云南昌宁蔗区不同耕层土壤养分的垂直分布

研究了蔗园土壤养分的垂直分布特征。结果表明:(1)不管是在旱地蔗园还是在水田蔗园,0～30cm土层的有机质、水解氮、速效磷、速效钾等主要养分含量明显高于30～60cm的土层,但全氮、全磷、全钾在0～30cm土层与30～60cm土层之间没有明显的变化。(2)旱地蔗园的有效铁、有效锰和有效铜0～30cm土层比30～60cm土层高,有效锌含量在0～30cm的土层与30～60cm的土层之间变化不大。     

覆膜旱作稻田土壤有效N、P、K及盐分分层变化研究

以常规水作和裸地旱作作对照,对覆膜旱作栽培条件下稻田各土层(0～60cm)土壤有效N、P、K和盐分含量变化作了比较研究。结果表明:与常规水作相比,覆膜旱作稻田10～15cm土层的碱解氮与有效磷含量显著增加,其余差异不大。与裸地旱作相比,覆膜旱作稻田5～15cm土层的碱解氮含量及5～20cm土层的有效磷含量显著增加,其余差异不大。与常规水作和裸地旱作相比,覆膜旱作稻田土壤速效钾含量在20cm以上土层增加明显。当地下水位较高时,覆膜旱作稻田0～5cm表层土壤表现积盐,地下水位较低时表层表现脱盐。     

西安市郊区日光温室大棚番茄施肥现状及土壤养分累积特性

调查了西安市郊区100余个日光温室栽培番茄的施肥现状,并采集了60个日光温室土壤剖面样品,测定了土壤养分及盐分含量。结果表明,当地番茄的氮磷钾化肥的平均施用量分别为N 600 kg hm-2,623 kg P2O5hm-2和497 kgK2O hm-2。过量施肥特别是过量施用磷肥比较普遍。日光温室土壤0~20 cm和20~40 cm土层有机质、有效磷、速效钾含量均明显高于露地。不同地点日光温室土壤0~100 cm土层硝态氮含量及土壤电导率存在差别,但其含量均高于露地土壤,其中日光温室土壤0~100 cm土层硝态氮含量较露地的增加幅度在127%~433%之间。由于研究地区土壤多发育在河流冲积物上,地下水位埋藏浅,土壤质地相对较粗,因此,不合理施肥引起的土壤养分累积及损失,以及由此带来的环境问题值得关注。     

宁夏不同地区农田土壤磷素养分的空间变异特征

在宁夏灌区和旱区30块农田分别采集了0~120 cm深土壤剖面样品,测定了土壤全磷和速效磷含量,分析了土壤磷素养分含量的空间变异性。结果表明,在0~120 cm深土壤剖面中的全磷和速效磷含量,灌区土壤显著高于旱区土壤,在剖面点之间和土壤层次之间存在极显著差异,而且在土层间还存在着正相关。其变异系数总体上是旱区土壤大于灌区土壤,速效磷大于全磷。从地区来看,旱区土壤全磷和速效磷含量的变异系数随剖面深度的增加而增大,灌区土壤全磷量的变异系数在剖面层次之间差别不大,而速效磷的变异系数随剖面深度的增加而呈降低趋势。在0~120 cm深土壤剖面中,土壤全磷和速效磷的累积量灌区较旱区分别高出26.8%和65.0%,在土类间也存在较大差异。     

哈尔滨市辖区黑土速效养分空间异质性分析

研究在哈尔滨市所辖黑土区的6个市县进行,共采集表层(0～20cm)黑土土样411个,测定了全部样点的有机质、全氮的养分含量,同时测定了部分样点的碱解氮、速效磷、速效钾的养分含量,利用地统计学中协同克立格分析方法并结合经典统计学和GIS技术分析碱解氮、有效磷、速效钾养分空间异质性。分析表明有效磷空间分布符合指数模型,碱解氮、速效钾符合高斯模型,其块金值与基台值之比分别为50.0%、39.7%、6.3%,有效磷和碱解氮为中等程度空间相关水平,速效钾为强度空间相关水平;与克里格对比,应用协克里格插值绘制的三种速效养分空间分布图精度显著提高,为协克里格方法在土壤养分空间异质性分析上的应用提供了实践依据。     

吉林省玉米主产区土壤有机质和速效养分分布特征

结合国家测土配方施肥项目的进行,根据吉林省16县市土壤采样点的实测数据,分析了土壤有机质,碱解氮,速效磷,速效钾的分布特征.结果表明:土壤有机质含量表现出东高西低的分布趋势;碱解氮的分布趋势同有机质;速效磷含量总体处于中等偏高水平,但分布差异较大,全省范嗣内速效磷含量东部>中部>西部;速效钾含量分布与速效磷相反,西部大于中东部地区.根据东中西部不同的养分分布特点、气候特点及玉米的需肥规律,相应的氮磷钾肥配比为:东部2.5:1:1.5,中部3:1:1.5,西部2～3:1:1.     

香蕉园土壤养分肥力时空变化研究

对香蕉园土壤养分肥力的研究是制定香蕉养分管理策略的基础。本研究采集了广东省香蕉主产区果园土壤样本110个,评价土壤养分肥力现状,并与第二次土壤普查结果相比,探讨养分肥力的时空变化。结果表明香蕉园土壤养分肥力整体上较高,缺素少,而硼是普遍缺乏的元素;与20世纪80年代初相比,香蕉园土壤养分肥力已经发生很大变化,主要表现为有机质明显下降、有效磷和速效钾的显著提高。从化肥消耗量变化、施肥结构及香蕉种植模式三方面探讨了时空变化的主要原因。     

河南开封土壤养分变化特征及其持续利用途径研究

通过 1 984～ 1 998年河南开封不同土壤耕层有机质与氮磷钾养分分析 ,论述了不同农业利用方式和农田管理措施下不同土壤耕层养分的时空变化特征和硝态氮累积特性 .由于“重氮磷 ,轻有机肥 ,忽视钾素补给” ,土壤养分变化的总趋势以下降 ,钾素耗竭性明显 .土壤养分空间变化较为复杂 ,但不同土壤间耕层养分为普通淡色潮湿雏形土 >底锈干润雏形土 >石灰淡色潮湿雏形土 >灌淤旱耕人为土 >简育干润雏形土 >干润砂质新成土 .硝态氮累积表现为由上至下递减或由上至下递增和相对积累于土体某一深度 .最后研究提出了土壤持续利用的有效技术途径 .     

不同灌溉方法对保护地土壤有机质及氮素影响的研究

分层采集连续7年分别用渗灌、滴灌和沟灌灌溉的保护地0～80cm土层土壤样品,测定有机质、全氮及无机态氮和有机态氮含量,研究灌溉方法对土壤氮素形态及其数量剖面分布的影响。结果表明,三种灌溉处理0～80cm剖面土壤有机质含量变化范围为8.47～36.48 g kg-1,渗灌与滴灌有机质剖面分布相似,二者与沟灌差异较大;沟灌除30～40cm层次有机质含量低于渗灌和滴灌外,其它层次有机质含量均高于渗灌和滴灌处理。土壤全氮含量变化范围为0.72～3.97 g kg-1,在0～20cm土层不同灌溉方法之间差异显著,渗灌最大,沟灌次之,滴灌最小。无机硝态氮、铵态氮含量的变化范围分别为19.16～1442.06 mg kg-1和0～15.28 mg kg-1,在0～20cm土层各处理之间差异较为明显,以渗灌最大,沟灌次之,滴灌最小。有机态氮含量的变化范围为683.79～2512.87 mg kg-1,各处理之间的差异主要表现在0～30cm土层,其中0～10cm土层以渗灌处理有机态氮含量最高、沟灌次之,滴灌最低,10～30cm沟灌处理有机态氮含量却高于渗灌和滴灌处理。     

塔里木沙漠公路防护林区土壤微生物的立地条件效应

通过分析来源于塔克拉玛干沙漠腹地防护林地的土壤样品,揭示了不同立地条件下防护林土壤微生物的差异及对土壤环境因子的响应规律,主要结论如下:(1)不同立地条件下土壤微生物活性差异极显著,呈现沙垄基部＞沙垄中部＞沙垄顶部＞板结平沙地＞流沙地的规律,而土壤深度间微生物数量表现为10～20cm＞20～35cm＞0～10cm,差异不明显.(2)三种微生物对环境因子的响应有所差异,细菌与土壤总孔隙度、含水量有显著正相关关系.与全K含量显著负相关;放线菌与全P、全K和全盐含量明显负相关,与全N正相关;真菌与全K、全盐含量负相关,与有机质含量和孔隙度大小正相关.(3)土壤不同深度范围内土壤因子对微生物活性的影响程度不同,0～10cm土层主要取决于有机质和N素含量;而土壤盐分状况和孔隙结构对10～20cm微生物较为重要;20～35cm土层中微生物需要满足一定养分供应和土壤结构.因此,土壤微生物对不同立地条件下土壤环境条件响应不同,微生物种群数量表现出一定差异,最终可能影响到微生物在土壤养分转化和促进土壤发育中的作用.     

天津滨海盐碱土地区城市绿地土壤微生物特性研究

对天津滨海盐碱土地区城市绿地土壤微生物特性研究表明不同绿地植物配置模式下0～40cm土壤微生物数量差异极显著,防护林>灌 草>乔木>乔 草>草坪>滨海盐土,0～20cm土层微生物数量是20cm～40cm的3～4倍。在细菌、放线菌和真菌三大类群中,细菌占绝对优势,其次是放线菌和真菌。滨海盐土微生物的季节变化不大,防护林土壤中微生物总数最多时出现在秋季,乔木、乔 草、灌 草、草坪绿地土壤中微生物数量最多时出现在夏季或秋季。细菌、放线菌数量与土壤全盐含量呈显著负相关,细菌的数量与土壤有机质含量呈极显著相关,真菌数量与土壤养分相关不显著.芽孢杆菌的11个种在不同土壤条件和植物配置模式下的生态分布是不同的,最常见的是蜡质芽孢杆菌、拟霉芽孢杆菌、枯草芽孢杆菌、地衣芽孢杆菌和蜂房芽孢杆菌,放线菌主要是链霉属,包括链霉菌属的10大类群,分布最广的类群是灰褐类群、金色类群和青色类群,真菌分布有11个属。在不同植物配置下芽孢杆菌、放线菌和真菌的组成、优势种的组合也存在显著差异。     

东北地区不同纬度梯度农田土壤Olsen-P的分布特征

本文研究了中国东北地区不同纬度梯度农田土壤Olsen-P在0～100cm剖面中的分布特征。结果表明,除公主岭和大石桥外,其他各点土壤Olsen-P含量在0～20cm土层较高,20～40cm土层迅速下降,40～100cm各土层又逐渐升高,但底层要远低于表层。不同纬度梯度下各点0～20cm土层Olsen-P含量为暗棕壤>黑土>棕壤,高纬度地点Olsen-P含量具有高于低纬度地点的趋势;20～100cm各土层Olsen-P含量总体表现为黑土和暗棕壤相对较高,棕壤区偏低,没有明显的纬度分异现象。施肥等农田管理措施对0～20cm土壤Olsen-P含量有明显影响,其他土层Olsen-P含量可能主要受磷素运移特点和成土母质等因素影响。     

黑土有效硫含量状况及其评价

对三个典型黑土区采样分析了土壤有效硫的含量情况,并对有效硫分级进行了讨论。结果表明:黑土耕层(0～20cm)土壤有效硫含量平均值为27.7mgkg-1,变幅为7.09～109.14mgkg-1;20～40cm土壤中有效硫含量平均为18.17mgkg-1,变幅为0.43～68.9mg kg-1。黑土有效硫含量耕层最高,随土层深度的增加土壤有效硫含量迅速下降。黑土耕层有效硫含量随开垦年限增长呈下降趋势。黑土有效硫含量随着溶液电导率增加而增加。按缺硫标准进行评价,北安地区耕层土壤有效硫含量小于16.0mg kg-1的农田面积约占9.5%,公主岭地区占16.1%,海伦地区占26.7%。     

Industrial inspection performance depends on both viewing distance and oculomotor characteristics.

The influence of viewing distance and individual differences in the oculomotor resting states (dark vergence and dark focus) on both inspection performance and visual fatigue was investigated by asking 24 college students to perform a visual inspection task for 40 min twice, once with a 20 cm viewing distance and once with a 60 cm viewing distance. During the task participants visually searched enlarged images of contact lenses for six different types of defects. Lens images were presented at a constant visual angle (17.5 degrees) on a CRT. Inspection performance varied significantly across the two viewing distances: participants spent on average more than twice as much time inspecting individual lenses in the near condition (mean = 18.32 s lens(-1)) than in the far condition (mean = 7.25 s lens(-1)). Participants also reported greater visual fatigue in the near condition than in the far condition. At both viewing distances, participants who experienced relatively large inward shifts in dark vergence also tended to be slow inspectors. Neither inspection performance nor measures of fatigue were related to dark focus. These results support existing evidence against the use of near viewing distances and suggest that an oculomotor mechanism links inspection performance and visual fatigue to viewing distance.     

Distance estimation with mixed real and virtual targets in stereoscopic displays

In this paper we investigated the accuracy of center-to-center distance perception in near field augmented reality visual targets viewed by stereoscopic glasses. One real and one virtual targets were presented in four layout or target orientations (two horizontal and two vertical, by altering the relative positions of real and virtual targets) at three different parallax conditions (on screen, 5 cm from screen and 10 cm from screen) and four levels of scaled between targets’ distance (10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm). The result revealed overall underestimation with an accuracy of about 84%. Interestingly, it was noticed that the main effects of layout, parallax and center-to-center distance were significant. Generally, accuracy improves when targets put vertical, close to observers’ position and smaller separation of targets. Significant interactions among the three main factors were also reported. The results are of great importance as it provides guide for the developers to decide where to present targets depending on the need for relative accuracy of judgment. Some engineering implications of the result are also discussed in this paper.     

Gender, women's work and ergonomics

A submaximal test for estimating the physical work capacity has been developed and compared with a more complicated bicycle test. The testing procedure is a modified Harvard step test which in its original form is a maximal test The pulse rate was counted during work.

The step height was 40 cm for young males and 27 cm for the older ones and for the females 33 cm; the stepping rate was 22·5 steps per min.

The average values for ‘ step test 40 cm ’, and ‘ bicycle test 900 kgm/min ’ for male subjects were: oxygen intake 2·11 ±0·04 and 2·15±0·02 l./min ; pulse rate during work 130±1·5 and 132± 1·9 beats/mm respectively. The average values for ‘ step test 33 cm ’ and ‘ bicycle test 600 kgm/min ’ for female subjects were : oxygen intake 1·56±0·03 and 1·48±0·02 l./min ; pulse rate during work 140±1·6 and 138 ±2·2 beats/min respectively. The mechanical efficiency did not vary with the body height or weight.

As the aerobic capacity for trained individuals without excessive fat is closely correlated to the body weight the light ones will be tested at a relatively higher intensity than the heavy ones, when the bicycle test is used with a fixed load. In the step test the load varies with the body weight but the oxygen intake per kilogram body weight is constant.     

多晶SiC薄膜的生长及其压阻特性

在Ａｒ、ＣＨ４的混合气体中用反应性磁控溅射法生长了多品ＳｉＣ薄膜。溅射靶使用了单晶硅片。ＳｉＣ薄膜的生长速率１０～４０ｎｍ／ｍｉｎ。Ａｒ的分压为６０ｍｔｏｒｒ（１ｔｏｒｒ＝１３３．３２２Ｐａ，以下同），ＣＨ４的分压为４０ｍｔｏｒｒ，衬底温度为７５０℃时，薄膜具有显著的多晶特性。杂质浓度、Ｈａｌｌ迁移率、电阻率分别为１０（１８）ｃｍ（－３）、１０ｃｍ（２）／Ｖ·ｓ、１０（－１）１０（－２）Ωｃｍ。压阻系数约为１５。     

THE ENERGY EXPENDITURE OF WALKING ON SNOW AT VARIOUS DEPTHS

Tho energy expenditure of walking at natural pace on snow was determined. The results are expressed as a function of tho depth of the depression of tho feet into the snow, Depressions of 0, 10, 20, 30 and 40 em gave an energy expenditure of 0-63, 1-42, 2-05, 5-72 and 8-30 cal/kg body weight per horizontal metro, respectively. Tho enorgy expenditure could be expressed as a linear function of the depression, using two equations, one for depressions less than and the other for thoso greater than 15 cm. The results are discussed.     

连续侧线出料精馏分离混合氯化苯

为了得到高纯度的氯苯和二氯苯的同分异构体,本文采用连续侧线出料精馏法从氯苯和二氯苯同分异构体的混合物中分离出氯苯,并为继续分离混合二氯苯提供了基础.本文详细考察了多种因素对连续侧线出料精馏过程的影响,最终确定的最佳操作条件为:进料温度90℃,进料速率2.00ml/min,塔顶采出量0.30ml/min,塔高50 cm(H1=20cm,H2=30 cm).结果表明,在最佳条件下,塔顶氯苯纯度可以达到99.12%,塔顶氯苯得率达到88.12%,塔底二氯苯同分异构体纯度达到97.86%.本文研究结果为进一步提纯二氯苯提供了条件.     

A technique to estimate topsoil thickness in arid and semi-arid areas of north-eastern Jordan using synthetic aperture radar data

A Japanese Earth Resources Satellite (JERS)-1 L-band synthetic aperture radar (SAR) dataset was used for estimating topsoil thickness, of different types, in arid and semi-arid areas in north-eastern Jordan. In this research, the relationship between remotely sensed data, backscattering coefficient and the thickness of topsoil was investigated. Based on the dielectric constant properties of the topsoil samples, the relationship between the backscattering coefficient and the topsoil thickness was obtained by developing a multilayer modelling analysis. Using this model, the topsoil thickness had been estimated by means of the derived backscattering coefficients from JERS-1 SAR image. The estimated thickness values of the different topsoil types were found to be comparable with field ground data. The estimated minimum thickness for hardpan topsoil is 55?cm; Qaa topsoil, 74?cm; and topsoil of herbaceous area, 46?cm, while the estimated maximum thickness is more than 98?cm, more than 100?cm, and 82?cm, respectively. Ground data, on the other hand, revealed the minimum thickness for hardpan topsoil to be 50?cm; Qaa topsoil, 70?cm; and topsoil of herbaceous area, 40?cm, while the maximum thickness is more than 120?cm, more than 100?cm, and 80?cm, respectively.