Asbestiform chain silicates: new minerals and structural groups

The discovery and characterization of structurally ordered and disordered phases that are intermediate between amphiboles and micas have shown that the biopyriboles are a much more complex family of minerals than has previously been recognized. In addition to single-chain, double-chain, and sheet structures, there are also minerals with triple chains and with alternating double and triple chains. Many crystals exhibit disorder in the sequence of double and triple chains, and isolated chains that are wider than triple are common. This structural disorder helps to explain why asbestiform amphiboles are fibrous. The new phases have now been found in several localities, and it is possible that similar phenomena in other minerals could also have been overlooked. In particular, there is no reason to suppose that analogous substances and structures with both single and double chains do not occur between the pyroxenes and the amphiboles. Since the pyroxenes are used extensively by geologists to assess rock histories and formation temperatures and pressures, it is essential that the extent of this type of disorder be evaluated. It is possible that what appears to be only an interesting mineralogical problem may prove to be a petrological nightmare.     

Silica in sea water: control by silica minerals

Silicate minerals typical of those carried in the suspended load of streams release silica to silica-deficient sea water and abstract silica from silicaenriched sea water. Experimental rates of release and uptake permit the conclusion that the suspended solids carried into the oceans by streams are a major control of the concentration of silica in the ocean.     

Developing city water supplies by drying up farms: Contradictions raised in water institutions under stress

Constraints on the expansion of western water supply projects have turned the attention of urban water developers to market purchases of agricultural water supplies as a source of new water. The conventional wisdom of natural resource economics suggests that such shifts should have minimal impact on the agricultural area-of-origin, promote efficiency in water use, and provide an inexpensive and environmentally preferable alternative to building more dams and reservoirs. However the concentration of urban demand combines with water-extensive irrigation practices in western agriculture and a characteristically bipolar economic and social structure in western irrigation communities to create a potential for severe stress on rural economies and communities. The adaptation of supply-oriented western water institutions to market-oriented functions has not provided a decision-making context that accounts for costs imposed on rural communities; moreover, historically water-rich rural communities have not evolved a water policy infrastructure capable of responding to stress. Before the promise of low-cost water supply through the market mechanism can be realized, the structural contradictions inherited from the traditional water-management institutions must be faced and dealt with by both rural source regions and urban water importers.     

Vasopressin and neurophysin: high concentrations in monkey hypophyseal portal blood

Vasopressin and its binding protein, neurophysin, were measured by radioimmunoassay in the hypophyseal portal blood of monkeys after cannulation of individual long portal veins. Mean vasopressin concentrations (13,800 picograms per milliliter) in portal blood were more than 300 times as high as those in the systemic circulation (42 picograms per milliliter). Neurophysin concentration was approximately 25 times as high in portal as in systemic blood. By immunoperoxidase techniques, high concentrations of neurophysin were demonstrated around portal capillaries of the median eminence. These studies indicate direct secretion of vasopressin and neurophysin into the portal circulation; the quantities secreted during stress may be sufficient to exert significant effects on secretion of anterior pituitary hormone.     

Magnesium in sea water: an electrode measurement

Magnesium ion in standard I.A.P.O. sea water was measured with a magnesium-sensitive electrode. The results, presented either as magnesiumion activity (0.017) or as the amount of ionized magnesium (0.048M or about 90 percent of the total magnesium), agree well with the data from the chemical model for sea water proprosed by Garrels and Thompson.     

水分供应对春小麦农艺性状和生理指标的影响

在甘肃河西走廊绿洲灌区,研究了品种间不同灌水处理春小麦在农艺性状和生理指标方面的差异。选用3 个春小麦品种(系),在冬灌1 800 m3／hm2。基础上,生育期设3次灌溉(拔节期、开花期、乳熟期)、2次灌溉(拔节期、开花期)和1次灌溉(拔节期)3种灌水处理,每次灌水1 050 m3／hm2,3种水分处理生育期总灌水量分别为3 150 m3／hm2 (T1),2 100 m3／hm2(T2),1 050 m2／hm2(T3)。结果表明:不同品种、不同灌水处理下,春小麦的农艺和生理指标差异明显。生育期2次灌水处理(T2)的平均产量、水分利用效率和千粒重较T1和T3分别提高了13．38％和11．49％,19．56 ％和19．79％,14．16％和13．06％;同时表明,减少水分供应可促进早熟,导致叶温升高;随着生育进程,灌水处理间的气孔导度、叶片含水量和相对含水量的差异逐渐增大,灌浆中期三者均以T1最大、T2次之、T3最小。     

Chlorine oxide in the stratospheric ozone layer: ground-based detection and measurement

Stratospheric chlorine oxide, a significant intermediate product in the catalytic destruction of ozone by atomic chlorine, has been detected and measured by a ground-based 204-gigahertz, millimeter-wave receiver. Data taken at latitude 42 degrees N on 17 days between 10 January and 18 February 1980 yield an average chlorine oxide column density of approximately 1.05 x 10(14) per square centimeter or approximately 2/3 that of the average of eight in situ balloon flight measurements (excluding the anomalously high data of 14 July 1977) made over the past 4 years at 32 degrees N. We find less chlorine oxide below 35 kilometers and a larger vertical gradient than predicted by theoretical models of the stratospheric ozone layer.     

Isopiestic technique: measurement of accurate leaf water potentials

Sunflower leaf tissue of known potential was obtained by equilibrating an interveinal leaf sample, at constant temperature in air, with a potential determined by sucrose solutions. Equilibration occurred within 17 hours. Except for one determination, all measurements of the water potential of the equilibrated samples with an isopiestic technique were within 0.1 bar of the known potential of the tissue. This finding indicates that thermocouple psychrometers can measure accurate values of water potential when an isopiestic technique is used.     

基于遗传算法的城市库群联合供水调度研究

【目的】确定西安市黑河供水系统的水库库群最佳联合引水组合,制定不同代表年的库群联合供水调度方案,为发挥西安市黑河供水系统的最大效益提供参考。【方法】从黑河供水系统实际出发,以6种库群引水能力组合方案为基础,建立库群联合供水调度模型,运用遗传算法进行求解,寻求最佳联合引水组合。通过分析不同代表年的需水要求,制定库群联合供水调度方案。【结果】利用所建立的库群联合供水调度模型进行可供水量计算,结果表明,西安市黑河供水系统的多年平均年可供水量最优为72 727.06万m³,城市供水保证率最优达98.18%,即黑河供水系统具有较大的供水潜力。并据此确定的最佳联合引水组合为：石头河水库、金盆水库、西骆峪水库、田峪水库、高冠峪水库、梨园坪水库、太平峪水库、石砭峪水库和甘河水库的引水能力分别为6,12,3,5,4,4,4,4和5 m³/s。无突发事件条件下,平水年、一般枯水年和特别枯水年西安市黑河供水系统的年可供水量分别为46 794.70,46 365.69和35 502.25万m³,突发事件情况下分别为54 413.45,53 984.44和47 887.59万m³。【结论】所制定的调度方案可以充分挖掘黑河供水系统的库群供水能力,提高水资源利用效率,最大程度地保障西安市未来的城市供水安全。     

气相色谱法测定城市污泥中多氯联苯与有机氯农药

建立了以丙酮和石油醚超生提取,用硫酸尧高纯铜粉和硅胶柱净化的可同时检测长江三角洲地区城市 污泥中有机氯污染物的气相色谱法。与传统方法相比,在保证足够准确度尧精确度和灵敏度的前提下,该方法具有前 处理简单尧测定成本低尧样品用量少的特点,且可同时测定城市污泥中有机氯农药（OCPs）和多氯联苯类（PCBs）化合 物。应用该方法对我国长江三角洲地区城市污泥中PCBs 和OCPs 进行测试,结果表明,方法最低检出限为0.09~ 0.33 滋g/kg,达到了微量分析要求。加标回收试验中,PCBs 回收率为59.50%~101.51%,OCPs 回收率为57.21%~ 89.62%,相对标准偏差为1.89%~14.67%。     

发展农产品快速检测技术确保饮食安全

发展农产品快速检测技术是一项利国利民的大事 ,不仅是保护消费者利益的重大举措 ,也是推进农业结构调整 ,提高农产品市场竞争力 ,增加农民收入的有效措施。建立与国际接轨的农产品及其加工品质量标准体系和检测监督机制、措施 ,进行农产品品质检测重要性的宣传 ,同时认真贯彻执行《中华人民共和国产品质量法》。引进、吸收和消化国外先进的农产品检测技术和设备 ,利用我国农产品生产和加工的人才优势 ,通过政府资助开展农产品检测研究。加速制定有利于无公害食品发展的扶持政策 ,包括对无公害食品的生产、加工、流通等方面的政策扶持 ,确保广大人民吃上放心食品     

Radiuin-226 and radon-222 in the coastal waters of west Florida: high concentrations and atmospheric degassing

On the central portion of the west Florida continental shelf, radionuclide activities show unusually wide variations: radium-226 activities up to 350 disintegrations per minute per 100 liters, radon-222 activities up to 1300 disintegrations per minute per 100 liters, and deficiencies of radon-222 as low as -10 disintegrations per minute per 100 liters. Florida's phosphate-rich strata seerm to be the principal source of the radionuclides, with the transfer occurring directly from sediments or indirectly in streams, ground-water flow, and geothermal springs. Winter storm fronts may enhance radon degassing in the shelf waters.     

水利信息化技术在农业灌溉用水精准计量中的应用价值

随着我国当前社会与经济的快速发展,国家在经济迅速提升过程当中,越来越重视农 业经济的发展情况。我国当前的农业在进行种植过程当中开始应用灌溉技术,但是在我国当前 农业灌溉用水精准计量工作开展过程当中,存在一定的问题,所以为了能够更好的解决此类问 题,部分地区已经开始将水利信息化技术应用到该项工作当中。因此,本文将会就水利化信息 技术在农业灌溉用水精准计量中的应用价值进行仔细分析。     

肉类品质无损检测技术的研究进展

介绍了国内外肉品质量无损检测技术的研究情况。通过研究肉品的电磁特性、声学特性、光学特性等,提出了近红外技术、超声波技术、机器视觉技术等无损检测技术和方法,使肉类质量检测达到在线、快速、准确的目的。并对肉品检测技术的进一步研究和应用方向进行了探讨。     

农田土壤水分测定与模拟研究进展

土壤水分不仅是农业生产中影响产量的重要调控因子,而且还影响环境污染物质的迁移和土壤的持续利用。本文对土壤水分各测定方法的优缺点进行了评述。提高土壤水分监测传感器精确性和观测数据自动采集、区域土壤水分的遥感监测是当前和未来的主要发展方向。对国内外应用较多的土壤水分模型做了概括和总结,其模拟方法主要以土壤水动力学方法、土壤水分平衡方法为主,随机模型受到关注。本文还对土壤水分的未来研究进行了展望。     

西瓜夏种优质高产栽培技术

1选择品种要选择品质好、产量高、耐高温高湿、抗病性强的品种,如庆红宝、黑丰霸王、景丰宝等。2选地整地要有利于排灌西瓜耐旱不耐涝,只要积水时间稍长就会引起烂根死秧。因此7～8月份要注意排涝。应选择地势高、能灌能排的砂质土壤。做畦的方式可采用起垄栽培,单行栽培的垄背     

Behavioral maintenance of high concentrations of blood ethanol and physical dependence in the rat

Rats maintained on an intermittent food schedule with an available ethanol solution drink to excess (13.1 grams of ethanol per kilogram of body weight, daily). Removal of ethanol produces symptoms of physical dependence including death from tonic-clonic seizures. Overindulgence in oral self-administration of an aqueous ethanol solution, resulting in unequivocal physical dependence, approximates a model of human alcoholism.