TOWARD ESTABLISHING THE CONCEPT OF PHYSICAL URBAN AREA IN CHINA

I.IntroduchollWiulegeOgraphystudiestheterritoria1systemsabouttherelationsbforeenhumanbeingSandthenature[I4],urbanmpaphyfocusesspecificallyonthespatialoopltizationandprocessofurbanterritory,anditsinteraCtionwiti1Otherterritorialsystems.Usually,wedoresearch…     

The almost constant-speed two-body problem with resistance

The almost constant-speed motion of a mass acted upon by a Newtonian attraction and a resisting force is treated. The equation of orbit is derived for a specific type of resistance which covers the familiar case of Danby's drag(=r ^–2) whilst the vector invariants are obtained by direct operation on the vector form of the equation of motion.     

Seasonal variation of atmospheric dimethylsulfide at Amsterdam Island in the southern Indian Ocean

Daily measurements of atmospheric concentrations of dimethylsulfide (DMS) were carried out for two years in a marine site at remote area: the Amsterdam Island (37°50S–77°31E) located in the southern Indian Ocean. DMS concentrations were also measured in seawater. A seasonal variation is observed for both DMS in the atmosphere and in the sea-surface. The monthly averages of DMS concentrations in the surface coastal seawater and in the atmosphere ranged, respectively, from 0.3 to 2.0 nmol l^-1 and from 1.4 to 11.3 nmol m^-3 (34 to 274 pptv), with the highest values in summer. The monthly variation of sea-to-air flux of DMS from the southern Indian Ocean ranges from 0.7 to 4.4 mol m^-2 d^-1. A factor of 2.3 is observed between summer and winter with mean DMS fluxes of 3.0 and 1.3 mol m^-2 d^-1, respectively.     

城市生态景观的构建研究

运用景观生态学、旅游规划学、城市规划理论来认识城市生态景观并分析其具有和谐性、整体性、多样性、畅达性、安全性、可持续性等特点，阐述以人为本、尊重地域和历史文化、生态、满足市民休闲与游憩需求等构建原则，认为重点抓好自然廊道和斑块等自然生态景观的建设、重视人工廊道和城市建筑密集区的景观效果、完善城市生态景观的空间结构体系等是构建和谐城市生态景观的重要途径。     

西安南郊丰水年秋季土壤水分研究

 通过对西安南郊丰水年秋季土壤含水量的测定，研究了地下0~6 m之间土壤含水量的变化与土壤干层的恢复问题。研究结果表明，丰水年西安南郊人工林下2~3 m的土壤含水量在20％左右，远远高于正常年份的土壤含水量，而且大于表层和深层的土壤含水量。分析得出，土壤干层发育较弱的地区在降水丰富的年份可以得到一定程度的恢复；西安地区基本适合进行人工造林；通过人工措施，增强降水入渗和土壤含水量，对树木成活和长期的生长应当具有明显的作用。     

河南省城区经济发展研究

文章首先介绍了城区经济的概念、特征和类型，在分析河南省城区经济发展状况的基础上，论述了该省城区经济的地位和作用，提出了河南省城区经济发展构想以及对策措施。     

单频GPS接收机天线扼流圈的研制与测试

讨论了多路径效应对GPS共视比对的影响及削弱其影响的方法。结合综合原子时项目的需求,研制了适用于单频GPS接收机的天线扼流圈,并用零基线比对方法进行了测试。结果表明,研制的天线扼流圈可有效地削弱多路径效应的影响,并可明显地改善单频GPS接收机NTSCGPS-1的抗干扰能力。     

Mais comment s'écoule donc un glacier ? Aperçu historique

Ice and snow have often helped physicists understand the world. On the contrary it has taken them a very long time to understand the flow of the glaciers. Naturalists only began to take an interest in glaciers at the beginning of the 19th century during the last phase of glacier advances. When the glacier flow from the upslope direction became obvious, it was then necessary to understand how it flowed. It was only in 1840, the year of the Antarctica ice sheet discovery by Dumont d'Urville, that two books laid the basis for the future field of glaciology: one by Agassiz on the ice age and glaciers, the other one by canon Rendu on glacier theory. During the 19th century, ice flow theories, adopted by most of the leading scientists, were based on melting/refreezing processes. Even though the word ‘fluid’ was first used in 1773 to describe ice, more the 130 years would have to go by before the laws of fluid mechanics were applied to ice. Even now, the parameter of Glen's law, which is used by glaciologists to model ice deformation, can take a very wide range of values, so that no unique ice flow law has yet been defined. To cite this article: F. Rémy, L. Testut, C. R. Geoscience 338 (2006).     

中国城市群发育现状分析

伴随着市场经济和工业化、城市化的推进。中国城市群正在逐渐形成并快速发展。文章在对城市群概念进行讨论的基础上，选取2002年各项经济指标，从总体经济实力、人均发展水平、中心城市与县域经济发展状况诸方面，对中国各大城市群的发育状况与存在问题进行了综合对比分析，强调国家应采取以城市群为依托的“多极联动”区域发展战略。     

三江平原旱田耕作对湿地土壤理化性质的累积影响初探

在中国科学院三江平原湿地生态试验站综合实验场,对不同耕作年限的湿地土壤(0~20 cm)进行环境累积效应分析。结果表明,随着开垦时间的增加,土壤的理化性质发生渐变,物理性质方面,土壤容重和比重逐渐增大,而孔隙度和田间持水量逐年减少;化学性质方面,土壤pH值随开垦时间的增加而增加,有机质和其他养分则随开垦时间的增加而逐年降低。弃耕后土壤性质有所恢复。土壤性质在开垦初期变化较明显,而后逐渐变缓。