冲绳海槽二万年以来沉积物中烯酮化合物与古温度的研究

应用烯酮化合物的不饱和比值U₃₇k计算得出冲绳海槽海水古温度波动幅度在15.9～26.2℃之间,平均为22.9℃,和冬季实测表层水温22.0℃相接近,探讨了U₃₇k值在冲绳海槽指示的古海水温度和季节有关,主要反映在冬季。     

加强地方地震工作的重要性

结合龙岩市防震减灾工作的实际,分析地方地震部门所具有的社会职能,并从宏观职能、微观职能、联合职能、管理职能4个方面进行探讨,说明地方地震部门应正确行使职能,提出加强地方地震工作的重要性。     

基于次序权重平均法的购房选择地理空间多准则决策

居民的购房选择是对居住区位进行选择的复杂过程,其实质是居住空间的个人行为决策问题。在调研工作基础上,论文分析并构建了居民购房选择决策评价指标体系,以北京市为实验区应用GIS制作居住适宜性基础准则(指标)地图。研究一种可以适应购房者差异化的购房需求与偏好的购房地理空间决策方法,通过层次分析法提取购房个体的偏好信息,确定个人准则权重。采用次序加权平均算法(Ordered Weighted Averaging,OWA)针对个人准则权重计算个人次序权重,结合二者对居住适宜性基础准则地图进行集结,计算多种决策风险下的个人居住适宜性准则地图,对意向住房进行分析评价,动态生成相应决策方案,为购房者提供购房决策支持,减少主观意愿与客观环境带来的决策风险。最后通过一个实验对以上方法进行实现。     

Establishing the thermal threshold of the tropical mussel Perna viridis in the face of global warming

With increasing recognition that maximum oxygen demand is the unifying limit in tolerance, the first line of thermal sensitivity is, as a corollary, due to capacity limitations at a high level of organisational complexity before individual, molecular or membrane functions become disturbed. In this study the tropical mussel Perna viridis were subjected to temperature change of 0.4 °C per hour from ambient to 8–36 °C. By comparing thermal mortality against biochemical indices (hsp70, gluthathione), physiological indices (glycogen, FRAP, NRRT) and behavioural indices (clearance rate), a hierarchy of thermal tolerance was therein elucidated, ranging from systemic to cellular to molecular levels. Generally, while biochemical indices indicated a stress signal much earlier than the more integrated behavioural indices, failure of the latter (indicating a tolerance limit and transition to pejus state) occurred much earlier than the other indices tending towards thermal extremities at both ends of the thermal spectrum.     

Present-day crustal movement and tectonic deformation in China continent

Velocity field of China continent constrained by Global Positioning System (GPS) reveals both continuous and block-like styles of deformation. Continuous deformation commonly characterizes actively deforming mountain ranges such as the Tianshan Mountain, Qilian Mountain, and Tibet. The block-like movement often represents deformation in the tectonically stable regions such as Ordos, South China and Tarim blocks. GPS measurements indicate 5.1±2.5 mm/a left-lateral strike-slip rate along the Altun fault. Eastward convergence along the Longmenshan fault is less than 6.7 ± 3.0 mm/a. South China moves 11–14 mm/a eastward compared with the stable Eurasia. These low slip rates do not imply rapid eastward extrusion of China continent predicted by the model of “continental extrusion”. It appears that “crustal thickening” model more properly describes both continuous and block-like styles of deformation in China continent.     

Environmental degradation in the Hexi Corridor region of China over the last 50 years and comprehensive mitigation and rehabilitation strategies

The regional hydrology and ecosystems of the Hexi Corridor region of northwestern China have changed over the last half century under the driving force of intense human activity and regional climate changes. Streamflow issuing from mountains in the eastern section of the Corridor by way of the Shiyang River has decreased significantly. Annual mountain outflow from the Heihe and Shule Rivers in the central and western portions of the Corridor, respectively, have tended to increase; however, their downstream discharge has decreased sharply. These lower reaches clearly display anthropogenic hydrological features. Water salinization and pollution have worsened. Presently, up to 208 km of river courses exhibit the poorest water pollution grades of IV and V. Overall, the forested area in the south Qilian Mountain region has decreased by 16.5% in the last 50 years, but has recently begun to show a gradual increase. However, natural desert forests in the northern portion of the Hexi Corridor have continued in a trend of degradation and rapid disappearance, with 3431 km² lost in Minqin and Ejin counties alone. Grasslands have been progressively degraded and their area decreased such that grasslands in the Hexi Corridor region only cover 46.86% of their former area. Desertification has been exacerbated and the grasslands' stock capacity reduced. In the Hexi Corridor region desertification has proceeded swiftly over the last 50 years, reaching, in the early 1980s, a maximum annual rate of 2.15% of total initial grassland area. However, from the late 1980s through the 1990s their desertification rate has dropped significantly. A unified watershed-scale plan for water use and management in different regions of the Hexi Corridor, considering water demands for economic development as well as ecosystem maintenance and remediation, must be implemented. The improved and ultimate sustainability of regional development for the Hexi Corridor is linked to following ecological criteria in exploiting land resources, and to systematically protect ecosystem function, allowing for sound ecosystem development.     

垂直基准定义及联接

介绍了利用地球位模型、地面重力资料、GPS和水准测量结果确定定全球高程基准及局部性垂直基准联接的基本原理和方法 ,给出了计算公式 ,并列出了国际上有关研究所获得的主要成果 ,最后对我国所需要进行的相关研究工作提出了建议     

Effects of altitude on critical ionization velocity experiments in space

The efficiency with which critical ionization velocity (CIV) discharges can be generated in space experiments is affected by the altitude at which the experiments are conducted. At around 500 km higher plasma density enhances plasma lower hybrid instability, momentum coupling efficiency, and charge exchange which is needed for seed ionization. At higher altitudes where atomic hydrogen and helium become the dominant ambient neutral species, the conditions for CIV discharge may improve considerably because less energy is lost to atmospheric ionization, even though the ambient density is reduced.