镍基WC-金刚石复合镀层的制备和摩擦磨损特性研究

本文选用碳化钨硬质颗粒作为增强材料与金刚石颗粒共同沉积到镍基金属中,以提高电镀金刚石钻头胎体的耐磨性。首先采用单因素实验分析方法,研究了复合电镀主要工艺参数对复合镀层中WC颗粒含量以及沉积速率的影响,然后经综合分析优化出最佳工艺参数,采用复合电镀工艺制作出镍基WC-金刚石复合镀层,并与镍基金刚石复合镀层的磨损特性进行了比较。结果表明：碳化钨硬质颗粒的引入,使得复合镀层的质量磨损量和摩擦系数减少,耐磨性提高。     

Dielectric spectroscopy measured on dry,oil-, freshwater- and brine-wetted rocks using an insulating layer method and its relations to petrophysical parameters

Dielectric measurements, in the frequency range from 100 Hz to 15 MHz, were carried out using an insulating film method, on shaly and clean sandstone samples, dry, oil-impregnated, partially or fully saturated with fresh water or solutions of NaCl, at different concentrations. The results show that two kinds of polarization relating to interface dominate: the inner surface polarization (ISP) at the pore surface in rocks and the outer surface polarization (OSP) on the outer surface of the rock sample. Both ISP and OSP are of the Debye type and can be fitted very well using the Cole–Cole equation. The dielectric spectra of ISP reflect the length scale of pore size or throat size, whereas the relaxation strength depends heavily on the inner pore surface area. Clay contributes to dispersion in rocks, mainly through increasing the inner surface. When the effect of water content is minimized, the dielectric properties measured on brine-wetted rock samples show great salinity dependence. The increase in salinity shifts the relaxation spectra to the high frequency end; it also enhances the relaxation strength. In the frequency range studied, no dispersion in dry and oil-saturated samples has been observed, which underscores the key role played by water in dielectric polarization in rocks.     

耕地保护经济补偿运行机制及补偿效应分析

在对耕地保护经济补偿机制内涵界定的基础上,提出了"农业保险+社会保障+实物技术货币一体化的区内经济补偿机制"和"基于上级政府调控和财政转移支付的耕地保护区际经济补偿协商机制",并对区内和区际经济补偿方式、运行机理进行了分析.同时,在对耕地保护经济补偿效应概念、类型界定的基础上,结合农户问卷调查,对耕地保护经济补偿效应进行了系统分析.研究表明:(1)耕地利用生态社会效益的外部性是耕地非农化的根本原因,而构建耕地保护的经济补偿机制则是抑制耕地非农化的根本途径.(2)耕地保护的经济补偿体系由区内经济补偿和区际经济补偿共同组成,耕地保护经济补偿方式、补偿标准是影响其补偿效应的重要因素.     

THE MIRE IN NORTHEAST OF CHINA

The northeast region is one of the principal mire distribution regions in China. According to the process of peat formation and accumulation , middle geomorphology type controlling water source supplement and the plant cover, 2 types, 10 subtypes and 27 mire bodies are divided. The mire area decreases gradually from north to south. There is more peat mire in the mountain and there is mainly gley mire without peat in the plain. The paper also explains the mire types in the principal mire distribution region and the utilization of mire in the fields of agriculture, forest, animal husbandry. The mire is a wetland ecosystem. It can reserve a lot of water, adjust rivers, humidify air. Thereby , attention must be paid to protecting ecological balance in the process of reclaiming mire and the mire protection.     

中国地壳运动观测网络基本网观测精度研究

“中国地壳运动观测网络”于1998～2002年开展过5次基本网GPS联测。利用GIPSY软件处理结果进行的统计分析表明：基线定位水平分量精度为2～5mm，垂直分量为7～15mm；基线变化的水平分量测定精度为0．5mm／a，达到了流动观测的最高水平。分析基线定位误差发现：固定误差是目前相对定位的主要误差；与基线长度有关的比例误差对于水平分量而言，基本可以忽略。对速率的统计分析说明：至少4年观测间隔，才有可能获得比较精确、可靠的测站速率结果。     

Immunosuppressive activities of fucoidan from Laminaria japonica

Effects of fucoidan fromLaminaria japonica on 2,4-dinitrochlorobenzene induced delayed-type hypersensitivity (DTH) reaction and the serum levels of IgG, IgM, complement C3 and C4 were investigated in the present study. Results showed that oral administration of fucoidan at dose of 150 and 300 mg/(kg· d) for 9 days before the hapten challenge significantly inhibited 2,4-dinitrochlorobenzene induced delayed-type hypersensitivity reaction; and also inhibited the humoral immunity. Serum C3 and C4 levels were markedly reduced by fucoidan at dose of 150 and 300 mg/kg; and serum IgG and IgM levels were reduced by fucoidan at dose of 300mg/kg. The inhibitory effects of fucoidan on delayed-type hypersensitivity suggested that it may be potential medication for chronic inflammatory diseases in the future. This study was supported by National Foundation for New Drug Research & Development (NFND) No.144.     

清代测绘科技的辉煌及其历史遗憾

清代自康熙年间开始 ,我国在另有所图的西方传教士的参与下 ,进行了史无前例的全国地图测绘工作 ,取得了辉煌的测绘科技成就 ,但由于当时的闭关主义、科技政策、文化传统、价值观念等因素的影响 ,导致了中国社会错失追赶西方的历史机遇     

广州市休闲旅游资源空间分布及其可达性特征

基于休闲旅游资源POI数据,采用最邻近指数、核密度及栅格分析等方法,探讨广州市不同类型休闲旅游资源的空间特征及其可达性空间格局,并解析可达性空间格局的形成机制。结果表明：1）广州市休闲旅游资源总体上呈现“中心城区密集、边缘区稀疏”的分布特征,随着与市中心距离的增加,空间集聚度不断下降。2）不同类型休闲旅游资源空间分布特征差异明显,文化类集聚程度最高,康娱类呈单核集聚,自然类呈板块式集聚,专项类最接近随机分布。3）广州市休闲旅游资源可达性空间格局的交通指向性明显,呈现以中心城区为核心,沿交通干线向外渐降,至从化区北部达到最低的特点。4）不同类型休闲旅游资源的可达性空间格局存在差异,整体可达性最高的是康娱类,可达性最低的是专项类。5）广州市休闲旅游资源可达性格局在“资源-交通-人口-行政”体系综合作用下逐渐形成的。     

Observational study of the physical and chemical characteristics of the winter radiation fog in the tropical rainforest in Xishuangbanna,China

Science China Earth Sciences - We conducted a three-month field experiment focusing on the physical and chemical characteristics of fog in a tropical rainforest in Xishuangbanna, Southwest China,...