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341.
One of the main problems in celestial mechanics is the management of long developments in Fourier or Poisson series used to describe the perturbed motion in the planetary system.In this work we shall develop a software package that is suitable for managing these objects. This package includes algorithms to obtain the inverse of the distance based on an iterative method, a set of integration algorithms according to several sets of temporal variables.This paper contains a comparative study on the use of the true, eccentric, and elliptic anomalies in semi-analytical methods on celestial mechanics. 相似文献
342.
为推断南四湖湖鲚种群来源,采用线粒体控制区(D-loop)基因序列测定技术,对3个不同水域湖鲚(Coilia ectenes taihuensis)种群的遗传结构特征及其变异进行研究,并分析它们之间的系统发育关系.结果表明3个不同湖鲚种群的平均单倍型多样性和核苷酸多样性分别为0.9646和0.0097,除3个单倍型共享外,不同地理单元中具有较高的单倍型多样性.AMOVA和成对Fst值分析均表明,不同湖泊群体间未发现明显的遗传分化,各地理单元中的单倍型相互散布在不同的种群中.系统发育分析结果显示,不同湖泊湖鲚种群的单倍型形成3个分支,但每一地理群体没有显示出明显的地理位置与单倍型间的对应关系.结合南四湖历史资料和当前渔业监测结果,推测湖鲚为2002年实施长江向南四湖应急补水时洪泽湖湖鲚迁移扩散进而在南四湖建群的. 相似文献
343.
344.
The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events.The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention.However,in China,the precipita- tion data are measured by weather stations(WS)of China Meteorological Administration and hydrological rain gauges(RG)of national and local hydrology bureau.The WS data usually have long record with fewer stations,while the RG data usually hav... 相似文献
345.
垂测电离图反演对研究电离层结构及运动、电离层波传播、空间气象应用等具有重要意义,一直以来受到十分广泛的重视.F_1层未充分发展的回波描迹是垂测电离图中观测到的最多的一种情况,此时垂测描迹上表现为F_1层到F_2层的平滑过渡,而不是F_1层充分发展时出现的尖点,然而现有电离层模型以及反演算法更多的是针对F_1层充分发展情况,即模型剖面在F_1层峰高处近似为抛物形状,此处电子浓度剖面梯度为无穷大,这不符合F_1层未充分发展时的剖面形态,即F_1层剖面未到达抛物顶点处就已经达到该层电子浓度的最大值然后到达F_2层,剖面梯度为一个有限的数值.因此,本文针对垂直探测中经常出现的F_1层未充分发展情况,引入F_1层模型设定临频这一参数,建立了F_1层未充分发展时的基于移位切比雪夫多项式的电离层模型,并从电离层剖面的光滑性考虑,在所建模型的基础上,提出了约束优化F_1层参数、F_2层参数的垂测电离图反演方法.然后,通过仿真分析,从理论上验证了所建电离层模型和反演算法的合理性,并通过反演电子浓度剖面合成的垂测、斜测描迹与实测数据的对比,对反演算法的有效性进行了进一步的试验验证. 相似文献
346.
WANG Guangcai TAO Shu Department of Urban Environment Sciences Peking University Beijing SHEN Zhaoli ZHONG Zuoshen Department of Environment Sciences China University of Geosciences Beijing 《《地质学报》英文版》2000,74(2):394-399
The WATEQ4F-based "multiple step method", or the method of running WATEQ4F repeatedly, was used to evaluate the error propagation in computations of water-mineral interactions under the circumstances of constant and varied temperatures due to the uncertainties of input variables. The results show the following: the errors of water chemistry analysis can strongly affect the modelling results of water-mineral reactions; different input variables (errors) have different effects on the saturation indices (S.I.) of different minerals; in many cases, the S.I. errors of minerals change with temperatures. 相似文献
347.
The chorophyll fluorescence ratio F685/F735 in vivo can be a useful indicator for stress detection inhigher plants and seaweed. DCMU [3 - (3, 4 - dichlorophenyl ) - 1, 1 - dimethylurea] treatment influencesthis ratio. Th effects of DCMU on F685/F735 of marine red, brown and green algae under excitationlight of different wavelengths were investigted. In the brown algae, Laminaria japonica and Undariapinnatifida,DCMU did not increase this ratio under blue light excitation but increased the ratio slightlyunder excitation by green light. For the red algea, Halymenia sinensis, DCMU increased the ratiomarkedly under both blue and green ligh excitation. The percentage increase could reach 50% (undergreen light excitation) and was due to unequal enhancement at the two emission maxima by DCMU. Afraction of chlorophyll which contributed to fluorescence in the 735 nm region was less sensitive toDCMU and was likely from photosystem I of red algae. In the green alga, Ulva pertusa, DCMU causeda slight increase in F685 相似文献
348.
《The Professional geographer》1985,37(3):357-389
Book Reviewed in this article: Redundant Spaces in Cities and Regions? Studies in Industrial Decline and Social Change . J. Anderson, S. Duncan and R. Hudson. eds. The Social Consequences and Challenges of New Agricultural Technologies . Gigi M. Berardi and Charles C. Geisler, eds. Determinants of Fertility in Developing Countries, Vol. I, Supply and Demand for Children . Rodolfo A. Bultao and Ronald D. Lee, eds. Computer Mapping: Progress in the‘80s . James R. Carter. Washington: Colonial Africa . A. J. Christopher. Geography of the Soviet Union . J. P. Cole. Chicago Mapmakers, Essays on the Rise of the City's Map Trade . Michael P. Conzen, ed. Changes in the Land: Indians, Colonists and the Ecology of New England . William Cronon. Mizner's Florida: American Resort Architecture . Donald W. Curl. Geographical Studies on the Soviet Union: Essays in Honor of Chauncy D. Harris . George Demko and Roland J. Fuchs, eds. Fluvial Hydrology . S. Lawrence Dingman. Pueblo Indian Water Rights: Struggle For a Precious Resource . Charles T. DuMars, Marilyn O'Leary and Albert E. Utton. Women in the Cities of Asia: Migration and Urban Adaptation . James T. Fawcett, Siew-Ean Khoo, and Peter C. Smith, eds. America's National Parks and Their Keepers . Ronald A. Foresta. Neighborhood Revitalization and the Postindustrial City . Dennis E. Gale. China in Canada: A Dialogue on Resources and Development . R. Louis Gentilcore, ed. China: The 80s Era . Norton Ginsburg and Bernard A. Lalor, eds. Boulder, CO: Global Resources: Challenges of Interdependence . Martin I. Glassner, ed. River Networks . Texas: A Geography . Terry G. Jordan with John L. Bean, Jr. and William M. Holmes. The American Frontier: An Archaeological Study of Settlement Pattern and Process . Kenneth E. Lewis. Water Resources, Geography and Law . Olen Paul Matthews. A Field Guide to American Houses . Virginia and Lee McAlester. Population: Patterns, Dynamics, and Prospects . James L. Newman and Gordon E. Matzke. Wood, Brick, and Stone, The North American Settlement Landscape, Vol. 1: Houses . Allen G. Noble. Historical Analysis in Geography . William Norton. The Displaced Worker and Community Response: Case Study of Portsmouth, Scioto County, Ohio . H. Milton Patton and Janet W. Patton. Disaster Management: Warning Response and Community Relocation . Ronald W. Perry and Alvin H. Muskatel. The Anthropology of Space: Explorations into the Natural Philosophy and Semantics of the Navajo . Rik Pinxten, Ingrid van Dooren, and Frank Harvey. What STYLE Is It? A Guide To American Architecture . John C. Poppeliers, S. Allen Chambers, Jr., and Nancy B. Schwartz. Appalachia: A Regional Geography—Land, People and Development . Karl Raitz and Richard Ulack. An Introduction to Urban Geography . John R. Short. Ford, A Village in the West Highlands of Scotland: A Case Study of Repopulation and Social Change in a Small Community . John B. Stephenson. Income and Jobs: USA Diagnosing the Reality . George Sternlieb and James W. Hughes. Weather and Climate of the Antarctic . W. Schwerdtfeger. History and Ecology: Studies of the Grassland, James C. Malin . Robert P. Swierenga, ed. Optimal Control of Spatial Systems . K. C. Tan and R. J. Bennett. Social Science and Revolutions . Stan Taylor. The Global Textile Industry . Brian Toyne, Jeffrey S. Arpan, David A. Ricks, Terence A. Shimp and Andy Barnett. Integrated Water Development: Water Use and Conservation Practice in Western Colorado . James L. Wescoat, Jr. Proceedings of the First International Symposium on Maps and Graphics for the Visually Handicapped . Joseph W. Wiedel, ed. 相似文献
349.
王小明 《地球科学与环境学报》1989,(2)
本文从电磁场基本方程出发引入标量函数F,讨论了磁偶极源激发下导电半空间瞬变电磁场的传播规律,从理论上证明了“烟圈”效应的存在性,得到了一些有益的结论。 相似文献
350.