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1.
以单片机为核心,采用软件、硬件相结合的方法,充分利用单片机的硬件中断资源,实时响应地面的声波逻辑脉冲,分离其接收和发射逻辑。同时该仪器以地面声波逻辑为工作时序,分时采集模拟道数据、脉冲道数据及向地面传输PCM数据。该脉码传输仪既能完成PCM3506的全部功能,又能监测仪器工作环境的温度及测井套管接箍的压力。 相似文献
2.
3.
Assessing the potential impacts of alternative landscape designs on amphibian population dynamics 总被引:2,自引:1,他引:2
An individual-based, spatially explicit population model was used to predict the consequences of future land-use alternatives for populations of four amphibian species in two central Iowa (midwest USA) agricultural watersheds. The model included both breeding and upland habitat and incorporated effects of climatic variation and demographic stochasticity. Data requirements of the model include life history characteristics, dispersal behavior, habitat affinities, as well as land use and landcover in geographic information systems databases. Future scenarios were ranked according to change in breeder abundance, saturation, and distribution, compared to baseline conditions. Sensitivity of simulation results to changes in model parameters was also examined. Simulated results suggest that while all four species modeled are likely to persist under present and future scenario conditions, two may be more at risk from future landscape change. Although the study species are all widespread generalists regarded as having a low conservation priority, they depend on wetlands and ponds, increasingly endangered habitats in agricultural landscapes. Broader conservation strategies in the region would ensure that these currently common organisms do not become the endangered species of the future.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
4.
Traffic has a considerable effect on population and community dynamics through the disruption and fragmentation of habitat
and traffic mortality. This paper deals with a systematic way to acquire knowledge about the probabilities of successful road
crossing by mammals and what characteristics affect this traversability. We derive a model from traffic flow theory to estimate
traffic mortality in mammals related to relevant road, traffic and species characteristics. The probability of successful
road crossing is determined by the pavement width of the road, traffic volume, traversing speed of the mammals and their body
length. We include the traversability model in a simple two-patch population model to explore the effects of these road, traffic
and species characteristics on population dynamics. Analysis of the models show that, for our parameter ranges, traffic volume
and traversing speed have the largest effect on traffic mortality. The population size is especially negatively affected when
roads have to be crossed during the daily movements. These predictions could be useful to determine the expected effectiveness
of mitigating measures relative to the current situation. Mitigating measures might alter the road and traffic characteristics.
The effects of these changes on traffic mortality and population dynamics could be analysed by calculating the number of traffic
victims before and after the mitigating measures.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Aida Raio Raffaele Peluso Xavier Nesme Astolfo Zoina 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(2):163-174
Agrobacteria were previously isolated from tumors developing on branches and aerial and hypogeous roots of weeping fig plants in Italy and in The Netherlands. A representative group of 48 strains was analyzed by PCR–RFLP of 16S and 16S + IGS ribosomal regions, PCR–RFLP of six Ti plasmid (pTi) regions and characterized for plasmid content. Two groups of agrobacteria were separated by cluster analysis of PCR–RFLP profiles of rrs gene: seventeen strains were similar to the new species Agrobacterium larrymoorei, while the remaining strains were included within the agrobacterium biovar 1 group. Sixteen different plasmid profiles from one to five plasmids were observed. In addition, 21 ribotypes and 20 pTi structures were arranged in many different combinations, showing that fig agrobacteria were characterized by a wide heterogeneity. A general lack of correlation between strain ribotypes and plasmid content was observed. 相似文献
6.
研究基于硬叶兜兰(Paphiopedilum micranthum)表型变异,通过相关性、主成分以及聚类等分析,对9个硬叶兜兰野生居群的22个表型性状指标进行了调查研究,探究硬叶兜兰居群间及居群内表型多样性,为硬叶兜兰资源的进一步保护和利用奠定基础。结果表明:硬叶兜兰在居群间具有丰富的表型多样性,居群内变异较少。平均表型分化系数(Vst)为64%,居群间表型分化高于居群内表型分化。22个性状的平均变异系数(CV)范围为9.52%~31.48%,9个居群平均变异系数为14.55%~18.51%,在表型间差异显著,在居群间差异不显著。主成分分析表明,花纵径等花部性状和株高等营养性状是硬叶兜兰变异的主要因素。Pearson相关性分析表明,株高、中萼片长和花瓣长与大部分性状都呈现显著正相关;冠幅、叶片数等营养性状与海拔存在显著正相关性,而花横径、花纵径等生殖性状与海拔存在显著或极显著负相关性。聚类分析结果表明,9个居群可以聚类为3个类群,和硬叶兜兰地理分布距离一致。 相似文献
7.
以温州市洞头区人工养殖羊栖菜和野生羊栖菜为研究样本,详细描述了羊栖菜成熟孢子体有性生殖,假根与侧生枝无性生殖的繁殖生物学特征和生活史流程。详细记录了羊栖菜卵、精子和受精卵的减数分裂和有丝分裂过程,假根、茎(主茎和侧生茎)、叶(气囊)和生殖托(雌托和雄托)等4类器官生长、发育和分化过程,胚、幼孢子体和成熟孢子体形态结构特征。在此基础上对现有羊栖菜繁殖生物学特征及生活史流程进行了补充和修正,增加了羊栖菜侧生枝无性生殖和羊栖菜幼孢子体期有性生殖的相关内容,并重新绘制了羊栖菜生活史流程图。该研究结果将为开展羊栖菜养殖生态学研究,深层次解析羊栖菜生殖节律、种群繁衍与环境关系奠定基础。 相似文献
8.
菘蓝秋季光合特性 总被引:2,自引:0,他引:2
比较了15个不同居群菘蓝的光合色素含量、净光合速率差异及6个重点不同居群菘蓝净光合速率对光强的响应特性、7个典型居群的光合日变化.结果表明,叶缘无齿四倍体居群、叶缘具齿四倍体居群、叶片被蜡居群、甘蓝型居群光合色素含量较高,山东居群、山西居群、四川居群光合色素含量较低;甘蓝型菘蓝净光合速率(Pn)最高为23.27 μmol/(m2·s).四倍体净光合速率均高于二倍体.7个重点居群中四倍体类型菘蓝的光饱和点和补偿点相对于二倍体类型都较高,其中四倍体最高分别为2 375.00 μmol/(m2·s)、536.61 μmol/(m2·s),二倍体最高为2 100.00 μmol/(m2·s)和505.16 μmol/(m2·s).菘蓝的光合日变化曲线为双峰曲线,有明显午休现象. 相似文献
9.
The common pistachio psylla, Agonoscena pistaciae, is a serious global pest menacing pistachio orchards. Considering the dangers of using excessive chemical pesticides, it seems that using natural insecticides such as diatomaceous earth is a suitable way to lower the residual amount of highly hazardous pesticides. In this study, the effects of diatomaceous earth with different additives, including dipotassium hydrogen phosphate, polyurethane glue as a wood adhesive, and potassium silicate, were investigated in several concentrations over two years in orchard conditions. Although all treatments showed significant effects, the most effective treatments were (diatomaceous earth+dipotassium hydrogen phosphate) and (diatomaceous earth+polyurethane glue). Therefore, the use of diatomaceous earth combined with the additive materials mentioned can potentially be a safe method for the integrated management of the common pistachio psylla. 相似文献
10.