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551.
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553.
利用大连地震台地磁Z分量观测资料,对其日变幅度、低点时间和日变形态的年变化进行分析,由此初步总结地磁Z分量日变化的规律及特征,对识别地磁场异常变化或干扰变化具有一定参考意义。 相似文献
554.
大珠母贝术后处理研究 总被引:1,自引:0,他引:1
用蚌复康(A组)、鱼蚌康复剂(B组)和盐酸普鲁卡因(C组)对人工插核后的大珠母贝进行术后处理,并经室内人工管养度过休养期。结果显示:术后成活率C组为70.0%,A组为60.0%,对照组为364%;留核率A组为66.7%,C组为57.1%,对照组为50.0%。表明蚌复康与盐酸普鲁卡因可以明显提高植核母贝的术后成活率和留核率;另外,休养期在室内度过也有助于提高留核率。 相似文献
555.
Peter Rogerson 《Journal of Geographical Systems》2005,7(1):101-114
When assessing maps consisting of comparable regional values, it is of interest to know whether the peak, or maximum value, is higher than it would likely be by chance alone. Peaks on maps of crime or disease might be attributable to random fluctuation, or they might be due to an important deviation from the baseline process that produces the regional values. This paper addresses the situation where a series of such maps are observed over time, and it is of interest to detect statistically significant deviations between the observed and expected peaks as quickly as possible. The Gumbel distribution is used as a model for the statistical distribution of extreme values; this distribution does not require the underlying distributions of regional values to be either normal, known, or identical. Cumulative sum surveillance methods are used to monitor these Gumbel variates, and these methods are also extended for use when monitoring smoothed regional values (where the quantity monitored is a weighted sum of values in the immediate geographical neighborhood). The new methods are illustrated by using data on breast cancer mortality for the 217 counties of the northeastern United States, and prostate cancer mortality for the entire United States, during the period 1968-1998.The research assistance of Ikuho Yamada is gratefully acknowledged. I also am grateful for the support of Grant 1R01 ES09816-01 from the National Institutes of Health, the support of National Cancer Institute Grant R01 CA92693-0, and the helpful comments made by the referees 相似文献
556.
Wallace H. Campbell 《Pure and Applied Geophysics》1987,125(2-3):427-457
The electrical conductivity of the Earth's upper mantle can be inferred from geomagnetic quiet-day,Sq, variations recorded at the world's observatories using the, coefficients of a spherical harmonic analysis (SHA) that separate the external (source) and internal (induced) parts of the surface field. The conductivity profile determined from such an analysis can be sensitive to special characteristics of the quiet field itself as well as the separation techniques employed. This review of the Sq-analysis features critical to a conductivity derivation is pictorially presented along with the equations for application of theSchmucker (1970) technique to theSHA coefficients for a conductivity determination. Three examples illustrate the use of these equations with differentSq models. 相似文献
557.
B. Broder 《Pure and Applied Geophysics》1981,119(5):978-989
The diurnal cycle of ozone at the surface and within the PBL is examined. It is concluded that the intrusion of air masses from ozone-rich layers in the lower troposphere results in late evening ozone maxima observed at ground stations on mountain slopes as well as within distinct layers of the PBL above the valley bottom. The ozone-rich layers are assumed to exist due to meso- or large-scale horizontal transport of smog air masses and a local cross-valley wind system is shown to be responsible for the occurrence of the intrusion processes. 相似文献
558.
利用2011—2015年5—9月华中4省河南、湖北、湖南、江西逐日日用电量、日峰负荷、日谷负荷与同期气象数据,探讨炎热天气过程对电力负荷的影响特征,并分别对4省建立基于积温热累积效应的电力负荷预测模型。结果表明:持续3d以上的炎热天气过程对电力负荷增长影响显著,其中湖北的电力负荷增量最大;当气温大于等于积温热累积效应的气温临界值时,对电力负荷增长有显著影响,其中湖南的日平均气温、日最高气温、日最低气温的初始敏感值分别为31℃、36℃、27℃,强敏感值分别为32℃、39℃、29℃;建立基于积温热累积效应的电力气象负荷多元回归预测模型,经2016年5—9月应用检验,华中4省的平均相对误差均控制在5%以内,根据具体天气情况进行适当订正,对国家电网公司华中分部电力调度具有参考价值。 相似文献
559.
日常活动视角下居民健康影响的性别差异——以广州为例 总被引:2,自引:1,他引:1
中国城市化转型背景下,居民的公共健康成为城市地理研究的一个热点。越来越多研究关注健康的性别差异,但基于日常活动视角分析居民健康的影响因素和路径的性别差异研究较为缺乏。因此,作者尝试通过构建结构方程模型探讨不同性别群体居民属性、建成环境、日常活动对健康影响的差异。研究发现:全职男性、全职女性与非全职女性的自评健康存在显著差异,得分依次降低;健康影响因素和影响路径存在性别差异,女性日常活动受到更多约束,其健康更大程度受所住社区周边建成环境和日常活动的影响;女性亚群体之间的健康及影响路径也存在差异;在考虑居民健康性别差异的同时,需要重视就业状况对健康的影响。日常活动视角能揭示居民属性和建成环境对健康影响的路径,有助于理解居民健康影响的性别差异。本文拓宽了健康影响因素的研究框架,对转型背景下改善建成环境,减少日常活动约束,关注健康的性别差异具有重要的现实意义。 相似文献
560.
ABSTRACT Daily average net radiation (DANR) is an important variable for estimating evapotranspiration from satellite data at regional scales, and is used for atmospheric and hydrologic modeling, as well as ecosystem management. A scheme is proposed to estimate the DANR over large heterogeneous areas under clear-sky conditions using only remotely sensed data. The method was designed to overcome the dependence of DANR estimates on ground data, and to map spatially consistent and reasonably distributed DANR, by using various land and atmospheric data products retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) data. An improved sinusoidal model was used to retrieve the diurnal variations of downward shortwave radiation using a single instantaneous value from satellites. The downward shortwave component of DANR was directly obtained from this instantaneous value, and the upward shortwave component was estimated using satellite-derived albedo products. Four observations of air temperature from MOD07_L2 and MYD07_L2 data products were used to derive the downward longwave component of DANR, while the upward longwave component was estimated using the land surface temperature (LST) and the surface emissivity from MOD1 l_L2. Compared to in situ observations at the cropland and grassland sites located in Tongyu, northern China, the root mean square error (RMSE) of DANR estimated for both sites under clear-sky conditions was 37 W m-2 and 40 W m-2, respectively. The errors in estimation of DANR were comparable to those from previous satellite-based methods. Our estimates can be used for studying the surface radiation balance and evapotranspiration. 相似文献