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991.
氯虫苯甲酰胺200SC对水稻的控害作用及对产量的影响   总被引:1,自引:0,他引:1  
通过氯虫苯甲酰胺(康宽TM)200SC对水稻螟虫的实验结果表明,氯虫苯甲酰胺对水稻二化螟和稻纵卷叶螟的防治效果远远优于噻虫嗪、毒死蜱和杀虫单,防效分别达到了89.32%和92.23%,并对天敌昆虫和水稻生长安全.再生稻测产表明,氯虫苯甲酰胺对水稻的生长有一定的刺激作用,能明显提高再生稻产量,增产率为32.44%.  相似文献   
992.
应用2008年分布在茅台酒原料基地,海拔370~1 301m地段209个农户栽培的有机高粱产量和品质资料,采用气候曲面技术(ANUSPLI)方法得到各地段的温度、降水量和日照数据,并对各地段有机高粱产量和品质及原产地气象条件进行了相关分析.结果表明:气温日较差对高粱产量、单宁质量分数有显著影响;降水量对高粱产量、单宁和淀粉质量分数有显著性影响;日照时数对高粱产量、单宁和淀粉质量分数有显著影响;其中气温、降水量和日照对高粱单宁质量分数的影响都为显著负相关.气象条件对高粱蛋白质质量分数无明显影响.该文依据相关分析结果建立了气候区划指标,并做出了优质酒用有机高粱栽培基地的气候区划,其优质有机高粱栽培基地最适宜区在赤水河流域中段的贵州省仁怀市北部、西部和西南部地区,适宜区在仁怀市东部和南部地区.  相似文献   
993.
利用替代法得到了复合指数形变幅杆的频率方程,在此基础上解算出谐振长度、放大系数等重要参数,并借助于ANSYS软件对复合变幅杆进行模态分析.结果表明该方法对复合形变幅杆的设计是可行的,也显示了ANSYS在变幅杆设计中的重要性.这给其他复合变幅杆的设计提供了参考.  相似文献   
994.
Recognizing the successes of treed Gaussian process (TGP) models as an interpretable and thrifty model for nonparametric regression, we seek to extend the model to classification. Both treed models and Gaussian processes (GPs) have, separately, enjoyed great success in application to classification problems. An example of the former is Bayesian CART. In the latter, real-valued GP output may be utilized for classification via latent variables, which provide classification rules by means of a softmax function. We formulate a Bayesian model averaging scheme to combine these two models and describe a Monte Carlo method for sampling from the full posterior distribution with joint proposals for the tree topology and the GP parameters corresponding to latent variables at the leaves. We concentrate on efficient sampling of the latent variables, which is important to obtain good mixing in the expanded parameter space. The tree structure is particularly helpful for this task and also for developing an efficient scheme for handling categorical predictors, which commonly arise in classification problems. Our proposed classification TGP (CTGP) methodology is illustrated on a collection of synthetic and real data sets. We assess performance relative to existing methods and thereby show how CTGP is highly flexible, offers tractable inference, produces rules that are easy to interpret, and performs well out of sample.  相似文献   
995.
This paper proposes a maximum clustering similarity (MCS) method for determining the number of clusters in a data set by studying the behavior of similarity indices comparing two (of several) clustering methods. The similarity between the two clusterings is calculated at the same number of clusters, using the indices of Rand (R), Fowlkes and Mallows (FM), and Kulczynski (K) each corrected for chance agreement. The number of clusters at which the index attains its maximum is a candidate for the optimal number of clusters. The proposed method is applied to simulated bivariate normal data, and further extended for use in circular data. Its performance is compared to the criteria discussed in Tibshirani, Walther, and Hastie (2001). The proposed method is not based on any distributional or data assumption which makes it widely applicable to any type of data that can be clustered using at least two clustering algorithms.  相似文献   
996.
During the refereeing procedure of Anthropomorphic Quantum Darwinism by Thomas Durt, it became apparent in the dialogue between him and me that the definition of information in Physics is something about which not all authors agreed. This text aims at describing the concepts associated to information that are accepted as the standard in the Physics world community.  相似文献   
997.
Displacing Epistemology: Being in the Midst of Technoscientific Practice   总被引:2,自引:2,他引:0  
Interest the Erklären?CVerstehen debate is usually interpreted as primarily epistemological. By raising the possibility that there are fundamentally different methods for fundamentally different types of science, the debate puts into play all the standard issues??that is, issues concerning scientific explanation and justification, the unity and diversity of scientific disciplines, the reality of their subject matter, the accessibility of various subject matters to research, and so on. In this paper, however, I do not focus on any of these specific issues. I start instead from the fact that the very existence of the debate itself is an issue; in fact, it poses a philosophical problem that almost everyone but the hardest line logical empiricists has come to realize cannot be resolved epistemologically. In my view, however, that it cannot be resolved ontologically, either. I think the problem is at bottom hermeneutical, and its resolution requires that we focus first, not on the objects of science or the methods of studying them, but on the character of the philosophical orientation assumed by those who would try to resolve it. In this paper, I explain why I think this is so by analyzing (1) Dilthey??s contribution to the original debate, (2) Husserl??s reaction to Dilthey, and (3) Heidegger??s critical evaluation of both. This line of philosophical development??this movement of self-understanding from critiques of objectivism to hermeneutical phenomenology??is of course already a central feature of much work in continental philosophy of science. In my conclusion, however, I argue for the less well-established??even if apparently approved??idea that it ought to be a central feature of technoscience studies as well.  相似文献   
998.
Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.  相似文献   
999.
Oxysterols direct immune cell migration via EBI2   总被引:1,自引:0,他引:1  
Epstein-Barr virus-induced gene 2 (EBI2, also known as GPR183) is a G-protein-coupled receptor that is required for humoral immune responses; polymorphisms in the receptor have been associated with inflammatory autoimmune diseases. The natural ligand for EBI2 has been unknown. Here we describe the identification of 7α,25-dihydroxycholesterol (also called 7α,25-OHC or 5-cholesten-3β,7α,25-triol) as a potent and selective agonist of EBI2. Functional activation of human EBI2 by 7α,25-OHC and closely related oxysterols was verified by monitoring second messenger readouts and saturable, high-affinity radioligand binding. Furthermore, we find that 7α,25-OHC and closely related oxysterols act as chemoattractants for immune cells expressing EBI2 by directing cell migration in vitro and in vivo. A critical enzyme required for the generation of 7α,25-OHC is cholesterol 25-hydroxylase (CH25H). Similar to EBI2 receptor knockout mice, mice deficient in CH25H fail to position activated B cells within the spleen to the outer follicle and mount a reduced plasma cell response after an immune challenge. This demonstrates that CH25H generates EBI2 biological activity in vivo and indicates that the EBI2-oxysterol signalling pathway has an important role in the adaptive immune response.  相似文献   
1000.
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