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1.
长白山北坡不同土壤N2O和CH4排放的初步研究   总被引:20,自引:0,他引:20  
用箱法技术原位测定了长白山北坡不同土壤(苔原土、生草森林土、棕色针叶林土和暗棕色森林土)6—8月间的N2O和CH4排放.结果表明,这些土壤既是N2O的源,又同时是CH4的汇.N2O通量变化于6.17—12.33μg·m-2·h-3之间(平均9.37μg·m-2·h-1),CH4通量为-85.63—-7.58μg·m-2·h-1(平均-41.45μg·m-3·h-1),并观察到在N2O排放和CH4吸收之间有着相互消长关系.实验室培养实验表明,最大反硝化作用活性存在于土壤上层(0—6cm);不同土壤的反硝化作用活性明显不同.山地暗棕色森林土的CH4吸收作用也主要发生在土壤的上层(0—12cm).  相似文献   

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Cu对中国林蛙蝌蚪的急性毒性   总被引:18,自引:1,他引:18  
试验测定了不同温度条件下Cu2+对中国林蛙蝌蚪的急性毒性.结果表明,在水温为9~13℃、18℃和24℃条件下,Cu2+对10d龄中国林蛙蝌蚪96h的LC50分别为5.01、3.80和2.99mg·L-1,致死阈浓度分别为4.0、2.5和1.6mg·L-1,而在96h内的无可观察效应浓度分别为2.5、1.6和1.0mg·L-1.18℃条件下Cu2+对20d龄中国林蛙蝌蚪的96hLC50为2.17mg·L-1.  相似文献   

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银王亮丝草的试管微繁殖   总被引:2,自引:0,他引:2  
1植物名称银王亮丝草(Aglaonema com-mutatumcv."SilverKing”),又名银王粗肋草、银王万年青、银皇帝。2材料类别带腋芽的茎段。3培养条件以MS为基本培养基。芽诱导培养基附加6-BA2.0~2.5mg·L-1(单位下同);芽增殖培养基附加6-BA4.0~4.5及NAA0.01~0.02;生根培养基采用3/4MS附加IBA3.0~3.5及GA33,0。所有培养基蔗糖及琼脂含量分别为3%和0.75%,pH值均调至5.8。培养温度26~28℃,光照8~10h·d-1,光照…  相似文献   

4.
高寒草甸放牧生态系统夏秋草场轮牧制度的模拟研究   总被引:2,自引:0,他引:2  
黄大明 《生态学报》1996,16(6):607-611
利用GMAME1模拟高寒草甸放牧生态系统夏秋草场在临界放牧压力下的270种轮牧制度,并对其累积采食量进行比较分析。结果指出:在高寒草甸放牧生态系统中,最佳的轮牧小区数目为3或4个。证明了Morley规则:最佳轮牧小区数目应该小于10。推荐2个高寒草甸地区最佳的轮牧模式供野外实验和放牧规划参考:(1)3个轮牧小区,每小区每次持续放牧29d,放牧压力为30.14kJ/m2·d,累积牧草采食量最高为4250.443kJ/m2。(2)为保持牧草结构的稳定和各轮牧小区牧草生物量的均匀性,可以采用3个轮收小区,放牧持续时间7d,放牧压力I(145)=28.8914kJ/m2·d,累积采食量为4073.34kJ/m2。  相似文献   

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不同质地土壤的水热状况及其对冬小麦产量形成的影响   总被引:4,自引:0,他引:4  
对豫东平原3种质地土壤的水热状况和冬小麦籽粒生长特征进行了研究.结果表明,冬小麦籽粒生长阶段,粘壤土5cm处的日平均温度最低,为18.3℃,砂壤土最高,为19.5℃,中壤居中,为19.1℃.3种土壤的含水量大小顺序为粘壤>中壤>砂壤,粘壤土上小麦籽粒灌浆时间最长,千粒重最高,分别为38d和45.5g,砂壤土小麦籽粒灌浆时间最短,千粒重最低,分别为33d和42.4g,中壤土小麦2项指标居中,分别为36d和43.1g.高产栽培条件下,粘壤土冬小麦产量最高,为8253kg·hm-2,中壤次之,为7980kg·hm-2,砂壤最低,为7617kg·hm-2  相似文献   

6.
福建武夷山甜槠群落能量的研究   总被引:43,自引:0,他引:43  
在生物量、生产力研究基础上,对武夷山甜槠(Castanopsis eyrei(Cham p.ex Benth.) Tutch.)群落各组分的热值、群落能量现存量、能量年净固定量以及太阳能转化效率进行了研究。结果表明:(1)甜槠群落各组分样品的干重热值具有一定的差异,树皮热值最高,细根热值最低。(2)甜槠群落的能量现存量达780584.1 kJ·m - 2,其中地上部分为678913.8 kJ·m - 2,占总量的86.98% ;地下部分为101670.3 kJ·m - 2,占13.02% 。(3)甜槠群落的能量年净固定量(1992年)为26856.2 kJ·m - 2·a- 1,林地太阳光合有效辐射能的转化效率为1.296% 。  相似文献   

7.
北京山地温带森林的土壤呼吸   总被引:107,自引:3,他引:107       下载免费PDF全文
本文通过在北京山地3种温带森林中为期一年的观测,得到了土壤呼吸速率与地下5cm土壤温度之间的函数关系。据此并根据气象资料推算得到了白桦林、辽东栎林和油松林的年土壤呼吸量分别为1132gCO2m-2a-1,143gCO2m-2a-1和866gCO2m-2a-1。与国外同纬度地区相比,该地年土壤呼吸量偏低。结果还显示,土壤呼吸与地下5cm土壤温度的相关性好于与地表温度的相关性,并且水分含量对土壤呼吸也有影响。1994年秋季进行的昼夜连续观测表明,日土壤呼吸速率最高的时刻在中午12:00~下午4:00,最低的时刻在黎明前5:00~6:00。  相似文献   

8.
长寿花叶片愈伤组织的诱导和植株再生   总被引:10,自引:1,他引:9  
1植物名称长寿花(Kalanchoeblossfel-diana)。2材料类别叶片。3培养条件培养基:(1)MS+2,4-D1mg·L~(-1)(单位下同)+6-BA0.1;(2)MS+NAA1+6.BA0.1;(3)MS+6-BA1+NAA0.1;(4)1/2MS。以上培养基均加蔗糖30g·L~(-1),琼脂8g·L~(-1),pH值为5.8,高压灭菌,培养温度23~26℃,光照12h·d~(-1),光照度1000lx左右。4生长与分化情况4.1无菌材料的获得从实生苗上取下叶片,经自来水冲洗后,用…  相似文献   

9.
1植物名称王瓜(Trichosanthescuc-umeroides),采自浙江天目山。2材料类别顶芽、带腋芽的茎段。3培养条件诱导分化培养基:(1)MS+6-BA0.5mg·L-1(单位下同);(2)MS+6-BA1;(3)MS+6.BA2+2,4-D1。诱导生根与生长培养基:(4)MS;(5)MS+IAA2;(6)MS+6-BA1+2,4-D1。每种培养基均附加3%蔗糖,0,7%琼脂,pH5.8。培养温度(25±1)℃,光照每天12h,光照度20001x左右。4生长与分化情况4.1无菌材料的…  相似文献   

10.
510.6nm激光照射对兔血管平滑肌细胞增殖的影响   总被引:2,自引:0,他引:2  
本文用510.6nm 波长激光以功率密度1、5、10 m W/cm 2 和能量密度2、4、6J/cm 2 照射体外培养的兔血管平滑肌细胞(SMC),通过3H- TdR掺入率和细胞生长曲线测定细胞增殖率。结果显示,上述激光照射量均能抑制细胞增殖率,其中以10m W/cm 2 组的作用最为显著  相似文献   

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It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.  相似文献   

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Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.  相似文献   

17.
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.  相似文献   

18.
肝癌中HBV和HCV基因和抗原的分布及意义   总被引:1,自引:0,他引:1  
采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细  相似文献   

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For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.  相似文献   

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