谈县级地震部门依法管理建设工程抗震设防要求

以山西省祁县依法管理工程抗震设防要求为例，论述了强制性审核、确定一般工业、民用建设工程抗震设防要求的重要性及其深远意义。结合工作实际．总结了部分依法行政、规范管理和落实抗震设防要求的经验。     

陕西农村房屋抗震设防现状及对策

陕西省近年来发生的泾阳和石泉两次地震造成了农村房屋不同程度地破坏。通过对这两次地震的现场考察,分析总结了陕西农村房屋抗震设防现状及存在的主要问题,并提出了相应的改进措施及对策建议。     

The effect of bed mobility on resistance to overland flow

When sediment grains are transported as bed load in overland flow, there is a net transfer of momentum from the flow to the grains. When these grains collide with other grains, whether on the bed or in the flow, streamwise flow velocity decreases and resistance to flow increases. Resistance to flow generated in this manner is termed bed‐load transport resistance. Resistance to flow f over a plane bed may be partitioned into grain resistance f_g and bed‐load transport resistance f_bt. We use the symbols f_btf and f_btm to denote f_bt for flows over fixed beds and over mobile beds, respectively, and we compute the effect of bed mobility on flow resistance f_mob by subtracting f_btf from f_btm. The data for this study come from 54 flume experiments with fixed beds and 38 with mobile beds. On average f_mob is approximately equal to half of f_btm, which is about one‐quarter of f. Hence, f_mob is about one‐tenth of f. Predictive equations are developed for f_btf, f_btm and f_mob using dimensional analysis to identify the relevant independent variables and regression analysis to evaluate the coefficients associated with these variables. Values of f_mob are always positive which implies that mobile beds offer greater resistance to flow than do fixed beds. Evidently bed‐load grains colliding with mobile beds lose more momentum to the bed than do grains colliding with fixed beds. In other words, grain collisions with mobile beds are less elastic than those with fixed beds. Copyright © 2005 John Wiley & Sons, Ltd.     

Interannual Variability in Pollen Dispersal and Deposition on the Tropical Quelccaya Ice Cap*

Pollen collected from snow samples on the Quelccaya Ice Cap in 2000 and 2001 reveals significant interannual variability in pollen assemblage, concentration, and provenance. Samples from 2000, a La Niña year, contain high pollen concentrations and resemble samples from the Andean forests (Yungas) to the east. Samples from 2001, an El Niño year, contain fewer pollen and resemble those from the Altiplano. We suggest that varying wind patterns under different El Niño/Southern Oscillation (ENSO) conditions may affect the processes of pollen transport over the Altiplano and on the ice cap, although confounding variables such as flowering phenology and sublimation should also be considered     

嵌岩桩嵌岩段侧摩阻力浅析

为求出嵌岩桩嵌岩段侧摩阻力的表达式，假定嵌岩桩桩侧破坏由桩岩接触面上的滑动引起，桩岩接触面的压力由加载前岩土层自重产生的侧压力和由剪切膨胀产生的应力增量组成。用弹性力学的方法求解出桩侧正应力，引入了岩石破坏的Hoek-Brown强度准则，由此求出了嵌岩段桩侧阻力的表达式，并指出了此公式的适用范围。最后结合工程实际进行了对比分析，表明本文方法具有一定的实用性。     

北冰洋海冰和海水变异对海洋生态系统的潜在影响

最近30年来,北冰洋海冰和海水发生了急剧变化:海冰覆盖面积减少、冰层变薄、水温升高、淡水输入增加、污染加剧,正威胁着现有与海冰关系密切的生态系统。预期随着变化的持续,与海冰相关的食物链将在部分海域消失并被较低纬度的海洋物种所取代、总初级生产力有望增加并为人类带来更多的渔获量、而北极熊和海象等以海冰作为栖息和捕食场所的大型哺乳动物的生存前景堪忧。今后人类将更为重视对北冰洋生态环境变化规律的认识并加以运用、关注北冰洋特有物种的命运并加以力所能及的保护、评估北冰洋生态系统的变化对人类社会经济的影响以期及早采取应对措施。数据积累是目前制约北极研究的最大障碍,但随着 SEARCH 等大型国际研究计划的实施,对北冰洋生态系统的监测和研究将更为系统和全面。     

Late Holocene environmental conditions in Coronation Gulf,southwestern Canadian Arctic Archipelago: evidence from dinoflagellate cysts,other non‐pollen palynomorphs,and pollen

Boxcore 99LSSL‐001 (68.095° N, 114.186° W; 211 m water depth) from Coronation Gulf represents the first decadal‐scale marine palynology and late Holocene sediment record for the southwestern part of the Northwest Passage. The record was studied for organic‐walled microfossils (dinoflagellate cysts, non‐pollen palynomorphs), pollen, terrestrial spores, and sediment characteristics. ²¹⁰Pb, ¹³⁷Cs, and three accelerator mass spectrometry ¹⁴C dates constrain the chronology. Three prominent palaeoenvironmental zones were identified. During the interval AD 1470–1680 (Zone I), the climate was warmer and wetter than at present, and environmental conditions were more favourable to biological activity and northward boreal forest migration, with reduced sea‐ice and a longer open‐water (growing) season. The interval AD 1680–1940 (Zone II) records sea‐ice increase, and generally cool, polar conditions during the Little Ice Age. During AD 1940–2000 (Zone III), organic microfossils indicate an extended open‐water season and decreased sea‐ice, with suggested amelioration surpassing that of Zone I. Although more marine studies are needed to place this record into an appropriate context, the succession from ameliorated (Zone I) to cooler, sea‐ice influenced conditions (Zone II) and finally to 20th‐century warming (Zone III) corresponds well with several terrestrial climatic records from the neighbouring mainland and Victoria Island, and with lower‐resolution marine records to the west. Copyright © 2011 John Wiley & Sons, Ltd.     

Temporal variation of soil erosion resistance on sloping farmland during the growth stages of maize (Zea mays L.)

Maize growth has great effects on soil properties and thus likely induces the changes in soil erosion resistance on sloping farmland. However, temporal variation of soil erosion resistance during the growth stages of maize is still unclear in the mountainous yellow soil area where maize is the dominant crop. In this study, four maize plots (MP) and four bare land plots (CK) were conducted to investigate soil erosion resistance, and multiple indicators of soil erosion resistance were measured including the total soil anti-scourability (TAS), mean weight diameter (MWD), soil erodibility K factor and soil shear strength (SH). A comprehensive soil erosion resistance index (CSERI) was employed to quantify the temporal variation of soil erosion resistance during the growth stages of maize (seedling stage, SS; jointing stage, JS; tasselling stage, TS; maturing stage, MS). The results showed that TAS, MWD, SH increased significantly with maize growth and SH decreased when at MS. But K factor decreased significantly over time. CSERI increased significantly during the growth stages of maize and the CSERI of JS, TS, MS increased on average by 74.72, 180.68 and 234.57% than that of SS. Compared to CK, CSERI of MP increased by 49.90, 66.82, 55.60 and 38.61% during the growth stages of maize. The temporal variation of soil erosion resistance was closely related to the changes in maize cover, maize roots and soil organic carbon. The findings demonstrated that it is necessary to consider the temporal variation of soil erosion resistance in the mountainous yellow soil area.