丙硫咪唑对幼儿蛲虫感染的防治效果观察

本文采用透明胶纸法于1989、1990年两次对海口市机关幼儿园进行蛲虫检查,并用丙硫咪唑治疗。1989年蛲虫感染的检出率为63.69％,服丙硫咪唑一年后1990年同期的检出率为54.71％,感染率较上年下降(P<0.01),1990年服用丙硫咪唑两周后复查,虫卵阴转率为88.31％。通过对该药治疗蛲虫病近、远期效果的观察比较,并探讨了如何有效地进行蛲虫病防治的问题。     

关于单层神经网络结构特征的一个结果

目前有许多神经网络模型以 Hebb 规则做为学习的基础.在 Hebb 规则中不包含神经元的几何结构信息.但对点数相同的二维点阵和一维点阵,大脑易于记忆二维点阵,因为它有更多的几何结构特征.Kohonen在中论述了生物神经网络的结构特征.本文在Hopfield 网络中引入几何结构信息,对其联想记忆过程做了理论分析和实验研究,试图研究单层神经网络的结构特征对联想记忆的影响,并探讨实现局域连接的可能性.1 Hopfieid 神经网络模型及结构信息的引入Hopfield在文中提出了一个神经网络离散模型.此模型中包括 N 个神经元,它们     

未来物业管理企业的竞争力

当前,物业管理企业作为朝阳行业,发展势头迅猛,竞争力也越来越强,企业要获得核心竞争力必须在品牌、服务、管理、专业方面作好,以实现未来物业的竞争力.     

铸铁中第三组元的偏析参数

本文从schiel方程推导出在给定冷却速度下铸铁枝晶奥氏体及共晶奥氏体中第三组元的偏析参数KS和偏析梯度KR的计算式,并讨论了计算值与实测值之间的差别。     

模糊综合评判优选长春花细胞分化条件

研究不级其浓度配比对长春花细胞分化的影响；利用综合评判方法优选不同培养目的培养条件。为开发利用该过程提供理论准备。     

污水处理工程中的消毒比较

文章叙述了在水资源紧缺的今天,对污染的水资源进行消毒的传统方法和新理念。     

教育控制论在教育实习中的应用

本文从教育控制论的观点出发,阐明教育实习控制目标,介绍教育实习控制系统模型,并运用程序控制和反馈控制的理论论述提高教育实习质量的途径。     

PN code generator based on generalized bent function for SW/SFH system

Generalized Bent function and generalized Bent function sequences are introduced in this paper. The main performance of these sequences used as SW/SFH (Short Wave/Slow Frequency Hopping) code are studied. And the hardware circuit and the sofiware program flow chart of the SW/SFH PN code generator are also given, which is based on generalized Bent function sequence generator by using a single chip microcomputer. Supported by the National Naatural Science Foundation of China & National Deference Foundation of China Gan Liangcai: born in Dec. 1941, Professor     

Long-term sensory deprivation prevents dendritic spine loss in primary somatosensory cortex

A substantial decrease in the number of synapses occurs in the mammalian brain from the late postnatal period until the end of life. Although experience plays an important role in modifying synaptic connectivity, its effect on this nearly lifelong synapse loss remains unknown. Here we used transcranial two-photon microscopy to visualize postsynaptic dendritic spines in layer I of the barrel cortex in transgenic mice expressing yellow fluorescent protein. We show that in young adolescent mice, long-term sensory deprivation through whisker trimming prevents net spine loss by preferentially reducing the rate of ongoing spine elimination, not by increasing the rate of spine formation. This effect of deprivation diminishes as animals mature but still persists in adulthood. Restoring sensory experience after adolescent deprivation accelerates spine elimination. Similar to sensory manipulation, the rate of spine elimination decreases after chronic blockade of NMDA (N-methyl-D-aspartate) receptors with the antagonist MK801, and accelerates after drug withdrawal. These studies of spine dynamics in the primary somatosensory cortex suggest that experience plays an important role in the net loss of synapses over most of an animal's lifespan, particularly during adolescence.     

A separate two-stage pulse tube cooler working at liquid helium temperature

A novel 4 K separate two-stage pulse tube cooler (PTC) was designed and tested. The cooler consists of two separate pulse tube coolers, in which the cold end of the first stage regenerator is thermally connected with the middle part of the second regenerator. Compared to the traditional coupled multi-stage pulse tube cooler, the mutual interference between stages can be significantly eliminated. The lowest refrigeration temperature obtained at the first stage pulse tube was 13.8 K. This is a new record for singlestage PTC. With two compressors and two rotary valves driving mode, the separate two-stage PTC obtained a refrigeration temperature of 2.5K at the second stage. Cooling capacities of 508mW at 4.2K and 15W at 37.5K were achieved simultaneously. A one-compressor and one-rotary valve driving mode has been proposed to further simplify the structure of separate type PTC.