河南省主要农作物灌溉用水定额分析

针对河南省现状灌溉用水情况,在大量调研资料的基础上通过回归分析模型计算得出不同灌溉分区及全省平偏枯年份主要作物灌溉用水基准定额和调节系数,进而确定了不同灌溉条件下各作物的灌溉用水定额。结果为现阶段河南省农业灌溉实施"总量控制、定额管理"提供了决策指导。     

数控车床对刀方法研究

数控机床加工前要进行对刀,对刀处理的好坏直接影响到数控加工的精度与效率.文章根据数控车床加工时的不同精度要求,介绍了两种简捷而又实用的对刀方法.     

兰州市基准地价变化成因分析

通过对兰州市2次定级估价成果进行对比分析,从经济发展水平、基础设施建设、土地招拍挂制度、商圈集聚效应、企业经营状况以及土地取得成本等方面探讨了基准地价水平变化的原因以及各种影响因素与地价变化的关系。得出兰州市基准地价的变化将会呈现商业用地、住宅用地持续上涨,工业用地基本持平略有上涨的趋势。     

Remediation of Cadmium Pollution in Soils by Different Amendments: A Column Study

Abstract

A column study was conducted to determine the effect of city compost, lime, gypsum, and phosphate on cadmium (Cd) mobility in three well‐recognized benchmark soils of India [viz., (Islamnagar) Vertisol, (Amarpur) Inceptisol, and (Khala) Alfisol]. Columns made of PVC were filled with soil treated with different treatment doses [viz., 0.5% city compost, 1% city compost, 2% city compost, 2.5 t lime/ha, 5 t lime/ha, 2.5 t lime/ha+0.5% city compost, 2.5 t gypsum/ha, 2.5 t gypsum/ha+0.5% city compost, and 100 kg P₂O₅/ha as potassium phosphate (KH₂PO₄). The columns were leached with 100 mg L^?1 Cd under saturated condition. The amount of water moving through the soils was measured as the pore volume. A delayed breakthrough curve (BTC) of Cd in the presence of lime has been observed in all the studied benchmark soil series. Among the treatments, lime application reduced the movement of Cd from surface soil to lower depth of soil to a large extent resulted in 9, 25, and 45% more retention of Cd in surface soil of the Islamnagar, Amarpur, and Khala series respectively. Explanation for reduced Cd mobility in limed soil can be derived from pH changes of soils. In comparison to control soil, phosphate application caused 6, 21, and 30% more retention of Cd in surface soil in the Islamnagar, Amarpur, and Khala series, respectively. Combined application of lime and city compost reduced the movement of Cd in the soil profile. It appears that organic matter controls the sorption of Cd in soils. The amount of Cd sorbed increased with increasing organic carbon content, but gypsum application may leach Cd beyond the root‐zone depth. A rapid breakthrough curve was observed under gypsum‐treated soils. Retardation factor revealed that a somewhat lower degree of Cd retention occurred in the Khala series, which might possibly be attributed to less clay content and low pH. Overall, the column study indicated that total Cd accumulation occurred up to depths of 5–7.5 cm, 7.5–10 cm, and 10–15 cm in soils of Islamnagar, Amarpur, and Khala series, respectively.     

基于“三权分置”的农地承包权评估方法探讨

在城乡中国的背景下,“三权分置”的新时期中国农地制度创新理论为土地产权改革提供了机遇,农地承包权价值内涵构成及价格评估是值得深入研究的课题,这不仅给农用地流转提供依据,也是自然资源资产价值核算的关键。本研究从“三权分置”的政策背景演变入手,重释了承包权内涵及价值构成,并在分析影响价值因素的前提下探讨了采用收益还原法与叠加法来评估承包权基准地价。研究认为,（1）承包权是因农户具备了集体经济组织成员身份,从而享有对农村集体土地承包的权利;身份权特征明显,具有主体专一、财产收益、效益处分及有效占有等4个特点;（2）集体成员身份权具有身份性、平等性、共同性及约束性等4个特性,享受成员权的主体形式可以是农户家庭也可以是集体经济组织的个人或是两者的结合;（3）依据农地承包权的生产收益权价值和社会保障价值构成,采用收益还原法和叠加法两种方法来评估承包权价格,在确定社会保障价值时可以借用征地区片综合地价中的社保费用值来量化。本研究在维护农户土地权益前提下,以期为全面有序开展农地质量价格评估和价值核算提供有益参考。     

Studies on Nutrient Distribution in Some Zambian Soils with Special Reference to Sulphur Using GIS (Geographic Information Systems) II. Evaluation of Plant-Available Sulphur and Its Distribution in Major Zambian Soils

Relationship between the contents of soil sulphur and plant sulphur was studied in order to evaluate the distribution of plant-available sulphur in Zambian soils. Four soils series with distinct differences in texture and organic carbon content had been selected among representative benchmark soil series and used to cultivate maize (Zea mays L.) as a test plant in pots. From the results of the pot experiment, critical levels of sulphur deficiency in plants and soils were evaluated and the levels of available sulphur for maize nutrition were rated into four classes using data on the relative yield of maize. The optimum method to determine the available sulphur content of the soils was applied to the analysis of other benchmark soils. Satisfactory regression models for assessing the relation between the content of available soil sulphur with other soil constituents among benchmark soil could not be identified. A distribution map for available sulphur was drawn in a step-by-step format by using a different scale of the soil map, soil units and the legends of soil map databases. As a result, it was confirmed that sulphur-deficient and marginal areas were widely distributed throughout the country. Finally, soil acidity problems associated with sulphur application, the inconsistency of the content of available sulphur with that of total sulphur and limitation of the map utility were examined.     

不同基准下的公差分析与研究

以磁体馈线系统线圈终端盒外壳体为例,基于公差分析软件CETOL6σ建立零件尺寸链,对其模型进行分析.在产品设计阶段研究不同基准下尺寸公差分析,通过对建立的模型尺寸链进行分析,然后从分析结果中得出尺寸链中重要尺寸,保证重要尺寸及公差以保证产品质量.该方法为提高产品加工质量提供一定的指导,并且缩短了产品周期.     

Studies on Nutrient Distribution in Some Zambian Soils with Special Reference to Sulphur Using GIS (Geographic Information Systems) II. Evaluation of Plant-Available Sulphur and Its Distribution in Major Zambian Soils

Relationship between the contents of soil sulphur and plant sulphur was studied in order to evaluate the distribution of plant-available sulphur in Zambian soils. Four soils series with distinct differences in texture and organic carbon content had been selected among representative benchmark soil series and used to cultivate maize ( Zea mays L.) as a test plant in pots. From the results of the pot experiment, critical levels of sulphur deficiency in plants and soils were evaluated and the levels of available sulphur for maize nutrition were rated into four classes using data on the relative yield of maize. The optimum method to determine the available sulphur content of the soils was applied to the analysis of other benchmark soils. Satisfactory regression models for assessing the relation between the content of available soil sulphur with other soil constituents among benchmark soil could not be identified. A distribution map for available sulphur was drawn in a step-by-step format by using a different scale of the soil map, soil units and the legends of soil map databases. As a result, it was confirmed that sulphur-deficient and marginal areas were widely distributed throughout the country. Finally, soil acidity problems associated with sulphur application, the inconsistency of the content of available sulphur with that of total sulphur and limitation of the map utility were examined.     

荒漠化监测与评价指标体系框架

根据荒漠化的定义以及荒漠化的特点,荒漠化监测与评价指标体系由4个部分组成,即压力指标、状态指标、影响指标和防治指标。压力指标描述的是对自然资源的状态带来影响并导致荒漠化发生的自然和人为驱动因素,用来对荒漠化发展趋势进行评估并进行荒漠化早期预警;状态指标描述的是土地生态系统的状态和特性,可以分为物理指标、化学指标和生物指标,它们分别描述土地生态系统的物理、化学和生物特性;影响指标用来评价荒漠化对人类及其环境带来的影响;防治指标用来评价防治荒漠化采取的行动和措施以及采取这些行动和措施带来的社会经济和自然条件的改善。     

Establishing an upper level of intake for vitamin A in Atlantic salmon (Salmo salar L.) postsmolts

The vitamin A (VA) concentration in salmon aquaculture feeds is varying and may lead to sublethal adverse effects. In this study, 135 g Atlantic salmon postsmolts were given eight diets in duplicates with 6, 12, 26, 55, 82, 112, 360 and 749 mg retinol (ROL) kg⁻¹ for 116 days. Subsequently, fish given 6, 82 and 749 mg ROL kg⁻¹ were transferred to a common net pen and given a standard commercial diet for further 28 weeks. Feed conversion rate, liver functionality and markers of VA homoeostasis were not negatively affected by dietary VA level, but chronic high VA intakes led to adverse effects on growth and bone health. In plasma, there was an antagonistic effect of dietary ROL on circulating 1,25 (OH)₂ vitamin D₃ (calcitriol). Moreover, a dose–response of VA on craniofacial deformities, condition factor and vertebral morphometry and mechanical strength was observed. Vertebral deformities were observed after 28 weeks on a standard diet and not immediately after the 116 days on the experimental diet. Elevated VA is a risk factor for bone deformities, and the dietary intake of VA should not exceed 37 mg ROL kg⁻¹ body weight day⁻¹ in Atlantic salmon postsmolts.