猪舍夏季降温技术应用研究现状   总被引：5，自引：0，他引：5  

刘平  马承伟  李保明  崔引安 《农业工程学报》1997,13(5):47-52

叙述了国内外猪舍夏季降温技术研究与应用的现状及存在的问题，喷淋、湿垫—风机降温系统、细雾蒸发降温系统一般被应用于降低猪舍内的高温。对于夏季降温技术研究应继续完善已有的降温方法在猪舍的应用，同时要开展针对我国气候特点及猪舍建筑实际的夏季降温方式，特别是南方炎热地区开放型猪舍的降温技术措施的研究。  相似文献   

甘肃小陇山林区日本落叶松人工林单株生物量的研究   总被引：2，自引：0，他引：2       下载免费PDF全文

沈亚洲  孙晓梅  张江涛  杜彦昌  马建伟 《林业科学研究》2011,24(4):517-522

柯甘肃小陇山林区不同年龄的日本落叶松人工林单木各器官生物量进行了测定,并运用回归分析和模型选优的方法建立了日本落叶松人工林单株生物量估测数学模型.结果表明:日本落叶松幼龄林、中龄林、近熟林、成熟林单株的平均总生物量分别为3.617、29.846、123.954、177.482 kg,各林龄段干、根、枝、皮、叶各器官生物...  相似文献   

N、P、K大量元素对油茶生长指标及产量的影响     

李爱华向珊珊  明廷柏李金柱彭易坡  丁小飞张 帅 《湖北林业科技》2011,(2):28-31

设计OPT、OPT-N、OPT-P、OPT-K和CK共5个处理的施肥试验,其结果表明:施肥能显著提高油茶植株高生长,并使地径增粗、茶果增产.同时在对现有油茶林地土样中N、P、K大量元素及有机质含量分析的基础上,明确该林分影响植株高、地径生长、油茶产量的主要因子,从而有针对性地提出施肥方案,使肥效达到最大化.  相似文献   

滩地淹水胁迫对杨树生长与木材显微结构的影响   总被引：7，自引：1，他引：7  

汤玉喜  刘友全吴立勋吴敏 《中南林学院学报》2005,25(6):29-33

对5种不同淹水时间类型滩地1～10年生杨树单株材积生长动态进行了分析．结果表明。不同类型之间单株材积生长量均存在显著差异．且随着林龄增长，其差异逐步减小；不同淹水胁迫下，当年年轮宽度、纤维细胞数量、木材基本密度均存在显著差异，纤维长度和宽度差异不显著，杨树年轮宽度与径向纤维细胞数、导管数、径向纤维比量呈正相关；随淹水胁迫程度加深，当年形成层细胞分裂受到了显著抑制，纤维细胞以及导管数量减少，林木径向生长量下降．径向导管比量提高，纤维比量下降，细胞壁腔比减小，木材密度明显降低．对5种淹水类型滩地的林木生长进行了系统聚类，合并划分为4种生长类型，对其中3种常规造林宜林类型杨树生长潜力进行了预测。  相似文献   

遮蔽与呈现——《花腔》人物生存状态论     

张小彩 《信阳农业高等专科学校学报》2008,18(3):79-82

李洱的长篇小说《花腔》问世以后,研究评论者众多。《花腔》以破解主人公葛任的生死之谜为主线,以三个当事人的口述和大量的引文来完成叙事。讲述与引文相互补充、说明、参考、对照,将一段葛任的历史演绎为一组故事碎片,在这种众声喧哗揭示历史真相的过程中,不仅主人公葛任的个体生命之花得以呈现,而且文本中被遮蔽的诸多生存状态浮出水面。本文正是从这个角度出发,试图从"花腔"的层层遮蔽中透视特殊语境下几个主要人物生存的某种尴尬和艰难。  相似文献   

华南生态区超级稻育种的主要成就及未来发展趋势     

林青山  江奕君 《沈阳农业大学学报》2007,38(5):732-738

中国超级稻研究项目启动至今,对促进我国的粮食增产,提升我国水稻育种水平发挥了重要作用。广东省农业科学院自1996年以来,作为中国超级稻研究项目主要发起和承担单位,承担了该项目的华南稻区超级稻选育研究工作。在开创水稻生态育种并取得显著成就的基础上,经过10年攻关,再创华南超级稻育种新辉煌。先后构建出"早长、根深"超级稻株型模式和华南广适应型优质超级稻株型模式;在优质超级晚稻育种和广适型超级稻育种方面率先取得重大突破;先后育成一批达标优质超级稻,主要代表品种有:品质可与泰国优质香米相媲美的优质超级稻品种胜泰1号、我国超级晚稻育种取得突破的先锋品种桂农占和大穗高结实的广适型超级稻品种玉香油占等,这些超级稻正迅速在生产上大面积推广应用,创造了显著的社会经济效益。  相似文献   

Correlation of Individual Heterozygosity of Microsatellite Marker Loci with Heterosis of Growth Traits in Pig Populations     

ZHANG Jing-hu XIONG Yuan-zhu DENG Chang-yan JIANG Si-wen LEI Ming-gang LI Jia-lian LI Feng-e ZHENG Rong 《中国农业科学(英文版)》2006,5(8):635-642

To investigate the correlation of individual heterozygosity and heterosis of three traits in crossbred F1 pig populations, the F1 populations were built by random mating Yorkshire x Meishan （YM, n = 82）, and its reciprocal （MY, n =47） and two straightbred populations （Yorkshire = 34, Meishan = 55） were used as control groups. The heterosis of birth weight （BWT）, average daily gain （ADG）, and feed conversion ratio （FCR） were acquired as well. In the research, the significant marker loci for the heterosis of the three traits were observed by one-way ANOVA （P〈0.01） in a total of 39 marker loci on SSC4, SSC6, SSC7, SSC8, and SSC13, and the numbers of the significant marker loci were 12 （BWT）, 18 （ADG）, and 17 （FCR）, respectively, based on which the general heterozygosity （GH） was divided into significant marker loci heterozygosity （SH） and insignificant marker loci heterozygosity （IH）. Furthermore, the trends of alteration in heterosis with the stepwise increase in heterozygosity by 0.05 were explored. This was done by the regression analysis of the three kinds of heterozygosity against heterosis of the three traits. The results showed that, for BWT, the heterosis increased with the increase in GH （r=0.9337, P=0.0021） and SH （r=0.9165, P=0.0102）; for ADG, the heterosis increased with the increase in IH （r=0.7012, P=0.0353） and GH （r=0.7470, P=0.0537, near significant）; for FCR, the heterosis of feed efficiency increased with the increase in IH （r=0.8721, P=0.0022）. The results indicated that the correlation was not always higher or more significant for SH with heterosis than it was for IH or GH with heterosis, and it might be because of the reciprocal cancellation of the positive effect and negative effect of QTL linked to the significant marker loci.  相似文献   

Effects of simulated grazing on growth and persistence of Artemisia frigida in a semiarid sandy rangeland   总被引：4，自引：0，他引：4  

F. R. Li  A. F. Zhao  H. Y. Zhou  T. H. Zhang  X. Zhao 《Grass and Forage Science》2002,57(3):239-246

Abstract To assess the tolerance of fringed sagewort (Artemisia frigida Willd.) to grazing in semiarid sandy rangeland, forty‐five fringed sagewort plants of similar size were chosen randomly from sandy rangeland and divided into three cohorts (fifteen plants per cohort) that were subjected to simulated grazing management in 1998. Plants were cut in spring on 24 April and again in summer on 26 July at either 2–3 cm (severe), or at5–6 cm (moderate), or uncut to serve as the control. Plant responses to intensity of cutting were monitored over two consecutive years differing substantially in the amount and seasonal distribution of rainfall. Cutting in spring (moderate or severe) did not influence plant height, average canopy diameter, the number of branches, and specific branching density measured in July 1998. Moderate cutting in summer reduced plant height compared with the uncut treatment but did not influence other plant growth variables in September 1998. However, severe cutting in summer during the reproductive stage strongly reduced plant height, canopy size, the number of branches, individual shoot weight and specific branching density in September 1998 compared with moderate and no cutting and its negative impacts on the growth of this species were evident in the following year. Severe cutting in spring significantly increased the number of flowering shoots, whereas cutting in summer (at either level) reduced the capacity of fringed sagewort to produce flowering shoots. Also, the negative impact of summer cutting on seed production continued in the following year. The production of plant biomass was similar in the three treatments in 1998, but it was significantly lower in cut than uncut plants in 1999. The reduced biomass was due to a decline in plant height, canopy size, number of branches and specific branching density. Compared with the uncut plants, the cut plants tended to allocate a greater proportion of their biomass to vegetative shoots and leaves than to flowering shoots in 1998; in 1999, although cutting treatments had ceased, the cut plants still allocated a greater proportion of new biomass to vegetative shoots and less to flowering shoots, but a similar proportion to leaves.  相似文献   

Growth potential and habitat requirements of endangered age‐0 pallid sturgeon (Scaphirhynchus albus) in the Missouri River,USA, determined using a individual‐based model framework          下载免费PDF全文

David Deslauriers  Laura B. Heironimus  Tobias Rapp  Brian D. S. Graeb  Robert A. Klumb  Steven R. Chipps 《Ecology of Freshwater Fish》2018,27(1):198-208

An individual‐based model framework was used to evaluate growth potential of the federally endangered pallid sturgeon (Scaphirhynchus albus) in the Missouri River. The model, developed for age‐0 sturgeon, combines information on functional feeding response, bioenergetics and swimming ability to regulate consumption and growth within a virtual foraging arena. Empirical data on water temperature, water velocity and prey density were obtained from three sites in the Missouri River and used as inputs in the model to evaluate hypotheses concerning factors affecting pallid sturgeon growth. The model was also used to evaluate the impacts of environmental heterogeneity and water velocity on individual growth variability, foraging success and dispersal ability. Growth was simulated for a period of 100 days using 100 individuals (first feeding; 19 mm and 0.035 g) per scenario. Higher growth was shown to occur at sites where high densities of Ephemeroptera and Chironomidae larvae occurred throughout the growing season. Highly heterogeneous habitats (i.e., wide range of environmental conditions) and moderate water velocities (0.3 m/s) were also found to positively affect growth rates. The model developed here provides an important management and conservation tool for evaluating growth hypotheses and(or) identifying habitats in the Missouri River that are favourable to age‐0 pallid sturgeon growth.  相似文献   

基于年龄弱势群体的保障房住区景观设计研究     

陈群  谢纯 《安徽农业科学》2017,45(4)

分析保障性住房主要居民构成,认为保障性住房居民中的年龄弱势群体主要是由老年人和儿童构成。目前保障房住区景观存在景观空间单调、缺乏观赏性,很少从年龄弱势群体来进行景观设计和建设等问题。针对这些问题,提出了一些设计手法,希望在今后保障房住区景观设计和建设中,设计者更多考虑年龄弱势群体的行为和心理等因素进行设计,使保障性住房景观更加人性化。  相似文献