英语教学网站辅助大学英语教学的实践与反思     

李林森  王娟 《成都信息工程学院学报》2007,22(5):654-657

详细探讨了英语教学网站在大学英语教学中的辅助作用.并在自主学习模式这一教学理念的指导下,介绍了英语教学网站的实现过程和管理使用方式,同时论证了在大学英语教学中应用教学网站所具有的独特优势以及注意事项.  相似文献   

Recent climate trends on the northern slopes of the Tianshan Mountains, Xinjiang, China     

Hongfeng Zhang  Zhiyun Ouyang  Hua Zheng  Xiaoke Wang 《山地科学学报》2009,6(3):255-265

In arid regions, mountains fulfill important ecological and economic functions for the surrounding lowlands. In the scenario of global warming, mountain ecosystems change rapidly, especially in the arid region of northwestern China. This paper provides an assessment of the changes in temperature and precipitation in the historical records of climate on the northern slopes of the eastern Tianshan Mountains. A Mann-Kendall nonparametric trend and Sen＇s tests are employed to analyze the interannual changes and innerannual variability in temperature and precipitatiofi in the regions of low to high altitude. The present study finds that the largest increases in annual temperature are observed at stations in the low altitude regions. The significant increasing trends in temperature tend to occur mainly in late winter and early spring at stations from middle to high altitude, but in summer and autumn at stations of low altitudes. The increasing trends in annual precipitation are found from the middle to high altitude areas, but decreasing trends are found in the low altitude areas. The significant increasing trends in precipitation occur mostly in winter and earlier spring at stations from the middle to high altitudes, while the increasing and decreasing trend coexists at stations of low altitude with most of the significant trend changes occurring in March, June and August.  相似文献   

Washington photometry of open cluster giants: two moderately metal-poor anticentre clusters     

M. Celeste Parisi  Juan J. Clariá  rés E. Piatti  Douglas Geisler 《Monthly notices of the Royal Astronomical Society》2005,363(4):1247-1256

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柴达木盆地矿产开发中环境地质问题及防治对策   总被引：2，自引：2，他引：0  

谢娟  张骏  杨军  孙亚乔  成玉祥  李毅 《地球科学与环境学报》2005,27(4):79-82

在柴达木盆地环境现状实际调查基础上，根据调查资料论述了柴达木盆地地区矿产开发引起的主要环境地质问题及其危害。分析了引起土地沙化．土壤盐渍化，水土污染，崩塌地面塌陷，生态环境恶化产生原因，并在地质环境保护方面提出合理化建议，以期为西部开发过程环境保护提供依据。  相似文献   

Size increment of jumbo flying squid Dosidicus gigas mature females in Peruvian waters, 1989–2004     

Juan Argüelles  Ricardo Tafur  Anatolio Taipe  Piero Villegas  Friedeman Keyl  Noel Dominguez  Martín Salazar 《Progress in Oceanography》2008,79(2-4):308

Changes in population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters were studied based on size-at-maturity from 1989 to 2004. From 1989 to 1999, mature squid belonging to the medium-sized group prevailed, but from 2001 on, mature squids were larger. This change is not related to the changes in sea surface temperature and we hypothesized that it was caused by the population increase of mesopelagic fishes as prey.  相似文献   

Processes affecting the hydraulic stability of coastal revetments made of geotextile sand containers     

Juan Recio  Hocine Oumeraci 《Coastal Engineering》2009

Softer and flexible protection alternatives, such as structures made of geotextile sand containers (GSC) are often used instead of hard coastal structures made of concrete or rubble material.  相似文献   

Defining ecological indicators of trawling disturbance when everywhere that can be fished is fished: A Mediterranean case study     

S. de Juan  M. Demestre  S. Thrush 《Marine Policy》2009

Selecting indicators of the response of the benthic community to fishing effort restrictions is important for testing the efficacy of management actions that seek to minimise ecosystem degradation. Components of epifaunal communities are sensitive to trawling, and concordant measurements of trawling effort can be used to establish a link between response and impact variables. Trawling effort on Mediterranean fishing grounds can be assessed, but the lack of data from communities inhabiting these areas makes establishing the response–impact relationship difficult. This study addresses this challenge by investigating benthic communities from the NW Mediterranean subjected to a gradient of fishing effort, and confirms that indicators based on functional components of epibenthos can be a useful tool to describe the response of communities to disturbance across habitat types.  相似文献   

Artisanal fishers' perceptions regarding coastal co-management policies in Chile and their potentials to scale-up marine biodiversity conservation     

Stefan Gelcich  Natalio Godoy  Juan C. Castilla 《Ocean & Coastal Management》2009,52(8):424-432

No-take Marine Protected Areas (Nt-MPAs) constitute an indispensable tool for biodiversity conservation. Nevertheless, there are other instruments such as marine coastal co-management policy frameworks which may be also considered as tools for conservation or as ancillary conservation instruments. Using focus groups, semi-structured interviews and survey questionnaires we analysed small-scale artisanal fishers' perceptions towards a coastal co-management regime in Chile and the potential to generate capacities and a social setting to scale-up marine conservation. Empirical evidence from the study shows artisanal fishers have indeed been empowered through the coastal co-management experience; however, there exist heterogeneity in their willingness to participate in the creation of Nt-MPAs, mainly determined by occupational mobility. Chilean artisanal fishers strongly support a bottom-up process in the conservation of marine biodiversity, though the need for top-down steering and guidance is also stressed, especially regarding enforcement.  相似文献   

Orbital structure of self-consistent triaxial stellar systems     

Roberto O. Aquilano  Juan C. Muzzio  Hugo D. Navone  Alejandra F. Zorzi 《Celestial Mechanics and Dynamical Astronomy》2007,99(4):307-324

We used a multipolar code to create, through the dissipationless collapses of systems of 1,000,000 particles, three self-consistent triaxial stellar systems with axial ratios corresponding to those of E4, E5 and E6 galaxies. The E5 and E6 models have small, but significant, rotational velocities although their total angular momenta are zero, that is, they exhibit figure rotation; the rotational velocity decreases with decreasing flattening of the models and for the E4 model it is essentially zero. Except for minor changes, probably caused by unavoidable relaxation effects, the systems are highly stable. The potential of each system was subsequently approximated with interpolating formulae yielding smooth potentials, stationary for the non-rotating model and stationary in the rotating frame for the rotating ones. The Lyapunov exponents could then be computed for randomly selected samples of the bodies that make up the different systems, allowing the recognition of regular and partially and fully chaotic orbits. Finally, the regular orbits were Fourier analyzed and classified using their locations on the frequency map. As it could be expected, the percentages of chaotic orbits increase with the flattening of the system. As one goes from E6 through E4, the fraction of partially chaotic orbits relative to that of fully chaotic ones increases, with the former surpassing the latter in model E4; the likely cause of this behavior is that triaxiality diminishes from E6 through E4, the latter system being almost axially symmetric. We especulate that some of the partially chaotic orbits may obey a global integral akin to the long axis component of angular momentum. Our results show that is perfectly possible to have highly stable triaxial models with large fractions of chaotic orbits, but such systems cannot have constant axial ratios from center to border: a slightly flattened reservoir of highly chaotic orbits seems to be mandatory for those systems.  相似文献   

Talc-beating serpentinized peridotites from the southern Mariana forearc： implications for aseismic character within subduction zones     

汪小妹  曾志刚  刘长华  陈俊兵  殷学博  王晓媛  陈代庚  张国良  陈帅  李康  欧阳荷根 《中国海洋湖沼学报》2009,27(3):667-673

The serpentinized peridotites overlying the subducted zones in the Izu-Bonin-Mariana (IBM) arc system have been interpret as the cause of the low-velocity layer identified beneath the IBM froearc, in turn few earthquakes occurred along the plate boundary. Chrysotile, which is a low temperature and highly hydrated phase of serpentine with low frictional strength, has been suggested as the low velocity material in the serpentinized peridotites, besides, brucite is inferred to be likely conducive to stable sliding. However, such idea encounters challenging in our serpentinized peridotites from the southern Mariana forearc, which absent both the above minerals. The presence of talc, which characterized by its weak, low-friction and inherently stable sliding behavior, provides new clue. Here we report the occurrence of talc in serpentinized peridotites collected from the landward trench slope of the southern Mariana forearc. We infer that talc is mainly forming as a result of the reaction of serpentine minerals with silica-saturated fluids released from the subducting slab, and talc also occurs as talc veins sometimes. Due to its unique physical properties, talc may therefore play a significant role in aseismic slip in the IBM subduction zone.

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