奇偶型Hanoi塔问题研究

讨论了一种奇偶型Hanoi塔问题及其4种具有禁止移动约束的模型,给出了每种禁止条件下的递归算法,并计算了最小移动次数的控制项.     

客观信息的模型和度量研究

当今时代,信息的重要性毋庸置疑.但是,人们对于信息的认识依然众说纷纭,对于信息度量的研究同样莫衷一是.本文基于前人的丰富研究成果,总结了在信息的性质及度量方面已经取得的重要进展和存在的主要不足,探讨了信息的本质内涵和数学表达等基本问题.基于对信息客观性的认识,提出了信息的定义和六元组模型,讨论了信息的基本性质,建立了信息的广阔性、细致性、持续性、丰富性、包容性、延迟性、遍及性、真实性和适配性9类度量的定义和数学表达,形成了客观信息论的基础理论框架,能够系统全面地支持信息与信息系统的分析研究.     

Compositions of aliphatic des-A-triterpenes in the Hani peat deposit,Northeast China and its biological significance

Aliphatic des-A-triterpenes, the degradation products of pentacyclic triterpenes have been tentatively assigned in samples taken from a 963-cm-thick peat sequence from the Hani region of Northeast China using gas chromatography-mass spectrometry (GC-MS) in order to understand and identify these des-A-triterpenes response to climate and ecology. The study indicates that aliphatic des-A-triterpenes are abundant in the Hani peat bog. The high relative abundance of the total des-A-triterpenes mainly occurs at the Holocene periods and is corresponding to the low sedimentation rate. The mechanism of des-A-triterpenes accumulation is not consistent with the previous studies. It is proposed that the biological community is also one influence factor. The obvious stage variations of the total des-A-triterpenes in the whole sequence reveal the different biological (microbes and plants) processes and responses, possibly revealing the four large replacements of biological community and functional composition in the swamp environment over the 16000 cal a BP. The low total des-A-triterpenes values occur at about 10200, 8700, 7700, 6600, 4480–3940 and 3040 cal a BP, reflecting the multiple millennial micro-environment oscillations under the macro-environment of the swamp during the Holocene. The ratios of diene and monoene des-A-triterpenes (DT/MT), des-A-lupane and diene and monoene des-A-triterpenes (DL/(DT+MT)), ratios of individual compounds exhibit vertical opposite to the total des-A-triterpenes. Namely, these ratios are high during the last deglaciation and late Holocene whereas they are low at other periods, indicating different compounds have different responses to micro-environment and microbial activities. This study discusses the diversity of biological community and biological functional composition response to micro-environment, which not only provides the complement in Northeast China, but also bears important fundamental information for the implication to ecological environment in the future.     

氮化物半导体电子器件新进展

氮化物宽禁带半导体是实现大功率、高频率、高电压、高温和耐辐射电子器件的一类理想材料.基于氮化镓(GaN)异质结的高电子迁移率晶体管(HEMT)是氮化物电子器件的主流结构,该结构利用高电导率二维电子气实现强大的电流驱动,同时保持了氮化物材料的高耐压能力.近年来,GaN HEMT器件主要在微波功率和电力电子2个领域得到了快速发展.本文评述了GaN微波毫米波功率器件和高效电力电子器件的若干研究进展,并提出了氮化物电子器件仍存在的问题及解决方向.     

Secondary structural analysis of the mRNA regions encoding the hemagglutinin cleavage site basic amino acids of the avian influenza virus H5N1 subtype samples

Here we report the codon bias and the mRNA secondary structural features of the hemagglutinin （HA） cleavage site basic amino acid regions of avian influenza virus H5N1 subtypes. We have developed a dynamic extended folding strategy to predict RNA secondary structure with RNAstructure 4.1 program in an iterative extension process. Statistical analysis of the sequences showed that the HA cleavage site basic amino acids favor the adenine-rich codons, and the corresponding mRNA fragments are mainly in the folding states of single-stranded loops. Our sequential and structural analyses showed that to prevent and control these highly pathogenic viruses, that is, to inhibit the gene expression of avian influenza virus H5N1 subtypes, we should consider the single-stranded loop regions of the HA cleavage site-coding sequences as the targets of RNA interference.     

Efficient and reproducible folding simulations of the Trp-cage protein with multiscale molecular dynamics

Folding simulations are often time-consuming or highly sensitive to the initial conformation of the simulation even for mini protein like the Trp-cage. Here, we present a multiscale molecular dynamics method which appears to be both efficient and insensitive to the starting conformation based on the testing results from the Trp-cage protein. In this method the simulated system is simultaneously mod- eled on atoms and coarse-grained particles with incremental coarsening levels. The dynamics of coarse-grained particles are adapted to the recent trajectories of finer-grained particles instead of fixed and parameterized energy functions as used in previous coarse-grained models. In addition, the compositions of coarse-grained particles are allowed to be updated automatically based on the coherence during its history. Starting from the fully extended conformation and other several different conformations of the Trp-cage protein, our method successfully finds out the native-like conformations of the Trp-cage protein in the largest cluster of the trajectories in all of the eight performed simulations within at most 10 ns simulation time. The results show that approaches based on multiscale modeling are promising for ab initio protein structure prediction.     

Research on defects and domain characteristics of MgO-doped near-stoichiometric lithium tantalate in room-temperature polarization process

MgO-doped congruent and near-stoichiometric lithium tantalate single crystals were grown by Czochralski technique and flux method respectively. Optical absorption studies showed that the UV absorption edge was very sensitive to the composition of the crystals and the decrease in defects led to the blue-shift of the UV-edge. The unit domain shape also related to the composition, and the observed results of the crystal wafers that etched by hydrofluoric acid indicate that the domain structure of near- stoichi...     

公路工程标底的编制原则与方法

论述工程工程标底的编制原则与方法。     

A comparative study of n -alkane biomarker and pollen records: an example from southern China

We report the results of a comparative study of n-alkane biomarkers and pollens in lacustrine and peat deposits at Dingnan, Jiangxi Province in southern China, and discuss the likely causes for the discrepancy in the interpretations of the n-alkane biomarker and pollen records in terms of climate and vegetation change. The results show that past changes in climate and vegetation revealed by the n-alkane record are not always consistent with the pollen assemblage record in the whole section. Biomarkers do not permit direct identification of the plant family and/or genus and mainly record compositions of local plant remains, while pollens mainly reflect the regional vegetation change. Biomarkers and pollen records complement each other, providing a better picture of local and regional environments. Furthermore, biomarkers are more sensitive than pollen to climatic and vegetational change. Several climatic events are clearly identified by the n-alkane biomarker proxies, such as C₃₁/(C₂₇+C₂₉+C ₃₁) ratio and can be correlated to the North Atlantic Heinrich event, B/A, YD and two dry-cool events during the early Holocene such as the periods of 9850 to 9585 cal a B.P. and 8590 to 7920 cal a B.P. These events are consistent with those found in the surrounding regions, suggesting that the regional climate was coupled with global-scale abrupt climatic events. Our results suggest that biomarker and pollen data can record the more detailed climate and vegetation information, thus improving the resolution and precision of vegetation and climate reconstruction. Supported by National Natural Science Foundation of China (Grant No. 40602004) and National Basic Research Program of China (Grant No. 2004CB720200)     

Relationship between the later strong gas-charging and the improvement of the reservoir capacity in deep Ordovician carbonate reservoir in Tazhong area, Tarim Basin

Some large-scale oil-gas fields have recently been discovered in marine carbonate in China, especially the significant discoveries in deep reservoir that reveals a favorable exploration prospect. Tazhong area is the first-order tectonic unit in Tarim Basin, where there are nearly trillion cubic meters of natural gas resources in the Ordovician limestone reef flat complex in Lianglitage Formation. The reservoir is shelf edge reef flat complex, characterized by ultra-low porosity, low permeability and strong heterogeneous, with a current burial depth of 4500―6500 m. Studies find that the formation and distribution of deep reservoir of the Lianglitage Formation were controlled not only by the early high-energy sedimentary facies and corrosion, but the fracture network formed by the strong gas-charging process since the Himalayan epoch, which played an important role in optimizing and improving reservoir properties. This paper discusses the relationship between the strong later gas-charging and the improvement of the reservoir capacity in deep Ordovician carbonate reservoir, and also builts the corresponding mechanisms and modes, which is favorable for the prediction and evaluation of the advantageous exploration targets.