Analysis of survey data

Data from surveys should be weighted using expansion weights to avoid biased estimates for the inference population. Calculation of expansion weights is a stepwise procedure that can be thought of as allowing respondents to represent all eligibles from the population. Design will have an impact on the variance of the estimates. Furthermore, the impact may be to inflate or deflate the variance and is often variable-dependent. Accounting for the design in estimating the variance will require specialized analysis procedures and often specialized software.     

离心泵灌水方法探讨

通过对离心泵灌水原理的分析，提出了不同使用条件下离心泵的灌水方法，为水泵用户提供了广阔的选择灌水方法的空间，对泵站的运行管理具有现实意义。     

Population Characteristics of Dendrolims Superans in Daxing'an Mountains

CollectionofdataFiveI1tlndredf1eadsofD..`IIl,L;l-I;(Ilt`crecoIlectedilltIletbrest.oraroul1dtbrestarcadtIril1gtl1epeakofap-pearancetYol11I99lloI992.TI1el1tlInberoftb111aIca11dlllaIeaduItst`ererecorded.T``/ostal1dardpIotsucrecI10seninYol1gqingandHa[1jiayuan…     

谈应用Photoshop cs软件绘制林业规划设计图的方法

介绍利用Photoshop CS软件绘制林业规划设计图,方法时尚、便于掌握、色彩鲜艳、成本低和效率高。在使用中,注意电脑系统、相关设备的配置;绘制方法和手段要正确;掌握一些技巧,才能充分发挥该软件的优越性,得到高质量的林业规划设计图。     

Silicate mineral weathering rate estimates: Are they precise enough to be useful when predicting the recovery of nutrient pools after harvesting?

Are current estimates of silicate minerals weathering rates precise enough to predict whether nutrient pools will recover after forest harvesting? Answering this question seems crucial for sustainable forestry practices on silicate dominated soils. In this paper, we synthesize estimated Ca and K weathering rates (derived using seven different approaches) from a forested area in northern Sweden (the Svartberget-Krycklan catchment) to evaluate the precision of weathering rate estimates. The methods were: mass-balance budgets (catchment and pedon-scale); long-term weathering losses inferred from weathered soil profiles (using zirconium as a conservative tracer); strontium isotopes (⁸⁶Sr/⁸⁵Sr) as proxy for catchment export of geogenic Ca; climate based regressions; a steady-state, process-based weathering model (PROFILE) and a dynamic, conceptual catchment geochemistry model (MAGIC). The different methods predict average weathering rates of 0.67 ± 0.71 g Ca m⁻² year⁻¹ (mean ± stdev) and 0.39 ± 0.38 g K m⁻² year⁻¹, suggesting a cumulative weathering release during a forest rotation period of 100 years that is the same magnitude as losses induced by forest harvesting at the end of the period. Clearly, forestry practices have the capacity to significantly alter the long-term nutrient status of the soil and cation concentrations in soil-water runoff. However, the precision in weathering estimates are lower than that needed to distinguish between effects on nutrient pools by different forest practices (complete-tree harvesting versus conventional stem only harvest). Therefore, we argue that nutrient budgets, where weathering rates play a crucial role, cannot be used as basis for resolving whether different harvesting techniques will allow nutrient pools to recover within one rotation period. Clearly, this hampers the prerequisite for sound decision making regarding forestry practices on silicate mineral dominated soils.     

贵州百里杜鹃煤矿采矿区生态环境治理方法探讨

分析贵州百里杜鹃煤矿采矿区的生态环境现状,遵循自然和经济规律,以科技为先导,采取生物治理为主,结合水土保持工程、科技支撑体系建设,有计划、有步骤地进行矿区生态环境综合治理。     

葡萄酒中农药残留的色谱分析法研究进展

概述了目前应用于研究检测葡萄酒中农药残留的色谱分析方法的研究进展，主要分析方法包括：气相色谱（GC）分析法、液相色谱（HPLC）分析法、气相色谱-质谱联用（GC/MS）分析法、液相色谱-质谱联用（HPLC/MS）分析法。并对目前葡萄酒农药残留的现状进行了分析。     

不同覆盖方式对冬闲稻田马铃薯生长及产量的影响

在冬闲稻田里以中薯3号为试验材料，进行了稻草覆盖、摆播稻草+地膜覆盖、沟播稻草+地膜覆盖、地膜覆盖、敞土等不同覆盖方式栽培马铃薯的田间比较试验。结果表明：冬闲稻田地膜覆盖栽培的马铃薯出苗最早，地膜覆盖和沟播稻草+地膜覆盖栽培的马铃薯出苗率最高；敞土栽培的马铃薯植株的株高显著低于覆盖栽培；摆播或沟播稻草+地膜覆盖栽培马铃薯的产量和商品薯率最高，稻草覆盖栽培和地膜覆盖栽培次之，产量和商品薯率显著高于敞土栽培；摆播或沟播稻草+地膜覆盖栽培马铃薯的效益最高，地膜覆盖和稻草覆盖栽培马铃薯的效益次之，敞土栽培马铃薯的效益最低。     

Sampling for ants in different-aged spruce forests: A comparison of methods

It is necessary to use special sampling method for studying of each animal group. However each method has its specificity and describes the studied community a bit differently. Three common methods for sampling of ants were compared: soil excavation, pitfall traps and baits. Ants were sampled in 25 patches in a large spruce forest in the Czech Republic during 2005 and 2006. Each patch represented one of five age classes (0–2, 3–5, 8–12, 26–41 and 85–105 years old), and the patches were located in five sites such that the five patches in each site formed a chronosequence. The percentage of variability in ants as explained by other sampling techniques was as follows: 60.0% of the variability in bait data was explained by pitfall trap data, while only 19.7% of the variability in pitfall trap data was explained by excavation data. Species and numbers of ants on baits were strongly affected by bait type: Myrmica species preferred honey whereas Formicinae preferred tuna bait. Assembly composition in pitfall traps varied significantly between study sites. The position of sampling site in landscape (location in the forest regardless of the immediate habitat type where the trap was located) hence strongly affected ants. Proportions of ants in particular methods were equal in the majority of cases. For excavation samples, ant numbers and species were more influenced by the immediate habitat than the wider habitat, but the opposite was true for samples from pitfall traps.