Magnetic properties of hydrothermally recrystallized magnetite crystals

The discrepancy between the magnetic hysteresis properties of magnetite crystals that are precipitated from solution (<0.3 micrometer) and of crushed sifted grains (>0.3 micrometer) is not an inherent property of magnetite but is caused by the highly stressed state of crushed material and by adhering finer fragments. The size trends of magnetic properties exhibited by submicrometer-size precipitated grains continue in the size range from 1 micrometer to 1 millimeter in a set of hydrothermally recrystallized magnetite crystals. Coercive forces of these narrowly sized crystals follow a power law over a wide size range (0.1 micrometer to 1 millimeter) as predicted by theory. Dislocation etch pits show similar dislocation densities for hydrothermally grown (3 x 10(10) meter (-2)) and natural (1 x 10(10) meter(-2)) magnetite crystals. Hysteresis parameters of hydrothermally grown crystals are similar to those of natural crystals but are about one-fifth of those for crushed grains.     

碳酸钙及其与壳聚糖联用对石灰性土壤铬污染的钝化效应

为探索石灰性土壤上铬污染修复的有效方法,采用田间试验,探究碳酸钙及其与壳聚糖联用对土壤铬污染的钝化效果。结果表明:供试土壤中铬的主要存在形态为残渣态,占总铬含量的71.28%。外源铬的添加显著(P<0.05)增加了土壤中各形态铬的含量,尤以氧化态铬含量增加较多,可占总铬含量的76%以上,而水溶态铬含量最低只有0.45%。施用碳酸钙或碳酸钙-壳聚糖显著(P<0.05)降低了铬污染土壤中水溶态铬的含量,同时显著(P<0.05)增加了残渣态铬的含量。铬污染土壤采用碳酸钙和碳酸钙-壳聚糖处理后,铬钝化率分别增加21.64和35.44个百分点。土壤铬污染导致玉米叶片中丙二醛、可溶性蛋白含量和过氧化氢酶活性显著(P<0.05)增加。向铬污染土壤中添加碳酸钙或碳酸钙-壳聚糖后,玉米叶片中的丙二醛浓度分别显著(P<0.05)下降20.57%和31.92%。碳酸钙或碳酸钙-壳聚糖添加降低了玉米对铬的吸收和富集,与单独添加碳酸钙的处理相比,添加碳酸钙-壳聚糖显著(P<0.05)降低了玉米籽粒、根、茎的铬含量,尤其是显著(P<0.05)降低了玉米籽粒对铬的富集系数。该研究结果可为石灰性土壤铬污染的“边生产边修复”提供方法参考。     

锰尾矿中锰对小麦生长的营养效应

通过盆栽试验研究了锰尾矿中锰对小麦产量构成、叶绿素产量和锰素营养的影响。结果表明:施锰改善了小麦的株高、穗长、穗粒数、百粒重等产量构成因素,其中锰矸石与锰渣混合处理(处理E)的穗粒数最高,达34.17粒,百粒重达4.15 g;小麦拔节期、孕穗期的叶绿素总含量分别提高了10.6%~13.7%和18.1%~26.8%,籽粒和茎叶的锰含量分别提高了37.5%~55.8%和12.6%~25.7%。盆栽试验后,土壤残余锰低于种植前。为综合利用锰尾矿,以锰矸石与电解锰渣混合的形式作为锰肥效果更好。     

Diagenesis of carbonate sediments: interaction of magnesium in sea water with mineral grains

Samples of natural fine-grained carbonate sediment from Florida Bay, Florida, undergo mole-for-mole cation exchange with aqueous solutions of MgCl(2) and CaCl(2) in the laboratory. The exchange reaction, which involves the surface of the grains of sediment, can be essentially described by a simple mass action-law equation. Enrichment of Mg++ beyond the amounts found within particle interiors should take place on the surface of CaCo(3) sediments immersed in sea water; it may be on both exchangeable and unexchangeable sites.     

The Tagish Lake meteorite: a possible sample from a D-type asteroid

A new type of carbonaceous chondrite, the Tagish Lake meteorite, exhibits a reflectance spectrum similar to spectra observed from the D-type asteroids, which are relatively abundant in the outer solar system beyond the main asteroid belt and have been inferred to be more primitive than any known meteorite. Until the Tagish Lake fall, these asteroids had no analog in the meteorite collections. The Tagish Lake meteorite is a carbon-rich (4 to 5 weight %), aqueously altered carbonaceous chondrite and contains high concentrations of presolar grains and carbonate minerals, which is consistent with the expectation that the D-type asteroids were originally made of primitive materials and did not experience any extensive heating.     

钙质结核的微形态及矿物学特征

土壤中的钙质结核可分为软结核、硬结核和钙质硬盘３种形态，其化学组成以ＣａＣＯ３为主，矿质全量组成的各氧化物平均含量水平的顺序为：ＣａＯ〉ＳｉＯ２〉Ａｌ２Ｏ３〉Ｆｅ２Ｏ３〉ＭｇＯ〉Ｋ２Ｏ〉Ｎａ２Ｏ〉ＴｉＯ２〉ＭｎＯ〉Ｐ２Ｏ５。但在某些软结核中，ＳｉＯ２含量仍大于ＣａＯ含量。微形态分析结果表明，软结核为碳酸盐颗粒的胶结体，常嵌埋较多的土壤基质、石英、长石等粗颗粒；硬结核多为碳酸盐和方解石的胶结体，许多     

Dissolution of pyroxenes and amphiboles during weathering

Augite, hypersthene, diopside, and hornblende all undergo dissolution during weathering by means of the formation, growth, and coalescence of distinctive, parallel, lens-shaped etch pits. Similar etch features can be produced if these minerals are treated in the laboratory with concentrated hydrofluoric acid plus hydrochloric acid. These pits most likely form at dislocation outcrops, and their shape and orientation are controlled primarily by the crystallography of the underlying mineral. The results are similar to those found for soil feldspars and suggest that silicate weathering, in general, takes place by selective etching and not by general attack of the surface with consequent rounding as necessiated by bulk diffusion-type weathering theories.     

The Effect of Planting Oilseed Rape and Compost Application on Heavy Metal Forms in Soil and Cd and Pb Uptake in Rice

Pot experiments were conducted under greenhouse condition to investigate whether Cd and Pb uptake by rice could be reduced when it was rotated with oilseed rape and compost application. The results showed that the rice grown after oilseed rape had significantly lower Cd and Pb concentrations in both straw and grains. Cd and Pb concentrations in the grains of the rice rotated with oilseed rape decreased by approximately 46-80% and 17-86%, respectively, although the Cd and Pb removal by oilseed rape ranged only from 2.39-3.67 and 0.032-0.13% of the total content in soil. Compost amendment also decreased the bioavailability of Cd and Pb in the soil and reduced Cd and Pb uptake by oilseed rapes and rice. The concentrations of Cd and Pb significantly decreased in the exchangeable and carbonate fractions and Pb concentration decreased in the organic matter and sulfide fractions in the contaminated soil after planting oilseed rapes.     

陕西省咸阳市、商州市烟草病毒病毒原鉴定初报

2001年在咸阳市，商州市采集了101个毒株，经过生物学测定，血清学反应（琼脂双扩散法和酶联免疫吸附法），电镜观察鉴定出5种为害烟草的病毒，它们是烟草普通花叶病毒（TMV），黄瓜花叶病毒（CMV），烟草蚀纹病毒（TEV），马铃薯Y病毒（PVY），烟草环斑病毒（TRSV），其中烟草普通花叶病毒病，黄瓜花叶病毒病和烟草蚀纹病毒病是当前生产上发病率较高，造成损失较大的3种病毒；同时，烟草普通花叶病毒（TMV）和黄瓜花叶病毒（CMV），烟草普通花叶病毒（TMV）和马铃薯Y病毒（PVY）的复合侵染也是当前生产上亟待解决的主要问题。     

山东暗色粘性土的特性及发生学研究

本文对山东省主要暗色粘性土进行了形态学、粘土矿物学、物理化学特性以及发生学的研究。结果表明,大部分粘质砂姜黑土和暗色粘质湿潮土具有明显的变性特征,表现为干时开裂、湿时膨胀,剖面上部土体中有大量的滑擦面和明显的土壤翻转现象。土壤微形态以具有因强烈胀缩而产生的光性定向粘粒和裂纹裂隙为主要特征,并有较多铁锰和碳酸盐的浓聚物。土壤粘粒的硅铁铝率较高,粘土矿物以蒙脱石为主,蒙脱石的发生与其所处的地球化学环境密切相关。耕层之下的黑土层粘粒含量最高,且以蒙脱石占绝对优势,因此胀缩性最强,是具有变性特征最明显的层次。土壤的强烈胀缩性是这些暗色粘性土形态发生的内在原因,干湿交替的土壤水分状况则是其形态发生的必要条件。     

"Molecule corrals" for studies of monolayer organic films

Scanning tunneling microscopy (STM) studies have demonstrated that monolayer-deep, flat-bottomed, circular etch pits can be grown on highly ordered pyrolytic graphite by high-temperature etching in the presence of oxygen. In this work, these graphite etch pits are used as "molecule corrals" to isolate ensembles of molecules for study by STM. The nucleation of self-assembled molecular films in the corrals took place by nucleation events separate from those leading to self-assembly on the surrounding terrace and allowed the measurement of the nucleation rate constant in the corrals. The dependence of the nucleation rate for self-assembly on pit size shows that nucleation occurs at open terrace sites and that step edges (that is, the corral's perimeter) and confinement inhibit film growth.     

Concentration-gradient-driven convection: experiments

Concentration-gradient-driven convection was studied by measurement of the rate of dissolution of the lower face of a KCl single crystal in contact with various solvents. The rate of mass transfer due to convective stirring appeared to follow the Rayleigh number to the one-third power law. A regular pattern of etch pits due to the convective stirring action was observed in the crystal face after exposure to water for 5 minutes. Schlieren photographs of the early stages of dissolution showed a regular pattern of spikes having approximately the same dimensions as the etch pits in the crystals.     

小麦黑胚籽粒营养品质的测定

采用洛阳农科所提供的小麦品种，对黑胚籽粒营养品质进行了测定，结果表明：小麦黑胚病感病品种黑胚粒中Mg、Ca的含量高于健粒，中感及高感品种黑胚粒中K、Mg、Ca的含量低于健粒；黑胚粒中Fe、Mn、Zn、Cu的含量有的品种高于健粒，有的品种低于健粒。小麦黑胚病使籽粒内粗蛋白含量增加，淀粉含量与氨基酸总量降低。     

烟稻轮作与烟草病害关系的研究

经４年研究表明：烟稻轮作能有效地控制烟草青枯病的发生，并减轻烟草赤星病和烟草野火病的危害。烟草花叶病、黄瓜花叶病、烟草蚀纹病与烟稻轮作的关系有不明显。     

植被培育抗旱分析

随着气候的演变,植被培育面临严峻的干旱缺水形势。为进一步增强抗旱的主动性和有效性,主要以作物栽培为背景,重点论述了有关抗旱的基础问题。通过分析干旱的特点、表现形式、区域差异、相对性、降水和灌溉水的利用状况、应对干旱的策略等,以明晰抗旱的依据。认为土壤水分亏缺是干旱的主要表征;土壤干旱的滞后性,也即和大气干旱的非同步性,是抗旱的一个重要依据。通过对抗旱途径的讨论,细分出避旱、御旱二个方面,并且认为御旱应当是正常的生产方式。抗旱具有高效、节约用水的特征,直接抗旱和间接抗旱都是必要的。最后,还补充阐述了水文干旱、降水资源化利用的意义。     

基于空间技术北京市地貌类型区划研究

地貌类型区划图是区域土地利用及农业规划中重要的基础数据,而北京市现有的地貌类型区划数据存在比例尺过小、与北京市当前的土地利用图不一致等问题。针对这一问题,在收集总结研究区已有地貌区划方案的基础上,确定了北京市地貌划分的类型及划分标准。首先以研究区高精度DEM为主要数据源,同时参考研究区的地质图,利用相应的空间分析技术初步确定地貌类型区划界线。然后,利用SPOT5遥感影像和DEM生成的三维景观对地貌类型区划进行了验证和局部调整,并通过外业实地调查进行核实。最后,生成与研究区土地利用现状图在比例尺、参考坐标系等方面一致的地貌类型区划数据,为北京市土地利用规划提供了基础数据。     

水稻、小麦碳酸盐耐性突变体的筛选

用 Na N3处理水稻、小麦 ,在 M3世代中筛选出了水稻碳酸盐耐性突变体。结果表明 ,水稻品种之间有耐性差异 ,耐性突变体有稳定遗传的趋势。可培育出稳定遗传的新材料。     

Foraminiferal evidence of a shallow calcium carbonate solution boundary, ross sea, antarctica

In the Ross Sea, Antarctica, distributions of calcareous Foraminifera and other calcareous microorganisms are dominantly controlled by a shallow calcium carbonate solution boundary that occurs at depths of about 500 meters. Possible causes of substantial undersaturation of Ross Sea bottom waters in calcium carbonate are very low temperatures and high salinities, which favor the solution of calcium carbonate and, possibly, high concentrations of carbon dioxide.     

中国榆科花粉形态及其在分类上的意义

收集了国内榆科中7属22种花粉,利用光学显微镜和扫描电子显微镜对花粉形态进行了观察和研究。榆科花粉形态可分为两个基本类型。萌发孔和外壁纹饰作为分科、分属、分种的重要依据。榆科花粉形态的研究,为榆科的分类提供孢粉学方面的参考资料。     

彩色小麦F2代种皮颜色遗传规律

用蓝粒小麦和紫粒小麦杂交,对F₂代单株和单穗粒色遗传分离比例进行分析表明,F₂代疯狂分离,出现了多种分离类型。籽粒颜色分离强度在单株水平大于单穗水平,2种颜色分离大于3种颜色分离。紫蓝粒同穗主要受2对基因互作控制,基因间互作类型多少依次是抑制作用、互补作用和重叠作用。红蓝粒同穗主要受2对基因互作控制,其次是受1对基因控制,再次受3对基因互作控制;2对基因互作类型多少依次是互补作用、抑制作用和重叠作用。红紫粒同穗,红白粒同穗和蓝白粒同穗均由2对基因控制。各籽粒颜色间的显隐性关系是红粒对紫粒是显性,红粒和紫粒对蓝粒是显性,红粒、紫粒和蓝粒对白粒是显性。因此,除了紫粒表现果皮遗传,蓝粒表现花粉直感外,紫粒和蓝粒杂交后代中粒色还存在复杂的基因互作模式,基因剂量效应等遗传效应。