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1.
Acrocyathus是一类块状体或丛状体的四射珊瑚,在北美分布于下石炭统,我国见于上石炭统,但丛状体的在我国系首次发现。在连续切片上,可见两个生长阶段,其繁殖方式有侧芽繁殖和边缘泡沫板内繁殖,系统分类上另置独立的科级分类。根据形态分析,该珊瑚栖息在动水,能量略高及食料丰富的浅水环境。当前标本为一新种:A.jiyuanensissp.nov.。  相似文献   

2.
甘肃晚二叠世二齿兽化石的发现及相关地层研究   总被引:1,自引:0,他引:1  
记述了甘肃肃南县鲁沟上二叠统肃南组的二齿兽一新种──Dicynodon sunanensis sp. nov.。它以额骨与前颌骨相连,在接触处具一深的凹坑,和向前延伸的位于前颌骨中线上的一浅沟;左右鼻骨不在中线相遇。泪骨向前延伸超过前额骨等特征区别于Dicynodon的其他种。它与新疆锅底坑组的Dicynodon bogdaensis关系密切。祁连山地区二叠系、三叠系的研究对比表明:1)肃南组的命名剖面──大青沟剖面只包括肃南组下部,该组由上下两部分组成,这在羊露河剖面和鲁沟剖面中可以得到证实。2)过去广泛使用的西大沟组(群)或“中下三叠统”,其地质体是指整合于窑沟组杂色岩之上,和产晚二叠世安加拉与华夏型混生植物群的肃南组之下的一套紫红色粗碎屑岩层。3)鲁沟剖面中覆于肃南组之上,和伏于下、中侏罗统含煤岩系之下的砂岩夹砾岩及细砂岩层,被命名为鲁沟组,属下三叠统。  相似文献   

3.
川东北二叠纪吴家坪期牙形石(刺)序列及其世界对比   总被引:14,自引:3,他引:11  
对四川省宣汉县渡口和南江县桥亭吴家坪期地层的系统采集和研究结果表明,吴家坪期至少包括7个牙形石带,自下而上为Clarkinadukouensis带,C.asymmetrica带,C.leveni带,C.guanyuanensis带,C.transcaucasica带,C.orientalis和C.inflecta带。其中,前3个带的层位低于一直作为吴家坪期早期的C.liangshanensis带。吴家坪阶的顶界以置于C.inflecta带与C.subcarinata带之间较妥。同时,建立了Clarkinadukouensis,C.asymmetrica,C.bizarrensis,C.daxianensis,C.demicornis,C.inflecta,C.longicuspidata等7个新种。  相似文献   

4.
早白垩世单缝孢真蕨植物新材料及其分类归属   总被引:1,自引:0,他引:1  
在原位繁殖器官研究的基础上,描述了产于辽宁铁法盆地早白垩世地层中的单缝孢真蕨植物化石:Athyrium asymmetricum meng、Dryopterites gracilis sp.nov.D.liaoningensis sp.nov.和Asplnium popovii Samylina,并讨论了其分类归属.  相似文献   

5.
昆明附近早寒武世遗迹化石   总被引:3,自引:0,他引:3  
报道了昆明地区下寒武统筇竹寺组玉案山段和沧浪铺组乌龙箐段所发现的遗迹化石共13属15种,其中1新属6新种为:QipanshanichnusgyrusLuoetTaoichnogen.etichnosp.nov.,ArthrophycusqiongzhusiensisLuoichnosp.nov.,BifungiteskunyangensisLuoichnosp.nov.,CruzianabeifengwanensisLuoetGaoichnosp.nov.,PalaeophycusbeifengwanensisLuoichnosp.nov.,ArchaeichniumkunmingensisLuoichnosp.nov.。这些遗迹化石均产于开阔台地相潮下带的低能环境,为浅海相的Gruziana遗迹相。  相似文献   

6.
贵州省悬钩子属种质资源考察   总被引:15,自引:0,他引:15  
对贵州省东北、东南、西南和西北4个地区悬钩子属(RubrsL.)野生种类的分布、生长习性等进行了调查。共采集55种7个变种,其中R.grayanus,R.mallotifolius,R.tsangvrus,R.faberi,R.henryi为贵州省新记录种。R.setchuenensisR.coreanus,R.corchorifolius,R.lambertianus,R.niveus,R.mullibracteatus,R.tephrodes分布最广。除R.setchuenensis,R.tephrodes外均有驯化利用价值。调查发现,具红、黄、黑三种不同果色的插田泡,秋季结果的小柱悬钩子、红泡刺藤和大乌泡。基本查清了贵州省悬钩子属植物的种类和分布,为进一步引种、保存和发掘利用提供科学依据。  相似文献   

7.
吉占和   《广西植物》1995,15(2):106-109
本文报道了2个新种(元阳石豆兰BulbophyllumyuanyangenseTsui,长帽隔距兰CleisostomalongioperculatumTsi)、2个新组合(翼萼卷瓣兰BulbophyllumretusiusculumRchb.f.var.oreogenes(W.W.Smith)Tsi,角萼卷瓣兰B.retusiusculumRchb.f.var.tigridum(Hance)Tsi)和1个新命名(细茎毛兰EriatenuicaulisS.C.ChenetTsi)。  相似文献   

8.
湘西中寒武世多节类三叶虫新属种   总被引:1,自引:0,他引:1  
描记湘西江南斜坡带中寒武统花桥组的多节类三叶虫4新属7新种:Changqingialaevissp.nov,Fissanomocarellapaibiensisgen.etsp.Nov.,Huayuaniasubcalvagen.etsp.nov,Luaspisdecorosagen.etsp.Nov.。Paranomocarellafortissp.Nov.,Wangcuniawangcunensisgen.etsp.nov和Zhujiahunanensissp.Nov.。Fissanomocarellagen.nov.属Anomocarellindae科;Wangcuniasen.nov.和Huayuaniasen.nov.分别存疑地归入Papyraspidae科和Anomocarellidae科;Luaspisgen.nov.的科级分类位置未定。所有新属种与华北和东北南部中寒武世动物群关系较密切,是斜坡相混生动物群的重要分子。  相似文献   

9.
云南西藏蝠蛾属四新种(鳞翅目:蝙蝠蛾科)   总被引:3,自引:0,他引:3  
本文报道了云南西北部和西藏东南部的高寒草甸中分布的蝠蛾属4新种:剑川蝠蛾Hepialusjianchuanensissp.nov.,甲郎蝠蛾H.jialangensissp.Nov.,察里蝠蛾H.zariensissp.nov.,异翅蝠蛾Hepialusanomopterussp.nov.4个新种都是冬虫夏草真菌的寄主昆虫。  相似文献   

10.
兰科盆距兰属(Gastrochilus)植物的修订   总被引:1,自引:0,他引:1  
吉占和   《广西植物》1996,16(2):123-154
本文对盆距兰属(Gastrochilus)植物作了修订,共分3个组,含46种和1变种,其中1个组(Sect.Caespitosi)和8个种(G.carnsus,G.garhwalensis,G.linearifolius,G.guangtungensis,G.subpapillosus,G.nanchuanensis,G.saccatusandG.gongshanensis)为新的,首次在本文作了描述报导。本属属的形态特征,研究历史和订正后属下的分类群检索表,种的文献引证、简短的特征记要和地理分布以及在属中被排除的分类单位索引均提供在本文。  相似文献   

11.
It has been suggested that as a result of the action of natural selection the mean value of any biological measurement would be the most normal value and associated with the most favorable survival rate. Selection is said to be stabilizing (or normalizing or balancing) if individuals with intermediate values for a given quantitative trait have the highest fitness. Birth weight is perhaps the most clear-cut example of a human character subject to stabilizing selection. This paper presents the distribution of birth weights among 8382 Philadelphia Black infants and the rate of perinatal mortality for the birth weight classes. Using these data, several analyses of stabilizing selection are made. The data were taken from the Collaborative Study on Cerebral Palsy, Mental Retardation, and other Neurological and Sensory Disorders of Infancy and Childhood.  相似文献   

12.
Relationships between dermatoglyphic variables, including finger ridge counts and finger, palmar, and plantar pattern intensities, and weight and length at birth, were tested in a sample of 184 boys and 202 girls from Warsaw schools. No convincing evidence for such relationships has been obtained from the results of correlations and one-way analysis of variance, although there are indications that some palmar traits may be related to length at birth in females. The data agree with the common belief that birth weight and birth length are mainly determined by influences operating in later stages of pregnancy, that is, after the 20th gestational week.  相似文献   

13.
It has been suggested that maternal nutrition, and fetal and infant growth have an important effect on the risk of cardiovascular disease in adult life. We investigated the population-based distribution of deaths from cerebrovascular diseases (ICD9 codes 430, 431, or 434) in Japan in 1986–1994 as a function of birth month, by examining death-certificate records. For a total of 853 981 people born in the years 1900–1959, the distribution of the number of deaths according to the month of birth was compared with the distribution expected from the monthly numbers of all births for each sex and for the corresponding birth decade. For those born between 1920 and 1949, there were significant discrepancies between the actual numbers of deaths from subarachnoid hemorrhage (ICD9 430) and the numbers expected, and these differences were related to the month of birth. Those born in summer, June–September, consistently had an elevated risk of death, particularly men, where the excess risk was 8%–23%. This tendency was also observed, less distinctly but significantly, for deaths from intracerebral hemorrhage (ICD9 431), but was not observed for those dying from occlusion of the cerebral arteries (ICD9 434). The observation that the risk of dying from subarachnoid hemorrhage was more than 10% higher among those born in the summer implies that at least one in ten deaths from subarachnoid hemorrhage has its origin at a perinatal stage. Although variations in hypertension in later life, which could possibly be ”programmed” during the intra-uterine stages, could be an explanation for this observation, the disease-specific nature of the observation suggests the involvement of aneurysm formation, which is a predominant cause of subarachnoid hemorrhage. Received: 22 October 1999 / Revised: 8 May 2000 / Accepted: 10 May 2000  相似文献   

14.
This paper considers a generalized birth process {Xm(t), t > 0} and presents a new stochastic model for the number of eggs laid by a parasite on a host. Also, given an underlying distribution for the number of visits between parasites and a host, this distribution is generalized by the distribution of the number of eggs per visit laid on the host. If a certain number of eggs are already present on the host, a parasite such as a Japanese weevil, may avoid oviposition in subsequent visits (see JANARDAN (1980)) to the same host. A class of generalized distributions are presented to model such situations. The case of a single egg laying parasite and a Poisson distribution for the number of visits of the parasite to the same host yields a distribution of particular interest. In order to develop this model, certain lemmas are derived. Finally a characteristic property of this stochastic model is presented.  相似文献   

15.
16.
Estimation of the number of adult grasshoppers, Mecostethus magister, was made by means of the mark-and-recapture method. The birth and death rates are possible to be estimated at the same time, but the immigration and the emigration rate are inevitably involved in these respectively. The immigration and emigration rates must be made clear to know the true birth and death rates. For this purpose the movement of the marked males in 1963 was analyzed. The grasshoppers dominantly moved in the directions of N, NW and W, and the difference in frequency among the movement directions was not so large. The distribution of the dispersal-distance relationship of each quadrate on each released day was fitted approximately to normal distribution. It could be concluded that almost all of the grasshoppers moved within the range of about 31–35m. The emigration rate from the quadrate (12×12m2) was about 0.73–0.77 and the difference in the rate among the released days was small. From these values the emigration rate from the station (84×60m2) was estimated as 0.21–0.23. Subtracting the emigration rate from the death-and-emigration rate, the true death rate was calculated. The death rate was very low until the number of males reached to the peak, then increased gradually. Supposing that immigration rate was equal to the emigration rate, the true birth rate was also estimated. But the presumption might not be pertinent, for the value of birth rates became negative.  相似文献   

17.
In order to examine the eruption order of the first two permanent teeth, kindergarten children 5 to 6 years old were examined in Hakone, Japan. Among a total of 817 children examined from 1976 to 1984, 349 were determined as I-type children, whose mandibular first incisor erupted earlier than the mandibular first molar, and 183 were as M-type children, whose first molar erupted earlier in the mandible. The mandibular I-type rate, i.e., the proportion of the I-type among a total of I- and M-type children, was 66% (349/532). In 1983-1984, the I-type rate was 70% among boys and 62% among girls, but the overall I-type rate did not differ significantly by the sex of the subject or by the year of examination. The I-type rate varied significantly with the season of subject's birth. Those born in October or November showed a significantly lower I-type rate (33%) than the other subjects (P less than 0.001), in spite of a shift of birth season with low I-type rate toward winter in 1983-1984. The difference of the I-type rate according to birth season suggests that the causes responsible for this change are primarily environmental and act at the prenatal or perinatal stage of life.  相似文献   

18.
The present communication is an attempt to describe the mode of propagation of AIDS epidemic and its control programme using a branching process as well as a birth-death and immigration model. A comparison of the project of AIDS control programme on the basis of its propagation by a continuous branching process model with that of a linear birth and death process with immigration shows a remarkable contrast. Branching process model shows that it is possible to control the propagation of the disease by suitably increasing the detection rate and lowering the infection rate. However, the propagation of AIDS models by birth and death Process with or without immigration shows that it is increasingly difficult to control the invasion of AIDS merely by controlling the birth, death and immigration parameters.  相似文献   

19.
A new contract net-style auction protocol is proposed as a framework for integrating process planning and shop floor control in heterarchical manufacturing systems. Process planning is partitioned into on-line and off-line activities; off-line process planning decisions are represented in a graph format and used as input for on-line process planning activities performed by machine controllers. Triggered by the opening round of an auction, the final on-line stages of process planning are dovetailed with the resource allocation process in the shop floor control system. The auction process allows final process planning decisions to be based on timely information, relying on the distribution of static process planning information rather than the distribution of a model of dynamic shop floor status and allowing a controller to identify all the primary and secondary resources and operations that must be provided for the incremental processing of a part.  相似文献   

20.
The birth rate of natural cladoceran populations can change rapidly (during 2–3 days), reflecting rapid changes in their environment. If the egg ratio is calculated on the basis of egg age distribution, the birth rate can be estimated at short sampling intervals (shorter than egg stage duration) by modified Paloheimo's (1974) formula. When female size structure and age of eggs in clutches at the beginning and the end of a sampling interval are known, death rates of ovigerous females and eggs in separate size classes can be determined and incorporated in birth rate estimates. All these methods have been employed using the data on the population of Diaphanosoma brahyurum from the lake Obsterno (North-Western Belarus) in July–August, 1992. The birth rate values computed by the proposed methods and Poloheimo's formula differed significantly in many cases. The accuracy of birth rate estimations from various calculation methods was tested using a computer simulation. The model contains the essential features of cladoceran life history: distinct egg, juvenile and adult stages, development of eggs and reproduction. The population was divided into 25 age classes, each of 1 day duration. Durations of the egg, juvenile and adult stages were set at 3, 6 and 20 days, respectively. The embryogenesis was divided into three egg stages, each of 1 day duration. Survivorship was set from 0.2 up to 1.0 for each age class. The survivorship and brood size were changed through each of five time intervals (days) that allowed to simulate an increase or reduction of population density. Fecundity, survivorship and egg stage duration remained constant during each of 5 days that assumed stability of an environment (this does not occur in nature). Nevertheless, the egg ratio, proportion of juveniles and birth rates were variable even under these circumstances. Computer simulations showed that Poloheimo's formula evaluates birth rate with the relative error of 62% and usually overestimates its values. We propose methods to decrease errors of birth rate estimations by 3.5–5.5 times.  相似文献   

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