秦岭及黄土区现代栎林的孢粉组合研究

根据秦岭及黄土区六种栎林的表土孢粉分析,探讨了不同栎林孢粉组合的差异。资料表明,六种栎林在乔木、灌木、草本、藤本花粉和蕨类孢子组成和数量方面均有一定差异。据此,我们选出了３７个科属的植物作为定量判别的依据,提出了定量判别不同栎林的标准。     

地球的早期热状态

行星生长理论表明天体在达到地球质量的十分之一时便发生部分熔融(Stevenson,1981),由巨型撞击角度出发形成的月球起源假说,也设定地球发生碰撞时会发生熔融或挥发(Kipp and Melosh,1987)。最近的高压相平衡实验(Tokahashi,1986;Ttoand Takahashi,1987)表明在一定的地幔成分条件下,液体与固体可以发生汇合,此可以用地球在生长过程中或稍后的熔融来加以解释。然而,微量元素分配的实验研究是明(Katz,et al,1987)模型球粒陨石值至少有一小部分镁铁榴石和钙钛矿的分镏,这些球粒陨石值被认为是上地幔中的残留亲石元素。与CI相比,超球粒陨石Mg/Si=1.12的比值(Palme and Nickel,1985)有可能反映在高压条件下,橄榄石是漂浮在深部的岩浆海中,同时,橄榄石与上地幔发生混合作用(Agee and Walker,1987),其     

西安地区第三层古土壤研究

野外观察发现,陕西西安地区的第三层古土壤是由3层构成的复合古土壤。通过对长安双竹村剖面及蓝田段家坡剖面的地层结构、磁化率、颗粒成分以及有机质含量的分析,可以把形成第三层古土壤的中更新世时段(330~272 ka B.P.)分为6个温湿、冷干阶段,构成为3个气候变化旋回。     

Foreign minorities from developing countries in Madrid

Spain, which has always been a land of emigrants, is currently a centre of attraction for immigrants, as are other countries in Mediterranean Europe. The proportion is not as high as in other countries with a longer tradition of immigration. In this survey we selected the six nationalities which provide the highest numbers of immigrants from the developing world, and which have the greatest racial or cultural contrast to the native population. We analyse their structural features, whether or not immigrants from the same country are collect in the Madrid Metropolitan Area, the recent mobility of the immigrant population, and the evolution of immigration since the Administration carried out a regularization process, as well as Spaniards' opinion of foreign immigrants.     

兰州黄河高漫滩沉积与洪水变化研究

根据兰州黄河高漫滩沉积剖面的观察和81个样品的粒度分析,研究兰州黄河马滩剖面沉积特征和当时的洪水变化。结果表明,马滩剖面明显分为15个沉积层,指示15次较大的洪水。这15个阶段河漫滩洪水深度和规模由大到小的变化顺序依次为第10>12>11>13>15>14>3>5>7>8>6>1>4>9>2阶段。据历史文献推算,马滩高漫滩沉积代表的15次洪水发生在170 a B.P.以来。兰州洪水沉积不连续,这15次洪水的每一次一般代表1 a雨季的短暂时间,两次洪水间隔时间通常为10 a左右,这10 a是没有洪水发生或洪水规模小的阶段,也是降水量正常或偏少的阶段。     

Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal

In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.     

一个用于评估控制液及系数的泡沫凝胶性能的模型

本文了简述了车用旋转轴扭矩测试技术的一些基本原理和方法。在此基础上又根据近年来对华北工学院测试技术研究所研制的扭矩存储记录仪的实车测试应用和体会，对该测技术的原理、特点和技术性能做了较详细地论述。