There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresse...There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.展开更多
Two new dinuclear lanthanidecomplexes,namely[Ln_(2)(dbm)_(2)(HL)_(2)(CH_(3)OH)_(2)]·4CH_(3)OH[Ln=Tb(1)and Dy(2),Hdbm=dibenzoylmethane]have been synthesized using prepared multidentate Schiff base ligand H_(3)L(hy...Two new dinuclear lanthanidecomplexes,namely[Ln_(2)(dbm)_(2)(HL)_(2)(CH_(3)OH)_(2)]·4CH_(3)OH[Ln=Tb(1)and Dy(2),Hdbm=dibenzoylmethane]have been synthesized using prepared multidentate Schiff base ligand H_(3)L(hydroxy‑acetic acid(4‑diethylamino‑2‑hydroxy‑benzylidene)‑hydrazide)with good biological activity.Structure characterizations show that the complex comprises two Ln3+ions,two dbm-ions,two HL^(2-)ligands,two CH_(3)OH molecules,and four free methanol molecules.Each Ln^(3+)ion is eight‑coordinated.The two central Lnions are bridged by twoμ_(2)‑O atoms leading to a parallelogram[Ln2O2]core.The interaction between the compounds(H_(3)L,1,and 2)and the calf thymus DNA(CT‑DNA)has been further confirmed by UV‑Vis spectrometry,fluorescence titration,and cyclic voltammetry.The results showed that both 1 and 2 could undergo insertion with CT‑DNA.CCDC:2343005,1;2343006,2.展开更多
目的探讨5F鞘组在经外周静脉穿刺置入中心静脉导管(peripherally inserted central catheter,PICC)中临床应用的效果。方法回顾性分析并总结2012年12月至2013年2月哈尔滨医科大学附属第一医院收治的应用5F鞘组10例行PICC患者的临床资料...目的探讨5F鞘组在经外周静脉穿刺置入中心静脉导管(peripherally inserted central catheter,PICC)中临床应用的效果。方法回顾性分析并总结2012年12月至2013年2月哈尔滨医科大学附属第一医院收治的应用5F鞘组10例行PICC患者的临床资料。结果 10例患者均顺利完成PICC,有2例患者术后出现静脉炎,其余患者均未发生严重的并发症。结论静脉穿刺条件差的患者应用5F鞘组行PICC导管有利于提高置管成功率。展开更多
Recent studies suggest that MHC class Ⅱ genetransfer could stimulate protective antitumor immunity.Whether xenogeneic MHC Ⅱ transfected tumor cells havethese effect is unknown. In this study, HLA-DR3 α and βchain ...Recent studies suggest that MHC class Ⅱ genetransfer could stimulate protective antitumor immunity.Whether xenogeneic MHC Ⅱ transfected tumor cells havethese effect is unknown. In this study, HLA-DR3 α and βchain cDNA were cloned by RT-PCR from human Blymphoma Raji cell line and confirmed by DNAsequencing. The recombinant expressing vectors wereconstructed by inserting the α and β chain cDNA intoPCEP4/pLXSN vectors respectively. After transfectingby lipofectamine and selecting with G418 and Hyg, theHLA-DR3 transfected mouse melanoma B16 recombinantclones were obtained. Approximately 59% of展开更多
AIM:To investigate whether cilostazol suppresses intimal hyperplasia and to elucidate its mechanism. METHODS:The effects of cilostazol to the expression of lectin-like oxidized low-density lipoprotein receptor-1(LOX-1...AIM:To investigate whether cilostazol suppresses intimal hyperplasia and to elucidate its mechanism. METHODS:The effects of cilostazol to the expression of lectin-like oxidized low-density lipoprotein receptor-1(LOX-1)at mRNA and protein levels,superoxide generation and neointimal hyperplasia in the rat carotid artery after balloon injury were examined.展开更多
This paper presents an approach for mitigating the cross-eye jamming using a dual-polarization array. By transmitting a sum beam and a difference beam in two orthogonal polarimetric channels, a synthesized transmitted...This paper presents an approach for mitigating the cross-eye jamming using a dual-polarization array. By transmitting a sum beam and a difference beam in two orthogonal polarimetric channels, a synthesized transmitted beam with spatially varying polarization is produced, such that the polarization of the transmitted radar wave varies in azimuth or elevation. Thus, the phases of the signals received on the two antennas of a cross-eye jammer become unequal, and an additional phase difference is introduced to disrupt the 180？ phase shifting in the retrodirective loop of the jammer. By means of beam scanning in a small angular range,the optimal beam steering configuration can be found to maximize the phase error for the mitigation of cross-eye jamming. As a result, the jamming performance of the cross-eye jammer degrades largely. Theoretical analysis and simulation results indicate that the proposed method is valid and feasible.展开更多
Through quantitative statistics and morphological characterization of ceramic fragments for ceramic composite bulletproof insert plates(CCBIPs),distribution characteristics of ceramic fragments within a specific size ...Through quantitative statistics and morphological characterization of ceramic fragments for ceramic composite bulletproof insert plates(CCBIPs),distribution characteristics of ceramic fragments within a specific size range were analyzed for different Armor Piercing Incendiary(API)and shot times.To quantitatively evaluate the effect of energy absorption for ceramic plates,a model of energy absorption during penetration for CCBIPs was established based on statistics of the size distribution of ceramic fragments(SDCF).Variation in the SDCF and its influence on energy absorption for CCBIPs were investigated.The results indicate that the distribution feature of ceramic fragments in the range of 0.25-2.25 mm is Gaussian distribution.Compared with Type 56 of API(56-API),ceramic fragments formed by 53-API with higher kinetic energy possess more quantity and more concentrated distribution,whose average equivalence size decreases by 6.5%,corresponding to increasing by 83.9%of estimated energy absorption.Besides,the ability of CCBIPs to resist the third shot is significantly weakened,whose estimated energy absorption decreases by 58.8%compared with the first shot.More concentrated distribution and fewer fragments are formed after the third shot,the average equivalence size of ceramic fragments increases by 6.9%,which may attribute to the micro-cracks induced by the previous two shots.展开更多
Chain length of closed circle DNA is equal. The same closed circle DNA＇s position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so clos...Chain length of closed circle DNA is equal. The same closed circle DNA＇s position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so closed circle DNA computing model is generalized. For change positive-weighted Hamilton circuit problem, closed circle DNA algorithm is put forward. First, three groups of DNA encoding are encoded for all arcs, and deck groups are designed for all vertices. All possible solutions are composed. Then, the feasible solutions are filtered out by using group detect experiment, and the optimization solutions are obtained by using group insert experiment and electrophoresis experiment. Finally, all optimization solutions are found by using detect experiment. Complexity of algorithm is concluded and validity of DNA algorithm is explained by an example. Three dominances of the closed circle DNA algorithm are analyzed, and characteristics and dominances of group delete experiment are discussed.展开更多
In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that ...In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that its period is prolonged while its computation time keeps unchanged. An interesting problem is to find the earliest time to release new tasks without any deadline missing,that is,the earliest smooth insertion time. In this paper,a general frame to calculate the earliest time with multiple rounds of deadline checking is given,which shows that the checking can be done from the request time of the new tasks. A smart way is provided and proved,which takes the value of theΔchecking of the current round as the time step to the next. These techniques potentially reduce the amount of the calculation and the number of the rounds of the checking to get the earliest time. Simulation results are also given to support the conclusion.展开更多
Heat shock protein 90 (Hsp90) is a major heatshock protein whose functions are necessary for livingorganisms, including both procaryotes and eucaryotes.Human Hsp90 consists of two forms, Hsp90α andHsp90β. Expression...Heat shock protein 90 (Hsp90) is a major heatshock protein whose functions are necessary for livingorganisms, including both procaryotes and eucaryotes.Human Hsp90 consists of two forms, Hsp90α andHsp90β. Expression of Hsp90α appears to be inducible bydifferent stimuli. Adenovirus EIA gene products andtransformation with the H-ras oncogene can induce aselective overexpression of Hsp90α. Hsp90α was展开更多
Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a...Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a secondary electrode and a movable cathode were explored to improve the thickness deposition uniformity during the nickel electroforming process. Regarding these techniques, a micro electroforming system with a movable cathode was particularly developed. The thickness variation of a 16 mm×16 mm electroformed sample decreased respectively from 150% to 35%, 12% and 18% by these three techniques. Combining these validated methods, anickelmold insert for microlens array was electroformed with satisfactory mechanical properties and high replication precision. It could be applied to the following injection molding process.展开更多
Objectives: To construct retroviral vectorsexpressing antisense polymeric RNAs targeted at the coresequence (+13-+47) of HIV-l TAR RNA, and to testthe anti-HIV properties of this construct in transducedCD4^+T cells. M...Objectives: To construct retroviral vectorsexpressing antisense polymeric RNAs targeted at the coresequence (+13-+47) of HIV-l TAR RNA, and to testthe anti-HIV properties of this construct in transducedCD4^+T cells. Methods: The polymeric TAR-Core DNAwas amplified by the"self-primers-template PCR"展开更多
Objective: To evaluate the efficiency and effect ofgene therapy for rabbit hind limb ischemia byintramuscular injection of VEGF cDNA. Methods:VEGF cDNA was obtained from the RNA in fetal liverwith RT-PCR and inserted ...Objective: To evaluate the efficiency and effect ofgene therapy for rabbit hind limb ischemia byintramuscular injection of VEGF cDNA. Methods:VEGF cDNA was obtained from the RNA in fetal liverwith RT-PCR and inserted into eukaryotic expressionvector, pSVK3, to generate pSV-VEGF. Thetranscription and expression of VEGF cDNA展开更多
Manufacture is facing more furiously competition in the new century. It tends to be globalized. Rapid response and technology innovation have become the key factor to the success of manufacture enterprise. At present,...Manufacture is facing more furiously competition in the new century. It tends to be globalized. Rapid response and technology innovation have become the key factor to the success of manufacture enterprise. At present, internet-based manufacturing develops rapidly. With the development of engineering material and machining techniques, better cutting properties of metal cutting tools are required. The world is paying more attention to the study of indexable carbide inserts with three-dimensional complex grooves which can affect cutting properties directly and chip-controlling. So the variety and specification of indexable insert develop quickly and the application of insert with three-dimensional complex chip-former becomes wider and wider. Because milling is an interrupted cutting, the process of milling is complicated and the failure of the milling inserts is severe. It is important to choose suitable milling inserts groove for particular machining conditions before actual machining, it will extend tool life and raise productivity. Optimization and choice of inserts with complex groove via internet may serve for manufacture enterprises all over the world. The milling inserts with three-dimensional complex grooves are optimized and chosen via Internet in this paper. The face-milling process is studied, with the mathematics models of cutting force for different shape of cutting edges established, the cutting forces predicted and stress-fields of different insert grooves analyzed by FEM, according to the predictable results and the most suitable insert groove for particular machining conditions are optimized and chosen. The complex groove optimization and choice are based on a client/server model, with the client and server being on different machines across the internet. Communication between the client and server uses the TCP/IP. The result of optimization and choice will be sent to the users via Internet. Manufacturers all over the world can get the desired insert groove without paying for expensive experiments. Thus, the cost and lead time of products are reduced.展开更多
The use of transfer DNA(T-DNA)as amutagen has been developed for tagging genes inmany crops,and results showed that T-DNAinsertion is a random event,and that theinserted genes are stable through multiplegenerations.Th...The use of transfer DNA(T-DNA)as amutagen has been developed for tagging genes inmany crops,and results showed that T-DNAinsertion is a random event,and that theinserted genes are stable through multiplegenerations.Through sequencing PCR-amplifiedfragments adjacent to the inserted elements,wecan construct the T-DNA flanking database,which would be useful for cloning the genestagged by T-DNA.展开更多
In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influenc...In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influence of dimension variations of the grinding wheel on machining accuracy were investigated. Firstly, the variation trends of the dimension due to centrifugal force generated in different wheel speeds were studied and the effect of stress stiffening and spin softening was presented. Triangular heat flux distribution model was adopted to determine temperature distribution in grinding process. Temperature field cloud pictures were obtained by the finite element software. Then, dimension variation trends of wheel structure were acquired by considering the thermo-mechanical characteristic under combined action of centrifugal force and grinding heat at different speeds. A method of online dynamic monitoring and automatic compensation for dimension error of indexable insert was proposed. By experimental verification, the precision of the inserts satisfies the requirement of processing.展开更多
BAC library for the Egyptian cotton Gossypiumbarbadense Giza 70,Giza 86,and Giza 75varieties have been constructed andcharacterized.The isolation and purification ofhigh molecular weight DNA from nucleiembedded in aga...BAC library for the Egyptian cotton Gossypiumbarbadense Giza 70,Giza 86,and Giza 75varieties have been constructed andcharacterized.The isolation and purification ofhigh molecular weight DNA from nucleiembedded in agarose microbeads was an essentialpart of this work.Several experimentalparameters were investigated展开更多
文摘There is nonradiative recombination in waveguide region owing to severe carrier leakage,which in turn reduces output power and wall-plug efficiency.In this paper,we designed a novel epitaxial structure,which suppresses carrier leakage by inserting n-Ga_(0.55)In_(0.45)P and p-GaAs_(0.6)P_(0.4) between barriers and waveguide layers,respectively,to modulate the energy band structure and to increase the height of barrier.The results show that the leakage current density reduces by 87.71%,compared to traditional structure.The nonradiative recombination current density of novel structure reduces to 37.411 A/cm^(2),and the output power reaches 12.80 W with wall-plug efficiency of 78.24%at an injection current density 5 A/cm^(2) at room temperature.In addition,the temperature drift coefficient of center wavelength is 0.206 nm/℃at the temperature range from 5℃to 65℃,and the slope of fitted straight line of threshold current with temperature variation is 0.00113.The novel epitaxial structure provides a theoretical basis for achieving high-power laser diode.
文摘Two new dinuclear lanthanidecomplexes,namely[Ln_(2)(dbm)_(2)(HL)_(2)(CH_(3)OH)_(2)]·4CH_(3)OH[Ln=Tb(1)and Dy(2),Hdbm=dibenzoylmethane]have been synthesized using prepared multidentate Schiff base ligand H_(3)L(hydroxy‑acetic acid(4‑diethylamino‑2‑hydroxy‑benzylidene)‑hydrazide)with good biological activity.Structure characterizations show that the complex comprises two Ln3+ions,two dbm-ions,two HL^(2-)ligands,two CH_(3)OH molecules,and four free methanol molecules.Each Ln^(3+)ion is eight‑coordinated.The two central Lnions are bridged by twoμ_(2)‑O atoms leading to a parallelogram[Ln2O2]core.The interaction between the compounds(H_(3)L,1,and 2)and the calf thymus DNA(CT‑DNA)has been further confirmed by UV‑Vis spectrometry,fluorescence titration,and cyclic voltammetry.The results showed that both 1 and 2 could undergo insertion with CT‑DNA.CCDC:2343005,1;2343006,2.
文摘目的探讨5F鞘组在经外周静脉穿刺置入中心静脉导管(peripherally inserted central catheter,PICC)中临床应用的效果。方法回顾性分析并总结2012年12月至2013年2月哈尔滨医科大学附属第一医院收治的应用5F鞘组10例行PICC患者的临床资料。结果 10例患者均顺利完成PICC,有2例患者术后出现静脉炎,其余患者均未发生严重的并发症。结论静脉穿刺条件差的患者应用5F鞘组行PICC导管有利于提高置管成功率。
文摘Recent studies suggest that MHC class Ⅱ genetransfer could stimulate protective antitumor immunity.Whether xenogeneic MHC Ⅱ transfected tumor cells havethese effect is unknown. In this study, HLA-DR3 α and βchain cDNA were cloned by RT-PCR from human Blymphoma Raji cell line and confirmed by DNAsequencing. The recombinant expressing vectors wereconstructed by inserting the α and β chain cDNA intoPCEP4/pLXSN vectors respectively. After transfectingby lipofectamine and selecting with G418 and Hyg, theHLA-DR3 transfected mouse melanoma B16 recombinantclones were obtained. Approximately 59% of
文摘AIM:To investigate whether cilostazol suppresses intimal hyperplasia and to elucidate its mechanism. METHODS:The effects of cilostazol to the expression of lectin-like oxidized low-density lipoprotein receptor-1(LOX-1)at mRNA and protein levels,superoxide generation and neointimal hyperplasia in the rat carotid artery after balloon injury were examined.
基金supported by the National Natural Science Foundation of China(6149069261401488)
文摘This paper presents an approach for mitigating the cross-eye jamming using a dual-polarization array. By transmitting a sum beam and a difference beam in two orthogonal polarimetric channels, a synthesized transmitted beam with spatially varying polarization is produced, such that the polarization of the transmitted radar wave varies in azimuth or elevation. Thus, the phases of the signals received on the two antennas of a cross-eye jammer become unequal, and an additional phase difference is introduced to disrupt the 180？ phase shifting in the retrodirective loop of the jammer. By means of beam scanning in a small angular range,the optimal beam steering configuration can be found to maximize the phase error for the mitigation of cross-eye jamming. As a result, the jamming performance of the cross-eye jammer degrades largely. Theoretical analysis and simulation results indicate that the proposed method is valid and feasible.
基金financially supported by the National Key Research&Development Project(2017YFB1103505)the Military Logistics Research Program(XXXC002)of China。
文摘Through quantitative statistics and morphological characterization of ceramic fragments for ceramic composite bulletproof insert plates(CCBIPs),distribution characteristics of ceramic fragments within a specific size range were analyzed for different Armor Piercing Incendiary(API)and shot times.To quantitatively evaluate the effect of energy absorption for ceramic plates,a model of energy absorption during penetration for CCBIPs was established based on statistics of the size distribution of ceramic fragments(SDCF).Variation in the SDCF and its influence on energy absorption for CCBIPs were investigated.The results indicate that the distribution feature of ceramic fragments in the range of 0.25-2.25 mm is Gaussian distribution.Compared with Type 56 of API(56-API),ceramic fragments formed by 53-API with higher kinetic energy possess more quantity and more concentrated distribution,whose average equivalence size decreases by 6.5%,corresponding to increasing by 83.9%of estimated energy absorption.Besides,the ability of CCBIPs to resist the third shot is significantly weakened,whose estimated energy absorption decreases by 58.8%compared with the first shot.More concentrated distribution and fewer fragments are formed after the third shot,the average equivalence size of ceramic fragments increases by 6.9%,which may attribute to the micro-cracks induced by the previous two shots.
基金supported by the National Natural Science Foundation of China(60574041)the Natural ScienceFoundation of Hubei Province(2007ABA407).
文摘Chain length of closed circle DNA is equal. The same closed circle DNA＇s position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so closed circle DNA computing model is generalized. For change positive-weighted Hamilton circuit problem, closed circle DNA algorithm is put forward. First, three groups of DNA encoding are encoded for all arcs, and deck groups are designed for all vertices. All possible solutions are composed. Then, the feasible solutions are filtered out by using group detect experiment, and the optimization solutions are obtained by using group insert experiment and electrophoresis experiment. Finally, all optimization solutions are found by using detect experiment. Complexity of algorithm is concluded and validity of DNA algorithm is explained by an example. Three dominances of the closed circle DNA algorithm are analyzed, and characteristics and dominances of group delete experiment are discussed.
基金Changsha Municipal Science and Technology Foundation(K15ZD053-43).
文摘In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that its period is prolonged while its computation time keeps unchanged. An interesting problem is to find the earliest time to release new tasks without any deadline missing,that is,the earliest smooth insertion time. In this paper,a general frame to calculate the earliest time with multiple rounds of deadline checking is given,which shows that the checking can be done from the request time of the new tasks. A smart way is provided and proved,which takes the value of theΔchecking of the current round as the time step to the next. These techniques potentially reduce the amount of the calculation and the number of the rounds of the checking to get the earliest time. Simulation results are also given to support the conclusion.
文摘Heat shock protein 90 (Hsp90) is a major heatshock protein whose functions are necessary for livingorganisms, including both procaryotes and eucaryotes.Human Hsp90 consists of two forms, Hsp90α andHsp90β. Expression of Hsp90α appears to be inducible bydifferent stimuli. Adenovirus EIA gene products andtransformation with the H-ras oncogene can induce aselective overexpression of Hsp90α. Hsp90α was
基金Projects(51305465,91123012)supported by the National Natural Science Foundation of China
文摘Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a secondary electrode and a movable cathode were explored to improve the thickness deposition uniformity during the nickel electroforming process. Regarding these techniques, a micro electroforming system with a movable cathode was particularly developed. The thickness variation of a 16 mm×16 mm electroformed sample decreased respectively from 150% to 35%, 12% and 18% by these three techniques. Combining these validated methods, anickelmold insert for microlens array was electroformed with satisfactory mechanical properties and high replication precision. It could be applied to the following injection molding process.
文摘Objectives: To construct retroviral vectorsexpressing antisense polymeric RNAs targeted at the coresequence (+13-+47) of HIV-l TAR RNA, and to testthe anti-HIV properties of this construct in transducedCD4^+T cells. Methods: The polymeric TAR-Core DNAwas amplified by the"self-primers-template PCR"
文摘Objective: To evaluate the efficiency and effect ofgene therapy for rabbit hind limb ischemia byintramuscular injection of VEGF cDNA. Methods:VEGF cDNA was obtained from the RNA in fetal liverwith RT-PCR and inserted into eukaryotic expressionvector, pSVK3, to generate pSV-VEGF. Thetranscription and expression of VEGF cDNA
文摘Manufacture is facing more furiously competition in the new century. It tends to be globalized. Rapid response and technology innovation have become the key factor to the success of manufacture enterprise. At present, internet-based manufacturing develops rapidly. With the development of engineering material and machining techniques, better cutting properties of metal cutting tools are required. The world is paying more attention to the study of indexable carbide inserts with three-dimensional complex grooves which can affect cutting properties directly and chip-controlling. So the variety and specification of indexable insert develop quickly and the application of insert with three-dimensional complex chip-former becomes wider and wider. Because milling is an interrupted cutting, the process of milling is complicated and the failure of the milling inserts is severe. It is important to choose suitable milling inserts groove for particular machining conditions before actual machining, it will extend tool life and raise productivity. Optimization and choice of inserts with complex groove via internet may serve for manufacture enterprises all over the world. The milling inserts with three-dimensional complex grooves are optimized and chosen via Internet in this paper. The face-milling process is studied, with the mathematics models of cutting force for different shape of cutting edges established, the cutting forces predicted and stress-fields of different insert grooves analyzed by FEM, according to the predictable results and the most suitable insert groove for particular machining conditions are optimized and chosen. The complex groove optimization and choice are based on a client/server model, with the client and server being on different machines across the internet. Communication between the client and server uses the TCP/IP. The result of optimization and choice will be sent to the users via Internet. Manufacturers all over the world can get the desired insert groove without paying for expensive experiments. Thus, the cost and lead time of products are reduced.
文摘The use of transfer DNA(T-DNA)as amutagen has been developed for tagging genes inmany crops,and results showed that T-DNAinsertion is a random event,and that theinserted genes are stable through multiplegenerations.Through sequencing PCR-amplifiedfragments adjacent to the inserted elements,wecan construct the T-DNA flanking database,which would be useful for cloning the genestagged by T-DNA.
基金Project(2010ZX04001-162)supported by the National Science and Technology Major Project of China
文摘In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influence of dimension variations of the grinding wheel on machining accuracy were investigated. Firstly, the variation trends of the dimension due to centrifugal force generated in different wheel speeds were studied and the effect of stress stiffening and spin softening was presented. Triangular heat flux distribution model was adopted to determine temperature distribution in grinding process. Temperature field cloud pictures were obtained by the finite element software. Then, dimension variation trends of wheel structure were acquired by considering the thermo-mechanical characteristic under combined action of centrifugal force and grinding heat at different speeds. A method of online dynamic monitoring and automatic compensation for dimension error of indexable insert was proposed. By experimental verification, the precision of the inserts satisfies the requirement of processing.
文摘BAC library for the Egyptian cotton Gossypiumbarbadense Giza 70,Giza 86,and Giza 75varieties have been constructed andcharacterized.The isolation and purification ofhigh molecular weight DNA from nucleiembedded in agarose microbeads was an essentialpart of this work.Several experimentalparameters were investigated
