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1.
IntroductionInordertomitigatetheproblemsofenergyshortage,environmentalpollutionandtheoverburdenedtransportationsystemsinChina,underthesupportofthestate,thenuclearheatingreactor(NHR)wasdevelopedbytheInstituteofNuclearEnergyTechnology(INET),TsinghuaUni…  相似文献   

2.
The quality of grain changes continually during its storage, including the change of its physical characteristics and physiological characteristics. This paper presents an approach to predict the change of the quality of stored grain with data mining technology. Logistic Regression, Decision Tree and Muitilayer Perceptron are applied to predict the change of the grains' quality control index and to obtain the grains' quality change probability. The grain sampling with higher probability can be processed earlier.  相似文献   

3.
Theqinghai TibetPlateauisendowedwithnaturalandgeographicconditions.These conditionsshapeupmanyuniquetouristresources,suchascolorfulgeomorphology,plentifulanduniquewildanimalsandplantsand pureandsimplefolkcustomwithancientculture,etc.Butasthetrafficisnotconvenientandthe trafficcostisveryhigh,toalargeextentthislimitsthedevelomentofthelocaltourism.Thelinesuccessivelypassesthroughtheplacesof culturalinterest,likenaturallyecologicallandscapesandagriculturalareas,semi agriculturalandmemi pastoralar…  相似文献   

4.
1introduction Intheprocessofmanufacturingcolumngear,thegearshaping isextensivelyadopted,butsometimesitiscompaniedwiththe gear’sextrusionwoundandthecutter’sabnormalabrasion wear.Onegenerallythinksthatthisphenomenonisrelatedto thecut thickness’variationduringthegearshaping.Soasetofformulastohelpstudythevariationofcut thicknessofchipscuttedoffwiththecutedgeandtotryto findoutthecauseoftheextrusionwoundofthegearandthe abnormalabrasionwearintheprocessofgearshapingwere deduced.2TheCut thicknessoft…  相似文献   

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6.
1Patternselectionandver ificationoftheTGPpen stock TheYangtzeRiverWaterResourcesCommission (CWRC)submittedASub jectReportonthePatternSelectionofthePenstockinthePowerStationoftheThreeGorgesProjectinDecember,1 993,inwhichthearrangementofthepenstockswasdefinitelystated ,twotypesofstructures (internalhydraulicpressurebornesolelybypenstockandinternalhydraulicpressurejointlybornebysteellinerandreinforcedconcrete)proposed ,acomparisonbetweenthetwooptionscomprehensivelyperformed ,andsuggesti…  相似文献   

7.
A new approach for the derivation of the principal invariants of the stretch tensor with respect to the right Cauchy-Green tensor is presented in this paper. According to the definition of the derivation of tensor function, the three first-order derivatives for the principal invariants of the stretch tensor are obtained through derivation directly to the right Cauchy-Green tensor by incremental method. Then the three second-order derivatives are yielded by the derivation to the right Cauchy-Green strain tensor directly. Furthermore, an explicit expression of the tangent modulus of the general Varga material is given as an example.  相似文献   

8.
The research of the paleoflood remains from archaeological sites is one of the most important jobs in the environmental archaeology.Based on the traditional archaeological methods and the archaeological finds from the Yuxi site,Fengdu County of Chongqing,the paper analyzes the difference between the cultural layers and the possible paleoflood layers from various angles,such as contents,shapes of gravels,pottery,etc.,identifies the possible paleoflood deposit layers,i.e.the paleoflood remains of the Yangtze River,and discusses the periodicity of the floods.  相似文献   

9.
0IntroductionThe Cauchy problemof Camassa-Hol mequationut-uxxt 3uux=2uxuxx uuxxx,t >0,x∈Ru(0,x) =u0(x) ,x∈R(1)was derived in Ref .[1] to describe the motion of solitarywaves of shallow water ,whereurepresents thefree surface ofthe water above a flat bot…  相似文献   

10.
Professor Wen Bangchun with the Northeast University of Technology was elected to be the member of the Technologital Science Department of the Chinese Academy of Sciences in November 1991. It is the highest honor given to Chi-nase scientists. Professor Wen was born in 1930 and graduated from the Depertment of Mechnics and Electronics of the Universi-ty. For more than 30 years, he has studied the science of vibration application engineering systematically, a frontier sci-ence of mechanics combined with vibration theory and of wide application values in industry.  相似文献   

11.
Mature-embryo-derived calli of japonica rice (Oryza sativa L) Taipei 309 were used for replicated protoplast isolation experiments. Six out of nine callus lines produced protoplasts with satisfactory yield of 5.20×106–8.96×106 protoplasts/g FW (fresh weight). The remaining three callus lines initiated from seeds of cryopreserved-callus-derived plants had rooty calli, resulting in low yield of protoplasts and a large number of isolated banana-shape intact cells. Viability of protoplasts ranged 87.46%–94.15%. The average size of protoplasts was 207.49–379.04 μm2 in different callus lines. Comparitive experiments were also carried out using both calli and suspension culture cells for protoplast isolation. The results demonstrated that protoplast isolation of calli was a substantially simplified and reliable method for preparing rice protoplasts. Jin Deming: born in Jan. 1959, Associated Professor  相似文献   

12.
【目的】研究鼠尾藻(Sargassum thun bergii)有性生殖相关因子间的关系,分析鼠尾藻群体的有性生殖能力。【方法】通过统计分析方法,研究藻体长度与侧枝数、侧枝长度与生殖托数、生殖托长度与生殖托挂卵数间的关系。【结果】藻体长度与侧枝数、侧枝长度与生殖托数、生殖托长度与生殖托挂卵数间都为线性正相关,利用回归方程推算,1株成熟的鼠尾藻藻体能产生2×105~3.3×106个受精卵。【结论】1株成熟鼠尾藻的产卵量基本可满足1m2的采苗生产需要。  相似文献   

13.
运用水样叶绿素荧光仪(WATER-PAM)研究Cu2+胁迫下,湛江叉鞭金藻(Dicrateria zhanjiangensis)和球等鞭金藻3011(Isochrysis galbana MACC/H59)叶绿素荧光特性的变化,同时监测微藻的生长情况.结果就叶绿素荧光参数而言,湛江叉鞭金藻和球等鞭金藻3011的叶绿素荧光参数Fv/Fm,Fv/F0,Yield和ETR均随着Cu2+浓度的增大而明显降低;就生长情况而言,随着Cu2+浓度的增大,两种海洋微藻细胞密度的增长明显变缓.在24 h时Cu2+对湛江叉鞭金藻的毒性大于球等鞭金藻3011,48~96 h时Cu2+对球等鞭金藻3011的毒性大于湛江叉鞭金藻,Cu2+的毒性随着胁迫时间的延长而逐步增大.  相似文献   

14.
为了进一步弄清桂西北种植光皮桦(Betula luminfera)的生长量,于1997年4月在广西林朵林场营造光皮桦人工纯林,与马尾松纯林进行对比研究,结果表明:3.5年生光皮桦林分的平均树高、平均胸径和平均蓄积量分别为7.42 m、7.50 cm和30.06 m3·hm-2,分别比同龄马尾松林分的平均高(4.58m)、平均胸径(4.96cm)、平均蓄积(18.193m3/hm2)提高62.0%、51.2%和65.3%。说明该区营造光皮桦人工幼林的生长量较大,建议在相似立地条件下局部推广营造光皮桦人工林。  相似文献   

15.
红色赤潮藻(Akashiwo sanguinea)和球形棕囊藻(Phaeocystis globosa)都是近年来在我国近岸海域频繁引发赤潮的藻类。为了探索红色赤潮藻和球形棕囊藻之间是否存在化感作用及作用方式,本研究采用不同起始密度培养红色赤潮藻与球形棕囊藻,并将前者的完整细胞培养液、无细胞滤液、藻液超声破碎液分别与球形棕囊藻进行混合培养,分析红色赤潮藻对球形棕囊藻细胞生长的影响。结果显示,在红色赤潮藻细胞起始密度保持5×105 cells/L的混合培养条件下,起始密度分别为5×105、1×106、2×106、1×107 cells/L的球形棕囊藻生长均受到明显的抑制;无论是含有红色赤潮藻完整细胞的培养液,还是其无细胞滤液或藻液超声破碎液,均对球形棕囊藻的生长具有显著抑制作用(P<0.01),抑制强度由强至弱依次为完整细胞培养液、无细胞滤液和藻液超声破碎液;相反,球形棕囊藻的存在对红色赤潮藻细胞的生长无显著影响(P>0.05)。因此,红色赤潮藻具有抑制球形棕囊藻生长...  相似文献   

16.
【目的】为探讨贝克喜盐草(Halophila beccarii Ascherson)种群更新及濒危机制,研究其土壤种子库空间分布特征及其生物影响因素。【方法】对广西合浦榕根山、防城港交东、防城港山心3个贝克喜盐草典型分布点进行调查取样,统计(或称量)样品种子、直立茎、雌花、果实数量、地上部分生物量和地下部分生物量。【结果】从水平方向分布来看,相同方向上不同距离处贝克喜盐草土壤种子库密度差异不显著,海草场潮沟、外海、海岸方向一侧的土壤种子库密度在榕根山和交东分别为271粒/m~2、180粒/m~2、52粒/m~2和52粒/m~2、23粒/m~2、16粒/m~2,差异显著,可见该海草种子水平空间分布格局受到落潮水流与落潮后流向潮沟的微水流的影响,受距离影响较弱;垂直方向上,上层(0~4cm)、中层(4~8cm)、下层(8~12cm)土壤底质中贝克喜盐草种子数量分别占总量的73.0%、20.8%和6.2%,上层土壤中种子数量显著高于中层和下层(P0.05),表明绝大部分的种子分布于土壤表层(0~8cm);贝克喜盐草海草场土壤种子库密度与其种群雌花密度、直立茎密度存在极显著线性正相关关系,其相关系数r分别为0.722 9(P0.01)、0.845 1(P0.01),与果实密度、地上部分生物量及总生物量呈多项式曲线关系。【结论】贝克喜盐草土壤种子库的水平空间分布受潮沟、入海河流等外界环境和地上植被的种群属性、种子自身特性等因素的影响,垂直方向上主要分布在表层底质中,且地上植被的种群属性是决定土壤种子库密度的关键因素。  相似文献   

17.
广西南丹山口林场引种秃杉的栽培技术初探   总被引:1,自引:0,他引:1       下载免费PDF全文
【目的】为解决杉木长期连栽产量递减的问题,总结杉木轮换树种秃杉(Taiwania flousiana)的引种栽培技术。【方法】从秃杉种源选择、种子采集、壮苗培育技术、造林技术设计与实施等方面对南丹山口林场引种秃杉栽培资料进行分析。【结果】样地测定显示,8年生、11年生、14年生、17年生的秃杉林分平均胸径依次为10.7cm,12.7cm,14.1cm,20.8cm;平均树高分别为8.6m,11.9m,13.3m,17.3m;林分平均蓄积量依次为93.428m3/hm2,153.418m3/hm2,203.824m3/hm2,223.400m3/hm2。秃杉林分各项生长量指标分别超过同等立地条件的杉木二代林的8.8%~112.0%。【结论】山口林场秃杉的引种栽培技术有一定的推广价值。  相似文献   

18.
梁俊勋 《广西科学》1998,5(2):156-160
在45m2室内人工模拟自然条件下进行褐家鼠和黄胸鼠取食行为生态学特征的研究。观察结果显示,两种鼠对所提供的食物的日平均取食量和觅食时所付出的活动行为强度均无明显差异,但在日内的7时、15时和23时之间的摄食量和活动量的差异均极显著。当所提供的食物源有选择机会时,褐家鼠选择的平均取食量是玉米碎>稻谷>大米;黄胸鼠是玉米碎>大米>稻谷,无食物选择机会时褐家鼠的取食量是稻谷>玉米碎>大米;黄胸鼠是大米>玉米碎>稻谷。褐家鼠和黄胸鼠在寻找选择食物的过程中,通常付出的活动行为强度(量)是23时点>7时点>15时点。褐家鼠和黄胸鼠的取食行为特征表现可用“摄食时间+食物源+行为反应”的模式表示。同时指出鼠的取食行为与防治实践之间关系的重要性。  相似文献   

19.
A laboratory study on the liquid–liquid extraction system has been carried out for the removal and recovery of methyl red from aqueous solutions using xylene as an extractant. The concentration of methyl red has been studied in the range of 1.72 × 10−4 to 1.72 × 10−3 mol L−1. The efficiency of dye extraction increased with increasing time of extraction. Distribution ratio is reasonably high (D = 49) even in the presence of inorganic salts. Extracted dye in the organic phase has been stripped into sodium hydroxide solution. The organic solvent is reused for reextraction of the dye from aqueous solution. The efficiency of reused organic solvent was maintained up to 10 runs. Loading capacity of dye has been found to be 14.32 mg. Under optimized conditions, real textile wastewater has been studied and the results are satisfactory.  相似文献   

20.
孙悦  李新正 《广西科学》2015,22(5):568-572
记述了中国海背肛虫属Notopygos仙虫科Amphinomidae两新纪录种——厚唇背肛虫Notopygos labiatus McIntosh,1885和安氏背肛虫Notopygos andrewsi Monro,1924。前者在中越北部湾海洋综合调查(1959~1962年)时,采集于广西北部湾潮下带;后者在全国海洋综合调查(1958~1960年)时,采集于西沙群岛潮间带。标本均保存在中国科学院海洋研究所海洋生物标本馆。本文对两新种的外部形态特征进行了仔细观察并描记。  相似文献   

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