最新刊期
卷 55 ， 期 6 ， 2016
- 摘要：Saline water intrusions at Modaomen waterway were numerically simulated by using MIKE3 based on measured water levels and salinities in November 2006 and January 2007. Calibrated and validated model showed good fitness for both water level and salinity in case of prediction and observation with good detection indexes. The results indicated that salinity stratification, influenced by topography, diversion ratio and other factors such as tidal fluctuation change, resulted in water density difference and then produced extraordinary change in salinity vertical circulation. The change of salt flux is relative to the tidal flux, suggesting that tide is the carrier of brine.关键词：MIKE3;saline water intrusion;Modaomen waterway;characteristic analysis
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发布时间：2023-12-11 - 摘要：As the critical water source of large cities such as Hong Kong and Guangzhou, the East River is influenced significantly in the hydrological processes by the Xinfengjiang, Fengshuba and Baipenzhu reservoirs. Copula functions are used to analyze the possibly-synchronous occurrence of high- and low-flow regimes in the East River. The results indicate that: ① The marginal distribution with the highest goodness-of-fit is log-normal distribution and generalized extreme value distribution. Meanwhile, the Gumbel Hougaard Copula has the best fitting efficacy for the inflow series of the hydrological stations; ② Three water-reservoirs have great impact on the synchronous occurrence of high and low flow events at 6 pairs of hydrological stations in the downstream, the reservoirs have the filling valley and modulating peak effects which cause flattened hydrological processes when compared to those in the upper and middle East River basin. Besides, the synchronous occurrences of normal vs. normal flows in the upper and the middle East River basin show an increasing trend, causing flattened hydrological variation of the East River basin; ③ The hydrological processes at the Longchuan, Lingyuan, Lingxia and Boluo stations are heavily influenced by hydraulic facilities and scare occurrences can be observed for the peak flood flow and flood discharge, which greatly reduced the flood risks; ④ The construction of water reservoirs can flatten the hydrological processes and reduce the occurrence frequency of high and low flows, being beneficial for flood mitigation.关键词：marginal distribution;copula functions;synchronous occurrences;return period
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发布时间：2023-12-11 - 摘要：Bayesian Model Averaging (BMA) is applied to monthly precipitation forecasting in the flood season over the Dongjiang basin to correct the bias of Climate Forecast System version2 (CFSv2). In the meantime, Standardized Anomaly (SA) is used to quantify the precipitation abnormality and incorporated into the deterministic and ensemble forecasting. A better precipitation forecasting model is then established by the combination of BMA and SA to improve accuracy of long-term precipitation forecasting in the Dongjiang basin. Conclusions are drawn as follows: ① The 50th percentile and below of ensemble forecasting have poor skill , whereas the 75th percentile is usually in agreement with observations. However, BMA has disadvantage in that it underestimates precipitation amount when extreme events occur. ② The value of SA based on the ensemble average of CFSv2 is too small, indicating a systematic bias of CFSv2. When the CFSv2 raw forecasting is corrected by gamma function and multinomial, both Threat Score and the number of greatly increases but Bias Score increases in the meanwhile; ③ The relationship between SA and BMA can be expressed as follows: the 95th percentile of ensemble forecasting is used when SA indicates an abnormal precipitation, otherwise the 75th percentile is used.关键词：BMA;SA;CFSv2;flood season;the Dongjiang basin
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发布时间：2023-12-11 - 摘要：Based on GIS technology, the integrated assessment on flood risk in Hanzhong city in Shaanxi Province was carried out by using administrative county as basic assessment unit. Natural factors including precipitation, precipitation variability, terrain elevation, slope and water system distribution were comprehensively considered in the flood hazard assessment. Socio-economic indicators including population density, annual grain output per unit area and GDP density were analyzed for the flood vulnerability assessment. A map of flood hazard assessment and a map of flood vulnerability assessment are constructed by combining with AHP and GIS technology. Then, superposition analysis method for flood hazard and vulnerability assessment was performed based on GIS technology, and the flood integrated risk assessment of Hanzhong city was obtained. The flood hazard risk of Hanzhong city was concentrated mainly in the Hanzhong basin and declined gradually from basin center to two sides around the main stream. The flood risk level is the highest in the southern part of Hanzhong, in the middle part of Chenggu county and in the northeastern part of Nanzheng county. The low level areas of flood disaster risk were Mian, Xixiang and Yang counties. Liuba county was the lowest in flood hazard risk. The assessment results are corresponding with the flood hazard occurrence in Hanzhong city in 2012, which can provide a scientific basis for making reasonable flood control and mitigation planning in Hanzhong city.关键词：flood hazard;risk assessment;the upper reaches of Hanjiang River;Hanzhong City;Shaanxi Province
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发布时间：2023-12-11 - 摘要：The Lower Cretaceous is the target stratum of potential regional oilgas exploration in the Modamuji Depression, Hailaer Basin. Organic geochemistry methods were applied to study geochemical characteristics of Lower Cretaceous hydrocarbon source rocks from the Modamuji Depression. The results showed that the organic matter of K1n and K1d formation is mainly type Ⅱ2-Ⅲ with various abundance and maturity. The proposed maturity evolution model based on restoration of burial history showed that the thermal evolution extent for main source rocks is generally low. The source rocks from K1d2are at the immature to low mature stage, those from K1d1are at low mature stage and those from K1n2are at low mature to mature stage. The hydrocarbon source rocks from K1n1showed a relatively high thermal evolution degree, which has reached the mature oil-generating stage. The comprehensive analyses indicated that K1d hydrocarbon source rocks are generally high in organic matters with a low thermal evolution and low hydrocarbongenerating potential. The thermal evolution degree of hydrocarbon source rocks increases with the buried depth. The K1n2hydrocarbon source rocks have entered the mature oil-generating stage with a moderate organic matter abundance and relatively higher hydrocarbon-generating potential. The hydrocarbon source rocks from K1n1are low in organic matter with relatively low hydrocarbongenerating potential.关键词：hydrocarbon source rocks;organic geochemical characteristics;organic matter abundance;organic matter type;maturity;Modamuji depression;Hailaer basin
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发布时间：2023-12-11 - 摘要：Brownian motion plays a very important role in both stochastic process and Schramm Loewner Evolution (SLE). Firstly, by using the properties of Brownian motions, it is derived that the probability expressions of Brownian motion exiting first at prescribed boundary parts of regions. The correctness of the obtained results is verified by numerical simulations. Secondly, the relationship between harmonic measure and probability of Brownian motion exiting first a simply connected domain at the specified boundary is discussed. The probability formulas of the former are derived by using the results of the latter. In addition, some other related results are obtained.关键词：Brownian motion;probability of first exit;Schramm-Loewner Evolution;harmonic measure
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发布时间：2023-12-11 -
Oscillations of certain third order nonlinear neutral functional differential equations with damping
摘要：The research on oscillation for general mechanical and electronic vibration mathematical models，which are usually functional differential equations, has important implications in both theory and practice. The oscillation of third-order nonlinear neutral functional differential equations with continuous distributed delay and damping terms is studied. By using the generalized Riccati transformation, H-function and integral averaging technique, some new sufficient conditions which insure that any solution of such equation oscillates or converges to zero are established. The corresponding known results are extended and improved.关键词：third-order neutral equations;damping terms;distributed delay;oscillation- 213
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发布时间：2023-12-11 - 摘要：The nullity of a graph is the multiplicity of zeroes in its adjacency spectrum. And the nullity of a graph G with n vertices equals to n minus the rank of adjacency matrix of G. The characteristic polynomials of graphs with nullity n－4 is computed. In particular, it is shown that some graphs with nullity n－4 are determined by their spectra. And some pairs of cospectral graphs with nullity n－4 are presented.关键词：characteristic polynomial;rank;nullity;cospectral graphs
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发布时间：2023-12-11 - 摘要：The rate of convergence for Newmantype rational interpolation to |x| is studied, and nodes near the zero of the Newman nodes are increased. Through the improvement of Newmans inequality, it is proved that the exact order of approximation is O〖JB((〗〖SX(〗1〖〗〖KF(〗n〖KF)〗e〖SX(〗3〖KF(〗n〖KF)〗〖〗2〖SX)〗〖SX)〗〖JB))〗, the result is better than the classical results of Newman. Further explanation: increases nodes in the near zero can improve the approximation order of the original.关键词：Newman nodes;Newman-type rational operators;Newman inequality;rational interpolation;order of approximation.
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发布时间：2023-12-11 - 摘要：The (k,d)- edge magic property of trees is studied. By using the connection between (k,d)- graceful labellings and (k,d)- edge magic total labellings for generating large classes of (k,d)- edge magic total trees from smaller graceful trees, the relationship between (k,d)- graceful labellings and (k,d)- edge magic labellings is established.关键词：graceful labellings;d)- graceful labellings;edge magic total labelling;(k;d)- edge magic total labelling
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发布时间：2023-12-11 - 摘要：The compactness of Toeplitz operators on Dirichlet space is studied. It is proved that finite sums of finite products of Toeplitz operators with bounded symbols are compact if and only if their Berezin-type transforms vanish on the boundary of the unit ball.关键词：Toeplitz operator;Berezin type transform;Dirichlet space;unit ball
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发布时间：2023-12-11 - 摘要：The fractional Noether symmetries and fractional conserved quantities for Hamilton system with time delay based on Caputo derivatives are discussed. The fractional Hamilton canonical equations of the corresconding system with time delay are established base upon the fractional Hamilton principle of the Hamilton systems with time delay. Then, the fractional Noether symmetries of the Hamilton system with time delay are obtained, which based on the invariance of the fractional Hamilton action with time delay under the infinitesimal transformations of group. Finally, fractional Noether theorems with time delay of the Hamilton system are established. At the end, one example is given to illustrate the application of the results.关键词：time delay;Hamilton system;Caputo derivatives;Noether symmetry;conserved quantity
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发布时间：2023-12-11 - 摘要：Based on the hot and humid climate outdoor testing site（Located in Qionghai） and sub-humid climate outdoor testing site(located in Guangzhou),the polycrystalline silicon photovoltaic modules fixed with resistive load were tested for studying performance changes in the real applications weather. The outdoor I-V tester and laboratory I-V tester were used to characterized the I-V parameters of various modules, the surface temperature of PV modules was recorded by the thermocouple in situ. The results showed that degradation of Isc, Pmax of PV modules were much higher applied in the hot and humid climate compared to the modules in sub-humid climate. The surface temperature of modules deployed in hot-humid climate was also higher than those in sub-humid climate.关键词：PV modules;typical climate;module surface temperature;PV modules performance degradation
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发布时间：2023-12-11 - 摘要：In order to satisfy the function demand of expressway traffic safety networked joint control, an expressway road network model is proposed, which is suitable for data presentation and operation. The model is constructed based on hierarchical topology network elements with landmark as a minimum size of the road network model partitions. The lanes are described precisely, and road network modeling units could be combined into abstract network according to different traffic demands. The model is composed by 6 parts including arc, arcnode, segment, segmentnode, lane and laneconnector, which could be used to describe the highway road network topology carefully. This model is tested in the emergency response of expressway by using the common section of Shen Hai expressway and ShanghaiShanxi expressway as a testing section, the result shows the model could satisfy traffic safety management demands effectively.关键词：expressway;highway network topology;data model
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发布时间：2023-12-11 - 摘要：A new calculation method of nonlinear oscillation circuit is presented and called as the response frequency alternation method. The phase angle is introduced as the independent functions. The waveform functional of the nonlinear oscillation circuit is shown as the cosine functional of the independent functions. The first derivative of the independent functions about the independent variable is meant by the response frequency of the circuit. The solution of the nonlinear state equation for the circuit is summed the determining of the response frequency for the circuit, and computed it with the alternation method. Using the differential relation of the response frequency between the phase angles, the approximate expression of the inverse transform for the independent variable is computed, and the expression of the variation for the state variable of the nonlinear oscillation circuit following with the time is shown as the parameter form of the independent functions. It is broken through the limit of the excitation parameters much less than 1 (i.e. weakly nonlinear) of the perturbation method and suitable for the strongly and weakly nonlinear circuit. A three-electrode oscillation circuit is discussed specifically with the excitation parameters of the 0.8 and 1, the calculation results are in good agreement with the numerical integral method after two times of iterative frequency, but the perturbation method is invalid.关键词：new computation method;nonlinear oscillation circuit;nonlinear state equation;waveform functional;response frequency alternation method
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发布时间：2023-12-11 - 摘要：Since the high density polyethylene(HDPE) is popularly used in areas such as the chemistry, construction and the military project, the types and the conditions for usage are verified. The uniaxial tensile test on the smooth surface specimens and the pattern surface specimens is performed, with different stretching speed and tensile directions. The experiment shows that the yield platform value of the smooth specimens also increases with the increase of the stretching speed, which is under the transversal tension. When the stretching speed is 150 mm/min, the smooth transversal tensile specimen has inconspicuous second yield point, which means that it has better performance on the tension. The rate dependence of the pattern specimens is more obvious and its value is 5.02% under 3 different stretching speed. However, the load the pattern specimens can undertake is lower contrast with the smooth specimens. It is easier for the pattern specimens to be broken than the smooth specimens, and it is also easier for the longitudinal tensile specimens to be broken than the transversal tensile specimens. Consequently, the smooth transversal tensile specimen has better tensile strength.关键词：the uniaxial tensile test;the rate dependence;the direction dependence;the high density polyethylene
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发布时间：2023-12-11 - 摘要：Meso-level heterogeneous distribution of interface mechanical parameters has been investigated. Numerical models for twin fibers pull-out test have been created by using finite element method. Influence of interface strength on damage pattern and mechanical properties have been studied on twin fibers pull-out test specimens. By applying load with displacement control, load-displacement curves, AE accumulative curves and interface shear stress distribution curves of twin fibers and concrete matrix test specimen have been plotted. The damage pattern and AE pattern of pull-out test specimen changed along with the interface strength. As interface strength is low, both peak load and toughness increase with interface strength, and both peak load and toughness dont change obviously with high interface strength.关键词：double fiber pull-out test;interface strength;acoustic emission;peak load;toughness
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发布时间：2023-12-11 - 摘要：The bare reaction of chiral transition of ibuprofen molecules and the mechanism of waterassisted proton transfer from carbon to carbonyl were studied using the B3LYP method of density functional theory and the MP2 method of perturbation theory. The molecular structure analysis showed that the hydrogen bond angles corresponding to the eight membered ring transition state bTS2·2H2O, and the ten membered ring transition state bTS2·3H2O in the processes of water-assisted proton transfer from carbon to carbonyl were all much larger than that corresponding to the six membered ring transition state bTS2·1H2O. Moreover the eight membered ring structure of transition state bTS2·2H2O was almost coplanar, and the ten membered ring structure of transition state a_TS1·3H2O/bTS2·3H2O was obviously out of plane. The study on the reaction path showed that there were six paths in the title reaction, where respectively proton only using ketonic O or methyl C and carbonyl O or carbonyl and benzene ring as the transfer bridge from one side to the other of chiral C. Calculations of potential energy surface showed that the path using proton was the dominant reaction channel, and carbonyl and benzene ring as the transfer bridge was the dominant reaction path. The Gibbs free energy barrier of the rate-determining step of bare reaction was 287.1 kJ·mol-1, which would be reduced to 144.9 kJ·mol-1because of the chains constituted by two water molecules. The results showed that the chiral transition of ibuprofen molecules could be realized in multiple paths and the water molecules had a better catalysis on H transfer heterogeneous reaction of ibuprofen molecules, as well as the presence of water molecules in the body of a life, temperature fluctuations, molecular frequent collisions and the action of some enzyme conditions were the cause of S-Ibu optical isomers.关键词：chiral;ibuprofen;density functional theory;transition state;perturbation theory;Gibbs free energy
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发布时间：2023-12-11 - 摘要：Shewanella is a gram-negative soil iron reducing bacteria, which has extracellular electron transfer ability. The composition of the extracellular polymer is one of the important factors that can directly influence the electron transfer effect. Extracellular polysaccharide (EPS) is an important component of extracellular polymers. The effect of different concentrations of CaCl2(0, 0.7，1.4， 2.1 and 5.0 mmol/L) on the EPS of Shewanella oneidensis MR-1 was herein studied by phenol sulfuric acid method combined with spectrophotometry, chromatography and mass spectrometry. The results showed that the amount of EPS would vary with the Ca2+concentration. Maximum EPS production of 0.3 g /mL was obtained in the culture medium with 2.1 mmol/L of Ca2+concentration, which was 5 times greater than that obtained without Ca2+. The amount of EPS obtained with 1.4 mmol/L Ca2+concentration was 0.08 g/mL, which was nearly the same to that obtained without Ca2+. The concentration of Ca2+in the medium did not significantly influence the structure of EPS produced by MR-1. EPS had a repeating unit with a ［→3)-α-D-Manp(1→］ backbone chain. The results of this study provide reference data for the further study of Shewanella extracellular polymers.
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发布时间：2023-12-11 - 摘要：4-acetyl-5,6,7-trimethoxy-1,4a-dimethyl-4,4a-dihydro-3-H-fluoren-3-one was synthesized by treatment of 3,4,5-trimethoxybenzaldehyde and excessive actylacetone, using H2SO4or CuCl2as a catalyst. The structure was analyzed by 1D NMR (1H NMR and13C NMR), 2D NMR (H-H COSY, HSQC and HMBC), LC-MS and elemental analysis and confirmed by crystal structure. The product showed strong fluorescence in ethano (λex=370 nm, λem=529 nm).关键词：dihydrofluorenone;concentrated sulfuric acid;copper chloride;fluorescent probe
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发布时间：2023-12-11 - 摘要：The SiO2microspheres with abundant thiol on the surface have the same property of adsorption to heavy metal ions as that of the mesoporous silica. In onepot, the thiol-functionalized SiO2microspheres were prepared by a sol-gel method, and SiO2microspheres had a narrow particle size distribution and well sphere with diameter around 1 μm. FTIR and Raman spectroscopy confirmed there were a great amount of thiols on the surface of microspheres. Meanwhile, the adsorption process of silver ions by the microspheres finished within u1tra-short time, which was in accord with the chelation of silver ions and thiols. And that was different from the diffusion adsorption of mesoporous silica. Furthermore, the pH value of solution had little effect on the adsorption capacity of silver ions and the adsorption maximum is 102 mg/g in Slips isotherm with R2=99.6%.关键词：thiol;SiO2;microspheres;adsorption;silver ions
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发布时间：2023-12-11 - 摘要：To investigate the water purification effects of different floatingbed systems and their influences on aquatic organisms, floating-bed systems vegetated with Vetiveria zizanioides, Iris pseudacorus, Apium graveolens or their combinations respectively were constructed, 6 species of phytoplankton as well as zebrafish (Danio rerio) were also added to the systems. The results showed that the three plant species could all grow well in the floating-bed. The growth of Vetiveria zizanioides and Iris pseudacorus were better than Apium graveolens. All floatingbed systems could prevent the increase of chemical oxygen demand (CODMn) in water. However, no significant difference was observed among different floating-bed systems. Floating-bed systems could also remove the nitrogen and phosphorus nutrients in the water effectively, with V. zizanioides having the best effect. In general, putting Danio rerio into the systems improved the water purification efficiency to some extent. Floating-beds cultivated with V. zizanioides significantly inhibited the growth of phytoplankton, while the inhibition effects of floating-beds vegetated with other plants were relatively lower or not significant. On the other side, the sensitivity of different phytoplankton species to floating-bed systems was different. The growth of D. rerio was significantly stimulated by floating-beds cultivated with V. zizanioides or I. pseudacorus, with V. zizanioides being more effective. Overall, V. zizanioides might be an excellent candidate for floating-bed cultivation in water purification and bloom prevention, while I. pseudacorus might be used in water purification of urban landscapes.关键词：plant floating-bed;water purification;phytoplankton;Vetiveria zizanioides;Iris pseudacorus;Apium graveolens
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发布时间：2023-12-11 - 摘要：The present study was designed to investigate the effect of Amentoflame (AF) on the angiogenesis of human umbilical vein endothelial cells ECV304 and the mechanisms involved. MTS assay was performed to assess the effect of AF on ECV304 cell proliferation. Wound Healing was performed to assess the effect of AF on ECV304 cell migration. Matrigel assay was performed to assess the effect of AF on ECV304 tube formation. Western blotting was used to analyze the expression of cell angiogenesis related proteins such as angiopoietin 2 (Ang-2)、Matrix metalloproteinase-9 (MMP-9) and p-AKT in ECV304 treated with or without AF. The results demonstrated that AF inhibited the proliferation, migration and tube formation of ECV304 concentration-dependently. Western blot showed that the expression of p-AKT, Ang-2 and MMP-9 were significantly down-regulated by 100 μmol/l of AF.关键词：angiogenesis;endothelial cells;Amentoflame
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发布时间：2023-12-11 -
Bioaccumulation of Cd, Zn and Pb by three heavy metal-resistant endophytic fungi isolated from rapes
摘要：The aim of this study was to select the effective microbial agents to remediate heavy metal pollutants by investigating the potential of the growing biomass of the three endophytic fungi through bioaccumulation to remove metals from contaminated water. In this study, three endophytic fungi Fusarium sp. CBRF14, Penicillium sp. CBRF65, Alternaria sp. CBSF68 tolerant Cd, Pb, and Zn were isolated from rapes growing in DaBao metal contaminated soils. And then we investigated the effects of initial metals (Cd, Pb and Zn) concentrations on the biomass, the metal bioaccumulation capacities and bioaccumulation percentages of the endophytic fungi. The results showed that the bioaccumulation percentages of Cd and Zn by CBRF14, CBRF65 and CBSF68 decreased with the increase of initial concentrations of Cd and Zn in general, however, the bioaccumulation percentage of Pb by CBRF14 and CBSF68 showed a pattern of “increase-decline”. With the increase of the initial Cd, Pb, and Zn concentrations, the biomass of CBRF14, CBRF65 and CBSF68 showed the declined trend, but the bioaccumulation capacities of metals increased. The maximum bioaccumulation capacities of CBRF14, CBRF65 and CBSF68 were 20.5~53.4 mg·g-1for Cd, 188.9~356.6 mg·g-1for Pb, and 28.4 ~ 292.8 mg·g-1for Zn, respectively. The results indicated that the three heavy metal-resistant endophytic fungi from rapes could live and accumulate metals in solutions with heavy metals, which suggested that they had the potential to remove heavy metals from metal-contaminated water. The results also indicated that plants accumulating multiple metals might harbor diverse fungal endophytes suitable for bioaccumulation of metals.关键词：fungal endophytes;bioaccumulation;growing mycelium;heavy metals- 252
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发布时间：2023-12-11 - 摘要：Haemocoagulase Acutus (Halase), a new hemostatic in development, is a highperformance thrombin-like enzyme (TLE) derived from snake venom of Agkistrodon acutus. Here we reported a new process established for separation and purification of Halase from snake venom. Combined with tangential flow filtration, ion exchange chromatography was conducted twice to effectively separate Halase, and two gel exclusion columns were used to remove pyrogen and salt. This new method is simple and efficient, and generates a high purity of Halase, making it a promising process in industrial scale application.关键词：Haemocoagulase Acutus;separation;purification;process
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发布时间：2023-12-11
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