华贵栉孔扇贝的人工育苗

华贵栉孔扇贝Chlamys(Mimachlamys)nobilis(Reeve)分布于印度尼西亚、日本部分海域以及我国南海等地，我国福建、广东沿海曾形成规模化养殖，后来发生爆发性大面积死亡，给养殖生产造成重大经济损失，导致其养殖生产陷入低谷。自我国政府与越南政府解决北部湾海域划界以来，广东雷州市大量转产转业渔民兴起了养殖扇贝的热潮。华贵栉孔扇贝因壳面色泽好、生长快、价格高，成为养殖户首选养殖对象。但目前由于种种原因，其育苗生产不稳定甚至失败。为此，笔者于2003年4月至8月在湛江市雷州珍珠一场进行了华贵栉孔扇贝人工育苗试验，为苗种生产提供参考。     

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggest that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photospheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field.     

Recent trends in Siberian urban growth

Future trends in urbanization in the USSR east of the Urals are considered using official Soviet data from 1959 to 1985. "Absolute and relative growth and growth rates are calculated for economic regions, oblast-level administrative entities, and individual cities, as well as for city-size categories. The nature of Siberian growth suggests that in addition to serving as centers of resource exploitation, Siberian cities also function as growth poles for more integrated development. The analysis serves as the preliminary stage for proposed future research on the extent of Siberian urban development and the integration of Siberia into the Soviet economy."     

Population development in Greater Santiago between 1970 and 1982: an analysis of district census results

"An attempt is made in the light of an analysis of population changes occurring in several sub-districts of Greater Santiago in the period between the last population censuses of 1970 and 1982, based on small-area census units (distritos and communas) to draw attention to the effects on the spatial growth of the city resulting from changed conditions in the political and juridical sphere since the change of power in 1973." The effect of changes in government policy concerning the liberalization of the property market and the illegal occupation of land are noted. (summary in ENG)     

山东莒南地质公园发现小型兽脚类恐龙足迹化石MinisauripUS

在山东省莒南地质公园内发现6个小型恐龙足迹化石,被归入足迹属Minisauripus。化石产于下白垩统大盛群田家楼组．时代为早白垩世巴列姆（Barremian）-阿普特期（Apdan）。5个较大,长约6cm,产于下部“主”层面上,其中4个组成2节行迹：1个较小,长约3cm,位于“主”层面30cm之上的上部层面上。山东Minisauripus的特征是：足迹个体小（长3．1～5．6cm,宽2．0～3．7cm）,三趾型,略不对称;足迹纵长,各趾近平行,趾垫较清晰;趾末端较钝,但爪迹较尖。Ⅲ趾比Ⅳ趾略长,而Ⅳ趾比Ⅱ趾略长且窄。此外,步幅较长,足长与步长之比约为10：1。与四川、韩国Minisau却淞不同之处是：足迹个体较大,长约是它们的2倍。继中国四川和韩国之后,山东是Minisau而淞在全球的第三个发现点。     

Numerical Experiment on Two-Dimensional Line Thermal

The time evolution of a two-dimensional line thermal-a turbulent flow produced by an initial element with signifi-cant buoyancy released in a large water body, is numerically studied with the two-equation k - e model for turbulence closure. The numerical results show that the thermal is characterized by a vortex pair flow and a kidney shaped concentra-tion structure with double peak maxima; the computed flow details and scalar mixing characteristics can be described by self-similar relations beyond a dimensionless time around 10. There are two regions in the flow field of a line thermal: a mixing region where the concentration of tracer fluid is high and the flow is turbulent and rotational with a pair of vortex eyes, and an ambient region where the concentration is zero and the flow is potential and well-described by a model of doublet with strength very close to those given by early experimental and analytical studies. The added virtual mass coeffi-cient of the thermal motion is found to be approximat     

不同饲料对凡纳对虾幼体生长与发育的影响

采用不同的饲料系列饲养各阶段凡纳对虾(Lito-penaeus vannamei)的幼体和仔虾，实验结果表明：在潘状幼体期(Z)～糠虾幼体Ⅱ期(M2)，投喂骨条藻 人工配合饲料系列，比单纯投喂骨条藻或单纯投喂人工配合饲料的成活率分别高18．5％和26.7％；糠虾Ⅱ期(M2)以后单独投喂人工配合饲料或单独投喂卤虫无节幼体的成活率无明显的差别；在人工育苗后期，用人工配合饲料代替卤虫无节幼体，育苗的成活率并没有下降。