Research on coda Q distribution in Beijing and its surrounding regions

Based on the single scattering model of seismic coda waves, we have calculated theQ-factor in Beijing and its surrounding regions by means of calculating the power density spectrum in frequency domain with a fixed time window. The digital seismic data of 69 earthquakes from Beijing Telemetered Seismographic Network are used. These earthquakes were recorded from January 1, 1989 to December 31, 1990 at 20 stations. This paper shows the variations of the codaQ-factors in the studied region with different sites, frequency and lapse time, and the temporal change of the codaQ-factors in these two years. The results indicate that codaQ-factor depends strongly on the lapse time and frequency. It is assumed that whenQ _C=Q ₀f^η, for the three time windows of 15–30s, 30–60s and 60–90s, the average values ofQ ₀ are 48, 115 and 217; and the average values ofη are 0. 89, 0.91 and 0.74, respectively. Contribution No. 95A0009, Institute of Geophysics, SSB, China. This work is a contract subject 85-04-01-02 of the State Seismological Bureau, China.     

中国地区近地面太阳紫外辐射的分布及其对大气臭氧层破坏的响应

本文在充分考虑太阳紫外辐射在大气中传输的物理过程的基础上,引入局地地面气压、臭氧和地表反照率的时空变化,利用Delta-Eddington近似法计算了中国地区冬季(1月)和夏季(7月)晴天时地面太阳紫外辐射(0.290—0.400μm)和紫外B辐射(0.290—0.325μm)的分布,并进一步计算出臭氧总量减少5％、15％时紫外B的变化.结果指出,由于臭氧总量的减少,中国北部地区紫外B的增加比南部地区显著.平均而言,臭氧总量减少1％时,冬季紫外B将增加1％左右,夏季紫外B将增加0.6％—0.7％.     

原子吸收分光光度法测定矿石中高含量的银和锌

本文介绍了用转角和降低喷雾量,在强盐酸介质中,火焰原子吸收直接测定矿石中高含量的银和锌。本法测得的结果稳定,未发现干扰,灵敏度、精密度、准确度及工作曲线均满足于许多矿石中高含量银和锌的测定。     

流动注射在线萃取-火焰原子吸收光谱法测定地质试样中痕量银

研究了在线萃取系统流程中最佳参数,提出一个流动注射在线萃取-火焰原子吸收光谱法测定地质试样中痕量Ag的分析方法。检出限为0.54ng/ml,对于含Ag 20ng/ml试样测定10次,精密度(RSD)为1.64％,分析速度可达20～30N/h,经地质标样分析验证结果可靠。     

泡沫塑料分离富集原子吸收法测定氰化液中金和银

研究了装有聚醚型泡沫塑料和三苯基膦负载聚醚型泡沫塑料的吸附柱对Au,Ag的分离富集的条件,并应用于氰化液、解吸液和电解液中Au和Ag测定中的预富集,Au和Ag的回收率均>98％。对含Au量为0.91μg/ml,含Ag量0.36μg/ml的试样,经过10次测定,其相对标准偏差分别为1.22％和2.31％。     

天然单斜辉石中Cr ~(3+)的晶位对称性和偏振吸收谱的分析

通过对单斜辉石系列钠铬辉石-硬玉样品中Cr~(3+)偏振吸收谱的谱带强度、形状及位置的分析,提出:这类矿物晶体中Cr~(3+)应处于四角畸变D_4对称晶场的晶位。由此计算出的谱带位置和观测结果一致。说明了D_4晶位假设更优于Khomenko等提出的三角畸变C_(3v)对称假说。     

Modelling of the lower ionosphere

The model of calculations of electron density profiles in D-region is suggested. The model includes four positive ions, four negative ions and electrons. The effective rate coefficients were received from detailed models of ionization-recombination cycle. The calculations, which were made, and the comparisons with experimental data (Ne-profiles and their variations, absorption of radiowaves) have showed, that in general the model described the basic features of D-region parameters.     

矿石中金的快速测定——Z/8000原子吸收光谱法

对于含硫化物样品,用2:1逆王水分解,泡沫塑料吸附,缩短(或省去)了除硫和有机碳的灼烧时间,解决了矿石中含硫和有机碳高时,经长时间灼烧,硫、碳仍除不尽,致使金的分析结果偏低的问题。逆王水分解后的试样用泡沫塑料分离富集金,回收率在95%以上。高含量金火焰法测定,低含量金石墨炉法测定,操作极为方便快速。火焰法测定时,特征浓度为0.48ppm/l%吸收,VC为2—11%;石墨炉法测定时,绝对灵敏度为2.48×10^-11g/l%吸收,VC为7.42%。     

新一代试样分解技术—微波溶样的现状与展望

本文通过回顾新一代试样分解技术－微波溶样的发展过程，在详述微波密封溶解优点的基础上，研讨了微波溶样的原理和有关设备的选择与设计，本文还评述了这一新技术的应用现状并展望该技术在分析领域中今后的发展前景。