检索结果-南通市图书馆

Chemical Research in Chinese Universities 2007年第2期23卷 221-225页

作者： LIU Zhen-feng wang yong YUE Xian-fang HAN Ke-li State Key Laboratory of Molecular Reaction Dynamics Dalian Institute of Chemical Physics Chinese Academy of Sciences Dcdian 116023 P. R. China

The mechanisms of insertion of O-H bond of Rh（ Ⅱ ）-methylene carbene into methanol and ethanol were studied by using B3LYP functional both in gas phase and in CH2 C12. The formation of free alcoholic oxonium ylides is found to be impossible. Alcoholic oxonium ylide are formed as the intermediates before beth the stepwise and the concerted transition states of insertion of O-H bend of Rh（ Ⅱ ）-methylene carbene into methanol and ethanol. With re- gard to the mechanisms of insertion of O-H of Rh（ Ⅱ ） -methylene carbene into alcohols, analysis of the energy bartiers of the two mechanisms indicate that the stepwise mechanism is more plausible than the concerted mechanism.

关键词： Oxonium ylide 1,2-Hydrogen shift Density functional calculation Dirhodium( Ⅱ ) methylene carbene

Assessment of Genetic Relationship of Foxtail Millet with Its Wild Ancestor and Close Relatives by ISSR Markers

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2012年第4期11卷 556-566页

作者： LI Wei ZHI Hui wang yong-fang LI Hai-quan DIAO Xian-min National Millet Improvement Center/Institute of Millet Crops Hebei Academy of Agricultural and Forestry Sciences Shijiazhuang 050031 P.R.China National Key Facility for Crop Gene Resources and Genetic Improvement （NFCRl）/Institute of Crop Science Chinese Academy of Agricultural Sciences （CAAS） Beijing 100081 P.R.China

Inter simple sequence repeat（ISSR） analysis was applied to samples of foxtail millet and its wild ancestor and other close relatives of the genus Setaria in order to detect domestication-related geographical structure and phylogenetic relationship of those ***-one accessions of nine Setaria species that originated from different regions were used in this *** out of the 27 ISSR primers screened amplified successfully and a total of 156 markers were scored for all the accessions,with a high level of polymorphism being *** dendrogram based on UPGMA cluster analysis showed clear geographic structure among foxtail millet and its wild ancestor green foxtail,which implies that northern China is the domestication center for both the Chinese and European foxtail millet landraces used in this *** result did not support the hypothesis that China and Europe are independent domestication centers for foxtail millet proposed by several previous studies based on morphological and isozyme *** dendrogram also clearly classified the Setaria sample used into two groups,a viridis and a pumila *** viridis group was composed of ***,***,***,***,***,and ***,and the pumila group consisted of *** and ***,which is consistent with the recently proposed hypothesis of multiple origin of Setaria *** phylogenetic relationships among different species are discussed.

关键词： Setaria foxtail millet ISSR domestication phylogenetic relationship

Effects of planting patterns on yield, quality, and defoliation in machine-harvested cotton

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2019年第9期18卷 2019-2028页

作者： wang fang-yong HAN Huan-yong LIN Hai CHEN Bing KONG Xian-hui NING Xin-zhu wang Xu-wen YU Yu LIU Jing-de Cotton Research Institute Xinjiang Academy of Agricultural and Reclamation Science/Northwest Inland Region Key Laboratory of Cotton Biology and Genetic Breeding Ministry of Agriculture and Rural Affairs

The aim of this study was to elucidate the effects of different machine-harvested cotton-planting patterns on defoliation,yield,and fiber quality in cotton and to provide support for improving the quality of machine-harvested *** the 2015 and 2016 growing seasons,the Xinluzao 45(XLZ45)and Xinluzao 62(XLZ62)cultivars,which are primarily cultivated in northern Xinjiang,were used as study *** wide-narrow row(WNR),wide and ultra-narrow row(UNR),wide-row spacing with high density(HWR),and wide-row spacing with low density(LWR)planting patterns were used to assess the effects of planting patterns on defoliation,yield,and fiber *** with WNR,the seed cotton yields were significantly decreased by 2.06–5.48%for UNR and by 2.50–6.99%for LWR,*** main cause of reduced yield was a reduction in bolls per unit *** variation in HWR yield was–1.07–1.07%with reduced bolls per unit area and increased boll weight,thus demonstrating stable *** terms of fiber quality indicators,the planting patterns only showed significant effects on the micronaire value,with wide-row spacing patterns showing an increase in the micronaire *** defoliation and boll-opening results showed that the number of leaves and dried leaves in HWR was the lowest among the four planting *** to the application of defoliating agent and before machine-harvesting,the numbers of leaves per individual plant in HWR were decreased by 14.45 and 25.00%on average,respectively,compared with WNR,while the number of leaves per unit area was decreased by 27.44 and 36.21%on average,*** rates of boll-opening and defoliation in HWR were the ***,the boll-opening rate before defoliation and machine-harvesting in HWR was 44.54 and 5.94%higher on average than in WNR,while the defoliation rate prior to machine-harvesting was 3.45%higher on average than in *** numbers of ineffective defoliated leaves and leaf trash in HWR were

关键词： machine-harvested cotton planting patterns defoliation yield quality

Estimating Aboveground Fresh Biomass of Different Cotton Canopy Types with Homogeneity Models Based on Hyper Spectrum Parameters

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2007年第4期6卷 437-445页

作者： BAI Jun-hu LI Shao-kun wang Ke-ru SUI Xue-yan CHEN Bing wang fang-yong Institute of Crop Sciences Chinese Academy of Agricultural Sciences/The National Key Facility for Crop Gene Resources and Genetic Improvement NFCRI Beijing 100081 P.R.China Key Laboratory of Oasis Ecology Agriculture of Xinjiang Construction Crops/The Center of Crop High-Yield Research Shihezi 832003 P.R.China

AGB （aboveground fresh biomass） is one of the most important parameters of the crop condition monitored with remote sensing. Hyper spectrum remote sensing with the fine spectrum information becomes the efficient method estimating the vegetation AGB. The research was conducted in Xinjiang, the largest cotton planting region of China. The paper analyzed the correlation between the cotton AGB and reflective spectrum and the first derivative spectrum, and the variation coefficient of the waveband reflectance. According to the analysis above, all of 23 parameters, including the hyper spectrum reflectance, the first derivative spectrum parameters and normalization vegetation indexes, were established. And then the estimation models on cotton AGB of relaxing and compact canopy type were established and tested respectively. The tested results showed that Fgo1, [901,502], [901,629], [901,672] among the reflective spectral parameters and D525, D956, D1019, D1751 among the first derivative spectral parameters had the homogenous effect on different cotton canopy types, and the determination coefficients of the models above all arrive at the significant level of 0.99 confidence interval. At last, the tested results of the homogeneity models for different canopy types indicated the parameters of [901, 502], [901,629], [901,672] have more satisfying veracity than others, and the relative errors are as low as 17.0, 16.3 and 16.7% correspondingly; in contrast, the estimation veracity of the first derivative spectrum parameters of single waveband is low.

关键词： canopy types of cotton AGB hyperspectrum parameters homogeneity estimation models

Spectrum Characteristics of Cotton Canopy Infected with Verticillium Wilt and Applications

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2008年第5期7卷 561-569页

作者： CHEN Bing LI Shao-kun wang Ke-ru wang Jing wang fang-yong XIAO Churl-hua LAI Jun-chen wang Na Key Laboratory of Oasis Ecology Agriculture Xinjiang Production and Construction Corps/Shihezi University Shihezi 832000 P.R. China Institute of Crop Science Chinese Academy of Agricultural SciencesThe National Key Facility for Crop Gene Research and Genetic Improvement （NFCRI） Beijing 100081 P.R.China College of Resources and Environment Northwest A ＆ F University Yangling 712100 P.R.China

Hyper spectrum remote sensing with fine spectrum information is an efficient method to estimate the verticillium wilt of cotton. The research was conducted in Xinjiang, the largest cotton plant region of China, by using the data which were collected both by canopy spectrum infected with verticillium wilt and severity level （SL） in the year 2005-2006. The quantitative correlation was analyzed between SL and canopy of reflectance spectrum or derivative spectrum reflectance. The results indicated that spectrum characteristics of cotton canopy infected with verticillium wilt changed regularly with the increase of SL in different periods and varieties, Spectrum reflectance increased in the visible light region （620-700 nm） with the increase of the SL, which inverted in near-infrared region and was extremely significant in the region of （780-1 300 nm）. When SL attained b2 （DI = 25）, cotton canopy infected with verticillium wilt was used as a watershed and diagnosed index in the beginning stages of the disease. The results also indicated that there were marked different characteristics of the first derivative spectrum in these SL, it changed significantly in the red edge ranges （680-760 nm） with different SL, i.e., red edge swing decreased, and red edge position equally moved to the blue. In this study 1 001-1 110 nm and 1 205- 1 320 nm were selected out as sensitive bands for SL of canopy. Inversion models established for estimating cotton canopy infected with verticillium wilt reached the most significant level. Finally, the different spectrum characteristics of cotton canopy infected with verticillium wilt were marked, some inversion models were established, which could estimate SL of canopy infected with verticillium wilt. The best recognized model was the first derivative spectra at （FD 731 nm- FD 1317 nm）, and it might be used to forecast the position of cotton canopy infected with verticillium wilt quantitatively.

关键词： cotton verticillium wilt canopy spectrum SL inversion models

Coil migrating out of a small wide-necked aneurysm embolized with stent-assisted technique

在线全文

学校读者我要写书评

暂无评论

介入放射学杂志 2006年第2期15卷 126-128页

作者： GAO Bu-lang LI Ming-hua wang yong-li fang Chun Department of Radiology Shanghai Sixth People＇s HospitalShanghai Jiaotong UniversityShanghai 200233Chian

Stent-assisted coiling is one of the techniques used to treat intracranial aneurysms with wide necks or unfavorable neck-to-fundus ratios, which have been traditionally considered as poor candidates for Guglielmi detachable coil ( GDC ) embolization owing to the significant risk of coil herniation into the parent artery[1-5]. With this technique, fusiform, wide-necked and geometrically difficult aneurysms as well as pseudoaneurysms have been successfully treated with different follow-up results. Herein, we present an aneurysm case with a coil escaping from the confinement of the stent.

关键词：血管疾病血管畸形造影诊断检查方式

Two new families of fourth-order explicit exponential Runge–Kutta methods with four stages for first-order differential systems

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2025年

作者： Xian Fa HU yong Lei fang Bin wang School of Mathematics and Statistics Changshu Institute of Technology School of Mathematics and Statistics Zaozhuang University School of Mathematics and Statistics Xi'an Jiaotong University

In this paper, we formulate two new families of fourth-order explicit exponential Runge–Kutta (ERK) methods with four stages for solving first-order differential systems y′(t)+My(t)=f(y(t)). The order conditions of these ERK methods are derived by comparing the Taylor series of the exact solution, which are exactly identical to the order conditions of explicit Runge–Kutta methods, and these ERK methods reduce to classical Runge–Kutta methods once M→0. Moreover, we analyze the stability properties and the convergence of these new methods. Several numerical examples are implemented to illustrate the accuracy and efficiency of these ERK methods by comparison with standard exponential integrators.

关键词：

Advancing gravitational theory through the tetrahedral constellation gravitational wave observatory

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第2期Mechanics & Astronomy) .卷 201-202页

作者： Yun-yong wang Zhou-Jian Cao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University

The Tetrahedral Constellation Gravitational Wave Observatory(TEGO) [1] represents a significant leap forward in gravitational wave detection, advancing our understanding of gravitational theory. By introducing a fourth spacecraft to form a tetrahedral configuration, TEGO enhances traditional triangular setups, enabling the simultaneous sensitivity to all six gravitational wave polarization modes, including those not predicted by general relativity.

关键词：

同方期刊数据库

Experiments and modeling of microstructural and mechanical behaviors of laser-welded Ni-based superalloy at high temperatures

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2025年第1期38卷 99-114页

作者： Ting HOU yong LI Degang wang Yuelin wang Marko VILOTIC School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Department of Structure Shenyang Aircraft Designand Research InstituteShenyang 110000China Engineering Center Shenyang Aircraft CorporationShenyang 110000China Faculty of Technical Science University of Novi SadNovi Sad 21102Serbia

The performance of welded Ni-based superalloys at high temperatures is essential to be evaluated due to their particular service environment for aero-engines and high-speed *** tensile properties and related microstructural evolutions such as the carbide precipitate and grain of a laser-welded Ni-based alloy were experimentally and numerically investigated at different temperatures(20,300,500,800℃).The results show that at room temperature,the strength of the Base Material(BM)was slightly smaller,with a difference of less than 1%,than the Welded Material(WM),which can be attributed to the more uniformly distributed needle-shaped carbide precipitates in the WM than those nonuniformly coarser spherical ones in the *** at 300℃ and 500℃,the strength of WM decreased more obviously compared with that of BM due to the more apparent growth of grain:13.52%loss in yield strength in WM alloys as compared with BM alloys at 300℃,and 16.57% at 500℃.At 800℃,the strength of BM and WM both decreased to a similar level due to Dynamic Recrystallization(DRX).However,a much higher elongation was observed for the BM than WM(less than 50%of BM),which can be attributed to the enhanced dislocation accumulation capability of the large spherical carbides along grain boundaries on the fracture surface in ***,a unified model considering the welding effects on both microstructures(dislocation,carbides,and grain)and mechanical properties evolutions at different temperatures was developed and *** on this model,the key temperature ranges(20–600℃)where apparent weakening of strength and uniform plasticity occurs for welded structures were identified,providing a direct guidance for potential structure and process design.

关键词： Ni-based superalloy Microstructure Mechanical properties Constitutive model High temperature

The Hilbert expansion of the Boltzmann equation in the incompressible Euler level in a channel

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2025年第1期68卷 39-88页

作者： Feimin Huang Weiqiang wang yong wang Feng Xiao Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Computing and Stochastic Mathematics(Ministry of Education) School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China

The study of the hydrodynamic limit of the Boltzmann equation with physical boundary is a challenging problem due to the appearance of the viscous and Knudsen boundary *** this paper,the hydrodynamic limit from the Boltzmann equation with the specular reflection boundary condition to the incompressible Euler equations in a channel is *** on the multi-scaled Hilbert expansion,the equations with boundary conditions and compatibility conditions for interior solutions,and viscous and Knudsen boundary layers are derived under different scaling,***,some uniform estimates for the interior solutions,and viscous and Knudsen boundary layers are *** the help of the L^(2)-L^(∞) framework and the uniform estimates obtained above,the solutions to the Boltzmann equation are constructed by the truncated Hilbert expansion with multiscales,and hence the hydrodynamic limit in the incompressible Euler level is justified.

关键词： Boltzmann equation incompressible Euler equations hydrodynamic limit Hilbert expansion specular reflection boundary condition viscous boundary layer Knudsen boundary layer