检索结果-南通市图书馆

3D-QSAR Study of Melittin and Amoebapore Analogues by CoMFA and CoMSIA Methods

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Structural Chemistry 2019年第2期38卷 201-210,165页

作者： TONG jian-Bo QIN shang-shang jIANG Guo-Yan Shaanxi key Laboratory of Chemical Additives for Industry Shaanxi University of Science and Technology

Peptides are one of the indispensable substances in life. The use of computer aided drug design(CADD) methods to design peptides and peptiodmimetics can short the design cycle, save research funding, improve the level of whole research to a large extent and guide the discovery of new drugs. In this paper, Melittin and amoebapore three-dimensional quantitative structureactivity relationship(3D-QSAR) models were established by using comparative molecular field analysis(CoMFA) and comparative molecular similarity indices analysis(CoMSIA) method. The result shows that, the correlation coefficient(q^2) was 0.583 and non-cross-validation correlation coefficient(r^2) was 0.972 for the melittin CoMFA model. The q^2 and r^2 were 0.630 and 0.995 for the best CoMSIA model, 0.645 and 0.993 for the amoebapore CoMFA model, and 0.738 and 0.996 for the best CoMSIA model. The statistical parameters demonstrated that the CoMFA and CoMSIA models had both good predictive ability and high statistical stability, and can provide theoretical basis for designing new high activity polypeptide drugs.

关键词： 3D-QSAR melittin analogues amoebapore analogues CoMFA CoMSIA

A novel signal feature extraction technology based on empirical wavelet transform and reverse dispersion entropy

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2021年第5期17卷 1625-1635页

作者： Yu-xing Li shang-bin jiao Xiang Gao School of Automation and Information Engineering Xi’an University of TechnologyXi’an710048China School of Electrical Engineering Xi’an University of TechnologyXi’an710048China

Feature extraction is an important part of signal processing,which is significant for signal detection,classification,and *** nonlinear dynamic analysis method can extract the nonlinear characteristics of signals and is widely used in different *** dispersion entropy(RDE)proposed by us recently,as a nonlinear dynamic analysis method,has the advantages of fast computing speed and strong anti-noise ability,which is more suitable for measuring the complexity of signal than traditional permutation entropy(PE)and dispersion entropy(DE).Empirical wavelet transform(EWT),based on the theory of wavelet analysis,can decompose a complex non-stationary signal into a number of empirical wavelet functions(EWFs)with compact support set spectrum,which has better decomposition performance than empirical mode decomposition(EMD)and its improved *** the advantages of RDE and EWT,on the one hand,we introduce EWT into the field of underwater acoustic signal processing and fault diagnosis to improve the signal decomposition accuracy;on the other hand,we use RDE as the features of EWFs to improve the signal separability and ***,we propose a novel signal feature extraction technology based on EWT and RDE in this *** results show that the proposed feature extraction technology can effectively extract the complexity features of actual ***,it also has higher distinguishing ability for different types of signals than five latest feature extraction technologies.

关键词： Feature extraction Empirical mode decomposition Empirical wavelet transform Permutation entropy Reverse dispersion entropy

Nanoparticle-strengthened Ni_(2)CoCrNb_(0.2)medium-entropy alloy with an ultrastrong cryogenic yield strength fabricated by additive manufacturing

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2023年第32期163卷 17-31页

作者： Fangping Wang Yaxiong Guo Qibin Liu Xiaojuan shang College of Materials and Metallurgy Guizhou UniversityGuiyang 550025China Guiyang Vocational and Technical College Guiyang 550081China key Laboratory for Modern Manufacturing Technology of Educational Ministry Guiyang 550025China

To improve the yield strength of metallic materials at low temperatures,a strategy of combining the calculation of phase diagrams(CALPHAD)technique with the overall valence electron concentration(OVEC)principle is applied,and a Ni_(2)CoCrNb_(0.2)medium-entropy alloy(MEA)with D022 superlattice(noted as theγ″phase)is *** MEA samples without defects were successfully fabricated using laser additive manufacturing(AM),followed by solution treatment at 1200℃for 1 h and then aging at 650℃for 120 *** nanoscaleγ″phase *** tensile results indicated that the MEA had superior yield strengths of∼1180 MPa and∼1320 MPa and tensile strengths of∼1335 MPa and∼1552 MPa at 293 k and 77 k,*** yield strength obtained was superior to that of currently reported medium/high-entropy alloys and typical advanced cryogenic *** mechanical properties of the Ni_(2)CoCrNb_(0.2)MEA demonstrated a strong temperature dependence,and the increased yield strength was mainly attributed to the increase in lattice friction stress at low *** research provides a new strategy for producing materials with ultrastrong cryogenic yield strengths by AM.

关键词： Additive manufacturing Medium-entropy alloys D0_(22)superlattice Temperature dependence Cryogenic performance

Dynamic modeling and RBF neural network compensation control for space flexible manipulator with an underactuated hand

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese journal of Aeronautics 2024年第3期37卷 417-439页

作者： Dongyang shang Xiaopeng LI Meng YIN Fanjie LI School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China

In space operation,flexible manipulators and gripper mechanisms have been widely used because of light weight and ***,the vibration caused by slender structures in manipulators and the parameter perturbation caused by the uncertainty derived from grasping mass variation cannot be *** existence of vibration and parameter perturbation makes the rotation control of flexible manipulators difficult,which seriously affects the operation accuracy of ***’s more,the complex dynamic coupling brings great challenges to the dynamics modeling and vibration *** solve this problem,this paper takes the space flexible manipulator with an underactuated hand(SFMUH)as the research *** dynamics model considering flexibility,multiple nonlinear elements and disturbance torque is established by the assumed modal method(AMM)and Hamilton’s principle.A dynamic modeling simplification method is proposed by analyzing the nonlinear ***’s more,a sliding mode control(SMC)method combined with the radial basis function(RBF)neural network compensation is ***,the control law is designed using a saturation function in the control method to weaken the chatter *** the help of neural networks to identify the uncertainty composition in the SFMUH,the tracking accuracy is *** results of ground control experiments verify the advantages of the control method for vibration suppression of the SFMUH.

关键词： Space flexible manipulator RBF neural network Underactuated hand Dynamic models Model simplification

Role of unc5b in retinal neovascularization in mice with oxygen-induced retinopathy

在线全文

学校读者我要写书评

暂无评论

International journal of Ophthalmology(English edition) 2011年第2期4卷 137-142页

作者： Dan Liu, Lei shang Department of Ophthalmology Xiangya Hospital of the Central South University Changsha 410013 Hunan Province China Department of Anatomy and Neurobiology Xiangya Medical School the Central South University Changsha 410013 Hunan Province China

AIM: To explore the role of unc5b in retinal neovascularization in murine oxygen-induced retinopathy (OIR). METHODS: On postnatal 7 (P7), C57BL/6j mice were exposed to 75% +/- 2% oxygen for 5 days. On postnatal 12 (P12), the mice were brought back to the room air (21% oxygen) to induce retinal neovascularization. Western blot analysis was performed to examine the temporal expression of unc5b in murine retinas. Double staining for unc5b and isolectin B4 were employed to determine the location of unc5b in murine retinas. The effect of unc5b on retinal neovascularization was evaluated by intravitreal injection of unc5b-FC in mice with OIR. Retinal neovascularization was measured by counting neovascular cell nuclei above the internal limiting membrane and by angiography of flat-mounted retinas perfused with fluorescein dextran. o RESULTS: Compared to age-matched normal mice, the expression of unc5b was significantly increased in retinas of OIR mice on P17 and P21. Unc5b was apparently expressed in retinal vessels of OIR while being negative in normal retinal vessels. Retinal neovascularization in eyes injected with unc5b-FC was significantly reduced. CONCLUSION: Unc5b-FC can effectively inhibit retinal neovascularization induced by OIR. It may serve as a powerful and novel therapy for ischemia-induced retinal disease.

关键词： oxygen-induced retinopathy unc5b unc5b-FC

Effects of soybean oil exposure on the survival,reproduction,biochemical responses,and gut microbiome of the earthworm Eisenia fetida

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Environmental Sciences 2023年第11期133卷 23-36页

作者： Yating Du Guangshen shang junjie Zhai Xing Wang College of Resources and Environmental Sciences China Agricultural UniversityBeijing 100193China Beijing key Laboratory of Biodiversity and Organic Farming Beijing 100193China Organic Recycling Research Institute(Suzhou) China Agricultural UniversitySuzhou 215100China

With increasing production of kitchen waste,cooking oil gradually enters the soil,where it can negatively affect soil *** this study,we explored the effects of soybean oil on the survival,growth,reproduction,tissue structure,biochemical responses,mRNA expression,and gut microbiome of earthworms(Eisenia fetida).The median lethal concentration of soybean oil was found to be 15.59%.Earthworm growth and reproduction were significantly inhibited following exposure to a sublethal concentration of soybean oil(1/3 LC50,5.2%).The activity of the antioxidant enzymes total superoxide dismutase(T-SOD),peroxidase(POD),and catalase(CAT)were affected under soybean oil *** glutathione(GSH)content decreased significantly,whereas that of the lipid peroxide malondialdehyde(MDA)increased significantly after soybean oil *** expression levels of the SOD,metallothionein(MT),lysenin and lysozyme were significantly *** abundance of Bacteroides species,which are related to mineral oil repair,and Muribaculaceae species,which are related to immune regulation,increased within the earthworm *** results indicate that soybean oil waste is toxic to ***,earthworms deployed defense mechanisms involving antioxidant system and gut microbiota for protection against soybean oil exposure-induced stress.

关键词： Gene expression Gut microbiota Eisenia fetida Soybean oil Reproduction

Engineering Plant Cytochrome P450s for Enhanced Synthesis of Natural Products: Past Achievements and Future Perspectives

在线全文

学校读者我要写书评

暂无评论

Plant Communications 2020年第1期1卷 57-63页

作者： Yi shang Sanwen Huang key Laboratory for Potato Biology of Yunnan Province The CAAS-YNNU-YINMORE Joint Academy of Potato ScienceYunnan Normal UniversityKunmingChina Lingnan Guangdong Laboratory of Modern Agriculture Genome Analysis Laboratory of the Ministry of AgricultureAgricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhenChina

Cytochrome P450s(P450s)are the most versatile catalysts and are widely used by plants to synthesize a vast array of structurally diverse specialized metabolites that not only play essential ecological roles but also constitute a valuable resource for the development of new *** accelerate the metabolic engineering of these high-value metabolites,it is imperative to identify and characterize pathway P450s,and to further improve their activities through protein *** this review,we focus on P450 engineering and summarize the major strategies for enhancing the stability and activity of P450s and successful cases of P450 *** in which the functions of P450s were altered to create de novo metabolic pathways or novel compounds are discussed as *** also overview emerging tools,specifically DNA synthesis,machine learning,and de novo protein design,as well as the evolutionary patterns of P450s unveiled from a massive number of DNA sequences that could be integrated to accelerate the engineering of these *** approaches would greatly aid in the exploitation of plant-specialized metabolites or derivatives for various uses including medical applications.

关键词： plant cytochrome P450 plant natural product protein engineering amino acid co-evolution protein design

A path planning algorithm based on Bezier curves for underwater vehicles

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Technology Letters 2010年第3期16卷 293-298页

作者： shang Liuji Wang Shuo Laborary of Complex Systems and Intelligence Sciences Institute of Automation Chinese Academy of Sciences Beijing 100190 P.R. China

An on-line path planning algorithm based on Bezier curves is presented for underwater vehicles. Aiming at the special requirements of underwater vehicles and 3D enviromnent, the algorithm consists of two steps ： the generation of spatial path and the processing of some constraints. A path for underwater vehicles is planned, which satisfies the velocity constraint and the centripetal acceleration constraint of underwater vehicles. The proposed path planning method can be used for the vehicle＇ s locomotion and navigation control.

关键词： path planning Bezier curves underwater vehicles

Vibration suppression for rotating space slender flexible structures based on novel deformation description and NNSMC controller with hyperbolic tangent function

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese journal of Aeronautics 2024年第10期37卷 339-364页

作者： Dongyang shang Xiaopeng LI Men YIN Sainan ZHOU School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China

Rotating Space Slender Flexible Structures(RSSFS)are extensively utilized in space operations because of their light weight,mobility,and low energy *** realize the accurate space operation of the RSSFS,it is necessary to establish a precise mechanical model and develop a control algorithm with high ***,with the application of traditional control strategies,the RSSFS often suffers from the chattering phenomenon,which will aggravate structure *** this paper,novel deformation description is put forward to balance modeling accuracy and computational efficiency of the RSSFS,which is better appropriate for real-time ***,the Neural Network Sliding Mode Control(NNSMC)strategy modified by the hyperbolic tangent(tanh)function is put forward to compensate for modeling errors and reduce the chattering phenomenon,thereby improving the trajectory tracking accuracy of the ***,a mathematical model for the RSSFS is developed according to the novel deformation description and the vibration theory of flexible *** of the deformation accuracy between different models proves that the novel modeling method proposed has high modeling ***,the universal approximation property of the Radial Basis Function(RBF)neural network is put forward to determine and compensate for modeling errors,which consist of higher-order modes and the uncertainties of external *** addition,the tanh function is proposed as the reaching law in the conventional NNSMC strategy to suppress driving torque *** control law of modified NNSMC strategy and the adaptive law of weight coefficients are developed according to the Lyapunov theorem to guarantee the RSSFS ***,the simulation and physical experimental tests of the RSSFS with different control strategies are *** results show that the control law according to the novel deformation description and the modified NNSMC strategy can obta

关键词： Space slender flexible structure Novel deformation description RBF neural network Vibration suppression Hyperbolic tangent function