检索结果-南通市图书馆

Hypersurfaces with Isotropic Para-Blaschke Tensor

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第7期30卷 1195-1209页

作者： jian bo FANG Kun ZHANG Department of Mathematics and Statistics Chuxiong Normal University

Let Mn be an n-dimensional submanifold without umbilical points in the （n ＋ 1）-dimen- sional unit sphere Sn＋l. Four basic invariants of Mn under the Moebius transformation group of Sn＋1 are a 1-form Ф called moebius form, a symmetric （0, 2） tensor A called Blaschke tensor, a symmetric （0, 2） tensor B called Moebius second fundamental form and a positive definite （0, 2） tensor g called Moebius metric. A symmetric （0,2） tensor D = A ＋ μB called para-Blaschke tensor, where μ is constant, is also an Moebius invariant. We call the para-Blaschke tensor is isotropic if there exists a function ,λ such that D = λg. One of the basic questions in Moebius geometry is to classify the hypersurfaces with isotropic para-Blaschke tensor. When λ is not constant, all hypersurfaces with isotropic para-Blaschke tensor are explicitly expressed in this paper.

关键词： Moebius geometry para-Blaschke tensor isotropic

3D-QSAR Studies on the Imidazopyrimidine Derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2020年第11期39卷 1985-1989页

作者： TONG jian-bo CAO Xu Shaanxi Key Laboratory of Chemical Additives for Industry Shaanxi University of Science and TechnologyXi'an 710021China

Comparative molecular field analysis(CoMFA) and comparative molecular similarity indices analysis(CoMSIA) for imidazopyrimidine derivatives were performed to get the molecular active conformation selection, molecular alignment, as well as the establishment of corresponding 3 D-QSAR model. The model established by this method has good ability to predict such compounds. For CoMFA model, the cross-validated q2 and non-cross-validated r2 values are 0.665 and 0.872, respectively. The best q2 value for CoMSIA model is 0.632 and r2 value is 0.923. Using this information and the three-dimensional equipotential map for molecular design can theoretically obtain some new antibacterial drugs with higher activity. There are two newly designed molecules with activity values of 7.921 and 7.872, which are higher than that of the template molecule No. 12 with an activity value of 7.850, and the QSAR research results can provide a theoretical reference for the synthesis of new drugs.

关键词： 3D-QSAR comparative molecular force field analysis molecular design

A Cluster Algorithm for the 2-D SU(3)×SU(3) Chiral Model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1996年第7期13卷 549-552页

作者： JI Da-ren ZHANG jian-bo Zhejiang Institute of Modern Physics Zhejiang UniversityHangzhou 310027

To extend the cluster algorithm to SU(N)×SU(N)chiral models,a variant version of Wolff's cluster algorithm is proposed and tested for the 2-dimensional SU(3)×SU(3)chiral *** results show that the new method can redu... 详细信息

关键词： SU(3) model chiral

Contribution of Root Proliferation in Nutrient-Rich Soil Patches to Nutrient Uptake and Growth of Maize

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2012年第6期22卷 776-784页

作者： LI Hong-bo ZHANG Fu-Suo SHEN jian-bo Department of Plant Nutrition China Agricultural UniversityKey Laboratory of Plant-Soil InteractionsMinistry of EducationBeijing 100193(China)

Root proliferation can be stimulated in a heterogeneous nutrient patch; however, the functions of the root proliferation in the nutrient-rich soil patches are not fully understood. In the present study, a two-year field experiment was conducted to examine the comparative effects of localized application of ammonium and phosphorus (P) at early or late stages on root growth, nutrient uptake, and biomass of maize (Zea mays L.) on a calcareous soil in an intensive farming system. Localized supply of ammonium and P had a more evident effect on shoot and root growth, and especially stimulated fine root development at the early seedling stage, with most of the maize roots being allocated to the nutrient-rich patch in the topsoil. Although localized ammonium and P supply at the late stage also enhanced the fine root growth, the plant roots in the patch accounted for a low proportion of the whole maize roots in the topsoil at the flowering stage. Compared with the early stage, fine root length in the short-lived nutrient patch decreased by 44%-62% and the shoot dry weight was not different between heterogeneous and homogeneous nutrient supply at the late growth stage. Localized supply of ammonium and P significantly increased N and P accumulation by maize at 35 and 47 days after sowing (DAS); however, no significant difference was found among the treatments at 82 DAS and the later growth stages. The increased nutrient uptake and plant growth was related to the higher proportion of root length in the localized nutrient-enriched patch. The results indicated that root proliferation in nutrient patches contributed more to maize growth and nutrient uptake at the early than late stages.

关键词： biomass growth stage intensive farming system localized nutrient supply root length

Complete Hypersurfaces with Constant Laguerre Scalar Curvature in R^n

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2016年第6期32卷 715-724页

作者： jian bo FANG Feng jiang LI School of Mathematics and Statistics Chuxiong Normal University Department of Mathematics Yunnan Normal University

Let x ： M^n-1→ R^n be an umbilical free hypersurface with non-zero principal curvatures. Two basic invariants of M under the Laguerre transformation group of Rn are Laguerre form C and Laguerre tensor L. In this paper, we prove the following theorem： Let M be an （n-1）-dimensional （n 〉 3） complete hypersurface with vanishing Laguerre form and with constant Laguerre scalar curvature R in R^n, denote the trace-free Laguerre tensor by L = L -1/n-1tr（L）· Id. If supM ｜｜L｜｜=0,then M is Laguerre equivalent to a Laguerre isotropic hypersurface; and if supM ｜｜L^-｜｜≡√（n-1）（n-2）R/ （n-1）（n-2）（n-3） , M isLaguerre equivalent to the hypersurface x^- ： H^1× S^n-2 → R^n.

关键词： Laguerre isoparametric hypersurface Laguerre second fundamental form Laguerre metric Laguerre form parallel Laguerre form

Diffeomorphism Classification of Smooth Weighted Complete Intersections

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2012年第2期28卷 299-312页

作者： jian bo WANG Yu Yu WANG Department of Mathematics Tianjin UniversityTianjin 300072P.R.China College of Mathematical Science Tianjin Normal UniversityTianjin 300387 P.R.China

Xn（d1,...,dr-1,dr.;w） and Xn（e1,...,er-1,dr;w） are two complex odd-dimensional smooth weighted complete intersections defined in a smooth weighted hypersurfaee

关键词： Weighted projective space weighted complete intersection weighted hypersurface diffeo-morphism classification

Temporal stability of aboveground net primary production in northern Tibet alpine steppe in response to nitrogen addition

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第11期16卷 2679-2686页

作者： WU jian-bo WANG Xiao-dan Key Laboratory of Mountain Environment Evolution and Ecological Regulation Institute of Mountain Hazard and Environment CAS

The mechanism that sustains the temporal stability of aboveground net primary production(ANPP)respond to nitrogen deposition is still ***,we investigated the mechanism of temporal stability of ANPP through the effect of N addition on diversity,species asynchrony andportfolio effects in northern Tibet alpine steppe over a period of three *** results showed that the community temporal stability did not significantly correlate with the species richness and Shannon–Wiener *** asynchrony and stability was also not significantly affected by N addition(p>0.05).Furthermore,there was no significant relationship between species asynchrony and temporal *** the value of portfolio effects(z)(z=1.304,95%confidence intervals:1.029–1.597)was more than 1,the portfolio effects was not a primary driver of temporal stability due to the biodiversity being *** above results suggested that the richness,species asynchrony and portfolio effect could not support for mechanism of stability at the alpine *** the results of path analysis,species temporal stability positively supports the community temporal stability in the alpine steppe *** to the character of environment and vegetation of alpine steppe at North Tibet,we inferred that dominance species stability is more important than species richness for the community temporal stability.

关键词： Community temporal stability Species richness Species asynchrony Species temporal stability Portfolio effects Nitrogen deposition

Thermal analysis of walls in a new-type billet caster tundish with a vacuum shell

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2017年第5期24卷 501-507页

作者： jian-bo Xie jian-an Zhou Lan-hua Zhou Bao Wang Hua Zhang State Key Laboratory of Refractories & Metallurgy Wuhan University of Science & Technology Wuhan 430081 Hubei China Key Laboratory of Ferrous Metallurgy and Resources Utilization Ministry of Education Wuhan University of Science & Technology Wuhan 430081 Hubei China School of Resources and Environmental Engineering Panzhihua University Panzhihua 617000 Sichuan China

To reduce thermal loss from molten steel in a tundish during continuous casting production, a new tundish fabricated by welding radiation-proof steel plates onto the steel plates of the exterior walls of a billet caster tundish was proposed. This new tundish was used to investigate the effect of pressures inside the vacuum chamber on the uniformity of the temperature of molten steel and the thermal conditions of the vacuum layer. The results show that the conversion radiation coefficient is not sensitive to pressure and its value at high temperatures is merely 1.5 times greater than that at low temperatures. Pressure is the key factor af- fecting additional factor of conversion convection. This factor is more than 100 times greater at 10-5 Pa than at 10-2 Pa, and the temperature at inner points at 10-2 Pa is, on average, 4 K higher than that at 10-5 Pa. Meanwhile, the local temperature difference of the inlet at 10-2 Pa is 1 K higher than that at 10-5 Pa. Thus, the proposed vacuum billet caster tundish can achieve low superheat teeming of steel because of the ther- mal preservation capability of the vacuum, which helps to reduce the tapping temperature and improve the uniformity of the temperature of steel.

关键词： Tundish Vacuum chamber Pressure Thermal preservation Superheat

Analysis of precipitation behavior of MnS in sulfur-bearing steel system with finite-difference segregation model

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第8期25卷 803-812页

作者： De-lin Hu Hui Liu jian-bo Xie Juan Cheng jian Li jian-xun Fu State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy and School of Materials Science and Engineering Shanghai University Shanghai 200444 China

To further reveal the influence of micro-segregation on the precipitation behavior of MnS in sulfur-bearing steel system, a coupled model of micro-segregation and MnS precipitation was established by the finite-difference method based on various calculation domains and the solid diffusion degrees, and a new controlled diffusion equation with more stable convergence was also used. 49MnVS3 and 1215 steels were used to analyze the influence of calculation domain, segregation model and S content on the precipitation behavior of MnS. The calculation results were verified by a high- temperature confocal laser scanning microscope （HT-CLSM）. The results show that the domain has little effect on the precipitation temperature, precipitation solid fraction and precipitation amount of MnS, but affects the precipitation location and segregation of the solutes. For low- and medium-sulfur steels, the temperatures calculated by the diffusion control growth （DCG） model and the Lever model were nearly identical, whereas the temperature calculated by the Scheil model was lower. However, for high-sulfur steels, the precipitation temperatures calculated by three segregation models were nearly same. The precipitation solid fraction is more reasonable to describe the precipitation behavior of MnS. The precipitation behavior of MnS, observed by the HT-CLSM, matches well with that in the DCG model.

关键词： MnS precipitation Micro-segregation Mathematical model Solidification In situ observation