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171.
172.
代内公平、国际贸易与可持续发展   总被引:5,自引:0,他引:5  
现阶段,不同国家或区域之间商品交流的种类与数量日益增大。由于发达国家与发展中国家在国际贸易中所扮演的角色不同,因此,在等经济价值交换规律的作用下,发展中国家的环境状况逐渐恶化。文章通过构建开放经济的物质流模型,探讨了物质交换行为对系统内部的自然环境的影响,并对1987年日本的物质流动状况进行了案例研究。分析表明,发达国家的经济发展水平在很大程度上依赖于其它国家内部自然资源与环境的支撑作用。  相似文献   
173.
试论世博会后昆明世博园的可持续发展   总被引:8,自引:0,他引:8  
’99昆明世博会后,如何实现世博园的可持续发展,成为学术界和世博园管理者不可回避、急需解决的现实问题。文章在论述世博园的性质、现状、面临的问题、影响世博园持续发展的因素的基础上,初步提出出世博园可持续发展的对策。  相似文献   
174.
175.
The purpose of this paper is to suggest how detailed single-pulse observations of slow radio pulsars may be utilized to construct an empirical model for their emission. It links the observational synthesis developed in a series of papers by Rankin in the 1980s and 90s to the more recent empirical feedback model of Wright (2003a) by regarding the entire pulsar magnetosphere as a non-steady, non-linear interactive system with a natural built-in delay. It is argued that the enhanced role of the outer gap in such a system indicates an evolutionary link to younger pulsars, in which this region is thought to be highly active, and that pulsar magnetospheres should no longer be seen as being driven by events on the neutron stars polar cap, but as having more in common with planetary magnetospheres and auroral phenomena.Received: 8 May 2003, Published online: 14 November 2003 Correspondence to: Joanna M. Rankin. On leave from: Physics Department, University of Vermont, Burlington, VT 05405, USA  相似文献   
176.
This study on the cytological changes of the body wall ,aspiratory intestine and crissal bursa in Urechis unicincuts by light microscope(LM) and transmission electron microscope(TEM) showed that the difference between the body wall and the natural environment rich in H2S was not obvious,that the wall color of the aspiratory intestine in H2S rich environment changed from normal semitransparency to dark brown.that its epithelia were disassembled and the electron density of its cytoplasm matrix was lower;and that in H2S rich environment many basoplhilic granules occurred in the epithelia of the crissal bursa.Granules with single membrane and myelinefingure were found with TEM.  相似文献   
177.
Rodríguez-Pacheco  J.  Sequeiros  J.  Del Peral  L.  Bronchalo  E.  Cid  C. 《Solar physics》1998,181(1):185-200
The most intense energetic particle (mainly proton) events in the energy range 36–1600 keV, during the years of maximum activity of solar cycle 21 (1978 to 1982), have been studied with regard to their spectra, temporal profiles, source location at the Sun, interplanetary plasma parameters and interplanetary magnetic field topology. In all the events, the particles were accelerated by the 'Diffusive Shock' acceleration mechanism, because all the events were 'long-duration events', shock-associated, and their spectra fitted to a power-law energetic particle spectrum dJ/dE E-\gamma with the exponent values ranging from 1.25 up to 1.94, with a mean value of 1.60 ± 0.06. We also show that the spectral indexes are related to the shock properties by a linear expression. The solar sources were located on a wide longitudinal belt extending from 50^ W up to 73^ E. Neither the spectral indexes nor the shock parameters present any dependence on the source location at the Sun. Finally, only one event showed the complete set of properties that characterize the presence of a magnetic cloud associated with the event.  相似文献   
178.
In a previous paper (Hou et al. in Celest Mech Dyn Astron 119:119–142, 2014a), the problem of dynamical symmetry between two Jupiter triangular libration points (TLPs) with Saturn’s perturbation in the present configuration of the two planets was studied. A small short-time scale spatial asymmetry exists but gradually disappears with the time going, so the planar stable regions around the two Jupiter TLPs should be dynamically symmetric from a longtime perspective. In this paper, the symmetry problem is studied when the two planets are in migration. Several mechanisms that can cause asymmetries are discussed. Studies show that three important ones are the large short-time scale spatial asymmetry when Jupiter and Saturn are in resonance, the changing orbits of Jupiter and Saturn in the planet migration process, and the chaotic nature of Trojan orbits during the planet migration process. Their joint effects can cause an observable difference to the two Jupiter Trojan swarms. The thermal Yarkovsky effect is also found to be able to cause dynamical differences to the two TLPs, but generally they are too small to be practically observed.  相似文献   
179.
Tsunami education activities, materials, and programs are recognized by the National Tsunami Hazard Mitigation Program (NTHMP) as the essential tool for near-source tsunami mitigation. Prior to the NTHMP, there were no state tsunami education programs outside of Hawaii and few earthquake education materials included tsunami hazards. In the first year of the NTHMP, a Strategic Plan was developed providing the framework for mitigation projects in the program. The Strategic Plan identifies education as the first of five mitigation strategic planning areas and targets a number of user groups, including schools, businesses, tourists, seasonal workers, planners, government officials, and the general public. In the 6 years of the NTHMP tsunami education programs have been developed in all five Pacific States and include print, electronic and video/film products, curriculum, signage, fairs and workshops, and public service announcements. Multi-state education projects supported by the NTHMP include TsuInfo, a bi-monthly newsletter, and Surviving a Tsunami, a booklet illustrating lessons from the 1960 Chilean tsunami. An additional education component is provided by the Public Affairs Working Group (PAWG) that promotes media coverage of tsunamis and the NTHMP. Assessment surveys conducted in Oregon, Washington, and Northern California show an increase in tsunami awareness and recognition of tsunami hazards among the general population since the NTHMP inception.  相似文献   
180.
Following the major contributions of Wegener and Argand (Part 1), it was the work of synthesis carried out by R. Staub that represented the major contribution Alpine geology made with respect to that heritage. The research work of young scientists (Gagnebin, Juvet, Wavre, Leuba) who had been influenced by Argand was of lesser importance. Ampferer’s ground breaking contribution, coming along with illuminating graphic illustrations, was all but ignored. Although remaining fairly popular, the theory of continental drift found itself under the heavy fire of criticism from influential geologists in the USA and in Europe. In order to test the validity of the idea, C.E. Wegmann suggested linking geological field work with oceanographic research. He showed that the trajectories of drifting had to be conceived as following the small circles of the sphere. With regard to Alpine geologists of the time, they were renowned for the high quality of their geological mapping. This remained the very special activity in which they excelled, but they focused on topics that were becoming narrower and narrower, and increasingly specialised. The new avenues for research that Holmes and Hess opened up had but little impact on Alpine geologists. In fact, they apparently remained unaware of a note by Holmes written in German and published in a Swiss journal. On the eve of the Second World War, the meeting of the Geologische Vereinigung devoted to the origin of the Atlantic Ocean confirmed that continental drift was being seriously challenged, although a few papers pointed to new developments, e.g. that in Iceland extensional tectonics had been active for the last 5,000 years. Most Alpine geologists were either highly critical of the theory of plate tectonic when it arrived or expressed serious reservations towards the idea. Of the exceptions, first Laubscher and then Bernoulli showed very clearly how important the new theory could be for understanding the evolution of Alpine orogeny. Continental drift and plate tectonics were very much the product of the creative imagination of human minds. Whereas Wegener used a broad range of confirmed results, plate tectonics sprang out of the new research being carried out in the domain of oceans. Graphic illustration was one of the favourite vehicles used to put across these new perspectives. Sometimes their impact remained alive long after their author had withdrawn his backing for the idea (as was the case for Argand’s “embryonic tectonics”); sometimes, even in spite of their very high standard, they were just ignored (which was the case for Ampferer).  相似文献   
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