无核葡萄胚发育及早期离体培养的研究:Ⅲ.培养方式对离体胚发育的影响

对5个无核葡萄品种的试验表明,不同培养方式对离体胚发育的影响是很明显的,其中4个品种胚发育率液体培养高于固体培养,‘京早晶’在液体培养中胚发育率高达73.7%,是目前国内外胚发育率最高的报道;液体培养比固体培养胚的发育程度高,发育整齐,无畸形胚,易成苗.     

黄土低山丘陵及坨甸草原区风蚀规律的研究

本文通过对黄土低山丘陵及坨甸草原区248个风蚀图斑资料的分析,运用线性模型理论,对此地区的风蚀规律进行了研究。获得了下垫面各因素与风蚀量关系的数学模型。找出了影响风蚀的主导因素,并系统阐述了植被覆盖度和土地利用类型对风蚀量大小的影响,且与水蚀规律进行了比较分析。     

Seroprevalence of porcine and human influenza A virus antibodies in pigs between 1986 and 1988 in Hassia

1,268 sera collected from slaughtered pigs in Hassia (FRG) from 1986 to 1988 were tested for antibodies against porcine and human influenza A virus strains using the single radial haemolysis test (SRHT). Antibodies against the porcine strains (subtype H1N1) A/Swine/Arnsberg/1/81, A/Swine/Iowa/15/30 and A/New Jersey/7/76 were detected in 411 (32.4%), 318 (25.1%) and 304 (24.0%) of sera, respectively. Up to 1988 a slight increase (10%) in the seroprevalence to A/Swine/Arnsberg/1/81 was noticed, whereas the results obtained with the other strains showed little variation. Antibodies against the human H1N1 strain A/Singapore/6/86 were only found in sera collected 1987 and 1988 in rates of 1.6% and 3.0%. Serological indication of infections with the human H3N2 strains A/Victoria/1/75, A/Hong Kong/1/68 and A/Philippines/2/82 could be shown in 286 (22.6%), 178 (14.4%) and 135 (10.6%) of the serum samples. Within the three year period the rate of sera positive for antibodies against A/Philippines/2/82 increased from 6.5% to 23.0%, whereas no variation in the rates were found using the other H3N2 strains. Antibodies simultaneously against porcine (H1N1) and human (H3N2) virus strains were detected in 9.9% of all sera tested.     

Biochemical Changes in Freshwater Prawn Macrobrachium rosenbergii During Larval Development

Abstract.— Quantitative changes in the protein, lipid and carbohydrate were studied in the early larval stages of developing freshwater prawn Macrobrachium rosenbergii reared under fed and starved conditions to understand the relative importance of these nutrients in energy metabolism of the growing larvae. Larvae obtained from several females were stocked into three 250-L tanks at a density of 30 larvae/L. The feeding regime consisted of newly hatched Artemia nauplii. Protein was always the major organic constituent followed by lipids and then carbohydrates of both fed and starved larvae. Protein levels of both fed and starved larvae increased during development, suggesting an important role in morphogenesis. The decline of lipid during the larval growth that was more rapid for starved larvae, suggests a probable utilization of lipid as the major metabolic source of energy. Carbohydrates formed less than 5 and 2.4% of the larval dry weight of fed and starved larvae, respectively, suggesting their limited role in larval metabolism.     

室内型胶合板天然耐久性的初步研究

作为一项反映材料优劣的重要的评价指标,天然耐久性直接决定了材料的使用寿命.笔者通过对胶合板胶合强度性能连续14年的跟踪测定,讨论和分析了胶合板的天然耐久性.最后总结出了胶合板在使用过程中随时间迁移其胶合强度性能随外界变化的规律,以期为胶合板的生产制备、生产工艺的改进及其应用领域的拓宽等方面起到一定的指导作用.     

Re-defining tillage erosion: quantifying intensity–direction relationships for complex terrain

Abstract. Current tillage erosion models account for the influence of tillage direction in the magnitude of the soil (tillage) transport coefficient. It is argued here that this is counter-intuitive and causes significant problems in modelling tillage erosion in areas of complex terrain. This article examines whether a re-modelling of tillage erosion is possible that separates tillage direction (an interaction with the landform) from the soil transport coefficient (a measure of tillage intensity representing the combination of implement erosivity and soil erodibility). Experimental data for mouldboard ploughing upslope, downslope and cross-slope at Coombe Barton Farm, Devon are examined. Integration of data for all directions into a single relationship, which relates translocation in the direction of tillage to slope in the direction of tillage and translocation perpendicular to tillage to slope perpendicular to tillage, is not possible using previously published methods of analysis. However, when total translocation distance is regressed against the tangent of the slope at 45° to the tillage direction (bisecting the tillage direction and the direction of overturning) it is found that a single relationship can be used to describe tillage in all three directions. Therefore, this relationship is used to determine a single value of the soil transport coefficient ( k _fTa) for constant soil and implement conditions but different tillage directions. This redefinition of tillage is important both for true estimation of tillage erosion severity, the adirectional coefficient being 40% larger than the directional coefficient, and for modelling of tillage erosion in complex terrain. These improvements are vital when tillage erosion simulation is used to direct soil conservation strategies.     

浅谈建立郑州市道路路面养护管理系统

路面管理系统是通过对路面运行状况、使用性能、使用周期、进行对比、分析，预测路面管理的最佳养护预算投资并在最佳养护经济投资条件等各种因素限制下，寻求道路养护管理最佳战略决策。     

深基坑锻锤基础冬期施工

在冬期施工，对于土方开挖、钢筋绑扎、人员的通行、砼的浇铸、砼的温度控制，基坑的保温等都带来一定困难，为此提出了深基坑锻锤基础才是最佳实践应用。     

农药酶免疫分析技术研究进展

自从酶免疫分析原理提出后，近30年来已获得了巨大的进步，成为农药分析的一个非常重要的方法。本文对农药酶免疫分析技术的原理和测定程序进行了评述．并总结了近年酶免疫分析在农药领域研究中的应用，最后，对农药酶免疫分析技术存在的问题和发展趋势作了讨论。     

除草剂最低致死剂量(MLHD)使用新技术概述

本文论述了荷兰MLHD技术的基本内容、技术原理、应用程序等．并针对荷兰的农业特点、开发背景，对该技术在荷兰与中国的应用前景及可行性等进行了比较分析．作者认为合理地利用该技术将有利于我国农业的可持续发展。