鹤庆—剑川地区岩溶发育特征及其控制因素

滇中鹤庆—剑川地区碳酸盐岩岩溶极为发育,其空间展布广,以连续纯碳酸盐岩型岩溶层组类型为主,岩溶形态多样,包括溶蚀平原、溶丘谷地、溶丘洼地等类型.滇中鹤庆—剑川岩溶系统具有沿断裂走向展布的显著特点,同时沿断层、褶皱轴部和构造裂隙岩溶发育程度明显较大.结合区域地质构造背景,研究认为鹤庆—剑川地区岩溶系统的发育主要受控于物质...     

Adjustment time of the first baroclinic Rossby wave in the global oceans

1Introduction Planetary waves involve the main processes bywhich perturbation signal in one part of the ocean istransferred to another part.In the1970s,mostof theprevious theoretical studies focus on the local Ekmanpumping and the nondispersive long baroc…     

Salinivibrio sp.YH4胞外丝氨酸蛋白酶EYHS耐盐性及生物信息学分析

摘要：目的 探讨菌株Salinivibrio sp.YH4分泌的丝氨酸蛋白酶EYHS的耐盐性及结构特征。方法 明胶底物酶谱法分析EYHS的耐盐性。应用生物信息学手段对EYHS及6种耐盐的S8家族丝氨酸蛋白酶结构特征进行分析。结果 EYHS在4 mol/L的NaCl溶液中仍具有活性,属于耐盐蛋白酶。EYHS及6种S8家族丝氨酸蛋白酶分子表面的loop区等无规则卷曲所占比例较高,α-螺旋与β-片层则主要位于酶分子内部。EYHS分子表面酸性氨基酸含量较高,且具有弱疏水内核。多序列比对发现蛋白酶的催化三联体两侧存在高度保守的基序和保守的极性氨基酸及芳香族氨基酸,并存在多个保守的Gly与Ala。同源模建和表面电荷分布显示,α螺旋和β片层围成了蛋白酶的催化腔,EYHS活性中心包含由Asp32、His65与Ser215组成的催化三联体,且催化位点区域表面静电势为负。结论 上述结构特征可能有助于耐盐丝氨酸蛋白酶EYHS在高盐环境下维持其稳定性和适度柔性,并有助于其催化功能的发挥,为深入研究耐盐丝氨酸蛋白酶的高盐环境适应性提供了一定的理论依据。     

Multiple Unmanned Underwater Vehicles Consensus Control with Unmeasurable Velocity Information and Environmental Disturbances Under Switching Directed Topologies

China Ocean Engineering - A consensus algorithm proposed in the paper is applied to tackle remarkable problems of unmeasurable velocities, the environmental disturbances, and the limited...     

基于功能视角的广州都市边缘区乡村发展类型分化及其动力机制

基于村庄规划详细调查数据库,采用空间集中度和功能识别等方法,深度剖析广州都市边缘区村域尺度乡村发展的类型分化及其动力机制.结果 表明:①广州都市边缘区村域乡村功能的空间梯度差异特征明显.乡村经济发展功能和社会保障功能呈现出由城区向城郊逐渐减弱的分异特征,农业生产功能和生态保育功能则由城区向城郊逐渐增强态势.以乡村主导功...     

Perceptions of Land Tenure Security in Rural China: The Impact of Land Reallocations and Certification

Abstract

Tenure security is commonly recognized as an important factor in stimulating long-term investments in land. Recent studies suggest that a distinction between legal, actual and perceived tenure security needs to be made in analyzing tenure security. This study discusses the relationships between legal, actual and perceived land tenure security in rural China, and empirically examines the impact of actual on perceived land tenure security by applying Probit models to household and village survey data collected in four provinces. Using household expectations about the absence of land reallocations within the next five years as the dependent variable, we find that tenure security is positively affected by the possession of land certificates in villages that periodically reallocated land but not in villages that did not do so. The estimated impact is larger for land certificates issued in the new round of land certification than for land certificates that were issued earlier.     

Spatial variation of the relationship between transport accessibility and the level of economic development in Qinghai-Tibet Plateau,China

As an important component of China' transportation systems, for a long time, the insufficient performance of transport in QinghaiTibet Plateau(QTP) was a bottleneck restricting the economic growth and social development in this area. Nevertheless, the implementation of the western development strategy has accelerated the preliminary construction of comprehensive transport network since 2000. Due to the large area and significant geographical heterogeneity, there is a growing need to understand the relationship between transportation and economic development based on the perspective of spatial difference. By using GIS-based raster analysis and Geographically Weighted Regression(GWR) model, we investigated the spatial-temporal distribution of highway, railway and airport accessibility, respectively, and estimated the correlation and heterogeneity between transport accessibility and the level of economic development. Results revealed that:(1) Transport accessibility in the QTP improved by 53.38% in the past 15 years, which is specifically embodied in the improvement of both highway and railway.(2) Accessibility presented prominent differentiation in the space, increasing from west to east and reducing with the rise of elevation, specifically, the best accessibility area of the highway is below 4000 m above sea level, while the area with an altitude of over 4000 m has the lowest aviation time cost.(3) In general, the long weighted average time cost to critical transport facilities posed significantly negative effect on county economic growth in QTP, more positively, the adverse effect gradually weakened over time.(4) Obvious heterogeneity exists at the influence of different transport accessibility factors on the level of economic development, reflecting both in the horizontal space and altitudinal belt. Therefore, region-specific policies should be addressed for the sustainable development of transport facilities as well as economy in the west mountain areas.     

A Review on Marine N2 Fixation: Mechanism,Evolution of Methodologies,Rates, and Future Concerns

Ocean Science Journal - Investigations on marine N2 fixation have gained momentum since 1960s with eventual establishments of relevant methodologies to identify species involved and quantify the...     

耀变体在射电波段的偏振研究

利用UMRAO数据库22个耀变体源的偏振数据,根据Lazarian&Pogosyan理论模型分析研究了耀变体射电波段的偏振随波长的变化,得出不同类的耀变体偏振随波长变化的原因。结果表明,与Lazarian&Pogosyan理论模型吻合较好。由此得出如下结论:(1)反常去偏振耀变体源中反常法拉第旋光起主导作用,反常去偏振相对较少;(2)热辐射与同步辐射混合作用,高频波段的偏振度小于低频波段的偏振度(反常去偏振);(3)当被观测波段波长小于吸积盘热辐射对应的维恩波长时,高频波段的偏振度大于低频波段的偏振度(常规去偏振)。     

Rift structures and its related unconformities on and adjacent the Dongsha Rise: insights into the nature of the high-velocity layer in the northern South China Sea

Marine Geophysical Research - It is curious that the typical feature of high-velocity layer (HVL) underneath the crust for the magma-rich margin was found in the magma-poor margin of the South...