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61.
WILD T_3经纬仪竖盘光路检修工艺 总被引:1,自引:0,他引:1
由于T_3仪器的竖盘光路采用与T_2不同的结构,因此竖盘光路的检修具有其特殊性。本文着重介绍竖盘的拆卸步骤,同时介绍一种简单的竖盘光路调整附加设备,从而简化了光路的调整。 相似文献
62.
本刊在1983年第5期上刊载的“EOT2000的四轴问题”一文对于EOT的四轴之间关系作了初步的探讨,为EOT的光学调整作了准备,本文将就结构原理及工艺上对EOT的光学调整进行论述。 相似文献
63.
Fast clogging problem of open check dams and a new type suggestion:curved footed type open check dam
Driftwood is one of the important physical components in mountainous rivers which causes severe hazards due to the clogging of bridges, culverts,and narrow sections during floods. Therefore, the understanding of driftwood dynamics and mitigation measures are crucial for managing wood in rivers.Open check dams are the most commonly used engineering measure for preventing driftwood from reaching downstream areas. Nevertheless, these open check dams frequently lose their sediment transport function... 相似文献
64.
GALVáN-CISNEROS Carlos M. VILLA Pedro M. COELHO Alex J.P. CAMPOS Prímula V. MEIRA-NETO Jo?o A.A. 《山地科学学报》2023,(2):285-298
Elucidating how multiple factors affect biodiversity and plant community assembly is a central issue in ecology, especially in vulnerable ecosystems such as tropical mountains. These studies are more relevant in global warming scenarios that induce the upward displacement of plant species towards reduced habitats and hostile environments in tropical mountains. This study aimed to analyze how altitude affects taxonomic and phylogenetic diversity in plant communities of tropical mountains. Thus, w... 相似文献
65.
Philippe Zarka Di Li Jean-Mathias Grie?meier Laurent Lamy Julien N.Girard Sbastien L.G.Hess T.Joseph W.Lazio Gregg Hallinan 《天文和天体物理学研究(英文版)》2019,(2)
We briefly review the various proposed scenarios that may lead to nonthermal radio emissions from exoplanetary systems(planetary magnetospheres, magnetosphere-ionosphere and magnetospheresatellite coupling, and star-planet interactions), and the physical information that can be drawn from their detection. The latter scenario is especially favorable to the production of radio emission above 70 MHz. We summarize the results of past and recent radio searches, and then discuss FAST characteristics and observation strategy, including synergies. We emphasize the importance of polarization measurements and a high duty-cycle for the very weak targets that radio-exoplanets prove to be. 相似文献
66.
This paper presents the changes of landscape structure in the Dem?novská Valley which ranks among the most valuable protected areas of Slovakia. The area was selected on the basis of changes associated with the rapidly growing tourism industry and the rise of an important destination in the center of Low Tatras National Park, Slovakia. To document any changes, we visually interpreted data from aerial and satellite images in three periods(1949, 2007 and 2013) and for predicting future changes we used land use planning documentation. Interpreted data were analyzed using overlay analysis and landscape metrics. Results showed extensive changes in the landscape structure mainly connected with the development of tourism infrastructure. We also identified long-term changes whose causes stem from the transformation of society and forest management in the past. The dynamics and extent of these changes may increase in the future. We propose to stop future development of ski slopes and expansion of related infrastructure, to focus on sustainability and environmentally friendly operation of the existing ski resort and to invest a substantial portion of profits to support projects aimed to preserve surrounding lands and wildlife. 相似文献
67.
HRN?IAROVá Tatiana KENDERESSY Pavol ?PULEROVá Jana VLACHOVI?OVá Miriam PISCOVá Veronika DOBROVODSKá Marta 《山地科学学报》2018,15(8):1615-1632
This study presents a methodology for assessment of the condition of hiking trails (HTs) and their impact zones in the central part of the Low Tatra mountain range, based on comparison of two complex data sets gathered in 33 years apart. The first field investigation was performed in 1980 and 1981, and the second in 2013 and 2014. The main goal was to perform a landscape typology in order to assess the susceptibility of landscape complexes to occurrence of anthropogenic and natural destruction processes and to assess the condition and prospects of HTs and their impacts on the adjacent alpine environment. Landscape complexes were characterised by selected abiotic, biotic and technical parameters of HTs and their impact zones. Due to the high variability of these parameters over the length of the HTs, we had to decide on how to map them. This was done using a square grid with 100 m-sized cells. For each cell with HT, the parameters were assigned the typical value within that cell. In total, 26.3 km of HT were studied, stretching over 266 grid cells. On comparison of the two data sets, it was seen that, 64% (171 grid cells) display a generally positive condition, with 54% (143 grid cells) even exhibiting significant improvement or continuously positive state of their condition. 36% (95 grid cells) were in bad condition, including 3% (9 grid cells) whose state had deteriorated, and 2% (6 grid cells) whose state had significantly deteriorated, in the time between the two assessments. 相似文献
68.
急性胸痛是一个重要的公共卫生问题,它可以造成高昂的医疗成本支出,并显著影响人民健康。急性冠脉综合征是急性胸痛血管性病变的主要原因,影像学检查可以快速、有效地对血管性病变进行排查诊断。本文主要就CT冠状动脉造影在急性胸痛中的临床实践做一综述。 相似文献
69.
Aleksandra ?AJNOVI? Nenad GRBA Franz NEUBAUER Milica KA?ANIN-GRUBIN Ksenija STOJANOVI? Nenad PETKOVI? Branimir JOVAN?I?EVI? 《《地质学报》英文版》2020,94(5):1591-1618
A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin, Bosnia and Herzegovina. A total of 46 samples collected from two boreholes, Pot 1 (depth of 193 m) and Pot 3 (depth of 344 m), showed that element abundances like boron (B), lithium (Li), strontium (Sr), uranium (U), chromium (Cr), nickel (Ni), magnesium (Mg), sodium (Na) and calcium (Ca) are much higher than average than in the upper continental crust (UCC). Chemical composition indicates at least two sources: (i) Mesozoic ophiolites occurring in the north of the investigated area, and (ii) dacito-andesitic pyroclastics (Mesozoic to Cenozoic). Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake, which formed during a warm climatic period, probably during the Miocene Climatic Optimum. A brief episode of humid climate conditions resulted in the basin filling-up and deposition of felsic sediments enriched in thorium (Th). Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter (OM). The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data. Conversely, the molecular distribution of n-alkanes as reliable climatic and δ-MTTC as paleosalinity indicators do not support this conclusion. 相似文献
70.