避风塘选址的探讨

避风塘的建设关系到渔民的生命与财产安全，是一项民心工程，但建设避风塘投入较大，为确保以最低的建设成本达到最大的社会效益，选址工作成为建设避风塘的首要问题，本主要从建设避风塘的基本原则、水域面积的确定、泥沙运动、防风条件等方面论述避风塘选址中涉及到的相关问题，为今后避风塘的建设提供参考。     

猕猴桃园地的选建

一、园地的环境条件。猕猴桃喜光怕曝晒，喜湿怕涝，喜微风怕强风，喜肥沃偏酸性的土壤。这就要求我们建园时，必须选在村前、山前土层肥沃的背风向阳地带，或建在防护效果显著的林网保护地带，或在其它果园内的空地中（园中园）。凡没有防风措施的空广地、没有水源及排水条件的地方或盐碱较重的地区不宜发展猕猴桃。     

装卸桥大车的制动与防风

装卸桥大车的制动与防风（３６５５００）福建省沙县贮木场陈笙收稿日期：１９９６－１２－２０贮木场用装卸桥工作地点为空旷场所，其长度、高度都较大且迎风面积大，易受大风袭击造成事故。而装卸桥的防风装置一直是较为薄弱的环节，传统的行走制动器和预防性防风装置不...     

全国主要药市近期统货价格

品名河北安国安徽毫州陕西西安山东哪城广西玉林河南禹州成都荷花池金银花55~6080一8545一508O30~3870~8045~50柴胡32一3534~3632一3633~354034~3535~38防风30~3560~6543~453550~6034~3640~45板蓝根6~76~87~86~77~96 .5~87~9大青叶3~42 .5~3333~4 .533~4黄芬98~99~108~1011~129~101O白术12~1515~1613~142018~2017~1817~19连翘14~1511~1313~141313一149一1114~15甘草7~88~97~88一9107~98桔梗14~1715~1718~192220~2216~1820~22旱半夏32~3435~36343538~4035~3638~40生地6~7676 .57~86~77全国主要药市近期统货价格@李发鹏!711706$陕西省药协富…     

畜禽饲养小经验三则

饲养家畜要补碘。碘是家畜(牛、马、驴、羊等)机体中重要的激素甲状腺素的组成部分。幼畜缺碘，生长发育停滞，基础代谢降低。成年家畜则发生甲状腺机能衰退，甲状腺肿大，生产力下降。缺碘会导致母牛不孕率增加，母马、母驴生下的驹身体极弱，甚至不能站立和吮乳等。     

春暖式大棚杏栽培管理技术

1建园技术1.1园地选择选择水源、大气、土壤无任何污染,背风向阳,土层深厚,肥沃疏松,排灌方便,pH值在6.5左右,地下水位在1m以下的砂     

临泽县小泉子滩防风固沙林及防护林体系效益浅析

对临泽小泉子治沙站营造的防风固沙林及农田防护林进行了观测研究，观测结果表明：在200cm观测高度时，固沙阻沙林内的风速降低了24．0％～55．0％，在150cm的高度时，风速降低了29．1％～55．8％。农田林内在200cm观测高度时，林后15m、30m的距离风速分别降低了28．4％、39．8％，在150cm的高度时，风速分别降低了28．8％、35．0％，在50cm的高度时，风速分别降低了31．0％、43．7％，林后30m比15m的距离风速降低的幅度大。因此，防风固沙林和农田防护林的防风效果非常显著。     

影响防风带近距离防风效果的结构因子的研究

以山西北部半干旱风沙区为研究区,调查现有防风林带的距离防风效果,用回归分析法分析了冠层疏通度、冠下疏通度、林带宽度、栽植密度、林带与风向夹角、林带高和平均枝下高占林带高的百分比与距离带缘5倍树高处的风速降低百分数之间的关系。结果表明：影响防风林带近距离防风效果的主导因子为冠下疏透度、林带与风向的夹角和枝下高占林带高的百分比。     

Effects of thinning on wind damage in Pinus thunbergii plantation ——Based on theoretlcal derlvation of risk—ratios for assessing wind damage

Based on paper of “Theoretical derivation of risk-ratios for assessing wind damage in coastal forest“,wind damage in the pine coasteal forest,which was thinned at four levels in December of 1997,was investigated for four successive growing seasons.Besides wind damage,the wind profiles outside and inside the coastal forest stand and the distributions of optical stratification porosity (OSP) were also observed.Based on these data,risk-ratios of wind damage for both individual trees and stands were estimated according to the methods developed in “Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest“.The results showed that risk-ratios of wind damage,which were calculated from the meen height and diameter only and from the combination of wind and stand sructure profiles,accurately predicted wind damage in the plantation.Relationships between different thinning ratios and incidence of wind damage showed that stand stability decreased soon after the thinning.This was due to the immediate effects of thinning on increasing the canopy roughness and wind load,and on decreasing the sheltering effects from surrounding trees.However,thinning strategies could improve the stability by long-term effects on growthand development of trees against extreme wind.Only canopy damage was recorded during the experimental period,no stem damage was found,even though the maximum 10-min wind speed outside the coastal forest attained 30.2m s^-1.The results obtained in this study indicate that thinning is the most effective silvicultural strategy available for managing coastal forest despite the increased probability of wind damage soon after thinning.     

HPLC法测定复方甲氧沙林洗剂中甲氧沙林和醋酸地塞米松的含量

本文采用高校液相测定了复方甲氧沙林洗剂中醋酸地塞米松和甲氧沙林的含量,固定相为:安捷伦Cl8(4.6mm×250mm,5um),甲醇-乙腈-水(40:30:30)为流动相,检测波长为240nm;甲氧沙林在10~80mg·m L-1范围内呈良好的线性关系;醋酸地塞米松在20~100mg·m L-1范围内呈良好的线性关系。甲氧沙林和醋酸地塞米松的平均回收率分别为99.6%、99.6%,RSD为0.81%(n=6)、0.83%(n=6);此方法简便、准确、重现性好,可用于复方甲氧沙林洗剂中甲氧沙林和醋酸地塞米松的含量测定。