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501.
M. L. Wesely D. L. Sisterson R. L. Hart D. L. Drapcho I. Y. Lee 《Journal of Atmospheric Chemistry》1989,9(4):447-463
Eddy correlation measurements of NO vertical flux were made periodically from October 1983 through June 1984 at a height of eight meters above grass in northeastern Illinois, U.S.A. From 207 data points, each representing a 25 min average, 19 daytime cases and 8 nighttime cases were selected on the basis of steady, nonadvective atmospheric conditions. Each case was represented by a set of data constituting a 3 to 5 hr average. Concentrations of O3, NO, and NO
y
(from which NO2 was inferred) and local atmospheric and surface conditions also were measured, to provide the information necessary to assess the relative importance of surface deposition, surface emission, and air chemistry on the observed NO flux. On the basis of a linear regression analysis applied with independent variables representing physical, chemical, and biological processes, surface uptake of NO was very small for data primarily collected in the daytime during spring, and measured deposition velocities at a height of 8 m were very small, much smaller than expected for NO2. For the same time period, the surface emission rates of elemental nitrogen in NO were in the range of 1.4 to 4.2 ng m-2 s-1 for moist, unsaturated soils at temperatures near 15° C. These emissions were partially masked in the measured fluxes by rapid in-air chemical reactions involving O3 and NO2. The effects of rapid in-air chemical reactions involving O3 were to decrease the (upward) flux of NO with height. While the information collected at night was too limited to strongly support hypotheses concerning emissions and deposition, a pathway for NO production by reactions involving NO3 and related compounds was indicated. For daytime conditions, this production pathway is not evident, probably because of the relatively strong effects of photochemical reactions involving NO, NO2, and O3.Formerly with the Chemical Technology Division of Argonne National Laboratory and currently affiliated with Bio-Rad Laboratories, Digilab Division, Minneapolis, MN, U.S.A. 相似文献
502.
The preliminary research results of vertical deformation dislocation model of GongheM
S
=6.9 earthquake show that, the causative structure is a hidden fault with strike N60°W, dipping S47°W, which lies near the
current subsidence center of Gonghe basin. The rupture length and width are 30km and 14km, the upper and lower bound depth
of the fault in width direction are 3km and 17km respectively. The maximum coseismic and preseismic vertical deformation of
GongheM
S
=6.9 earthquake are 247mm and about 100mm. The reasons why there existed rapid postseismic uplift are also given a tentative
discussion.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 289–295, 1993. 相似文献
503.
原子吸收石墨炉快速程序测定痕量金 总被引:1,自引:1,他引:1
制定了石墨炉快速测定Au的程序。通过快速干燥,省去灰化步骤或缩短灰化时间,使测定程序从常规法所需的79s缩短至18s(PE-3030)或25s(PE-603)。测定时间由2min降为1min,测定速度提高了一倍,并得到相似的准确度及精密度。 相似文献
504.
505.
应用RT-PCR技术检测草鱼出血病病毒。建立了一种快速、简易而可靠的dsRNA模板的制备方法。应用该方法制备模板进行RT-PCR扩增,可以有效地检测出病鱼组织及病毒感染的培养细胞裂解液中的草鱼出血病病毒,且全过程只需3~4h,大大缩短了检测时间 相似文献
506.
507.
运用伊利石结晶度线性剥离法,定量计算了华南、台湾和吕宋这 3 个主要物源区对南海北部陆坡MD12-3432和MD12-3434两个岩芯(分别为50. 80 m和8. 33 m)MIS 2期粘土相对贡献量的时间序列变化.结果显示,台湾对两个岩芯的贡献最大(36%~62%),吕宋的贡献次之(28%~50%),二者之和一般大于90%,而来自华南的贡献最小(3%~17%).台湾和吕宋的贡献量呈现显著反向的千年时间尺度快速波动,二者贡献量随东亚夏季风增强或减弱而显著变化,因此,吕宋/台湾贡献量比值可以用于指示东亚夏季风的快速演化.吕宋/台湾粘土贡献量比值在B?lling-Aller?d和Dansgaard-Oeschger 2事件期间的增加,反映了同时期东亚夏季风的快速增强;而在Heinrich 1和Heinrich 2事件期间的减小,则指示了东亚夏季风的减弱.吕宋/台湾贡献量比值对东亚夏季风快速变化的指示,在一定程度上要明显优于蒙脱石/(伊利石+绿泥石)比值.南海北部MIS 2期粘土矿物对东亚夏季风快速变化的响应具有明显的空间差异性,受洋流搬运扰动和物源控制作用影响,陆坡相对浅水区粘土矿物记录的东亚夏季风快速变化信息相对有限,而深水稳定的沉积环境则更有利于保存东亚夏季风快速变化信息. 相似文献
508.
快速集聚发展过程中的河谷型城市的空间整合与规划--以兰州市为例 总被引:3,自引:3,他引:0
中国西部部分河谷型城市自1949以来一直处于较为快速的集聚发展过程中。产业、各种基础设施大量在河谷中兴建。但是,由于地形条件的约束,这部分城市出现了建设用地紧张、环境问题突出、空间职能配置体系不合理等问题。以兰州市为例,通过对兰州城市在快速集聚扩张过程中空间结构存在问题的分析,提出了旧城“空间职能置换”和新城区建设的空间整合和规划思路,设想了未来50年兰州城市空间建设方案,探讨解决目前这类城市所面临的产业结构升级换代、城市现代化与环境综合治理等相关问题的思路与方法。 相似文献
509.
深圳快速城市化中地形对景观垂直格局的影响 总被引:5,自引:0,他引:5
基于RS 和GIS 的支持, 以深圳市为案例研究地形对景观格局及其垂直分布的影响, 进行景观格局时空动态分析。文章指出, 人类活动对土地的干扰程度表现为从低平地区向高 峻地区递减, 从而导致在以山地占主体的盐田等区在城市化前期低于地势平坦的福田等区; 随着城市的进一步加深, 福田等区多样性指数则快速降低, 盐田等区相对降低很少, 或还处 于上升状态。多样性指数在高程带和坡度带上多时段变化表明: 在垂直空间上, 土地利用结 构的垂直分异是景观格局垂直分异内在原因, 多样性指数的空间曲线和时间曲线具有反“U” 形库兹涅茨曲线特征, 但是这种曲线变化特征需要到一定的城市化阶段才能形成, 并且曲线 特征随城市化的加深而更加明显; 在时间上, 低海拔和低坡度地区的多样性指数的动态特征 也有类似库兹涅茨曲线的反“U”形, 而且随城市化的加深, 具有这种特征的高程带和坡度 带均在上移。 相似文献
510.
ShuiYong Fan Y.R. Guo Ming Chen JiQin Zhong YanLi Chu W. Wang X.Y. Huang YingChun Wang Y.H. Kuo 《寒旱区科学》2009,1(2):0135-0142
To improve the weather forecasting over the Beijing area for the 2008 Olympic Games,a triple-nested(27/9/3km) WRFVar/WRF system with 3-h update cycle was established.Experiments have been done for a convective event that occurred on August 1,2006.The results showed that the high-resolution rapid update cycle gave a good precipitation forecast;the tunings of background error statistics(BES) and observation-error statistics in WRFVar improved the skill of the precipitation forecast;the BES for the fine domain(3 km) obtained by interpolation from its parent domain(9 km) can be used in 3 km WRFVar as a reasonable approximation.The user can now save a great deal of work related to the derivation of the fine mesh BES from the forecast over a period of time;the rapid update cycle with 3-h frequency has satisfied the forecast,and the update cycle with 1-h frequency was not necessary. 相似文献