This paper has proved that the Diophantine equation x3+1=38y2 has only integer solutions(x,y)=(-1, 0),(31,±28).
A formal definition of proposition formulae was provided by context-free grammar,and the conversion from proposition formulae to polynomials was solved automatically. Using Wu′s Method, the paper presented another solution to the problem of theorem reasoning. In addition, a method for producing logical deduction was introduced.
A new method based on numeric computation for automated geometric theorem proving and discovering is shown. And a dynamic searching system of geometric theorem has been implemented,which can solve elementary geometric problems efficiently, including some non-constructive problems.
Based on the smaller information granularity security, granule technology was presented in this paper, and the information content security architecture model was also given. The model-based prototype system exampled with protecting WORD documents was implemented.
This paper studies the resource sharing in Tele-learning systems.A community P2P learning resource sharing model is proposed and the resource sharing will be restricted in certain communities. The metadata of digital learning resources is stated by LOM standard. By means of distributed metadata management in structured pure P2P topology, the distributed storage and bandwidth can be taken full advantage. The constitution of community, the publication and retrieval of learning resources are specified in this paper as well as implement of the model.
There are plenty of local copies of pages of remote web sites on local databases on most of web search engine sites. It is necessary to pull remote web pages periodically to refresh local copies of these pages on database in order to keep copies and source pages consistent，and which takes plenty of time and resources.The article proposes serveral policies to synchronize copy and source pages , proposes a Poission model of source page change, define freshness and fresh time, studies on these policies and compares their effectiveness.It is shown that the proposed policies improve the freshness of web pages significantly.
Uniform Ag nano-particles was synthesized within nanoscale pores of oxidized porous silicon (OPS) by a simple solution immersion-thermal decomposition approach，forming the compound structure of Ag/OPS/silicon. Ag films deposited on OPS were characterized by X-ray diffraction, and SEM showed the existence of silver nano-particles.
In this paper, we defined lowering and raising operator of single photon's two polarization states, and used the theory of linear transformation of operator in Fock space to study BS, PBS, wave plate and H transformation. We obtained their representation of operator .On the base of this; we studied some quantum information experiment, e.g. Teleportation, from a new aspect. Using the new representation, we can analyze the probability of photons output states .To do this, we try to find a new method to devise experiments much efficiently.
This paper advances a novel measurement of wave-height — differential algorithm.Compared with electric level method, the differential algorithm has its advantages. This article details its principle,algorithm and demonstrates it with a living example.
Syntheses of three novel heteroretinoids were reported. Novel heteroretinoids were 5-(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-3-pyrazole carboxylic acid, 2-Methyl -5-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalen-2-yl)-furan-3-carboxylic acid, 1-Butyl -2-methyl-5-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalen-2-yl)-1H-pyrrole-3-carboxylic acid.The results of biological test indicated that these compounds possessed some growth inhibition effects in leukemia cells.
Genomic DNA was isolated from the musculature of Macrobrachium nipponensis to establish a reproducible and stable PCR technical system. The ingredients and programs of amplified reactions were optimized respectively. The results showed that the profiles of PCR products could be improved obviously by using the 25 μL solution of 10×Buffer 2.5 μL, Mg+2 1.5 mmol/L, 4×dNTP 0.2 mmol/L, 1 U Taq DNA polymerase, 0.4 μmol/L of each primer and 200~300 ng of DNA template as well as the programs of 5 min at 95 ℃, 35 cycles of 1 min at 95 ℃, 50 s at 56 ℃, 1 min at 72 ℃ and finally, 10 min at 72 ℃. The optimized conditions could result in satisfactory specificity and reproducibility in amplifying 18S rRNA,COI,ND5 gene fragments, and consequently provide a useful means for the research of genetic diversity, molecular marker and germplasm identification in Macrobrachium nipponensis.
Amino acids composition and activities of four digestive enzymes including pepsin, tryptase, amylase, cellulase were determined in the eggs of freshwater prawn, Macrobrachium nipponense. These eggs were sampled from different embryonic development stages. The results indicated that digestive enzymes activities and amino acids correlated closely with the stages of embryonic development. Activities of pepsin, tryptase and amylase were relatively high during the whole embryonic development stages. Activities of pepsin, tryptase and amylase were high in early and late developmental stages, but relatively low during middle stages. Cellulose activity was low and showed no obvious change during different embryonic development stages. During protozoea stage, activities of pepsin, tryptase and amylase increased obviously. The content of dissolvable protein and amino acid had a decreased trend. It had relevance to the activities of related enzymes. However, content of the dissolvable protein and amino acid during gastrula stage were higher than that of during blastula stage. Among all the amino acids determined, content of Glu was the highest, the highest essential amino acid (EAA) content was Leu. There was little difference between the ratios of content of single EAA to total EAA during different stages of embryonic development of M. nipponense.
The purpose of this paper was to compare two methods of acquiring free sperms from spermatophores of Chinese mitten-handed crab (Eriocheir sinensis). Under the condition of pH 7.4 and different reaction temperatures (27 ℃,32 ℃,37 ℃,42 ℃and 47 ℃, respectively), trypsinase concentrations (0.05 %, 0.10 %, 0.15 %, 0.20 % and 0.25 %, respectively) and reaction times(5 min，10 min，15 min，20 min and 25 min, respectively), the best reaction condition of trypsinase digestion method (TDM) was studied by orthogonal tests and the sperm amounts which got from each gram of spermatophores was used as a criterion. According to the results of orthogonal tests, we found that enzymatic reaction time was the primary factor, and the reaction temperature and the trypsinase concentration also functioned. The maximum effect of trypsinase digesting works at temperature 37 ℃, trypsinase concentration 0.20 % and time 5 min. By using TDM the amounts of free sperms acquired from each gram of spermatophore were 7.41×108 which was significantly higher than that using HM which was only 3.33×108 and the sperm mortality rate was 4.75 % by using TDM which was significantly lower than that using HM which was 27.00 %. Furthermore, the acrosome reaction ability was detected by artificially-induced methodology and the reaction rates were 62.3 % (TDM) and 64.5 % (HM), and there was no significant difference between them. These results suggest that TDM is more effective than HM in acquiring free sperms.
15α-hydroxylation of 13-ethyl-estr-4-ene-3,17-dione using immobilized Penicillium raistrickii entrapped in calcium alginate gel was studied. The conversion conditions, which affected hydroxylation such as substrate concentration, the time to add substrate, conversion duration, were investigated. The results show that, the immobilized Penicillium raistrickii can be utilized repeatedly five times with no obvious decline of hydroxylation ability.
The effects of Puararia flavonoids(PF) on bovine vascular endothelial cells(VEC) in vitro injured by advanced glycation end products(AGEs) were investigated. When VEC was incubated with AGEs(4 g/L) for 48 hours, the growth of VEC was enhanced, the contents of lactate dehydrogenase(LDH) and malondialdehyde(MDA) and lipofuscin(LPF) were markedly increased(P<0.01), the contents of nitric oxide(NO-2/ NO-3) and glutatuhione(GSH) were reduced. Treatment with PF caused a reduction in LDH and MDA and LPF, the contents of GSH and NO-2/ NO-3 were increased. The results suggest AGEs has direct effects on VEC, perhaps oxidative stress participates in this process. PF can protect cultured VEC from being injured by AGEs, thereby exert favorable effect against the occurrence and development of chronic vascular complications in diabetic mellitus.
Gene expression of VHA-c was detected in Arabidopsis silique, flower, leaf, bolt, root. However, the expression level of VHA-c3 was much higher in leaves than in the other tissues. Analysis of the putative promoter of VHA-c3 was carried out in tobacoo leave system. A series of the promoter mutants were constructed in which various extents of VHA-c3 promoter were placed upstream of the GUS gene in vector pC1305.1. The expression of GUS was analyzed by Agrobacterium-mediated transient expression system.It was found that a 2 812 bp promoter region has high gene expression capacity. And there is a high potential key cis-element for leaf-specific expression between 2812-2 234 bp region.
中国综合性科技类核心期刊(北大核心)
