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A brief introduction to weakly supervised learning

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National Science Review 2018年第1期5卷 44-53页

作者： zhi-hua Zhou National Key Laboratory for Novel Software Technology Nanjing University

Supervised learning techniques construct predictive models by learning from a large number of training examples, where each training example has a label indicating its ground-truth output. Though current techniques have achieved great success; it is noteworthy that in many tasks it is difficult to get strong supervision information like fully ground-truth labels due to the high cost of the data-labeling process. Thus,it is desirable for machine-learning techniques to work with weak supervision. This article reviews some research progress of weakly supervised learning, focusing on three typical types of weak supervision:incomplete supervision, where only a subset of training data is given with labels; inexact supervision, where the training data are given with only coarse-grained labels; and inaccurate supervision, where the given labels are not always ground-truth.

关键词： machine learning weakly supervised learning supervised learning

Decomposition and Approximation of Multivariate Functions on the Cube

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Acta Mathematica Sinica,English Series 2013年第1期29卷 119-136页

作者： zhi hua ZHANG College of Global Change and Earth System Science Beijing Normal University

In this paper, we present a decomposition method of multivariate functions. This method shows that any multivariate function f on [0, 1]d is a finite sum of the form ∑jФjψj, where each Фj can be extended to a smooth periodic function, each ψj is an algebraic polynomial, and each Фjψj is a product of separated variable type and its smoothness is same as f. Since any smooth periodic function can be approximated well by trigonometric polynomials, using our decomposition method, we find that any smooth multivariate function on [0, 1]d can be approximated well by a combination of algebraic polynomials and trigonometric polynomials. Meanwhile, we give a precise estimate of the approximation error.

关键词： Decomposition of multivariate functions approximation of multivariate functions fundamental polynomial projection operator classification of boundary points

Classifying Genomic Sequences by Sequence Feature Analysis

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Genomics, Proteomics & Bioinformatics 2005年第4期3卷 201-205页

作者： zhi-hua Liu Dian Jia Xiao sun State Key Laboratory of Bioelectronics Southeast University Nanjing 210096 China.

Traditional sequence analysis depends on sequence alignment. In this study, we analyzed various functional regions of the human genome based on sequence features, including word frequency, dinucleotide relative abundance, and base-base correlation. We analyzed the human chromosome 22 and classified the upstream, exon, intron, downstream, and intergenic regions by principal component analysis and discriminant analysis of these features. The results show that we could classify the functional regions of genome based on sequence feature and discriminant analysis.

关键词： genome sequence feature analysis BBC PCA discriminant analysis

Influence of Gravity on Structure of Colloidal Crystal Using Simulated Microgravity

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Chinese Journal of Chemical Physics 2009年第1期22卷 41-45页

作者： Lei Liu Jie Wang Sheng-hua Xu zhi-wei sun Jing-tong Wang . National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences BerlinE 100190 China Department of Physics Southern University and A&M College Baton Rouge LA 70813 USA

Liquid mixtures of water and deuterium oxide as the liquid phase, were used to match the density of charged colloidal particles. Kossel diffraction method was used to detect the crystal structures. The experiments under the density-matched （g=0） and unmatched （g=1） conditions are compared to examine the influence of gravity on the crystal structures formed by self-assembly of 110 nm （in diameter） polystyrene microspheres. The result shows that the gravity tends to make the lattice constants of colloidal crystals smaller at lower positions, which indicates that the effect of gravity should be taken into account in the study of the colloidal crystals.

关键词： Colloidal crystal Microgravity Density-match Lattice constant

Triarylborane π-electron systems with intramolecular charge-transfer transitions

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Chinese Chemical Letters 2016年第8期27卷 1131-1138,1464页

作者： Zuo-Bang sun Sheng-Yong Li zhi-Qiang Liu Cui-hua Zhao School of Chemistry and Chemical Engineering Key Laboratory of Special Functional Aggregated Materials Ministry of EducationShandong University State Key Laboratory of Crystal Materials Shandong University

The incorporation of B element into π-conjugated system is an efficient strategy to tune the steric and electronic structure and thus optoelectronic properties of π-electron *** vacant p orbital on the tricoordinate B center makes it exhibit several electronic and steric features,such as electron-accepting ability through p-π~＊ conjugation,the high Lewis acidity to coordinate with Lewis bases,as well as the steric bulk arising from the aryl substituent on the B center to get enough kinetic *** a result,the boryl group is a very unique electron *** an electron-donating amino group is present,the triarylboranes would display intense intramolecular charge transfer transitions,which lead to interesting optoelectronic properties and great *** short review summarizes the recent progress in π-electron systems,which contain both B and N elements and thus display intramolecular charge-transfer *** triarylboranes are introduced based on their structural features,including the linear π-system with boryl and amino groups at the terminal positions,the lateral borylsubstituted π-system with amino groups at the terminal positions,the biphenyl π-system with an amino and a boryl groups at o,o＇-positions,nonconjugated U- and V-shaped π-system,macrocylcic π-system with B and N embedded in the ring,B,N-bridged ladder-type π-system,as well as the polycyclicπ-system with B embedded in the center.

关键词： Triarylborane Electron-acceptor Electron-donor Charge-transfer

Characterization of impurities in the bulk drug lisinopril by liquid chromatography/ion trap spectrometry

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第5期9卷 385-390页

作者： Pei-xi ZHU Dan-hua WANG Cui-rong sun zhi-quan SHEN Department of Chemistry Zhejiang University Hangzhou 310027 China Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

Two trace impurities in the bulk drug lisinopril were detected by means of high-performance liquid chromatography coupled with mass spectrometry （HPLC/MS） with a simple and sensitive method suitable for HPLC/MSn analysis. The fragmentation behavior of lisinopfil and the impurities was investigated, and two unknown impurities were elucidated as 2-（6-amino- l-（l-carboxyethylamino）- l-oxohexan-2-ylamino）-4-phenylbutanoic acid and 6-amino-2-（l-carboxy-3-phenylpropylamino）-hexanoic acid on the basis of the multi-stage mass spectrometry and exact mass evidence, The proposed structures of the two unknown impurities were further confirmed by nuclear magnetic resonance （NMR） experiments after preparative isolation.

关键词： Lisinopril Impurities High-performance liquid chromatography (HPLC) Multi-stage mass spectrometry (MS^n)

Role of anthropogenic forcing and atmospheric circulation in a lowtemperature event in February 2022 in eastern China

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Advances in Climate Change Research 2023年第6期14卷 921-929页

作者： zhi-Fan CHEN Ying sun Xuebin ZHANG Tim LI Jin-hua YU Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China Climate Studies Key Laboratory National Climate CenterChina Meteorological AdministrationBeijing 10008lChina Climate Research Division Environment and Climate Change CanadaToronto M3H 5T4Canada Department of Atmospheric Sciences University of Hawai at ManoaHonolulu HI 96822USA

In February 2022,eastern China experienced prolonged low temperatures,with significant impacts on agriculture,transportation,and power *** regional average temperature anomaly for February 2022 was-0.65℃,making it the third coldest February from 2000 to *** the influence of anthropogenic forcing and atmospheric circulation on low-temperature events is important for climate change adaptation and mitigation in the *** study used observational and model data from the Coupled Model Intercomparison Project Phase 6 to conduct an extreme event attribution *** results showed that anthropogenic forcing led to a 1.5-fold decrease in the probability of 2022-like events,with anthropogenic greenhouse gases being the primary contributors to this ***,aerosols slightly increased the likelihood of such *** evaluate the role of atmospheric circulation in this event,we chose Siberian High as the key circulation system and employed circulation similarity,intensity classification,and regression methods to estimate the impacts of circulation patterns,circulation in-tensity,and human-induced circulation *** results demonstrated that under the influence of the same anthropogenic forcing,the presence of an anomalous Siberian High and anomalously enhanced intensity of the Siberian High both increased the likelihood of such a cold event ***,anthropogenic forcing exerts a negligible effect on such cold events via anomalous circulation.

关键词： Low-temperature event Attribution Intensity of the Siberian high Anthropogenic forcing Atmospheric circulation

Universal sums of three quadratic polynomials

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Science China Mathematics 2020年第3期63卷 501-520页

作者： zhi-Wei sun Department of Mathematics Nanjing University

Let a,b,c,d,e and f be integers with a≥ c≥ e> 0,b>-a and b≡a(mod 2),d>-c and d≡c(mod 2),f>-e and f≡e(mod 2).Suppose that b≥d if a=c,and d≥f if c=*** b(a-b),d(c-d) and f(e-f) are not all zero,we prove that if each n∈N={0,1,2,...} can be written as x(ax+b)/2+y(cy+d)/2+z(ez+f)/2 with x,y,z∈N then the tuple(a,b,c,d,e,f) must be on our list of 473 candidates,and show that 56 of them meet our *** b∈[0,a),d∈[0,c) and f∈[0,e),we investigate the universal tuples(a,b,c,d,e,f) over Z for which any n∈N can be written as x(ax+b)/2+y(cy+d)/2+z(ez+f)/2 with x,y,z∈Z,and show that there are totally 12,082 such candidates some of which are proved to be universal tuples over *** example,we show that any n∈N can be written as x(x+1)/2+y(3y+1)/2+z(5z+1)/2 with x,y,z∈Z,and conjecture that each n∈N can be written as x(x+1)/2+y(3y+1)/2+z(5z+1)/2 with x,y,z∈N.

关键词： representations of integers universal sums quadratic polynomials

Synthesis of N-Aryl-2-(1′,6′-dihydro-6′-pyridazinone-3′-carbonyl) Thiosemicarbazides and Their Related Heterocyclic Compounds

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Chemical Research in Chinese Universities 2005年第2期21卷 172-176页

作者： WANGDuo-zhi CAOLing-hua DepartmentofChemistry XinjiangUniversityUrumqi830046P.R.China DepartmentofChemistry XinjiangUniversityUrumqi830046P.R.China／／StateKeyLaboratoryofElemento-organicChemistryNankaiUniversityTianjin300071P.R.China

Dihydro-3-hydrozinocarbonyl-6-pyridazinone(compound 2) were prepared from α-ketoglutaric acid and hydrazine hydrate. A series of N-aryl-2-(1′,6′-dihydro-6′-pyridazinone-3′-carbonyl) thiosemicarbazides 3a_3f were synthesized from the reaction of aryl isothiocyanates with compound 2. The terminal compounds 1,3,4-thiadiazole, 1,3,4-oxadiazole and 1,2,4-triazol-5-thione derivatives were cyclized from compounds 3a_3f. Their structures were confirmed by IR, 1H NMR, MS and elemental analyses.

关键词： Pyridazinone 1,3,4-Thiadiazole 1,3,4-Oxadiazole 1,2,4-Triazol-5-thione Synthesis.