluorescence in situ hybridization (FISH) analysis with X- and Y-chromosome-specific probes. We found that the hybridization rates were decreased by approximately 10% after MACS based on duplicated analysis for each sample. Copyright © 2001 John Wiley & Sons, Ltd.