光纤传感检测水中总铁的研制

讨论了光纤理化检测仪的原理 ,建立了抗坏血酸还原三价铁后 ,以菲咯嗪为显色剂 ,测定水中总铁的新方法。理论和实践证明 ,采用光纤传感检测适应现场检测的要求。     

进一步做实地质调查项目的问题探讨

地质大调查工作开展以来获得了大量的地质资料,取得了一批丰硕的调查成果。要进一步做实地质调查项目尚需重点解决好几个技术性实践问题:规范性地采集和积累资料,满足经济建设和社会公众对地质资料的需求;把握好综合研究项目的定位,把计划项目做实,形成整体性成果;重视项目设计书的编写,切实做好项目实施方案的部署。     

大连市实验室类污染状况调查及相关对策

对大连市科研院所、学校、医院及监测、检测、检验、试验等单位的实验室、化验室、试验场等排放污染物和处置情况进行了全面调查统计和分析，指出实验室废水、废气、危险废物未经处理直接外排对环境造成较大的污染隐患，并在分析实验室类污染存在问题的基础上提出实验室类污染的控制对策与管理建议。     

A canadian collaborative study of mosaicism in amniotic fluid cell cultures

Data on chromosomal mosaicism was collected retrospectively on 12 386 amniotic fluid samples cultured over a 10 year period in 14 Canadian centres. Level I mosaicism (a single abnormal cell—excluding single cell monosomy) was encountered in 863 cases (7.1 per cent). Level II mosaicism (multiple cells with the same abnormality in a single flask or colony) was encountered in 138 cases (1.1 per cent). Level III mosaicism (multiple cells distributed over multiple flasks or colonies) was encountered in 34 cases (0.3 per cent). Analysis of the details of these cases allowed five major conclusions to be drawn: (1) Single cell abnormalities should not be taken as an indication of true fetal mosaicism. Only rarely will this interpretation prove to be incorrect. (2) Mosaicism involving multiple cells confined to a single flask should not be regarded as an indication of true fetal mosaicism. Only occasionally will this interpretation prove to be incorrect. (3) Mosaicism involving multiple cells distributed over more than one flask should be regarded as a strong indication of true fetal mosaicism. Sixty per cent will be confirmed by karyotype analysis of the fetus or infant. (4) Mosaicism of the XX/XY type is usually due to maternal cell contamination. Occasionally it can be a female fetus with XY cells from an unknown source. (5) The in situ or colony method of chromosome analysis has no clear advantage over the flask method for either the detection of true fetal mosaicism or for the ability to distinguish true mosaics from false positives.     

Space-time modeling for the Missouri Turkey Hunting Survey

The Missouri Turkey Hunting Survey (MTHS) is a postseason mail survey conducted by the Missouri Department of Conservation. The 1996 MTHS provides information concerning the number of turkeys harvested by hunters on each day and the total number of trips made to the counties by these hunters on each day of the hunting season. The success rates are then found from this information. Small sample sizes produce large standard errors for the estimates at the county level. We use a Bayesian hierarchical generalized linear model to estimate daily hunting success rates at the county level. The model includes an autoregressive process for the days of the hunting season and spatially correlated random geographic effects. The computations are performed using Gibbs sampling and adaptive rejection sampling techniques. Results show that there are significant spatial corelations between counties and correlations between days of the hunting season. The estimates are close to the frequency estimates at the state level and much more stable at the county level.     

南岳衡山国内旅游客源市场调查分析

对南岳衡山旅游客源市场进行调查分析，可为其旅游产业定位、旅游开发建设的阶段定位、旅游基础设施资源定位、旅游产品开发定位、旅游从业人员定位提供依据，从而推动整个衡山旅游业的发展，并促进其经济发展．本文通过对南岳衡山客源市场的调查分析，提出了对其市场开发定位及开拓策略的建议．     

Designing an efficient adaptive cluster sample

The choice of neighborhood definition and critical value in adaptive cluster sampling is critical for designing an efficient survey. In designing an efficient adaptive cluster sample one should aim for a small difference between the initial and final sample size, and a small difference between the within-network and population variances. However, the two aims can be at odds with each other because small differences between initial and final sample size usually means small within-network variance. One way to help in designing an efficient survey is to think in terms of small network sizes since the network size is a function of both critical value and neighborhood definition. One should aim for networks that are small enough to ensure the final sample size is not excessively large compared with the initial sample size but large enough to ensure the within-network variance is a reasonable fraction of the population variance. In this study surveys that had networks that were two to four units in size were the most efficient.     

Effects of Earthworm Invasion on Plant Species Richness in Northern Hardwood Forests

Abstract:  The invasion of non-native earthworms ( Lumbricus spp.) into a small number of intensively studied stands of northern hardwood forest has been linked to declines in plant diversity and the local extirpation of one threatened species. It is unknown, however, whether these changes have occurred across larger regions of hardwood forests, which plant species are most vulnerable, or with which earthworm species such changes are associated most closely. To address these issues we conducted a regional survey in the Chippewa and Chequamegon national forests in Minnesota and Wisconsin (U.S.A.), respectively. We sampled earthworms, soils, and vegetation, examined deer browse in 20 mature, sugar-maple-dominated forest stands in each national forest, and analyzed the relationship between invasive earthworms and vascular plant species richness and composition. Invasion by Lumbricus was a strong indicator of reduced plant richness in both national forests. The mass of Lumbricus juveniles was significantly and negatively related to plant-species richness in both forests. In addition, Lumbricus was a significant factor affecting plant richness in a full model that included multiple variables. In the Chequamegon National Forest earthworm mass was associated with higher sedge cover and lower cover of sugar maple seedlings and several forb species. The trends were similar but not as pronounced in Chippewa, perhaps due to lower deer densities and different earthworm species composition. Our results provide regional evidence that invasion by Lumbricus species may be an important mechanism in reduced plant-species richness and changes in plant communities in mature forests dominated by sugar maples.     

The National Resources Inventory: a long-term multi-resource monitoring programme

Interest in natural resources and the environment has led to the development of new federal monitoring efforts, the expansion of existing federal inventory programmes, and discussions of inter-agency collaboration for natural resource assessment data collection. As federal programmes evolve, knowledge gained from existing long-term survey programmes can provide valuable contributions to statistical and operational aspects of survey efforts. This paper describes the National Resources Inventory (NRI), which has been conducted by the US Department of Agriculture's Natural Resources Conservation Service in cooperation with the Iowa State University Statistical Laboratory for several decades. The current NRI is a longitudinal survey of soil, water, and related environmental resources designed to assess conditions and trends every five years on non-federal US lands. An historical overview is provided highlighting the development of the survey programme. Sample design, data collection, and estimation procedures used in the 1992 NRI are described, and statistical issues related to long-term monitoring are discussed.     

中国森林资源的过去、现在与未来发展趋势

中国是少林国家。在20世纪70年代中期进行“四五”清查以前,中国只掌握一些局部性的调查数据。在1978—1981年间又进行了以省为总体的宏观抽样调查,即“五五”清查。两次清查结果很接近,但都表明中国森林太少,远低于世界平均水平和有代表性的国家。 古代中国的林区远比现在为大。森林面积则比现在大若干倍。中国缺林少材的现状是几千年来农业社会发展进程中火烧、滥伐、滥垦、滥牧的结果。其中,置森林于万劫不复的是滥垦和滥牧。这一过程至今尚未停止。 根据中国的自然条件和宜林地资源的状况,有条件大幅度扩大森林面积和增加森林蓄积量。经过努力,森林面积可达到2.53×10⁸ha,蓄积量可达到210×10⁸m³以上。都是现在的2倍多。但对保护生态环境和向国民经济提供木材和林产品来说,仍然不能完全满足需要。