便携式土壤电导率测试系统的开发

介绍了一种自行设计的，基于电流-电压四端法的便携式土壤电导率(EC)在线测试仪的开发情况。该测试仪包括土壤电导率传感器、控制与数据采集器和计算机应用软件等。传感器有4个电极，2个用于向土壤中输入恒流，另外2个用于检测与土壤电导率密切相关的电压降；控制与数据采集器把传感器产生的电压信号转换为数字信号，计算并显示电导率；计算机应用软件把接收到的数据存入Microsoft Access数据库。在实验室土槽内对该测试仪传感器的性能进行了测试，并与电导率仪测量结果进行了比较分析。结果表明，传感器输出电压与电导率仪测量值变化趋势一致，采用多种非线性数学模型对各组数据进行了曲线拟合，结果均在幂函数模型上获得最佳回归，测定系数(R^2)大于0．99。     

Thermal conductivity of monolithic organic aerogels

The total thermal conductivity lambda of resorcinol-formaldehyde aerogel monoliths has been measured as a function of density rho in the range from rho = 80 to 300 kilograms per cubic meter. A record-low conductivity value in air at 300 K of lambda approximately 0.012 watt per meter per kelvin was found for rho approximately 157 kilograms per cubic meter. Caloric measurements under variation of gas pressure as well as spectral infrared transmission measurements allowed the determination of solid conductivity, gaseous conductivity, and radiative conductivity as a function of density. The development of such low conductivity materials is of great interest with respect to the substitution of environmentally harmful insulating foams made from chlorofluorocarbons.     

Thermal diffusivity and conductivity of lunar material

The thermal diffusivity and conductivity of type C lunar samples returned by Apollo 11 are lower and less dependent on temperature than those of type A samples. The thermal properties of both types are lower than the corresponding properties of normal terrestrial rocks.     

Thermal radiation properties and thermal conductivity of lunar material

The thermal radiation properties were measured for lunar fines and chips from three different lunar rocks. Measurements for the fines were made at atmospheric pressure and at a pressure of 10(-5) torr or lower. The directional reflectance was obtained over a wavelength range of 0.5 to 2.0 microns for angles of incidence up to 60 degrees. The bidirectional reflectance-the distribution of reflected light-was measured for white light angles of illumination up to 60 degrees. The thermal conductivity was measured over a temperature range 200 to 400 degrees K under vacuum conditions.     

The effect of alumina on the electrical conductivity of silicate perovskite

Measurements of the electrical conductivity of silicate perovskite at 25 gigapascals and 1400 degrees to 1600 degreesC show that the conductivity of (Mg,Fe)SiO3 perovskite containing 2.89 weight percent Al2O3 is about 3.5 times greater than that of aluminum-free (Mg0.915Fe0.085)SiO3 perovskite. The conduction mechanism in perovskite between 1400 degrees and 1600 degreesC is most likely by polarons, because Mossbauer studies show that the aluminum-bearing perovskite has about 3.5 times the amount of Fe3+ as the aluminum-free sample. A conductivity-depth profile from 660 to 2900 kilometers based on aluminum-bearing perovskite is consistent with geophysical models.     

Xenon: effect on radiation sensitivity of HeLa cells

HeLa cells, plated onto plastic petri dishes, were exposed to various atmospheres composed of air and carbon dioxide; helium, oxygen, and carbon dioxide; and xenon, oxygen, and carbon dioxide in a pressure vessel. Survival curves with x-rays, 280 kilovolts (peak), show that air and helium have the same effect, but that xenon potentiates x-irradiation to the extent that the dose to produce a given level of survival with xenon is 0.58 of the dose required with air.     

Thermal conductivity of lunar and terrestrial igneous rocks in their melting range

The thermal conductivity of a synthetic lunar rock in its melting range is about half that of a terrestrial basalt. The low conductivity and increased efficiency of insulating crusts on lunar lavas will enable flows to cover great distances without being quenched by high radiant heat losses from the surface. For a given rate of heat production, the thermal gradient of the moon would be significantly steeper than that of the earth.     

绿洲土壤含硫气体释放的环境影响因素研究

挥发性含硫化合物(VOSCs),如H2S、COS、DMS、CS2和CH3SH等在全球硫循环中有着重要作用.通过室内培养分析了环境条件对新疆地区土壤释放的VOSCs的影响.单因素和正交试验的结果表明,土壤水分、温度、硫源物质和pH值是影响土壤CS2和DMS释放的主要因素.当土壤水分为50%～100%、温度35～45℃、硫源物质添加量在2.5 mg/S左右和pH值接近中性的条件下,土壤释放的CS2和DMS显著增加.     

完美主义对医学院校大学生人际关系敏感的影响

本文采用心理健康症状自评量表SCL-90和杨宏飞修订的Frost多维完美主义量表（FMPS）中文版对325名医学院校的大学生进行问卷调查。结果发现：①完美主义与人际关系敏感相关最显著;②积极完美主义与症状自评量表中的大部分因子呈负相关;③消极完美主义与症状自评量表中的大部分因子呈显著正相关。说明医学院校大学生完美主义的人格特质对其人际关系敏感的影响非常显著。     

土壤氧气可获得性对双季稻田温室气体排放通量的影响

为探讨土壤氧气可获得性(SOA)对双季稻田温室气体排放的影响,利用静态箱气相色谱法对多种管理措施影响下稻田温室气体排放通量和土壤氧化还原电位(Eh)、pH值及田间淹水深度(H)等3种SOA因子进行了观测。结果表明,甲烷(CH₄)排放最集中的Eh值、pH值和H范围分别为-100-0mV、5 < pH < 6和1-5cm,3个范围内分别观测到48.8%、61.1%和77.0%的CH₄排放,其中H对CH₄排放影响最明显,单独由其就可解释37.8%的CH₄排放通量(P < 0.0001)。对于氧化亚氮(N₂O),观测到较多的负通量,其纯排放最密集的3种SOA因子的范围分别是:0-100mV、5 < pH < 6和1-5cm,而200-300mV是其排放的临界Eh范围,高于此范围N₂O排放极少。厌氧的反硝化过程是双季稻田N₂O产生的主导过程。可为水稻田温室气体排放机理研究提供基础数据。     

A comparison of the contribution of various gases to the greenhouse effect

The current concern about an anthropogenic impact on global climate has made it of interest to compare the potential effect of various human activities. A case in point is the comparison between the emission of greenhouse gases from the use of natural gas and that from other fossil fuels. This comparison requires an evaluation of the effect of methane emissions relative to that of carbon dioxide emissions. A rough analysis based on the use of currently accepted values shows that natural gas is preferable to other fossil fuels in consideration of the greenhouse effect as long as its leakage can be limited to 3 to 6 percent.     

城市典型水域景观的热环境效应

城市热岛效应是当前快速城市化进程中最具代表性的生态环境问题之一.热岛效应进一步影响着城市气候变化与城市可持续发展.现存大量研究证明了土地覆被改变导致的热辐射变化及人为热释放共同作用产生了城市热岛.然而,当前对缓解城市热岛效应要素的研究并不多见.以上海市中心城区为例,首先基于SPOT5影像的分类,提取了城市水域景观,再利用Landsat7的ETM+的热红外波段,定量反演了城市地表热环境温度,然后利用GIS的空间分析功能,探讨了城市水域景观对热环境的影响.研究揭示水域景观在城市热环境中表现出明显的低温效应,而面状水域景观的热环境效应要强于线状河流景观.面状水域景观对热环境影响随着与热岛中心距离的增加而明显降低,此外还受到周围土地覆被的影响.线状河流景观的宽度与流经区域共同决定了其对城市热环境的影响能力.因此,在城市规划设计中,从缓解城市热岛效应出发,水域生态功能区的形态与空间设置可作为考虑因素之一.     

玉米皮载体阴离子添加剂对干奶牛作用效果研究

通过比较以玉米皮为载体配制阴离子添加剂与成品阴离子添加剂对干奶牛作用效果,探讨玉米皮作为阴离子添加剂载体可行性。采用单因素随机区组试验设计,将60头产前21 d健康荷斯坦奶牛随机分为3组,分别饲喂:对照组(A组):不含阴离子添加剂TMR;试验I组(B组):TMR+3%阴离子添加剂(干奶宝HRBYD-902);试验Ⅱ组(C组):TMR+3%阴离子添加剂(以玉米皮为载体阴离子添加剂)。结果表明,饲喂初期,试验Ⅰ组和Ⅱ组日平均干物质采食量(DMI)显著低于对照组(P0.05),随饲喂天数增加试验组与对照组之间差异逐渐变小,且试验I组与Ⅱ组间差异不显著(P0.05)。整个试验期对照组奶牛尿液p H稳定在7~8,饲喂第1周,两试验组奶牛尿液p H与对照组相比显著下降(P0.05),并于饲喂第2周、第3周p H稳定在6左右。产犊当天,试验Ⅰ组与试验Ⅱ组奶牛血清Ca2+浓度显著高于对照组,试验Ⅱ组略高于Ⅰ组,但差异不显著(P0.05)。试验Ⅱ组奶牛产后胎衣不下概率由30%降到0,乳房炎发生概率与对照组相比有所下降,且预防奶牛产后疾病方面效果好于试验I组。结果显示,饲喂玉米皮为载体阴离子添加剂可在保证奶牛DMI基础上降低奶牛尿液p H,提高奶牛产犊前后血清Ca2+浓度并降低产后胎衣不下及乳房炎发生概率。因此,玉米皮可作为阴离子添加剂载体使用。     

Trophic regulation of acetylcholine sensitivity of muscle: effect of electrical stimulation

Denervation of skeletal muscle results in a spread of acetylcholine sensitivity over the entire surface membrane. Electrical stimulation, programmed to mimic the normal activity pattern, was applied continuously to the denervated rat diaphragm in vivo. After 4 days, the acetylcholine sensitivity was far less in the stimulated diaphragms than in denervated controls. Muscle activity may account for "neurotrophic" regulation of the acetylcholine sensitivity.     

中俄原油管道沿线冻土区地基土的导热性及冻害防治

中俄原油管道穿越多年冻土带,由于管沟土的导热性差异,导致管道沿线冻土融沉变形问题严重.选取中俄原油管道沿线砾砂、粉土、粉质黏土、黏土及泥炭质土5种典型地基土进行导热系数测试,以掌握导热系数随影响因素的变化规律.测定5种地基土的导热系数,分析导热系数与含水率、干密度之间的关系,并建立回归方程;根据不同土质条件,分析导热系...     

玉米秸秆施用对棕壤有机碳激发效应及温度敏感性的影响

为了区分新加入玉米秸秆碳对原土壤有机碳激发效应及其温度敏感性的影响。本研究利用¹³C示踪方法,通过向高肥（连续施用腐熟猪厩肥30年,土壤有机碳含量17.03 g·kg^-1）与低肥（连续30年不施肥处理,有机碳含量10.70 g·kg^-1）棕壤中添加¹³C标记的玉米秸秆,在25℃（微生物适宜温度）和18℃（作物生长季平均温度）进行450 d的室内培养试验,定期测定CO₂-C和CO₂^-13C,探讨玉米秸秆碳矿化对不同肥力棕壤有机碳激发效应及其温度敏感性的影响。高肥棕壤有机碳的累积矿化量较高,且温度升高增加了棕壤有机碳的累积矿化量;低肥棕壤有机碳激发效应程度随温度升高的变化大于高肥棕壤,表现出0~140 d正激发效应程度下降更快,140~360 d负激发效应程度持续时间更长,360 d后正激发效应程度呈逐渐增大的趋势,其中18℃累积激发效应程度大于25℃;总体上高肥和低肥棕壤有机碳矿化的温度敏感性均呈现随时间逐渐下降的趋势,而玉米秸秆添加显著减缓了它们的下降,并表现出0~140 d低肥棕壤有机碳矿化的温度敏感性高于高肥棕壤,之后低于高肥棕壤的趋势,原土壤有机碳矿化的温度敏感性呈现出较大的变化,表现为0~300 d低肥棕壤高于高肥,之后呈相反的趋势。土壤肥力（有机碳水平的差异）和环境温度交互影响着玉米秸秆碳的分解,引起了棕壤有机碳激发效应的差异变化,培养140 d和300 d是温度敏感性差异变化的重要时期。     

固醇转运蛋白SCP-2研究进展

固醇转运蛋白（SCP-2,也称非特异性脂类转移蛋白）是一类碱性小分子蛋白质,存在于过氧化物酶体中,在体外可以增强质膜间胆固醇和脂类的运输,广泛存在于细菌、古细菌和真核生物中。大量的研究表明,它与多种物质的代谢过程有关,但由于它复杂的结构和功能,其具体作用机制目前仍未被明确阐述。为此,作者着重以真核生物SCP-2家族为例,介绍了SCP-2结构域的进化、结构与功能近年来的研究进展,并对SCP-2基因家族及SCP-2蛋白应用前景作了论述。     

刚毛藻对除草剂敏感性的研究

针对沿海地区水产养殖业中刚毛藻生长泛滥的问题,以刚毛藻为研究对象,通过室内生物测定方法研究刚毛藻对除草剂和助剂的敏感性。结果表明,刚毛藻对不同除草剂及助剂的敏感性存在差异,除草剂和助剂对刚毛藻都有很好的抑制作用,并且随着浓度的增加,对刚毛藻抑制作用明显增强。除草剂混剂比单剂对刚毛藻具有更好的抑制作用,而除草剂中加入助剂AEO和LAS对刚毛藻的抑制效果最为明显,此外,温度越高,光照越强,刚毛藻吸收药剂的速度加快,防效更高。     

不同饲料对棉铃虫幼虫体色遗传及药剂敏感性影响的研究(英文)

不同饲料对棉铃虫幼虫体色变化有影响 ,用嫩棉叶喂养的幼虫 ,其体色以黑色、红色、绿色、绿褐色为主 ,其中黑色比率最高达 32 3% ;用人工饲料喂养的幼虫 ,其体色以绿褐色、黑色、红色、灰褐色为主 ,其中绿褐色比率最高 (31 6 % ) .利用纯化 3代的不同体色交叉组合配对 ,其后代体色遗传不规律 ,与其亲代体色相一致的幼虫占多数 .利用质量浓度为 1 0 %的功夫和 2 0 5 %的保丰乳油 ,点滴法测定触杀效果 ,结果表明 ,绿色和灰褐色是较敏感的类型 ,红色和黑色为不敏感的类型     

土壤大孔隙结构对饱和导水率的影响

[目的]探究土壤不同孔径大孔隙结构特征及数量对土壤饱和导水率的影响,为研究区域土壤水分-溶质迁移规律、水土流失治理与土壤污染防治提供理论参考.[方法]以京郊密云水库五座山林场水源涵养林为研究点,基于工业CT扫描技术,对土柱中土壤大孔隙三维空间结构重建后,探究不同孔径大孔隙结构特征参数密度及数量密度对土壤饱和导水率的影响...