一种生成大周期伪随机数的新算法——改进的混合同余法

为了克服当前所生成的伪随机数周期小、每个随机数仅能出现1次而不能重复的缺点,本文提出了一种生成伪随机数的新方法,称为改进的混合同余法。     

青藏高原多年冻土概论

本文较系统地阐述了青藏高原多年冻土的地带性规律、冻土构造以及融区的类型和分布特征,详细论述了不同作用下形成的冻土(冰缘)地貌,并对青藏高原的冰缘期进行了初步划分与对比。     

洛宁铁炉坪银铅矿床围岩蚀变分带特征

本文通过对铁炉坪银、铅矿床围岩蚀变的研究，划分出６种基本蚀变类型，３种蚀变带。各蚀变带以矿体为中心对称分布，各带之间呈渐变过渡关系。并指出由蚀变作用引起围岩化学成分及微量元素含量的变化，岩石化学成分与矿物成分变化相一致，成矿与围岩蚀变相辅相成。还指出了围岩蚀变的找矿意义。     

转报通信协议的Petri net描述和检验

本文论述了作者引用和设计的用于微机转报网络的两个通信协议,并用Petri net进行描述和检验。分析结果表明:协议1适用于理想信道环境,协议2有广泛的实用性,在噪声信道环境下也能保持协议的合法性,网络不会出现死锁、死环。     

关于数直线R中分划R的子集

本文研究美国学者P.Bankston和R.J.McGovern提出的一个公开问题—数直线R中那些子集分划R?研究表明,R中的每一个0一维子集都分划R;对月中的1一维子集;本文给出了开集、闭集以及具有某种散性的子集分划R的充分必要条件。     

混沌与预报期限

混沌理论的提出是自然科学的重大进展,它与自然灾害的预报密切相关。在气象学方面,人们已初步对混沌影响预报的问题作了讨论,其结论是: (1) 影响是有时间期限的,超过这个期限影响才重要,不超过则不重要,这个期限称     

Isolation of PAH-degrading bacteria from mangrove sediments and their biodegradation potential

Surface sediment samples were collected from seven mangrove swamps in Hong Kong SAR with different degrees of contamination. The total concentrations of 16 PAHs in these sediments ranged from 169.41 to 1058.37 ng g⁻¹ with the highest concentration found in Ma Wan and the lowest in Kei Ling Ha Lo Wai mangrove swamp. In each swamp, three bacterial consortia were enriched from sediments using phenanthrene (Phe) as the sole carbon and energy source, and individual bacterial colony showing Phe degradation was isolated and identified by 16S rDNA gene sequence. The consortia enriched from Sai Keng and Ho Chung sediments had highest ability to degrade mixed PAHs in liquid medium, with 90% Phe and Fla (fluoranthene) degraded in 7 days. On the other hand, Kei Ling Ha Lo Wai-enriched consortia degraded less than 40% Phe and Fla. Pyrene (Pyr) was hardly degraded by the consortia enriched from sediments. Bacterial isolates, namely Rhodococcus (HCCS), Sphingomonas (MWFG) and Paracoccus (SPNT) were capable to degrade mixed PAHs (Phe + Fla + Pyr). Their degradation percentages could be lower, comparable or even higher than their respective enriched consortia, depending on the consortium and the type of PAH compounds. These results suggest that PAH-degrading bacteria enriched from mangrove sediments, either as a mixed culture or as a single isolate could be used for PAHs bioremediation.     

辽东隆昌地区辽河群划分及其构造样式演变

从岩石组合、沉积序列、接触关系及变形变质方面分析辽东隆昌地区的辽河群是一套在沉积上连续的,并且经历了相同变形变质历史的中浅变质沉积岩系。详细的构造分析表明它经历了三期构造变形,第一期为北北西向平褶皱,第二期为北北四向斜歪褶皱,第三期为北东东向宽缓直立褶皱。     

Nature of the Precambrian metamorphic blocks in the eastern segment of Central Tianshan: Constraint from geochronology and Nd isotopic geochemistry

The Central Tianshan Tectonic Zone (CTTZ) is anarrow domain between an early Paleozoic southernTianshan passive continental margin and a late Paleo-zoic northern Tianshan arc zone, which is character-ized by the presence of numerous Precambrian meta-morphic basement blocks. Proterozoic granitoidgneisses and metamorphic sedimentary rocks,namely Xingxingxia and Kawabulag and Tianhugroups, are the most important lithological assem-blages in these metamorphic basement blocks, and alittle of …