基于耦合关系的干旱绿洲区农村居民点整理分区研究——以张掖市甘州区为例

以张掖市甘州区为例,利用系统科学理论与方法,研究农村居民点整理与农村社会经济之间的动态耦合规律,并以甘州区18个乡镇为研究单元,构建了农村居民点用地整理分区评价指标体系,利用熵值法确定权重,计算农村居民点整理的综合评价值,运用层次筛选法将研究区划分为5个整理区。研究结果：①甘州区农村居民点与农村社会经济的耦合度演化分为3个阶段：1995—1997年,二者不甚协调;1998—2003年,二者都处于持续、稳定、最佳协调发展状态;2004—2007年,二者处于相对稳定协调状态;目前二者处于不甚协调发展阶段。②农村居民点整理分区包括优先整理区、强化整理区、适度整理区、一般整理区和完善整理区。     

The suitability of using leaf area index to quantify soil loss under vegetation cover

Soil erosion by water under forest cover is a serious problem in southern China. A comparative study was carried out on the use of leaf area index (LAI) and vegetation fractional coverage (VFC) in quantifying soil loss under vegetation cover. Five types of vegetation with varied LAI and VFC under field conditions were exposed to two rainfall rates (40 mm h⁻¹ and 54 mm h⁻¹) using a portable rainfall simulator. Runoff rate, sediment concentration and soil loss rate were measured at relatively runoff stable state. Significant negative exponential relationship (p < 0.05, R² = 0.83) and linear relationship (p < 0.05, R² = 0.84) were obtained between LAI and sediment concentration, while no significant relationship existed between VFC and sediment concentration. The mechanism by which vegetation canopy prevents soil loss was by reducing rainfall kinetic energy and sediment concentration. LAI could better quantify such a role than VFC. However, neither LAI nor VFC could explain runoff rate or soil loss rate. Caution must be taken when using LAI to quantify the role of certain vegetation in soil and water conservation.     

Continual erosion of bare rocks after the Wenchuan earthquake and control strategies

The newly bared rocks created by the Wenchuan earthquake are undergoing continual intensive erosion in the form of detachment and movement of individual grains. Grain erosion is defined as the phenomenon of breaking down bare rocks under the action of insolation and temperature change, detachment of grains from the rockwalls by wind, flow down of grains on the slope under the action of gravity, and accumulation of grains at the toe of the mountain, forming a deposit fan. The Wenchuan earthquake, which occurred in Sichuan on May 12, 2008, caused thousands of avalanches and landslides and left scars on slopes and a huge area of bare rocks. Grain erosion causes flying stones, injured humans and resulted in numerous slope debris flows. The process of grain erosion and strategies to limit the erosion were studied by field investigations and field experiments. According to these field investigations and field studies, the most serious grain erosion occurs in spring and early summer when it is very dry. Rocks are broken down to grains under the action of insolation and temperature change. Then, wind blows the grains from the bare rock down slope. Experimental results showed that the amount of grains blown down by wind per area of rock surface per unit time is proportional to the fourth power of the wind speed. However, the size of the grains blown down by wind increases linearly with the wind speed. An experiment proved that grain erosion can be controlled with two moss species. Moss spores were mixed with clay suspension and splashed on bare rocks. The moss species germinated on the rock surface in one month and greened the bare rocks in two months. The moss layer protected the rocks from insolation and mitigated the effects of temperature change, thus effectively mitigated grain erosion.     

低渗透油藏CO2驱过程中含水率变化规律

通过国内外多个油田水驱后实施CO2驱的矿场实例研究,发现注入CO2后很多油井存在含水率下降的现象;这种现象发生在CO2驱的整个开发阶段,包括注气初期阶段CO2未到达生产井、生产井见气阶段以及高气油比阶段。重点讨论了生产井见气前的开发规律,在该阶段油藏内以油水两相渗流为主,不受三相渗流作用的影响。通过现场动态反应并结合室内细管和长岩心实验,揭示了CO2与油、水2种介质的相互作用,得到了两个结论:第一是始于低含水阶段的CO2驱过程中气体穿越地层水驱替地层油到达生产井;第二是始于高含水阶段的CO2驱替规律在不同级别低渗透岩心中的差异非常明显:对于特低渗岩心,CO2突破前的采出程度占CO2驱总采出程度的73.27%,CO2突破后的采出程度占26.73%,对于一般低渗岩心,CO2突破前的采出程度仅占CO2驱总采出程度的16.72%,而CO2突破后的采出程度占到了CO2驱总采出程度的83.28%。     

滇东地区煤田构造格局与煤系赋存规律的研究

滇东地区位于特提斯和环太平洋构造体系的交接部位,煤田构造格局的总体特征是呈NNE向条带状展布。区内断层以NNE、NE向为主,受主要断裂影响,煤田在南北向呈带状,东西向呈段状展布,各煤矿区在平面上呈NE向带状分布。研究区煤系赋存受基底主干断裂的控制作用明显,变形强度由北向南逐渐增强,北部地区以褶皱构造为主,断层较少,煤层多保存于向斜构造中,保存较完整,煤层埋藏较深;南部受弥勒-师宗断裂带影响,断裂构造极为发育,对煤层破坏严重,煤系赋存不稳定。     

Experimental researches on reflective and transmitting performances of quarter circular breakwater under regular and irregular waves

A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater (QCB) in comparison with those of semi-circular breakwater (SCB). Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wave experiments, the reflection coefficients of QCB and their spectrums are studied. Finally, the comparisons between the experimental results and numerical simulations for QCB under regular and irregular wave conditions are presented.     

Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocate...     

A new ketosteroid from red alga Acanthophora spicifera

A new ketosteroid, along with six known steroids, was isolated from the ethanolic extracts of red alga Acanthophora spicifera (Vahl.) Boergesen. The structures, identified using chemical and spectroscopic methods including 2D NMR, were: (1) 22-hydroxy-5α-cholest-3,6-dione, (2) 6-hydroxycholest-4-ene-3-one, (3) cholest-4-ene-3,6-dione, (4) cholest-5-ene-3β-ol, (5) 5α-cholestane-3,6-dione, (6) β-Sitosterol and (7) Saringosterol. The MTT method was used to test the cytotoxicity of the compounds against the human cancer cell lines, HCT-8, Bel-7402, BGC-823, A549 and HELA. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity against human cancer cell lines.     

Synthesis and protein tyrosine phosphatase 1B inhibition activities of two new synthetic bromophenols and their methoxy derivatives

3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from 1H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2p-bromo-6p-(3q,4q-dimethoxybenzyl)- 3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(2),2,3-dibromo-1-(2p-bromo-6p-(2q-bromo-4q,5q-dimethoxy-benzyl)-3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(3),3,4-dibromo-5-(2p-bromo-6p-(2q-bromo-4q,5q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol(4)and 3,4-dibromo-5-(2p-bromo-6p-(3q,4q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol (5).PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay,and compounds 3 and 4 demonstrated interesting activity against PTP1B.     

MOR型蛇绿岩中地幔橄榄岩的地质特征

地幔橄榄岩是指来自陆下、弧下或洋脊下的岩石圈地幔岩,通常通过构造侵位(冷侵位)的方式存在于造山带中,如造山带橄榄岩、蛇绿岩中的橄榄岩以及火山岩中的地幔橄榄岩等。本文选取了4个具有MOR型属性的蛇绿岩中地幔橄榄岩体,对比研究了其与深海橄榄岩在岩石学、地球化学、同位素地球化学和岩石成因等方面的特征,认为与深海橄榄岩性质的综合对比是识别MOR型蛇绿岩中地幔橄榄岩的有效方法之一,同时在蛇绿岩的分类中具有较好的参考价值。