Demography of the Yarrow's spiny lizard, Sceloporus jarrovii , from the central Chihuahuan Desert

The demography of a population of Yarrow's spiny lizard, Sceloporus jarrovii , was examined from 2004 to 2006 in the canyon Las Piedras Encimadas, located in Gomez Palacio, Durango, México. Lizards were studied using a mark-recapture technique. Reproduction in females occurred between November and May, coinciding with dry conditions. Reproductive activity was highest (percent of females with vitellogenic follicles or embryos) in the middle of the dry season (November and December). Thirteen percent of females reached sexual maturity at an average age of 8.5 months. The population structure was similar in spring and fall, but not in summer. A notable feature of summer, coinciding with the wet season, was the greater number of hatchlings and juveniles. The overall sex ratio did not differ from 1:1. The density of adults varied from 12 to 62 animals ? 0.5 ha –1 . Temperate and arid-adapted populations of S. jarrovii exhibited broad similarity in timing of the reproductive season, whereas factors such as density, growth, age at sexual maturity, and survivorship differed.     

Predation of artificial Sage Grouse nests in treated and untreated sagebrush

We measured predation on 120 artificial Sage Grouse ( Centrarcus urophasianus ) nests in montane sagebrush grassland in northern Utah. We examined nests in areas that had been chained and seeded 25 years previously (treated areas) and in areas that were untreated. Predation rates of artificial nests were higher in areas of untreated sagebrush, even though these areas had greater sagebrush cover, taller shrubs, and greater horizontal plant cover. These results differ from those previously hypothesized for treated sagebrush habitat and may reflect a greater abundance of other potential prey species, especially lagomorphs, in untreated areas that attracted greater densities of predators. In addition, over 80% of nests were depredated by mammals, which hunt using olfaction and are less likely than avian predators to be affected by nest cover. We conclude that, after treated sagebrush has recovered to some degree, predation rates of Sage Grouse nests may be lower in treated sagebrush. Consequently, factors other than nest predation (e.g., winter food, thermal cover, insects, perennial forb abundance) may be more important reasons for preserving mature sagebrush stands for Sage Grouse.     

弹点散布方差的动态修正Bayes估计

针对小样本情形下用传统方法对参数进行估计难以得到满意结果,在采用矩法由历史数据估计先验分布参数的基础上,将先验信息和后验信息相对化,采用动态修正Bayes估计法,对零均值正态分布的方差进行估计,建立了动态递推模型．并用蒙特卡罗法进行仿真模拟,结果表明,所采用的方法提高了估计精度．     

重金属镉对花背蟾蜍蝌蚪生长发育的影响

研究了镉质量浓度在0.0015,0.0300和0.1500mg/L时对花背蟾蜍(Bufo raddei)蝌蚪生长发育的影响。结果表明:不同质量浓度镉能缩短花背蟾蜍蝌蚪50％出膜时间,但对蝌蚪最终孵化率没有影响;镉能影响蝌蚪的生存率,对蝌蚪的生长发育具有明显的抑制作用(P<0.01),但组间差异均不显著(P>0.05);同时各质量浓度水平均导致蝌蚪头部泡状膨大、‘S’型尾和体形奇小(为正常体长的0.50～0.67)等,致畸率0.1500 mg/L质量浓度水平最高(2.25％),0.0300 mg/L水平次之(2.00％),0.0015 mg/L水平最低(0.50％)。     

现场总线技术及其在火电厂中的应用

介绍了现场总线的结构、技术特点以及与DCS相比具有的优势.对现场总线在电厂应用中存在的问题及解决办法进行了讨论,对于现场总线在电厂中的应用前景阐明了看法.     

贯通节理岩体等效模型与弹性参数确定

提出了一种研究贯通节理岩体等效弹性参数的近似模型,导出了贯通节岩体基本弹性常数的解析估算公式,在此模型基础上编写了相应的较为通用计算程序,分析了多组节理的存在以及节理的倾角对岩体性能的影响,预测得到的节理岩体弹性矩阵和弹性常数与节理有限元数值方法的结果十分接近,是一种预测贯通节理岩体等效弹性参数的简单而实用的方法。     

多用户多径环境下DOA估计算法研究

针对移动通信中多用户多径环境下的DOA估计问题，提出利用CARE算法求出各用户的空间循征矢量，进而利用基于对称阵列的改进MUSIC算法求出各用户对应多径信号DOA的联合算法，仿真结果表明：结合CARE算法，基于对称阵列的改进MUSIC算法能自动对多用户的DOA进行分组，并能对每个用户的多径相干信号进行DOA估计，不需要做平滑计算，不需要判断多径信号的个数，不增加计算量。     

半导体物理

本书是一本教材，系统地介绍了半导体物理的理论知识。为了使学生能更好地理解和应用这些理论和概念，本书还对一些基于半导体的重要系统的原理进行了简单的解释。全书共分10章。第1章半导体简介，介绍了半导体的定义和重要性、半导体理论的基础和一维理想结晶固体的量子态；第2章理想半导体的量子态，重点介绍了三维半导体的量子态；第3章纯半导体的激发态和含杂质半导体的量子态；第4章均相半导体的统计学；第5章半导体中的迁移现象；第6章光效应；     

成本与变化性关系的灰色模型

在变化减少方案理论的基础上,对变化性二因素和制造系统成本的关系进行了研究,运用灰色系统理论,建立了成本与变化性关系的灰色模型;并应用某纺织机械厂浆纱机产品的成本与变化性关系对部分模型进行了验证．     

Preparation of composite tubular grafts for vascular repair via electrospinning

A novel type of composite vascular graft was developed via electrospinning in the present investigation.Collagen and chitosan were blended to form the inner and outer layer.Poly(1-lactide-co-caprolacto...