基于长度贝叶斯生物量估算法的北部湾带鱼资源评估

带鱼是南海西北部北部湾主要经济鱼类种群之一,估算其种群参数和评估其资源状况对北部湾渔业资源管理具有重要意义.本文利用2006-2016年北部湾带鱼(Trichiurus haumela)的生物学数据,通过长度贝叶斯生物量估算法(Length-based Bayesian Biomass Estimation Metho...     

Empirical distributions of galactic λ spin parameters from the Sloan Digital Sky Survey

Using simple dimensional arguments for both spiral and elliptical galaxies, we present formulae to derive an estimate of the halo spin parameter λ for any real galaxy, in terms of common observational parameters. This allows a rough estimate of λ, which we apply to a large volume-limited sample of galaxies taken from the Sloan Digital Sky Survey data base. The large numbers involved (11 597) allow the derivation of reliable λ distributions, as signal adds up significantly in spite of the errors in the inferences for particular galaxies. We find that if the observed distribution of λ is modelled with a lognormal function, as often done for this distribution in dark matter haloes that appear in cosmological simulations, we obtain parameters  λ₀= 0.04 ± 0.005  and  σ_λ= 0.51 ± 0.05  , interestingly consistent with values derived from simulations. For spirals, we find a good correlation between empirical values of λ and visually assigned Hubble types, highlighting the potential of this physical parameter as an objective classification tool.     

磷灰石结构通道离子对晶胞参数的影响

磷灰石晶胞参数受其结构中Ca多面体，磷氧四面体及结构通道位置上的类质同角替换的影响，本文探讨了54个磷灰石样吕的晶胞参数与结构通道离子F，OH，Cl相同象替换的影响，本文讨论了54个磷灰石样品的晶胞参数与结构通道离子F，OH，Cl相对含量的关系，发现Cl和取代是影响岩浆型磷灰石晶胞参数的主要因素，每原子／晶胞的Cl使a增大0．121 1（6）nm，c减少0．0633 （3）nm，根据成分与结构的经验关系式，可以验证电子探针对F的分析结果。     

Geochemical Characteristics of a Veinlet Kupferschiefer Profile from the Lubin Mine, Southwestern Poland

Previous studies have shown that the ascending, oxidizing brines play a very important role in Kupferschiefer mineralization. Fractures could be the pathway of the brines. In order to clarify the influences of the brines on bulk organic matter, aromatic hydrocarbons and Kupferschiefer mineralization, one veinlet Kupferschiefer profile from the Lubin mine, southwestern Poland was studied with the microscopic, geochemical and Rock-Eval methods. The microscopic results indicate that organic matter of the veinlet sample consists dominantly of bitumen. Its extract content is higher than in other samples. The dominant aromatic compounds are naphthalene and alkylated naphthalenes (Na-PAH), which have migrated into the veinlet sample from other sediments. The content of phenanthrene and its methylated derivatives (Ph-PAH) is much lower than in other samples. The reason may be due to their heavier mass than Na-PAH. It is more difficult for Ph-PAH to migrate. The Na-PAH was probably removed from the shale by dist