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离子交换树脂袋法测定鼎湖山季风常绿阔叶林土壤有效氮的初步研究 总被引:9,自引:0,他引:9
本文用离子交换树脂袋法(Ionexchangeresinbagmethod).测定了鼎湖山季风常绿阔叶林土壤有效氮动态.结果表明,鼎湖山季风常绿阔叶林土壤有效氮主要由铵态氮(NH4+-N)组成,且具有明显的季节性变化,两种不同深度(0-10cm,10-20cm)土层比较,硝态氮(NO3-N)年平均值在10-20cm土层显著地高于在0-10cm的土层(p=0.05);铵态氮年平均值在10-20cm土层则趋向低于在0-10cm的土层. 相似文献
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本文用离子交换树脂袋法(lonexchangeresinbagmethod),测定了鼎湖山马尾松人工林土壤硝态氮和铵态氮动态情况。结果表明,鼎湖山马尾松林土壤硝态氮和铵态氮均具有明显的季节性变化,以春季最高和夏季最低。硝态氮在0~10cm和10~20cm两土层的年平均值分别为1.722和1.429μg.d-1.g-1干树脂,铵态氮在0~10cm和10~20cm的年平均值则分别为19.137和14.696μg.d-1.g-1干树脂。硝态氮和铵态氮在试验的大部分季节表现出显著的直线相关关系(p<0.05),表明了铵态氮供应是调节硝化速率的一个重要因子。 相似文献
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采用小集水区定位研究方法,研究分析了尖峰热带山地雨林天然更新林生态系统5个水文年水分循环的动态特征。年降水量分配在169.8~350.0cm,林冠层截留率年变化11.0%~17.6%范围,旱、雨季变化在14.4%~31.4%和11.5%~19.4%之间;其中树干茎流率年平均为7.1%,雨季平均为6.8%,雨季月变化在2.2%~12.4%。总径流动态特性以每年7~9月的增加响应较快,11月至翌年2月径流衰减缓慢。水量平衡参数为:年均降水量2668.3mm,14.3%为冠层截留,46.7%为径流输出,53.3%为蒸发散失。土壤渗透水性能为,70cm厚土层,当雨量小于30mm,进入土层的水分全部被吸持,雨量在35~50mm,25%的降水量渗漏,雨量在50~100mm内,26.5%~56.3%的降水量下渗,其吸持和滞留贮存水性能与土壤的结构、持水量、孔隙度密切相关。 相似文献
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屎克螂适宜的繁殖条件初步研究 总被引:2,自引:0,他引:2
1991—1994年对屎克螂适宜的繁殖条件研究结果:1.土层40cm和60cm的平均温度分别为15.92±6.34℃和15.89±6.08℃;平均土壤含水量分别为26.70±3.74%和23.72±1.88%,使各虫态处于一个几乎恒温恒湿的条件,有利于生长发育与越冬,2.土壤含水量17%、20%、22%、26%和29%,其产卵最多的深度分别在65─70cm,75─80cm,65─80cm,65—80cm和35—50cm,分别占产卵总数的34.16%、42.42%、68.42%、55.40%和90.56%。3.不同土壤的产卵深度,沙壤土以土下45—50cm处最多,占产卵总数的34.78%;沙土以65—85cm最多,占产卵总数的86.67%;粘土以45—60cm最多,占产卵总数的51.11%。 相似文献
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南亚热带常绿阔叶林优势种群的生物量与生物量增量 总被引:2,自引:0,他引:2
粘木种群的生物量为70.14t/hm2,生物量增量为2.32thm2a-1。其总生物量的90%以上分布在d≥20cm的大树,仅有0.04%~0.05%分布在d<10cm的小树。在各器官的分配是:树干为65%,根为25%,枝为11%,而叶仅占有2%。粘木的平均径向增长为0.35cm/a。应用树干解析法和形率法估算树干的生物量,两者的结果差别不大。但形率法则既省力省时,又较方便。粘木的形率为0.71。 相似文献
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福建海产鱼类寄生吸虫二新种( 吸虫纲:复殖目:隐殖科) 总被引:3,自引:0,他引:3
从福建沿海的鲈鱼肠道里查获双巢亚科的厦门双巢吸虫,新种Biovariumxiamenensesp.nov,虫体大小2.54~4.20mm×0.30~0.40mm(2.903×0.369mm),虫卵18~22μm×10~14μm(20.4×11μm);从勒氏菌鲷的小肠里检获新隙亚科的厦门拟隐殖吸虫,新种Paracryptogonimusxiamenensisspnov,虫体大小0.800~0.1672mm×0.484~0.848mm(1.247×0.685mm),虫卵19~30μm×11~14μm(24×12μm),头棘55枚。 相似文献
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Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis
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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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
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
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JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
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
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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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H.-R. GREGORIUS 《Biological journal of the Linnean Society. Linnean Society of London》1984,23(2-3):157-165
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
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