复合相变蓄热墙体材料对日光温室热环境及番茄生长发育的影响   总被引：3，自引：0，他引：3  

韩云全  陈超  管勇  李琢  凌浩恕 《中国蔬菜》2012,1(18):99-105

为改善日光温室作物的生长环境,将北京工业大学建筑工程学院相变畜热技术研究团队研制的复合相变蓄热墙体材料应用于种植番茄的日光温室北墙内表面。对比试验结果表明,在种植条件完全相同的情况下,采用了复合相变蓄热墙体材料温室内的番茄,在整个生长过程中的形态指标始终好于未采用复合相变蓄热墙体材料的温室,而且前者的果实大,产量大幅提升。从温室北墙内表面温度、耕作层土壤温度、有效积温以及复合相变墙体蓄放热能力等方面,定量地评价了复合相变蓄热墙体对改善日光温室作物生长热环境的影响。  相似文献   

Stochastic simulation of forest fuel sourcing models under risk     

《Scandinavian Journal of Forest Research》2012,27(6):574-584

Abstract

Climate change effects such as storms and droughts are leading to increased risk of forest damage in central Europe. The aim of this paper was to evaluate forest fuel sourcing models including climate change-induced risks on forest fuel supply. Stochastic risk events, such as storms and bark beetle infestations, were modelled by means of a Monte Carlo simulation, and the economic performance was evaluated for two fuel-sourcing models supplying a single combined heat and power plant (CHP). The first sourcing model depicted a common sourcing model for Austrian CHPs, where only forest chips provided by long- and short-term suppliers were stored. The second sourcing model additionally enabled the storage of salvaged pulpwood to supply forest fuel from the plant's own inventory during shortage periods. Simulation results showed that storing salvage pulpwood as feedstock considerably reduced supply chain risks and resulted in lower procurement costs (1–3% less than normal delivered cost without storing salvaged pulpwood).  相似文献   

禽流感防制进展     

赵婧  邱小为 《畜牧兽医杂志》2012,31(2):39-40

禽流感（Avian influenza,AI）是由A型流感病毒所引起的禽类的一种传染病。能引起禽类呼吸系统到严重全身败血症等多种症状的烈性传染病。禽类感染后病死率很高,但对野生禽类多为不显性感染。自从1997年香港发生禽流感病毒H5N1亚型首次突破种属屏障感染人类并引起死亡以来,世界各国纷纷报道各种人禽流感病例的发生,人禽流感的关注程度也达到了前所未有的高度。近几年全球共有三大洲的19个国家和地区发生禽流感疫情。一些地区的疫情呈现蔓延的趋势,并且出现了人感染禽流感病毒的病例。禽流感不仅对养殖业造成重大损失,更对人类健康造成严重威胁。本文全面地介绍了禽流感的病原、流行病学、临床症状、病理变化、诊断和防制。  相似文献   

羧甲基纤维素/蜜胺树脂相变纳米储能材料的制备与表征     

胡晓峰  黄占华 《森林工程》2012,28(4):61-64,76

以羧甲基纤维素(CMC)改性的蜜胺树脂作为壁材,以石蜡为芯材,采用原位聚合法,制备CMC改性的蜜胺树脂相变纳米胶囊。采用FTIR、DSC、SEM及光学显微镜等现代分析仪器对产物的性能进行分析和表征,探讨乳化剂种类和芯材乳液制备转速对胶囊制备过程的影响。结果表明,采用复配乳化剂制备的相变胶囊的性能要优于使用单一乳化剂制备的相变胶囊;当制备芯材乳液的转速为8 000 r/min时,芯材乳液的性能最好;所制得的相变胶囊为球形、平均粒径约为50 nm,且包裹完全、粒径均匀,相变焓为81.87 J/g。  相似文献   

基于Landsat TM/ETM+影像的森林资源时空动态变化分析     

谢敏  李党辉  王照利 《陕西林业科技》2012,(5):27-30

本研究以陕北黄土高原大岭林场为研究对象,以1999和2006年两期TM/ETM+影像为主要数据源,结合森林资源调查数据,分析了该林场森林资源时空动态变化。结果表明:1999～2006年间,耕地和疏林地分布面积减少,阔叶林地、针叶林地、混交林地和灌木林地面积比例均有增加,充分说明天然林保护工程有利于森林资源的更新和林场的可持续发展。通过马尔科夫预测,2006～2013年变化动态最大的是疏林地,其次是灌木林地、阔叶林地、混交林地、耕地和针叶林地。  相似文献   

柠条锦鸡儿营养成分动态变化及其在绵羊瘤胃内的降解   总被引：1，自引：0，他引：1  

弓剑 《动物营养学报》2012,(10):1983-1991

本试验旨在研究内蒙古呼和浩特地区不同生育期柠条锦鸡儿营养成分的动态变化及其在绵羊瘤胃内的降解特性。分别于孕蕾期、开花期和结实期采集当年生柠条锦鸡儿嫩枝条,测定初水分后在65℃烘箱中烘干,测定常规营养物质含量;选用安装有永久性瘤胃瘘管的内蒙古小尾寒羊3只,采用瘤胃尼龙袋法评定不同生育期柠条锦鸡儿营养成分的瘤胃降解特性。试验结果表明:1)开花期和结实期柠条锦鸡儿的干物质(DM)和粗蛋白质(CP)含量显著高于孕蕾期(P<0.05);不同生育期柠条锦鸡儿有机物(OM)、粗脂肪和无氮浸出物含量无显著差异(P>0.05);结实期粗灰分含量显著高于孕蕾期和开花期(P<0.05);孕蕾期和开花期柠条锦鸡儿中性洗涤纤维(NDF)含量显著高于结实期(P<0.05),而酸性洗涤纤维(ADF)含量显著低于结实期(P<0.05);随着生育期的延续,柠条锦鸡儿木质素含量逐渐升高,开花和结实期显著高于孕蕾期(P<0.05);随着生育期的延续,柠条锦鸡儿钙含量显著提高(P<0.05),磷含量显著降低(P<0.05)。2)随着生育期的延续,柠条锦鸡儿DM的72 h消失率和有效降解率逐渐降低,开花期和结实期DM的有效降解率无显著差异(P>0.05);不同生育期柠条锦鸡儿CP的72 h消失率无显著差异(P>0.05),但有效降解率孕蕾期显著高于开花期和结实期(P<0.05);随着生育期的延续,柠条锦鸡儿OM和NDF的72 h消失率和有效降解率均显著降低(P<0.05);开花期和结实期柠条锦鸡儿ADF的72 h消失率和有效降解率无显著差异(P>0.05),但显著低于孕蕾期(P<0.05)。试验结果提示,结合不同生育期柠条锦鸡儿营养物质含量、饲草DM产量以及营养物质的瘤胃降解特性,开花期柠条锦鸡儿营养物质的利用效率最高,为最佳刈割时期。  相似文献   

一例犬卵巢纤维肉瘤的病理学诊断     

刘剑郁  孙宁 《动物医学进展》2012,33(8):134-136

某警犬基地一繁育种犬于2011年3月18日死亡,根据发病及死亡经过、尸体剖检和病理学诊断,结果为卵巢纤维肉瘤并发肺转移,同时对病因进行分析。  相似文献   

Assessing impact of climate change on forest cover type shifts in Western Himalayan Eco-region     

P. K. Joshi  Asha Rawat  Sheena Narula  Vinay Sinha 《林业研究》2012,23(1):75-80

Climate is a critical factor affecting forest ecosystems and their capacity to produce goods and services. Effects of climate change on forests depend on ecosystem-specific factors including dimensions of climate (temperature, precipitation, drought, wind etc.). Available information is not sufficient to support a quantitative assessment of the ecological, social and economic consequences. The present study assessed shifts in forest cover types of Western Himalayan Eco-region (700?4500 m). 100 randomly selected samples (75 for training and 25 for testing the model), genetic algorithm of rule set parameters and climatic envelopes were used to assess the distribution of five prominent forest cover types (Temperate evergreen, Tropical semi-evergreen, Temperate conifer, Subtropical conifer, and Tropical moist deciduous forests). Modelling was conducted for four different scenarios, current scenario, changed precipitation (8% increase), changed temperature (1.07°C increase), and both changed temperature and precipitation. On increasing precipitation a downward shift in the temperate evergreen and tropical semi-evergreen was observed, while sub-tropical conifer and tropical moist-deciduous forests showed a slight upward shift and temperate conifer showed no shift. On increasing temperature, an upward shift in all forest types was observed except sub-tropical conifer forests without significant changes. When both temperature and precipitation were changed, the actual distribution was maintained and slight upward shift was observed in all the forest types except sub-tropical conifer. It is important to understand the likely impacts of the projected climate change on the forest ecosystems, so that better management and conservation strategies can be adopted for the biodiversity and forest dependent community. Knowledge of impact mechanisms also enables identification and mitigation of some of the conditions that increase vulnerability to climate change in the forest sector.  相似文献   

Modeling susceptibility to deforestation of remaining ecosystems in North Central Mexico with logistic regression     

L. Miranda-Aragón  E.J. Trevi o-Garza  J. Jiménez-Pérez  O.A. Aguirre-Calderón  M.A. González-Tagle  M. Pompa-García  C.A. Aguirre-Salado 《林业研究》2012,23(3):345-354

Determining underlying factors that foster deforestation and delineating forest areas by levels of susceptibility are of the main challenges when defining policies for forest management and planning at regional scale. The susceptibility to deforestation of remaining forest ecosystems (shrubland, temperate forest and rainforest) was conducted in the state of San Luis Potosi, located in north central Mexico. Spatial analysis techniques were used to detect the deforested areas in the study area during 1993-2007. Logistic regression was used to relate explanatory variables (such as social, investment, forest production, biophysical and proximity factors) with susceptibility to deforestation to construct predictive models with two focuses: general and by biogeographical zone.In all models, deforestation has positive correlation with distance to rainfed agriculture, and negative correlation with slope, distance to roads and distance to towns. Other variables were significant in some cases, but in others they had dual relationships, which varied in each biogeographical zone. The results show that the remaining rainforest of Huastecaregion is highly susceptible to deforestation. Both approaches show that more than 70% of the current rainforest area has high and very high levels of susceptibility to deforestation. The values represent a serious concern with global warming whether tree carbon is released to atmosphere. However, after some considerations, encouraging forest environmental services appears to be the best alternative to achieve sustainable forest management.  相似文献   

祁连山高寒草甸生态系统昆虫群落特征   总被引：1，自引：0，他引：1  

蔡海  李婧梅  程茜  褚晖  陈懂懂 《草业科学》2012,29(1):121-127

2009年7月中旬于祁连山地区的中国科学院海北高寒草甸生态系统研究站,在滩地草甸、金露梅（Potentilla fruticosa）灌丛、山坡草甸和沼泽化草甸4个不同的生境中对昆虫进行百网取样,共获得908头昆虫。分别隶属于10目42科 65种。发现该地区双翅目昆虫是最繁盛的类群：第2个优势目为膜翅目,其次优势目为鞘翅目。昆虫物种多样性和丰富度依次为滩地草甸>金露梅灌丛>山坡草甸>沼泽化草甸;均匀度差异不大;优势度指数沼泽化草甸最高,滩地草甸最低。滩地草甸和山坡草甸昆虫群落的相似性最大;其次是金露梅灌丛;差异最大的是沼泽化草甸。通过分析发现,生境的变迁和气候的变化引起了昆虫群落结构和多样性的差异变化。  相似文献