Issue Ebookcover storyIssue Cover
List of IssuesDocument Types
- Keywords：rice,heterotic ecotypes,two-line hybrid rice1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The dynamic change of polyphenol oxidase,peroxidase,amylase and protease activities as well as of relevant chemical composition of three flue-cured tobacco varieties were studied.The results showed that activity of polyphenol oxidase,peroxidase,amylase and protease increased at the earlier stage of aging and decreased at the later stage.This activity reached 47.7?u/g,54.27?u/g,12?mg/g and 4.74?u/g respectively after aged 6 or 9 months.The contents of polyphenols and pigments tended to decrease with the length of aging time,they decreased 12.92% and 17.85% respectively,compared with those in tobacco leaves at earlier stage.The contents of starch and soluble protein also tended to decrease with the length of aging time;they decreased by 8.07% and 45.47% respectively,compared with the contents in tobacco leaves at earlier stage.Keywords：flue-cured tobacco,aging,enzyme activity,chemical components3|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：DGAT1 gene,beef cattle,SSCP assay,carcass traits4|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Full-length cDNA encoding transthyretin(TTR),a thyroid hormone-binding protein,of Pekin ducks was isolated by means of rapid amplification of cDNA ends(RACE) to investigate the potential involvement of TTR gene in duck lipogenesis.The full-length duck TTR mRNA encodes a single polypeptide of 150 amino acids,which consists of a signal peptide of 20 amino acids and a mature peptide of 130 amino acids,similar to the chicken counterpart.A structure of three extra amino acids,-Val-Ser-His,near the amino terminus of TTR subunit,which could lead to an increase in T3-binding affinity of the avian TTR,is conserved between in the duck and in the chicken.Expression profile of TTR gene in the duck was measured using real-time quantitative PCR(qRT-PCR). The highest concentration of TTR mRNA was detected in the choroid plexus,similar to those in the chicken,reptiles and mammals.Moreover,the expression abundance of TTR gene in choroid plexus was higher in the duck than in the chicken.It was also demonstrated that the TTR mRNA expressed in the fat tissues of ducks,especially in subcutaneous fat.Keywords：transthyretin,duck,cDNA cloning,expression1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：Beijing duck,vasoactive intestinal peptide,clone,sequence analysis0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：porcine,spermatozoa,cryopreservation,normal temperature preservation3|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：sheep,cobalt,vitamin B_(12),biological functions0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：This study was conducted to determine the effects of dietary XOS supplementation on growth performance and intestinal physiology and morphological parameters of mucous membrane of broilers.Four levels of XOS were set as 0,1,2,and 4 g/kg. Three hundred and 36 one-day-old Arbor Acre male broiler chicks were randomly allocated into four groups with 6 replicates each.The result showed that the accumulative mortality and feed conversion ratio during 0 to 7 wk were significantly reduced by XOS(P<0.05).Compared to the control,feeding with 2 g/kg XOS reduced by 4% the feed conversion ratio during 0 to 7 wk.The number of Lactobacillus in ileum significantly increased up to 26.3%,20.8% and 28.1% respectively,whereas the number of coliform in cecum decreased by 8%,26.9% and 12.0%(P<0.05),accordingly.XOS also could decrease the content of ammoniacal nitrogen to 77.8% and 68.3% of the control,and increase the content of monoprop,isobutyric acid and isovalerate in ileum(P<0.05).Dietary supplementation of XOS did not influence the morphology of intestinal mucous membrane.Keywords：XOS,performance,intestinal microorganisms,ammoniacal nitrogen,volatile fatty acid0|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：pork,light exposure,lipid oxidation,color change0|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The experiments were performed to investigate the relationship between the physical-chemical properties and the nutrient contents in layer manure in order to estimate its component contents as fertilizer.The results showed that the value of specific gravity(SG) could be used to evaluate total phosphorus and total potassium contents in layer manure and the correlative coefficients approached to 0.716 and 0.722 respectively;while electrical conductivity(EC) to evaluate total nitrogen,total phosphorus and total potassium in layer manure and the correlative coefficients amounted to 0.509,0.726 and 0.846 respectively. With increase of dilution multiple,the correlation coefficient of the regression equation between EC and the nutrient contents increase first and later decrease.The component contents of layer manure can be estimated by these two physical-chemical parameters,SG and EC.Keywords：layer manure,fertilizer value,electrical conductivity(EC),specific gravity(SG)1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：persimmon wine stillage,cattle manure,co-compost1|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：Mortierella isabellina Oudem mycelia(MIOM),TC(total cholesterol),TG(triglycerides),high density lipid-cholesterol(HDL-C),blood lipid lowering0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：An evaluation model on environmental benefit of water saving agriculture in arid continental river basin was established by the modified analytical hierarchy process.The criteria layer of this model was constituted by the balances of water amount,soil-water,silt-water,and salt-water,the control of water quality and the creature and landscape in an environment system.The factor layer of the model includes twenty-eight evaluation indicators.These exponents were assessed quantitatively by the modified analytical hierarchy process.In this model the evaluation object was delaminated serially at first,and then the weighing values of all the factors in each layer were determined by the mathematical method.At last,the compounding weighing values of relative significance of the lowest layer to the highest layer were calculated synthetically.The model provides a decision-making reference for the water resource development and utilization and the water-saving program at irrigation district in arid continental river basin.As an example,the environment benefit on an irrigation district in arid continental river basin of northwest China was evaluated,by this model,and expounded.The estimated result manifested that the environmental benefit in the irrigation district could be enhanced by 8.5 per cent and 14.9 per cent when the water use coefficient was raised from 0.3 to 0.4 and 0.5 respectively.The theoretical analysis and application instance testified that the model established by the modified analytical hierarchy process had the features of strong logic,simple structure and stable precise.Keywords：water saving in agriculture,environment benefit,evaluation model,modified analytic hierarchy process1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the land use data of each county,we introduced the concept of Lorenz curve and Gini coefficients(GC) to analyze the land use distribution in Beijing mountain area.The result indicated that the most unbalanced lands were those used for construction(GC=0.325) and garden(GC=0.276),followed by the cultivated land(GC=0.258).The unused land and that for forestry(GC=0.18) were balanced.With time,the unbalanced degree of the garden,construction and unused lands decreased,while that of the cultivated and forestry lands exhibited an opposite trend.Thus,in Beijing mountain area,the distribution of five major land use types is temporally and spatially unbalanced.This result can be helpful for structural optimization of land use.Keywords：spatial structure of land use,Beijing mountain area,Lorenz curve,Gini coefficient0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：position baseline,2G-R-B gray transformation,OTSU,Hough transformation4|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the conservation tillage systems for two crops a year region, the authors analyzed the influencing factors of evaporation under the conservation tillage.The fitting relations between evaporation and leaf index,as well as ground surface coverage,soil temperature,and surface soil moisture were investigated respectively.The results show that daily evaporation on the eight tillage systems has good cubic relations with the leaf index and ground coverage respectively;the evaporation on the seven tillage systems has good cubic relations with the soil surface water content;and the evaporation on the three tillage systems has good cubic relations with the surface soil temperature.So the evaporation quantity can be approximately estimated by the leaf index or surface coverage.Keywords：daily evaporation,surface ground coverage,conservation tillage,fitting function1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Four available porous pavement systems were studied to evaluate their infiltration capabilities of precipitation.The experiments were conducted to simulate different kinds of porous pavements with different sub-base materials in each of catchments,and the discharge volumes from each cell were monitored.The relationship between rainfall intensity,outflow and outflow duration was analyzed.Physical models were established in the laboratory.Because of storage of sub-base, the infiltration forms subsurface flow in the porous concrete block paving and sub-base,which increase infiltration into subgrade after rainfall.The results showed that the runoff coefficients of all treatments were 0 under a rainfall rate of 59.36?mm/h,and the infiltration coefficient of porous pavement was in direct proportion with porosity and inverse proportion with soil moisture.In all treatments,the optimum thickness of the porous pavement is 36-cm that consistes of a 6-cm porous surface course and a 30-cm sub-base(10-cm sands and 20-cm gravel).When rainfall rate is 59.36?mm/h,and the lasting time is 2 hours,the runoff coefficient of treatment 1 is 0.In condition of building new residential area,pavements,parks;and rebuilding former overage drainage system too cost,the porous pavement system is a substitute for different imporous surface.Keywords：porous pavement,sub-base,subgrade,artificial rainfall,infiltration0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Using the weight function method,the fracture of a submarine pipeline with circumferential surface cracks is studied.A practical formula for evaluating the stress intensity factors is derived,which is important in ocean engineering.Based on the solutions of stress intensity factors and statistical models of uncertainties,a reliability assessment method for submarine pipelines with surface cracks is proposed and a computational formula for predicting the probability of fracture is given.Finally,a typical numerical example is presented to illustrate the proposed method.The results show that the calculated stress intensity factor value will augment as increases of the length and depth of the crack,and the conclusion is consistent with those from the existed references.Taking the length and depth of the cracks,the thickness and radius of the pipe,and the longitudinal stress as random variables,the reliability of the crack submarine pipe will be decreased as expanding of the mean of the longitudinal stress while the bending moment keeps constant.Keywords：submarine pipeline,weight function method,stress intensity factor,reliability analysis,0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To realize the optimal power and the best fuel economy performance of an engine,the speed ratio matching strategies of a tractor with hydro-mechanical continuously variable transmission(HMCVT) system were studied.The engine output torque model and fuel consumption model were established based on the engine test results.On the basis of the engine rotary speed feature,the target speed ratios of HMCVT system in the numerical table were given,which realized the optimal power and the best fuel economy performance within the speed ratio range of the HMCVT system.The tractive performances from the tractor equipped with HMCVT and the original tractor were compared.The results showed that a tractor assembled with HMCVT could gain a continuously variable speed and the engine worked near full load under any traction load.As a result,the tractors with the HMCVT would improve themselves productivities and fuel economies.The speed ratio matching strategies are reasonable.Keywords：tractor,hydro-mechanical continuously variable transmission,engine model,speed ratio matching6|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
Comparison and research of grain production forecasting with methods of GM(1,N) gray system and BPNN
Abstract：Based on the project of National Grain Warning System,aiming at predicting the grain output of China,this paper has compared and analyzed forecasting performances of three methods,namely step regression,BP neural network and GM(1,N) gray system.According to the principle of calculable and having agricultural significance,we chose twelve important effecting factors,and established respective forecasting model with the above three methods.Results showed that the average error of the method of BPNN was 1.44% and its average forecast error on five years could reach 2.89%,which is better than the other two methods in performances.It can be used in the project of National Grain Warning System.Finally the paper lists feasible methods to optimize the BPNN farther.Keywords：step regression,GM(1,N) gray system,BP neural network,forecast of grain production3|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27- Abstract：Digital watermarking is an effective approach for information security and copyright protection.It has been a hot technology in the field of multimedia information security.In this paper,a watermarking algorithm for digital image based on DWT and DCT is introduced.This algorithm manipulates the original image by DWT,then adds watermark through Arnold transform onto the important wavelet coefficients located at the low frequency sub-band,which is split into blocks and manipulated by DCT.The test based on this algorithm demonstrates that the watermarking is robust to the common signal processing techniques including medium filtering and cutting.Keywords：watermarking,discrete wavelet transform,discrete cosine transform,Arnold transform0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The purpose of the paper is to design a new type of intrusion detection system with a transaction-level database,which can be used to detect illegal users and their malicious transactional operations on the basis of the intrusion detection theory,the role-based access control mechanism and the data mining technology.In the training period,the rule database is formed by the sequential pattern discovery method to mine the role log files.When the database works,the system can find malicious transactions by using the algorithm of database intrusion detection.Based on the test,we draw the conclusion that the detection granularity is finer and its maintenance is easier.Keywords：database security,intrusion detection,data mining,data dependency0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：A reformative algorithm,based on the short-time fractal dimension,is given to improve VAD(voice activity detection) in low signal-to-noise ratio(SNR) environments.Two ways to calculate the fractal dimensions of speech signals in common were compared,and one was selected to fit the speech signals.At the same time,a dynamically updated threshold was applied to adaptively detect the speech segments in noisy speech.The experimental results showed that the method could realize the detection of speech segment in low signal-to-noise ratio(SNR at 6-10dB) and had a good noise robustness.Keywords：VAD,fractal dimension,dynamic threshold,adaptive1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：A hot-upsetting forging process of Inconel751 alloy is very complicated,during which some defects of the head of work piece,such as thick crystalline grain,overheated and overburnt,upsetted split,and head fold,may happen.These defects have serious influences on the safe operating and technological progress of locomotive engine in China.The FEM software package,Marc/Autoforge 3.1, was used to simulate strain field and grain size distribution during hot-upsetting forging of Inconel751 alloy in this paper.The strain field and grain size distribution were obtained,and the influence of different deformations on Inconel751 alloy texture were analyzed.The result indicates that the effective strain field and grain distribution in hot-upsetting process of Inconel751 alloy show a ladder distribution.Keywords：hot-upsetting,numerical simulation,re-crystallization,strain field7|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The quantum chemistry calculation of shikonin derivates was carried out by the Gaussian 03 Program Package to investigate the relationship between the structure of shikonin derivates and its activity of anti-phytovirus.The geometrical configuration,orbital energy,orbital composition and net charge of each atom of the molecules were analyzed and the relationship between anti-phytovirus activities and the quantum chemical properties was studied.The conclusions were as follows: 1) the anti-phytovirus activities of shikonin derivates have a linear relationship with energy and composition of LUMO and the LUMO molecular orbitals play important role in the anti-phytovirus activities;2) the active sites of shikonin derivates were at the structure of naphthaquinone,and R groups was an effective structure modified site;3)when the compound molecule interacted with the target acceptor,the electron transfer between the shikonin derivates molecule and the target acceptor might be happened to form the electron-transferred-complex.Keywords：shikonin derivates,quantitative structure-activity relationship,anti-virus activity,quantum chemistry0|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Keywords：lutein,corn gluten meal(CGM),extraction,saponification,technology1|6|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
