日本柳杉髓心方材高频真空干燥试验

该文对日本人工林柳杉髓心方材进行系列高频真空干燥试验,掌握不同高频真空干燥条件下柳杉髓心方材的干燥特性并对干燥缺陷进行分析.结果表明,柳杉髓心方材虽难干燥,但在高频真空干燥前对木材进行合理的处理,如蒸汽和过热蒸汽预处理、沿木材长度方向制作一定深度和宽度的切口等,可有效地提高干燥质量,尤其是可减少开裂的产生.     

日本柳杉高频真空干燥及防止开裂的研究

通过对日本人工林木材柳杉髓心方材进行系列高频真空干燥试验 ,掌握柳杉髓心方材的干燥特性及相应的高频真空干燥条件。结果表明 :高频真空干燥前在常压下进行合理的蒸汽和过热蒸汽预处理 ,柳杉髓心方材可有效地提高干燥质量 ,尤其可防止开裂产生     

Standardization of Automated Vario EL III CHNS Analyzer for Total Carbon and Nitrogen Determination in Soils

The traditional methods for determination of carbon (C) and nitrogen (N) are cumbersome and time-consuming. With the development of automated methods, the time taken to analyze a sample has been reduced considerably. However, these need to be standardized with respect to the type and weight of soil sample used. A study on the determination of soil C and N was carried out to evaluate sample particle size and weight effects on C and N determined by a CHNS analyzer and conventional methods. Three texturally different soils were analyzed for C and N with the CHNS analyzer and traditional methods. The C and N contents measured with the CHNS analyzer were greater than those measured with traditional methods. With finer (<0.25-mm) fractioned samples, C and N contents were greater than in the coarse-fractioned. Carbon and N contents were greater with a sample weight of 10 than with 25 mg.     

牛卵母细胞胞浆内单精子注射的研究进展

综述了牛上进行卵胞浆内单精子注射（intracytoplasmic sperm injection ICSI）的研究进展：ICSI的囊胚率从1990年最早报道的1.8%提高到最新的40.1%。这要归功于技术的创新。在此分析了电脉冲仪（piezo-electric actuator）等新技术应用的效果，讨论了前期处理精子对ICSI的影响，比较了各种激活处理对ICSI的提高结果，同时展望了ICSI这门技术在畜牧生产和转基因研究上的应用前景。     

大豆田斜纹夜蛾种群空间分布型及抽样技术研究

应用5种聚集度指标以及Taylor的幂法则与Iwao的m*—m直线回归方程测定和分析了斜纹夜蛾(Spodoptera Litura Fabricius)在秋大豆田上的空间分布型及其内在结构,测定结果表明,斜纹夜蛾卵块呈均匀分布,而低龄幼虫(1￣2龄)呈聚集分布,高龄幼虫(3￣6龄)呈聚集分布或均匀分布,并利用Blackith种群聚集均数(λ)分析了其的聚集原因。在此基础上,并提出了最适理论抽样数[N=t2/D2(5.6415/m 15.3063)]与最佳序贯抽样模型[T_0(n)=2.5n±10.4770n~(1/2)]。     

小麦幼胚组织培养研究进展

小麦组织培养是利用基因工程改良小麦品种的重要基础和保证,小麦幼胚转化体系的建立对促进小麦基因工程研究和功能基因组研究具有重要的意义。以幼胚为外植体进行小麦组织培养的方法被大多数学者认为是最有效的培养方式。笔者就目前中国小麦幼胚组织培养研究现状,对品种、胚龄、培养基、外源激素、预处理、接种方式等研究现状进行了综述,目的是为了进一步建立和完善小麦幼胚再生体系和转化体系提高参考。     

崇明农村河道生态治理试点工程——以万平河为例

针对崇明农村河道水质较好但水体浑浊的特点,提出采取生态护坡建设、水生态净化系统构建、岸坡生态绿化等工程措施重点改善河道生境,使之成为生物生长繁殖适宜的环境。其中,水生态净化系统构建工程中为去除水中携带的悬浮物,并逐步净化水质达到生态及景观功能要求,设置了强化预处理区、滨岸带水生植物种植区、沉水植物悬床种植区及沉水植物种植区等处理环节。在满足河道岸坡安全性、耐久性的前提下,达到农村河道"自然、生态"的治理目标。     

Assemblage level monitoring of stream fishes: The relative efficiency of single-pass vs. double-pass electrofishing

The relative efficiency of single-pass electrofishing of longer stream sections vs. double-pass electrofishing of shorter reaches was evaluated in small (<5 m wide) wadable lowland streams in the Lake Balaton basin, Hungary. Two hundred meters long stream sections at 8 sites were divided into ten 20 m long sampling units each. These units were used to estimate the representativeness of species richness, species composition and relative abundance data at each level of sampling effort (single vs. double-pass, and number of sampling units pooled) using rarefaction and similarity-based approaches. Assemblage variables showed strong response to the length of the stream sampled (number of sampling units pooled). However, no differences were found between the single- and double-pass methods at any level of sample size for any assemblage variable. Estimates of species richness and species occurrence distributions required more sampling effort than estimates of species relative abundances, using any evaluation method. If a proxy estimate of sample representativeness cannot be obtained in the field, a minimum sampling of single-pass electrofishing of 100 m long sections may be necessary even in small wadable streams with low level of habitat and assemblage diversity to get a relatively unbiased picture on assemblage characteristics.     

Risk based surveillance for early detection of low pathogenic avian influenza outbreaks in layer chickens

Current knowledge does not allow the prediction of when low pathogenic avian influenza virus (LPAIV) of the H5 and H7 subtypes infecting poultry will mutate to their highly pathogenic phenotype (HPAIV). This mutation may already take place in the first infected flock; hence early detection of LPAIV outbreaks will reduce the likelihood of pathogenicity mutations and large epidemics. The objective of this study was the development of a model for the design and evaluation of serological-surveillance programmes, with a particular focus on early detection of LPAIV infections in layer chicken flocks. Early detection is defined as the detection of an infected flock before it infects on average more than one other flock (between-flock reproduction ratio R_f < 1), hence a LPAI introduction will be detected when only one or a few other flocks are infected. We used a mathematical model that investigates the required sample size and sampling frequency for early detection by taking into account the LPAIV within- and between-flock infection dynamics as well as the diagnostic performance of the serological test used. Since layer flocks are the target of the surveillance, we also explored whether the use of eggs, is a good alternative to sera, as sample commodity. The model was used to refine the current Dutch serological-surveillance programme. LPAIV transmission-risk maps were constructed and used to target a risk-based surveillance strategy. In conclusion, we present a model that can be used to explore different sampling strategies, which combined with a cost-benefit analysis would enhance surveillance programmes for low pathogenic avian influenza.     

森林资源信息样本影像数据库的建立方案

提出了通过建立森林资源信息样本影像数据库、提高森林资源信息的提取速度和可靠性的方案,并对森林资源信息样本影像数据库建立步骤、关键性技术、整体流程及其应用进行了分析和探讨.