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排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
Raza Syed Arshad Siddiqui Atiq W. Standing Craig 《Systemic Practice and Action Research》2019,32(2):125-153
Systemic Practice and Action Research - Most of the traditional technology acceptance models revolve around information systems (IS)/information technology (IT) adoption at individual user level.... 相似文献
2.
Imran Sadiq Shahzad Naseem Saira Riaz S. Sajjad Hussain Muhammad Naeem Ashiq Mazhar Rana 《自然科学进展(英文版)》2018,28(4):478-482
Rare earth Dy~(3+)and divalent Mn~(2+)elements substituting W-type hexagonal ferrites Ba_(1-x)Dy_xZn_2Fe_(16-y)Mn_yO_(27)(x=0,0.02,0.06,0.1 and y=0,0.1,0.3,0.5)were prepared by sol-gel method.The thermo-gravimetric analysis(TGA)and differential scanning calorimetry(DSC)was carried out to find the temperature at which single phase can be obtained.XRD patterns indicate the presence of the single phase for all the synthesized samples with the absence of any extra peak due to unreacted material and secondary phases.The occurrence of absorption bands at low wave numbers(563 and 446 cm~(-1)),can be assigned to the stretching vibration of metal and oxygen ions in FTIR spectra,which also confirms the single hexagonal phase for prepared material.The grains are of platelet like structure,which enhances the microwave absorption properties of hexagonal ferrites.The synthesized material exhibits the minimum reflection loss of-20.9 dB at 11.8 GHz frequency,which reflects the applications of this material in super high frequency devices.The microwave conductivity of the material increases with frequency. 相似文献
3.
Wentao Jiang Xiaonan Hu Muhammad Yaseen Liyi Shi Dengsong Zhang Jianping Zhang Lei Huang 《自然科学进展(英文版)》2019,29(2):163-169
A facile, green, cost effective, and template or surfactant free strategy via a two-step route i.e. UV irradiation followed by dissolution-growth for the controlled synthesis of Mn-Co composite nanorings at room temperature was proposed. The nanorings structures and the process were systematically studied via TEM, HRTEM, EDX and XRD. Bir-MnO_2 nanosheets first formed through the direct photolysis of KMnO_4 under UV light irradiation. This was followed by a dissolution-growth process via the dissolution of Bir-MnO_2 nanosheets by the generated H~+ from the redox reaction between the added Co(NO_3)_2 and residual KMnO_4, as well as the accompanied formation of CoOOH, and Mn-Co composite nanorings. It was found that a balance between the dissolution and growth rate was needed. Suitable pH, KMnO_4 presence and the starting nanosheets like Bir-MnO_2 were the key factors for the formation of nanorings. The obtained Mn-Co nanorings/TiO_2 showed enhanced efficiency for the catalytic oxidation of HCHO. Based on the above understandings, it is believed that the developed dissolution-growth method can be adopted for the designing and preparation of other Mn-Co composite nanostructures which can be further applied for environmental pollution remediation. 相似文献
4.
Robust Adaptive Multi-Switching Synchronization of Multiple Different Orders Unknown Chaotic Systems
Multi-switching synchronization(MSS) of multiple different orders unknown chaotic(UC)systems confines hacking in the digital transmission process. Similarly, the suppression of undesirable chattering increases synchronization performance. This paper proposes a new robust synchronization control(RASC) technique and discusses the MSS of multiple different orders UC systems. This controller accomplishes(i) quick convergence,(ii) reduces the transient oscillations, and(iii) the rate of convergence decreases in the vicinity of the origin that causes the suppression of chattering. Analysis based on the Lyapunov direct method assures this convergence behavior with any positive values of the feedback gains. This work also provides parameters updated law that estimates the true values of unknown parameters. Numerical examples of five UC systems different orders are simulated. The computer based graphical results validate the efficiency and performance of the proposed RASC technique and the synchronization strategy when compare to peer works. In the simulation, the proposed synchronization strategy successfully recovers an encrypted received image on a communication channel.The article suggests some future research problems to extend the use of the proposed work. 相似文献
5.
In recent years, graphene has attracted considerable research interest in all fields of science due to its unique properties. Its excellent mechanical properties lead it to be used in nano-composites for strength enhancement. This paper reports an Aluminum–Graphene Nanoplatelets(Al/GNPs)composite using a semi-powder method followed by hot extrusion. The effect of GNP nano-particle integration on tensile, compressive and hardness response of Al is investigated in this paper. It is demonstrated that 0.3 wt% Graphene Nanoplatelets distributed homogeneously in the matrix aluminum act as an effective reinforcing filler to prevent deformation. Compared to monolithic aluminum(in tension), Al–0.3 wt% GNPs composite exhibited higher 0.2% yield strength(+14.7%), ultimate tensile strength(+11.1%) and lower failure strain( -40.6%). Surprisingly, compared to monolithic Al(in compression), Al–0.3 wt% GNPs composite exhibited same 0.2% compressive yield strength and lower ultimate compression strength(- 7.8%),and lower failure strain(- 20.2%). The Al–0.3 wt% GNPs composite exhibited higher Vickers hardness compared to monolithic aluminum(+11.8%).Scanning electron microscopy(SEM), Energy-Dispersive X-ray Spectroscopy(EDS) and X-ray diffraction(XRD) were used to investigate the surface morphology, elemental percentage composition, and phase analysis, respectively. 相似文献
6.
ALI Muhammad 《东华大学学报(英文版)》2021,(2):118-128
In order to increase the application area of nanofibers, electrospun nanofiber yarns have drawn attention of many researchers around the globe. Once the production method of nanofiber yarn is mature enough to be universally accepted, many new gates of applications will open to the world. In this review, different electrospinning techniques of electrospun nanofiber yarns are divided into needle electrospinning and needleless electrospinning. Considering yarn twist as an important mechanism, needle electrospinning technique is further categorized into mechanical, electrical and field flow twisting methods. Moreover, parameters influencing the mechanical properties of electrospun nanofiber yarns are investigated. Methods of improving mechanical properties of nanofiber yarns are addressed, including hot-water-bath treatment, addition of carbon nanotubes(CNTs) and introducing regulators. Finally, applications of electrospun nanofiber yarns in different fields of smart textile and bioengineering are summed-up. In summary, challenges encountered in the industrialization of nanofiber yarns and future prospects are anticipated. 相似文献
7.
A total of 18 spider mite species belonging to 10 genera of the family Tetranychidae (Acari: Prostigmata) are reported from different provinces of Saudi Arabia (SA). Among these, two new species, Sonotetranychus madinahensis sp. nov. and Tetranychus salicornicus sp. nov., belonging to the subfamily Tetranychinae are described and illustrated. Also, five genera and 11 species are new to the mite fauna of SA. The distribution and host data of all recorded species in the current study are provided. A key to all spider mite species of SA is provided as well as a key to the species of the armenychus species group of the genus Tetranychus Dufour, based on males.
www.zoobank.org/urn:lsid:zoobank.org:pub:C41BB3ED-99D5-4DCF-B557-09526FA7D56B 相似文献
8.
Christoph Lipps Muhammad Badar Milada Butueva Tatyana Dubich Vivek Vikram Singh Sophie Rau Axel Weber Michael Kracht Mario Köster Tobias May Thomas F. Schulz Hansjörg Hauser Dagmar Wirth 《Cellular and molecular life sciences : CMLS》2017,74(7):1319-1333
Homeostasis of solid tissue is characterized by a low proliferative activity of differentiated cells while special conditions like tissue damage induce regeneration and proliferation. For some cell types it has been shown that various tissue-specific functions are missing in the proliferating state, raising the possibility that their proliferation is not compatible with a fully differentiated state. While endothelial cells are important players in regenerating tissue as well as in the vascularization of tumors, the impact of proliferation on their features remains elusive. To examine cell features in dependence of proliferation, we established human endothelial cell lines in which proliferation is tightly controlled by a doxycycline-dependent, synthetic regulatory unit. We observed that uptake of macromolecules and establishment of cell–cell contacts was more pronounced in the growth-arrested state. Tube-like structures were formed in vitro in both proliferating and non-proliferating conditions. However, functional vessel formation upon transplantation into immune-compromised mice was restricted to the proliferative state. Kaposi’s sarcoma-associated herpes virus (KSHV) infection resulted in reduced expression of endothelial markers. Upon transplantation of infected cells, drastic differences were observed: proliferation arrested cells acquired a high migratory activity while the proliferating counterparts established a tumor-like phenotype, similar to Kaposi Sarcoma lesions. The study gives evidence that proliferation governs endothelial functions. This suggests that several endothelial functions are differentially expressed during angiogenesis. Moreover, since proliferation defines the functional properties of cells upon infection with KSHV, this process crucially affects the fate of virus-infected cells. 相似文献
9.
SHAHID Muhammad Qasim 《科学通报(英文版)》2010,55(13):1255-1262
Oryza rufipogon exhibits abundant genetic diversity and contains many elite genes. In this work, a total of 441 accessions of O. rufipogon were genetically examined using the functional marker S5n, revealing that 18 accessions carried the S5n allele with a heterozygous genotype (S5nS5i/j). Of these accessions, 14 were from Guangdong Province, 2 from Guangxi Zhuang Autonomous Region, 1 from Hainan Province and 1 from Jiangxi Province. Further sequence analysis spanning both sides of the deletion in S5n allel... 相似文献
10.