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排序方式: 共有910条查询结果,搜索用时 15 毫秒
71.
Carlos Güntner Andrés González Renato Dos Reis Gabriel González Alvaro Vázquez Fernando Ferreira Patrick Moyna 《Journal of chemical ecology》1997,23(6):1651-1659
Macrosiphum euphorbiae, also known as the potato aphid, is a potato virus vector, associated with decreased tuber production. Feeding, toxicity, and reproductive effects of the major potato glycoalkaloids (α-chaconine and α-solanine), their common aglycone (solanidine), and a nonpotato glycoalkaloid (α-tomatine) and its aglycone (tomatidine) onM. euphorbiae were studied. As expected, neither α-chaconine nor α-solanine had a strong lethal effect on the aphid, but α-chaconine stimulated feeding at low concentrations. Both aglycones were deterrent and lethal at high concentrations and, like α-chaconine and α-tomatine, they delayed the appearance and decreased the number of nymphs. 相似文献
72.
Reports an error in the original article by G. P. Lombardo and R. Foschi (History of Psychology, 2003, 2, 123-142). In the reference list, several works by Pierre Janet were identified as being Paul Janet. The correct references are provided, where Paul Janet is identified by the initial P. and Pierre Janet is identified by the initials P. M. F.. (The following abstract of this article originally appeared in record 2003-03729-003.) Since the 1920s, the road to the acknowledgment of personality psychology as a field of scientific psychology that has individuality as its object began with the founding of the discipline by Gordon W. Allport. Historians of psychology have made serious attempts to reconstruct the cultural, political, institutional, and chronological beginnings of this field in America in the 20th century. In this literature, however, an important European tradition of psychological studies of personality that developed in France in the 2nd half of the 19th century has been overlooked. The aim of this article is to cast some light on this unexplored tradition of psychological personality studies and to discuss its influence on the development of the scientific study of personality in the United States. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Planar lightwave circuit six-port technique for optical measurements and characterizations 总被引:1,自引:0,他引:1
Molina-Fernandez I. Wanguemert-Perez J.G. Ortega-Monux A. Bosisio R.G. Ke Wu 《Lightwave Technology, Journal of》2005,23(6):2148-2157
The six-port approach is a well-established technique at microwave frequencies, where it has been extensively used as a simple and accurate means to measure complex reflection coefficients with a simple setup. However, its possible application at optical frequencies has not been sufficiently investigated. In this paper, a simple architecture to construct an optical six-port with a planar lightwave circuit (PLC) based on multimode interference (MMI) couplers is proposed for the first time. The proposed PLC is simulated, and the obtained results show a promising performance of the circuit in a wide wavelength range. This novel architecture will allow, in the near future, extending the successful six-port measurement technique up to optical frequencies. 相似文献
74.
Renata Braga Araújo Guilherme Henrique Trielli Ferreira Gustavo Henrique Orair Wagner Meira Jr. Renato Antônio Celso Ferreira Dorgival Olavo Guedes Neto Mohammed Javeed Zaki 《International journal of parallel programming》2008,36(2):226-249
Analyzing gene expression patterns is becoming a highly relevant task in the Bioinformatics area. This analysis makes it possible
to determine the behavior patterns of genes under various conditions, a fundamental information for treating diseases, among
other applications. A recent advance in this area is the Tricluster algorithm, which is the first algorithm capable of determining
3D clusters (genes × samples × timestamps), that is, groups of genes that behave similarly across samples and timestamps.
However, even though biological experiments collect an increasing amount of data to be analyzed and correlated, the triclustering
problem remains a bottleneck due to its NP-Completeness, so its parallelization seems to be an essential step towards obtaining
feasible solutions. In this work we propose and evaluate the implementation of a parallel version of the Tricluster algorithm
using the filter-labeled-stream paradigm supported by the Anthill parallel programming environment. The results show that
our parallelization scales well with the data size, being able to handle severe load imbalances that are inherent to the problem.
Further more, the parallelization strategy is applicable to any depth-first searches. 相似文献
75.
Pierluigi Debernardi Renato Orta 《Quantum Electronics, IEEE Journal of》2007,43(3):269-274
Bragg mirrors, the key element of vertical-cavity surface-emitting lasers, always present graded interfaces when current is pumped through them, so as to reduce their series resistance and related heating problems. We present here an analytical solution for the electromagnetic fields in graded Bragg mirrors. It allows to generate reference reflection and transmission coefficients that are compared with those obtained by the staircase approximation method. Graded mirrors are then analyzed in detail and it is shown that, with an optimized design, higher reflectivity than in the abrupt scheme can be achieved 相似文献
76.
Renato Alexandre C. Santana Ana Regina N. Campos Emanuelle A. Medeiros Aldrighi Luiz M. Oliveira Liana Maria F. Silva Shiva Prasad 《Journal of Materials Science》2007,42(22):9137-9144
A ternary alloy Ni–W–Co was electrodeposited and operational parameters in relation to its corrosion resistance and deposition
efficiency were optimized. A 22 full factorial design was successfully employed for experimental design analysis of the results. By means of response surface
analysis, the statistical model identified the following operating conditions for obtaining corrosion resistant alloy: 60 mA/cm2 current density, 70 °C temperature, 20 rpm cathode rotation and 8.0 pH. The alloy was deposited at 36% current efficiency,
with an average composition of 70% Ni, 8% Co, 22% W and traces of boron and with E
corr −0.508 V and R
p
4.56 × 104 Ohm. The deposit obtained under these conditions had an amorphous character and showed good adherence, high corrosion resistance
and presence of nodules on its surface. Electrochemical corrosion tests verified that the Ni–W–Co alloy had better corrosion
resistance than similarly electrodeposited Co–W amorphous alloy. 相似文献
77.
Juliano Toniolo Antonio S. Takimi Mônica J. Andrade Renato Bonadiman Carlos P. Bergmann 《Journal of Materials Science》2007,42(13):4785-4791
This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea
as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different
fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe3O4) and hematite (α-Fe2O3) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by stoichiometric chemical reaction.
The magnetic properties of the samples are also carefully discussed as superparamagnetic behavior. 相似文献
78.
Tatu S.O. Moldovan E. Ke Wu Bosisio R.G. Denidni T.A. 《Microwave Theory and Techniques》2005,53(9):2768-2776
A six-port Ka-band front-end architecture based on direct conversion for a software-defined radio application is proposed in this paper. The direct conversion is accomplished using six-port technology. In order to demodulate various phase-shift-keying/quadrature-amplitude-modulation (PSK/QAM) modulated signals at a high bit rate, a new analog baseband circuit was specially designed according to the I/Q equations presented in the theoretical part. An experimental prototype has been fabricated and measured. Simulation and measurement results for binary PSK, quaternary PSK (QPSK), 8 PSK, 16 PSK, and 16 QAM modulated signals at a bit rate up to 40 Mb/s are presented to validate the proposed approach. A software-defined radio can be designed using the new front-end and only two analog-to-digital converters (ADCs) because the I/Q output signals are generated by analog means. Previous six-port receivers make use of four ADCs to read the six-port dc levels and require digital computations to generate the I/Q output signals. With the proposed approach, the load of the signal processor will therefore be reduced and the modulation speed can be significantly increased using the same digital signal processor. 相似文献
79.
A six-port reflectometer with variable test port impedance over 2-6 GHz was designed, built, and tested. The potential use of this reflectometer is in large signal characterization of negative resistance devices and oscillators. Experimental source-pull/load-pull measurements on a commercial oscillator (Rieke diagram) were performed using this reflectometer over the entire Smith chart 相似文献
80.
Yoram Pressburger Renato Perucchio 《International journal for numerical methods in engineering》1995,38(8):1399-1421
This paper introduces an automatic self-adaptive finite element system for 3-D stress analysis of homogeneous elastic solids described in a Solid Modelling System (SMS). This system reduces the role of the analyst into two basic tasks: defining the problem (i.e. geometry, material properties and boundary conditions) and specifying the desired accuracy in the analysis. The approach followed in this work is based on Recursive Spatial Decomposition (RSD) of solids defined in a SMS. The system includes procedures for meshing, analysis, error estimation, and adaptive remeshing and reanalysis. The various procedures share the same hierarchical data structure built on the RSD. 相似文献