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排序方式: 共有66条查询结果,搜索用时 31 毫秒
1.
复数,实数及实对称数据下Bruun FFT算法的实现 总被引:3,自引:0,他引:3
本文在复数、实数以及实对称数据下研究和实现了Bruun FFT算法。文章分析和评价了各种数据下BruunFFT的运算量和特点,提出了算法的实现结构和方法。最后给了TMS320C30上的运算时间,我们实现的算法比基2FFT速度提高35%。 相似文献
2.
Recognition of protein structure in leukocyte chemotaxis 总被引:5,自引:0,他引:5
P C Wilkinson 《Nature》1973,244(5417):512-513
3.
Fromhold TM Patanè A Bujkiewicz S Wilkinson PB Fowler D Sherwood D Stapleton SP Krokhin AA Eaves L Henini M Sankeshwar NS Sheard FW 《Nature》2004,428(6984):726-730
Understanding how complex systems respond to change is of fundamental importance in the natural sciences. There is particular interest in systems whose classical newtonian motion becomes chaotic as an applied perturbation grows. The transition to chaos usually occurs by the gradual destruction of stable orbits in parameter space, in accordance with the Kolmogorov-Arnold-Moser (KAM) theorem--a cornerstone of nonlinear dynamics that explains, for example, gaps in the asteroid belt. By contrast, 'non-KAM' chaos switches on and off abruptly at critical values of the perturbation frequency. This type of dynamics has wide-ranging implications in the theory of plasma physics, tokamak fusion, turbulence, ion traps, and quasicrystals. Here we realize non-KAM chaos experimentally by exploiting the quantum properties of electrons in the periodic potential of a semiconductor superlattice with an applied voltage and magnetic field. The onset of chaos at discrete voltages is observed as a large increase in the current flow due to the creation of unbound electron orbits, which propagate through intricate web patterns in phase space. Non-KAM chaos therefore provides a mechanism for controlling the electrical conductivity of a condensed matter device: its extreme sensitivity could find applications in quantum electronics and photonics. 相似文献
4.
5.
In occupational therapy education in South Africa, community service (CS) focuses learning opportunities during fieldwork
placements. CS therefore enabled the researcher to utilise successive small scale research projects to guide learning of students
during fieldwork while simultaneously developing the occupational therapy service at a residential care facility. This community
setting provided a powerful environment through which research, in combination with opportunities for reflection, contributed
to nurturing skills needed by these future health professionals. A technical action research (AR) approach incorporated AR
cycles and opportunities for structured reflection. Therefore situations were created for the students to embrace experiential
learning. Experiential learning in the form of anticipatory reflection, reflection-in-action, reflection on reflection and
retrospective reflection impacted on the quality of the students’ work. Besides encouraging unique leaning opportunities for
students when engaging in research during their fieldwork placement, engagement in AR cycles simultaneously improved service
delivery to residents in the facility. Key benefits of this investigation were that fieldwork education utilising AR cycles
within a CS situation promoted students to identify voids in their theoretical background as well as practice skills; to apply
reflective practice that could contribute to their personal and professional development; and to utilize learning opportunities
optimally. Despite positive gains showed by this study, the role of power relations between the researcher as fieldwork educator
and the students prohibited the AR cycles from being more emancipatory in nature and should be addressed in follow-up studies. 相似文献
6.
Characterization of the chemotactic activity of casein for neutrophil leucocytes and macrophages 总被引:2,自引:0,他引:2
P C Wilkinson 《Experientia》1972,28(9):1051-1052
7.
A single point mutation has been engineered in the tyrosyl-tRNA synthetase that improves its affinity (KM) for its substrate ATP by a factor of 100. In the crystal structure of the tyrosyl tRNA synthetase (of Bacillus stearothermophilus), the side-chain hydroxyl of Thr 51 appears to make a weak hydrogen bond with the AMP moiety of the substrate intermediate, tyrosyl adenylate. In the absence of substrate, however, the hydroxyl group should make a strong hydrogen bond with water which would favour dissociation of the enzyme-substrate complex. We have used oligodeoxynucleotide-directed mutagenesis to construct two point mutants at this site: one to remove the hydroxyl group (Thr 51 leads to Ala 51) and the other, in addition, to distort the local polypeptide backbone (Thr 51 leads to Pro 51). We report here that both mutants have increased activity (kcat/KM for ATP) but one mutant (Pro 51) shows a massive 25-fold increase due mainly to a lowered KM for ATP. This demonstrates dramatically the potential of in vitro mutagenesis for improving the affinity of an enzyme for its substrate. 相似文献
8.
Summary The effect of dilutional hyponatraemia on cerebral blood flow and oxygen consumption, and net transfer of K+ to the circulation from brain tissue drained by the sagittal sinus was investigated in anaesthetized calves. Cerebral blood flow decreased, and net transfer of K+ to the circulation increased during hyponatraemia.Acknowledgments. The expert assistance of Miss B.N. O'Connor, Miss D. McNaughton and Mr P.M.M. Bircham is gratefully acknowledged. 相似文献
9.
Sayer JA Otto EA O'Toole JF Nurnberg G Kennedy MA Becker C Hennies HC Helou J Attanasio M Fausett BV Utsch B Khanna H Liu Y Drummond I Kawakami I Kusakabe T Tsuda M Ma L Lee H Larson RG Allen SJ Wilkinson CJ Nigg EA Shou C Lillo C Williams DS Hoppe B Kemper MJ Neuhaus T Parisi MA Glass IA Petry M Kispert A Gloy J Ganner A Walz G Zhu X Goldman D Nurnberg P Swaroop A Leroux MR Hildebrandt F 《Nature genetics》2006,38(6):674-681
10.
西部农业信息化建设问题的探讨 总被引:3,自引:0,他引:3
西部农业信息化水平低下制约着西部农业的发展。物质基础薄弱、信息意识淡薄、信息人才及资金短缺是造成西部农业信息化水平低下的原因。为加快西部信息化农业建设,应该从更新观念、加大政府支持力度、利用有限资源进行信息化基础建设、重视人才资源的开发、培育信息产品市场、加强农业应用系统和信息化农业技术的研究、加强示范应用体系等方面入手。 相似文献