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111.
Benharrat BELAIDI 《系统科学与复杂性》2007,20(1):41-46
In this paper, we investigate the growth of meromorphic solutions of higher order linear differential equation f^(k) +Ak-1 (z)e^Pk-1^(z) f^(k-1) +…+A1 (z)e^P1(z) f′ +Ao(z)e^Po(z) f = 0 (k ≤ 2), where Pj(z) (j = 0, 1,..., k - 1) are nonconstant polynomials such that deg Pj = n (j = 0, 1,..., k - 1) and Aj(z)(≠ 0) (j = 0, 1,..., k - 1) are meromorphic functions with order p(Aj) 〈 n (j = 0, 1,..., k - 1). 相似文献
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114.
de Wit PJ 《Cellular and molecular life sciences : CMLS》2007,64(21):2726-2732
Plants have an innate immunity system to defend themselves against pathogens. With the primary immune system, plants recognize
microbe-associated molecular patterns (MAMPs) of potential pathogens through pattern recognition receptors (PRRs) that mediate
a basal defense response. Plant pathogens suppress this basal defense response by means of effectors that enable them to cause
disease. With the secondary immune system, plants have gained the ability to recognize effector-induced perturbations of host
targets through resistance proteins (RPs) that mediate a strong local defense response that stops pathogen growth. Both primary
and secondary immune responses in plants depend on germ line-encoded PRRs and RPs. During induction of local immune responses,
systemic immune responses also become activated, which predispose plants to become more resistant to subsequent pathogen attacks.
This review gives an update on recent findings that have enhanced our understanding of plant innate immunity and the arms
race between plants and their pathogens.
Received 24 June 2007; received after revision 18 July 2007; accepted 15 August 2007 相似文献
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116.
As a novel bionic analytical technique, an electronic nose, inspired by the mechanism of the biological olfactory system and
integrated with modern sensing technology, electronic technology and pattern recognition technology, has been widely used
in many areas. Moreover, recent basic research findings in biological olfaction combined with computational neuroscience promote
its development both in methodology and application. In this review, the basic information processing principle of biological
olfaction and artificial olfaction are summarized and compared, and four olfactory models and their applications to electronic
noses are presented. Finally, a chaotic olfactory neural network is detailed and the utilization of several biologically oriented
learning rules and its spatiotemporal dynamic propties for electronic noses are discussed. The integration of various phenomena
and their mechanisms for biological olfaction into an electronic nose context for information processing will not only make
them more bionic, but also perform better than conventional methods. However, many problems still remain, which should be
solved by further cooperation between theorists and engineers.
Supported by the National Creative Research Groups Science Foundation of China (Grant No. 60421002) and National Basic Research
Programme of China (Grant No. 2004CB720302) 相似文献
117.
LIU JianCai XU JiaKai NING XinBao TIAN Run 《科学通报(英文版)》2007,52(17):2438-2442
The characterization of non-stationary signal requires joint time and frequency information. However, time and frequency are a pair of non-commuting variables that cannot constitute a joint probability density in the time-frequency plane. The time-frequency distributions have difficult interpretation problems arising from negative and complex values or spurious components. In this paper, we get time-frequency information from the marginal distributions in rotated directions in the time-frequency plane. The rigorous probability interpretation of the marginal distributions is without any ambiguities. This time-frequency transformation is similar to the computerized axial tomography (CT or CAT) and is applied to signal analysis and signal detection and reveals a lot of advantages especially in the signal detection of the low signal/noise (S/N). 相似文献
118.
Mechanism of the interaction between Au nanoparticles and polymerase in nanoparticle PCR 总被引:1,自引:0,他引:1
MI LiJuan ZHU HongPing ZHANG XiaoDong HU Jun FAN ChunHai 《科学通报(英文版)》2007,52(17):2345-2349
Nanoparticle PCR is a novel method to optimize DNA amplification. It performs well in improving specificity, enhancing sensitivity and speed. Several mechanisms were proposed in previous studies: one was based on the interaction between gold nanoparticles (AuNPs) and DNA while the other was attributed to the heat transfer property of AuNPs. In this paper, we propose that the interaction between AuNPs and DNA polymerase can significantly influence PCR. First, the addition of DNA polymerase can eliminate the inhibitory effects of excess AuNPs. Second, the addition of AuNPs will increase yield of the desired PCR product and make the optimum concentration of DNA polymerase move to higher value. Third, while excess polymerase might inhibit amplification efficiency, AuNPs can reverse this process and the yield of PCR amplification. Based on these results we propose a possible mechanism that AuNPs might modulate the activity of polymerase and improve PCR amplification. 相似文献
119.
A number of recently evolved animals possess poison glands for feeding and/or defense.However,examples of such animals are rare in the fossil record.We report a fossil arthropod Isoxys curvirostratus from the Early Cambrian Chengjiang biota of China.This species is regarded as the oldest known venomous arthropod based on the presence of venomous glands in its head region.The adult animal is 2-5 cm long and the body is covered entirely with a carapace.The presence of large stalk eyes and a pair of stout grasping appendages with a terminal spine suggest it was raptorial.Interestingly,the two pear-shaped,three-dimensionally preserved objects that are present in the head region and at the base of the grasping appendages closely resemble the venom glands of some living arthropods in size,shape,and position.These features indicate that the presence of venomous predators could date back 520 million years.Furthermore,our observations suggest that the feeding strategies and organs adapted for this purpose had already reached a high level of diversity and anatomical sophistication in the Early Cambrian ecosystems. 相似文献
120.
Flame spread over the surface of thermal insulation materials in different environments 总被引:1,自引:0,他引:1
Experiments were conducted in a plateau area in Lhasa and a plain area in Hefei China to investigate the flame spread characteristics on thermal insulation materials under different environmental conditions (pressure and oxygen concentration).Molded polystyrene foam (EPS) and extruded polystyrene foam (XPS) samples were placed horizontally on a small-scale flame spread experimental bench.Changes in the average length of the pool fire,flame spread speed,average flame height,and length of preheating zone were used to determine the effect of the plateau and plain environments on flame spread characteristics.These parameters were all larger in Hefei than in Lhasa,which indicates the fire hazard in Hefei will be higher than that in Lhasa if insulation materials of the same size are used. 相似文献