基于GIS的农业气象统计分析软件包的设计与实现

介绍一种基于ＧＩＳ的农业气象统计分析软件包的设计及实现过程,并详细介绍了所选用的软件开发方法及具体技术。     

混沌理论与非线性经济系统

简述了混沌的定义、特征以及混沌系统的判定方法,并初步探讨了混沌理论在非线性经济系统中的应用,重点讨论了该理论在非线性经济结构的统计检验和经济系统控制等方面的应用     

18－冠－6及其碱金属配合物构象和稳定性的分子力学研究

１８－冠－６及其碱金属配合物构象和稳定性的分子力学研究张士国,李红,杨频（滨州师范专科学校滨州２５６６０４）（山西大学分子所太原０３０００６）关键词分子力学,冠醚,配合物,构象１８－冠－６及其大部分配合物的晶体结构已被测定,但由于存在晶体堆积能而使分...     

第四统计力学-JRG群子统计理论的现状与展望

1978年,作者首次发表了群子统计理论及其在某些自然科学领域里应用的论文;接着于1984年出版了“模糊群子论”,系统地论述了线性群子理论方程及其某些应用。而后又把群子理论推广到群子间相互作用的非线性体系中,建立了重整化非线性群子理论方程。这些理论不仅能够推导出Fermi-Dirac,Bose-Einstein,Maxwell-Boltzmann统计方程,而且用很简单的方法可推导出著名的Van der Waals非理想气体方程,Kohlrausch电导方程,BET多层吸附方程。通过非线性群子方程又推导了汽液平衡组成关系式,高分子溶液第二维利系数与分子量之间的关系式,共聚物玻璃化温度与组成关系,高分子合金熔体粘度与组成关系,分子量分布关系式等。这些都表现了第四统计理论在各方面的普遍适用性和广泛应用的前景。     

Polarographic study of Tl+, Li+, Na+, K+, and Cs+ complexes with monensin anion in dipolar aprotic solvents

Summary The stability constants,K _sof monensin complexes with Li⁺, Na⁺, K⁺ and Cs⁺ ions were studied by a competitive polarographic method using the Tl⁺/Tl(Hg) redox couple as a sensitive electrochemical probe. TheK _svalues are strongly influenced by the solvents (acetonitrile, propionitrile, acetone, N,N-dimethylformamide, N-methyl pyrolidinone, N,N-dimethylacetamide, dimethylsulfoxide, N,N-diethylformamide and N,N-diethylacetamide were used in experiments) and vary inversely with the Gutmann donicity scale. Molecular mechanics computations revealed the probable structures of the complexes.

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Polarographische Untersuchung von Tl⁺-, Li⁺-, Na⁺- und Cs⁺-Komplexen mit Monesin-Anion in dipolaren aprotischen Lösungsmitteln

Zusammenfassung Es wurden die StabilitätskonstantenK _svon Monesin-Komplexen mit Li⁺-, Ma⁺- und Cs⁺-Ionen mittels einer competitiven polarographischen Methode unter Verwendung der Tl⁺/Tl(Hg)-Redoxelektrode als sensitiver elektrochemischer Sonde bestimmt. DieK _s-Werte werden stark vom Lösungsmittel (Acetonitril, Propionitril, Aceton, N,N-Dimethylformamid, N-Methylpyrrolidinon, N,N-Dimethylacetamid, Dimethylsulfoxid, N,N-Diethylformamid und N,N-Diethylacetamid) beeinflußt, wobei sie invers zurGutmann schen Donizitätsskala variieren. Die wahrscheinliche Struktur der Komplexe wurde mittels molekularmechanischer Berechnungen ermittelt.

     

Calix[4]arene-based ditopic receptor for dicarboxylates

Shape-selective recognition for the dicarboxylates in DMSO can be attained by a new calix[4]arene-based receptor 1 having two urea groups. Biologically active chorismate selectively bound in 1 over its dehydrated derivative. Molecular mechanics calculations gave a plausible explanation for the selective binding.     

A structural and energetics analysis of the binding of a series of N-acetylneuraminic-acid-based inhibitors to influenza virus sialidase

Summary A molecular dynamics/energy-minimisation protocol has been used to analyse the structural and energetic effects of functional group substitution on the binding of a series of C4-modified 2-deoxy-2,3-didehydro-N-acetylneuraminic acid inhibitors to influenza virus sialidase. Based on the crystal structure of sialidase, a conformational searching protocol, incorporating multiple randomisation steps in a molecular dynamics simulation was used to generate a range of minimum-energy structures. The calculations were useful for predicting the number, location, and orientation of structural water molecules within protein-ligand complexes. Relative binding energies were calculated for the series of complexes using several empirical molecular modelling approaches. Energies were computed using molecular-mechanics-derived interactions as the sum of pairwise atomic nonbonded energies, and in a more rigorous manner including solvation effects as the change in total electrostatic energy of complexation, using a continuum-electrostatics (CE) approach. The CE approach exhibited the superior correlation with observed affinities. Both methods showed definite trends in observed and calculated binding affinities; in both cases inhibitors with a positively charged C4 substituent formed the tightest binding to the enzyme, as observed experimentally.This paper is based on a presentation given at the 14th Molecular Graphics and Modelling Society Conference, held in Cairns, Australia, August 27–September 1, 1995.Presently on a visiting postdoctoral fellowship in the Department of Biomolecular Structure, Glaxo Research & Development Ltd, Greenford, Middlesex UB6 OHE, U.K.     

Charge calculations in molecular mechanics. Part 8 Partial atomic charges from classical calculations

Summary The CHARGE2 programme, which involves the classical calculation of both the inductive and resonance contributions to the partial atomic charges in molecules is described, and the charges and electrostatic potentials obtained presented for some illustrative examples.In substituted methanes (CH₃X, CF₃X, CCl₃X) the effects of varying the electronegativity of the substituents and the - and -substituent contributions are clearly illustrated for a variety of substituent groups X.The problems involved in the inclusion of silicon into this scheme are detailed, together with the methods of overcoming them. The partial atomic charges ( and contributions) and electrostatic potentials for some silicon oxygen compounds are presented and discussed.The partial atomic charges from CHARGE2 for all the natural amino acids as their N-acetyl, N-methyl-amides are given and compared with those obtained from the AMBER and ECEPP/2 force fields. Considerable differences in these figures are observed, with the AMBER charges consistently much larger than those from the other two methods.The CHARGE2 partial atomic charges and electrostatic potentials for the four common nucleic acids, adenine, cytosine, guanine and thymine, are given and compared with those derived from other calculations. Again there is general similarity but also there are considerable differences, with those from the AMBER force field somewhat larger than the other methods.For previous parts in this series, see Refs. 1-7.     

Quality assurance and statistical control

In scientific research laboratories it is rarely possible to use quality assurance schemes, developed for large-scale analysis. Instead methods have been developed to control the quality of modest numbers of analytical results by relying on statistical control: Analysis of precision serves to detect analytical errors by comparing thea priori precision of the analytical results with the actual variability observed among replicates or duplicates. The method relies on the chi-square distribution to detect excess variability and is quite sensitive even for 5–10 results. Interference control serves to detect analytical bias by comparing results obtained by two different analytical methods, each relying on a different detection principle and therefore exhibiting different influence from matrix elements; only 5–10 sets of results are required to establish whether a regression line passes through the origo. Calibration control is an essential link in the traceability of results. Only one or two samples of pure solid or aqueous standards with accurately known content need to be analyzed. Verification is carried out by analyzing certified reference materials from BCR, NIST, or others; their limited accuracy of 5–10% make them less suitable for calibration purposes.     

Robust estimates of the theoretical standard deviation to be used in interlaboratory precision experiments

Interlaboratory experiments often contain results that strongly deviate from other results obtained in the same laboratory under repeatability conditions, or laboratory means that strongly deviate from other laboratory means. In ISO 5725-2 [1] and IUPAC [2], the basic standards for the organisation and analysis of interlaboratory experiments for the determination of precision of a measurement method, outlier tests are performed in order to detect such situations and to finally decide whether these values are retained in the analysis or discarded as outliers. This outlier treatment, which always has a subjective aspect, becomes unnecessary by using robust estimates of the repeatability and reproducibility standard deviation. This paper proposes to use Rousseeuw’s Q _n as an extremely robust and efficient estimate of the standard deviation. Two examples show the performance of the new method.