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1.
文章报道了内蒙古典型草原羊草(Aneurolepidium chinense),大针茅(Stipa grandis),猪毛菜(Salsoaa collina)和芨芨草(Achnatherum splendens)的凋落物的分解速率与气温和降水之间的关系,建立了动态模型X(t)/X(O)=e^-(at-bΣT-cΣp).其中t表示时间,X(t)是t时凋落物残留量,ΣT是累计气温,ΣP是累计降水量。气  相似文献   

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甲壳动物的性别决定吴融(浙江省海洋水产养殖研究所温州.325000)甲壳动物一般为两性生殖.雌雄比率为1:1。据charnlaux-Cotton(1960)在端足目Orchest。again-marella(滨蚤)上的研究,知道性别的分化与造雄腺分泌...  相似文献   

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哺乳动物性别分化的调控   总被引:2,自引:0,他引:2  
哺乳动物性别分化调控的分子机制的研究特别是性别分化的层次调控、剂量补偿和性染色体进化这三个领域,已取得快速进展。已经发现Y染色体性别决定区基因(SRY)、X染色体DSS-AHC决定区基因1(DAX-1)、甾类生成因子1基因(SF1)和Wilms瘤抑制基因(WT-1)等与哺乳动物性别决定有关。SRY启动睾丸分化,但胚胎发育成雄性的其余步骤由睾丸分泌的激素控制。DAX-1编码一种女性特异功能的蛋白质,  相似文献   

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昆虫促前胸腺激素研究进展   总被引:4,自引:0,他引:4  
昆虫促前胸腺激素研究进展李毅平龚和(中国科学院动物研究所,北京100080)关键词促前胸腺激素受体信号系统促前胸腺激素(prothoracicotropichor-monePTTH)因其促进前胸腺(PG)合成和分泌蜕皮激素而得名,以前也称为脑激素,因...  相似文献   

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小兴安岭阔叶红松林凋落物产量及动态的研究   总被引:7,自引:0,他引:7  
小兴安岭阔叶红松林凋落物产量及动态的研究刘传照,李景文,潘桂兰,李传荣(东北林业大学红松研究所,黑龙江带岭153106)LitterProductionandDynamicsinBroadleavcd-KoreanPineForestsinXiaoxinganMountaiils¥LiuChuanzhao;LiJingwen;PanGuilan;LiChuanrong(InstituteofKoreanPineStudies,NortbeastForestryUniversity,Dailing,Heilongjiang153106).ChneseJournalofEcology,1993,12(6):29-33.Three-yearstudywasdoneonlitterproductionanddynamicsunderbroadleaved-KoreanpineforestsintheXiaoxinganMountains。Resultsshowedthatannuallitterfallis4.25±0.17t.ha ̄(-1).yr ̄(-1).Amongtotallitterfall,leaflit  相似文献   

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海洋微藻基因工程的选择标记   总被引:12,自引:0,他引:12  
6种海洋微藻新月菱形藻(Nitzschia closterium Ehr.)、牟勒氏角刺藻(Chaetocdros muelleri Lemm.)、三角褐指灌(Phaeodactylum tricornutum Bohl.)绿光等鞭金藻8701(Isochrysis galbana Parke 8701)、亚心形扁藻(Platymonas subcordi-formis(Wille)Hazen)和  相似文献   

7.
气候变化对农业害虫的潜在影响   总被引:23,自引:4,他引:19  
气候变化对农业害虫的潜在影响张润杰何新凤(中山大学昆虫学研究所生物防治国家重点实验室,广州510275)PotentialEfectsofClimateChangeonAgriculturalInsectPests.ZhangRunjie,HeXi...  相似文献   

8.
家蚕蜕皮与变态的内分泌调控   总被引:3,自引:1,他引:2  
顾世红 《昆虫知识》1999,36(2):70-74
家蚕的蜕皮与变态是由前胸腺分泌的脱皮素(molting hormone或 ecdysteroid简称 MH)及由咽侧体分泌的保幼激素(juvenile hormone)控制的,而促有前胸腺激素(prothoracicotropic hormone,以下简称PTTH)的功能为刺激前胸腺分泌蜕皮素。笔者近10年来从家蚕内分泌体系的一系列研究中发现,蜕皮素浓度的变化可以通过控制咽侧体的保幼激素的生物合成来影响幼虫发育,而PTTH的信息传递可通过调控前胸腺的功能,进而影响血淋巴中蜕皮素浓度。  相似文献   

9.
广东黑石顶常绿阔叶林生物量及其分配的研究   总被引:24,自引:0,他引:24  
本文采用标准木和回归分析法(乔木层)及样方收获法(灌木层,草本层)研究了黑石顶自然保护区南亚热带常绿阔叶林的生物量及其分配规律。1.四种回归模型:(a)Y=a+bX,(b)Y=aX^b,(c)Y=ac^bx,(d)Y=a+blnX都能成功地应用于该森林的生物量研究,但一般以(b)及(c)的相关系数较高。对较大胸径的样木组(D≥10cm)直径方程的唯一显著的模型。2.森林总生物量为357.976t·  相似文献   

10.
秦岭南坡旬河流域及邻近地区森林与其生境关系的初步研究康慕谊(西北大学地理系,西安710069)RelationshipbetweenForestVegetationandItsHabitatsinXunheRiverBasinofQinlingMountainandItsAdjacentAreas¥KangMuyi(DepartmentofGeography,NorthwestUniversity,Xiaan710069).ChineseJournalofEcology,1993,12(6):62-66.Principlesofvegetationecologyandmethodofmultivariateanalysis(DoubleSievingStepRegression)areappliedtorevealthegeneralrelationshipbetweenforestvegetationanditshabitatsintheupperandmid-dlereachesofXunheRiverbasinandtheiradjacentareas。Theresultsshowthatthespe  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   

18.
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   

19.
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   

20.
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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