豆蔻梢头二月初——让低年级习作有范、有物、有趣

写话不仅可以习得语言表达能力,而且在写话过程中可以发展儿童的思维,发展他们的想象,并且培养儿童对生活的热爱。在具体教学实践中,在规范学生表达的同时,需要寻找习作的素材,还要保护学生写话兴趣,提升其书面表达能力,使学生成为一个"会表达,乐表达"的"小作者"。

依达拉奉右莰醇治疗缺血性脑卒中的有效性和安全性研究进展

急性缺血性脑卒中特异性治疗策略包括改善脑血循环、他汀药物及神经保护等。神经保护剂理论上可以阻断缺血级联反应并阻止神经细胞死亡,在缺血性脑卒中的治疗中有很大的应用前景,但是既往对神经保护剂的临床研究结论并不一致。近期,越来越多临床研究结果显示,与依达拉奉相比,依达拉奉右莰醇改善缺血性脑卒中患者神经功能缺损的远期疗效更好,安全性相似,临床应用价值更优。本文将对多靶点神经保护剂依达拉奉右莰醇的作用机制、治疗缺血性脑卒中的有效性及安全性进行综述,以期为该药的临床合理应用提供参考。

The Minimum Norm of Solutions of the Boolean Matrix-Equation A^k=J

Let A be an n×n primitive Boolean matrix. γ(A) is the least number k such that A k=J. σ(A) is the number of 1 entry in A . In this paper, we consider the parameter M ′(k,n)= min {σ(A)|A k=J, trace (A)=0} and obtain the values of M ′(2,n) and M ′(k,n) for k≥2n-6 . Furthermore, the characterization of solution of A 2=J with trace (A) =0 and σ(A)=3n-3 is completely determined.

Numerical prediction of the long- term soil temperature variations around shallowsections of cross-river road tunnels

Considering the coupled heat transfer effect induced by parallel cross-river road tunnels, the long-term soil temperature variations of shallow sections of cross-river tunnels under the river beach are predicted using the finite difference method for numerical simulation. The boundary conditions and the initial values are determined by in situ observations and numerical iterations.The simulation results indicate that the ultimate calculated steady heat transfer time is 68 years, and most of the heat transfer is completed in 20 years.The initial constant temperature soil surrounding the tunnels is transformed to an annually variable one.An obvious temperature-varying region of the surrounding soil is discovered within 5 m from the tunnel exterior, as well as within the entire range of soil between the two tunnels.The maximum temperature increase value reaches 7.14 ℃ and the maximum peak-to-valley value of annual temperature increase reaches 10 ℃.The temperature variation of soils surrounding tunnels below 10 m is completely controlled by the heat transfer from the tunnels.The coupled heat transfer effect is confirmed because the ultimate steady temperature of soil between the two tunnels is higher than the ones along other positions.Moreover, the regression model comprising a series of univariate functions is proposed for the annual soil temperature fluctuation estimation for the locations varied distances around the tunnel.This investigation is beneficial to gain an insight into the long-term variation tendencies of local engineering geological conditions of the river beach above shallow sections of the cross-river road tunnels.

A New Clock-Driven ECO Placement Algorithm Based on Table-Lookup Delay Model

A new clock-driven ECO placement algorithm is pr es ented for standard-cell layout design based on the table-lookup delay model.It considers useful clock skew information in the placement stage.It also modifies the positions of cells locally to make better preparation for the clock routing . Experimental results show that with little influence to other circuit performa nce,the algorithm can improve permissible skew range distribution evidently.

Application of dynamic analysis of strength reduction in the slope engineering under earthquake

At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations. Based on the real dynamic tensile-shear failure mechanism of slope,the paper proposes dynamic analysis of strength reduction FEM (finite element method) and takes the reduction of shear strength parameters and tensile strength parameters into consideration. And it comprehensively takes the transfixion of the failure surface,the non-convergence of calculation and mutation of displacement as the criterion of dynamic instability and failure of the slope. The strength reduction factor under limit state is regarded as the dynamic safety factor of the slope under earthquake effect and its advantages are introduced. Finally,the method is applied in the seismic design of anchors supporting and anti-slide pile supporting of the slope. Calculation examples show that the application of dynamic analysis of strength reduction is feasible in the seismic design of slope engineering,which can consider dynamic interaction of supporting structure and rock-soil mass. Owing to its preciseness and great advantages,it is a new method in the seismic design of slope supporting.

Supersymmetric U(1) Gauge Field Theory with Massive Gauge Field

A new mechanism to introduce the mass of gauge field in supersymmetric gauge theory is discussed. The model has the strict local gauge symmetry and supersymmetry. Because we introduce two vector superfields simultaneously, the model contains a massive gauge field as well as a massless gauge field.

Probabilistic Norm of Operators and Continuity of Bounded Operators

In this paper,the equivalence for continuity and boundedness of the linear operators on a general PN space is proved by means of their probabilistic norm,and the corresponding result in [1] is improved.

Effects of Urechis unicinctus Juveniles on Chemical Characteristics of Organically Contaminated Coastal Sediment

Biological activities of marine benthos such as burrowing and feeding may change sediment characteristics.We conducted three experiments to examine the potential of using juveniles of a spoon worm Urechis unicinctus to improve the quality of organically contaminated coastal sediment.Sediment samples were collected from a site that was heavily contaminated with organic matter (Seonso) and two sites that were clean (Myo-do,Dolsan-do).Urechis juveniles,obtained by artificial fertilization and cultured in the laboratory,were introduced to the sediment (weight 3 kg,depth 10 cm) at a density of 500 individuals per aquarium (length 50 cm,width 35 cm,height 30 cm) (Experiment 1),or at densities ranging from 100 to 900 individuals per beaker (Experiment 2).To examine how sediment contamination can be modified by the effects of Urechis,500 individuals (per aquarium) were exposed to the Seonso contaminated sediment that had been mixed with 0-100% clean sand (Experiment 3).Each experiment lasted two months and sediment samples were collected every 15 d to determine the several indexes of sediment quality,which included acid volatile sulfide (AVS),chemical oxygen demand (COD) and total ignition loss (TIL).In Experiment 1,the existence of Urechis did not result in significant changes in quality indexes in the sediments collected from Myo-do,Dolsan-do.However,AVS,COD and TIL of the Seonso sediment all decreased significantly after co-incubation with Urechis juveniles for 30 to 45 d.Experiment 2 showed that a density of at least 300 juveniles per beaker was necessary to significantly reduce all three quality indexes,and the magnitude of reduction was positively correlated with juvenile density.Experiment 3 revealed that Urechis juveniles were effective in reducing the AVS,COD and TIL of the Seonso sediment that had been mixed with 60%,80%,and 80% of clean sand,respectively.The results of the present study therefore indicated that juveniles of this spoon worm have the potential to be used to improve the quality of organically contaminated sediment in coastal waters.

Robust H_∞ filtering for neutral jump system with time-delays and uncertainties

The problem of robust H∞ filtering for a class of neutral jump systems with time-delay and norm- bounded uncertainties is considered. By re-constructing the system, the dynamics of overall augmented error systems is obtained which involves unknown inputs represented by disturbances, model uncertainties and time-delays. As to the nominal system, sufficient conditions are provided for the existence of the mode-dependent H∞ filter by selecting the appropriate Lyapunov-Krasovskii function and the robust H∞ filter is proposed for the jump system while considering the time-delays and uncertainties. Both of above conditions for the existence of the H∞ filter and roust H∞ filter are presented in terms of linear matrix inequalities, and convex optimization problems are formulated to design the desired filters. By employing the proposed mode-dependent H∞ filter, the systems have the stochastic stability and better ability of restraining disturbances stochastically, and the given prescribed H∞ performance is guaranteed. Simulation resuhs illustrate the effectiveness of developed techniques.

Boundedness of the Littlewood-Paley Operator,the Function g(f),on BMO(T)

Littlewood-Paley operator,the function g(f), is considered as an operator on BMO(T). It is proved that if f E BMO (T), then g(f)∈BMO (T) and there is a constant C that is independent of f such that ‖g(f)‖_* ≤C‖f‖_*. Moreover,we have got the further results.

Edible Plants Enriched with Selenium

Selenium （Se） is an important element from the environmental and biological point of view. In the world, deficiency of Se in a diet occurs more often and nutritional supplements are recommended.The ability of several plants to accumulate and transform inorganic Se forms into its bioactive organic compounds has important implications for human nutrition and health. This work gives a brief overview of the study carried out to characterize Se species produced by different enriched edible plants which were grown in the presence of different Se species.

Analysis of Leakage in Bolted-Flanged Joints Using Contact Finite Element Analvsis

The evolution of leakage is studied using detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact condition based on slide-line elements using ABAQUS, a commercial finite element code, Slide-line elements also take into account pressure penetration as contact that is lost between flange and gasket. Results are presented for a particular flange, a raised face flange sealed by a mild steel gasket. A comparison of the results from the gasket contact analysis and the contact conditions specified by the ASME Boiler and Pressure Vessel Code, Sections VIII, Division 1 shows that the conditions specified in the ASME Code predict leakage relatively accurately.

Water vapor adsorption in activated carbon modified with hydrophilic organic salts

Five different kinds of hydrophilic organic salts were used to modify commercial activated carbon in order to prepare hydrophilic carbon materials. Properties of the samples were analyzed by surface area analyzer and SEM-EDX. The hydrophilic organic salts with different properties were introduced into activated carbon and significantly affected the properties of the samples.During adsorption experiments, the water vapor adsorption amount in modified samples increases by 0.57-17.12 times in temperature range from 303 to 323 K and at relative pressure below 0.50. Water molecules combined with surface hydrophilic groups through H-bonding exhibit good thermo stability. The effects of temperature, oxygen content and properties of the hydrophilic organic salts on water vapor adsorption were studied. It is indicated that water vapor adsorption in modified samples is mainly affected by the surface oxygen content. The carboxylate radicals in the hydrophilic organic salts greatly affect the micropore structure of the modified samples, while the metal ions in them exhibit limited influence. Different adsorption capacity of modified samples can be explained with the electronegativity of elements presented by Pauling.

Who Governs Public Health？ Donor Retreat and the Shifting Spheres of Influence in Southern African HIV/AIDS Policy Making

For the last decade, discussions about who governs policy on prevention and treatment of HIV/AIDS have revolved around the controversial relationship between Western donors and the power they have over their recipient governments. While these debates were once politically germane, recent trends show a decline of donor funding, as well as an increase of financial ownership of the epidemic within Southern Africa. Commensurate with this shifting financial influence, some well-governed, wealthy African states are beginning to deviate from global M＆E （monitoring and evaluation） indicators. These policy movements, away from global M＆E indicators, also correlate with increases in HIV prevalence, which signals the need for further investigation into policy efficacy.

Activity Concentrations and Associated Gamma Doses of 238U and 235U in Jordan

In this study, sixteen soil and vegetable samples from Tafila district were collected and analyzed from eight locations. Measurements of specific activity of natural gamma emitter radionuclides, 23SU and 235U, in these samples using gamma spectrometry, with the help of Genie 2000 software. Measurements were used to calculate the soil-vegetable transfer factor, and then the external radiation dose and internal radiation dose due to radioactivity of the ingested food. The specific activity of238U and 235U in soil were found to vary from （in Bq/kg）： 26-575 and 1.4-35.5, respectively. The specific activity of 238U and 235U in vegetables were found to vary from （in Bq/kg）： 0.019 to 0.632 and 0.0013-0.0375, respectively. The calculated transfer factor of Z3SU and Z35U range from 5.9 × 10^-4to 14.6 × 10^-4 for 238U and 4.9 × 10^-4 to 16.1 × 10^-4 for 235U. External absorbed dose rates were calculated to be in the range from 12.42 to 266.00 nGy/h. The annual effective dose was found to vary from 28.94 to 619.78 μSv/y. The annual internal effective dose due to 23SU and 23SU for fresh weights ofvegetablesl were found to vary from 0.9 × 10^-3 to 35.1 × 10^-3 μSv/y for 238U and 0.61 × 10^-4 to 17.62 × 10^-4 μSv/y for 235U.

The Category of Finitely Generated Meta-ProjectiveLeft R-Modules

In this paper, it is shown that for a QF ring R, the category of projectiveleft R-modules is a category with factorization if and only if gl.dim R ≤1, moreover, ifP(RR) = P(RR) = O,then the meta-Grothendieck groups obtained by left modules orby right modules are the same, up to isomorphism. It is also shown that the category of f.g. meta-pojective left R-modules is not only a category with factorization but also acategory with product such that it has a small skeletal subcategory.

Quasi-d-Koszul Modules and Applications

Let R be a Noetherian semiperfect algebra. A necessary and sufficient condition for a finitely generated R-module to be quasi-d-Koszul is given, which improves one of the main results in [1]. The authors also give a necessary and sufficient condition for the Minimal Horseshoe Lemma holding in mod(R). As an application, it is proved that the "Minimal Horseshoe Lemma" is true in the category of quasi-d-Koszul modules under certain conditions.

Categories of exact sequences with projective middle terms

Let A be a finite-dimensional algebra over an algebraically closed field k,ε the category of all exact sequences in A-rood, Mp （respectively, Ml） the full subcategory of C consisting of those objects with projective （respectively, injective） middle terms. It is proved that Mp （respectively, MI） is contravariantly finite （respectively, covariantly finite） in ε. As an application, it is shown that Mp = MI is functorially finite and has Auslander-Reiten sequences provided A is selfinjective. Keywords category of exact sequences, contravariantly finite subcategory, functorially finite subcategory Auslander-Reiten sequences, selfinjective algebra

Abelianness of the “missing part” from a sheaf category to a module category

This paper investigates the structure of the"missing part"from the category of coherent sheaves over a weighted projective line of weight type(2,2,n)to the category of finitely generated right modules on the associated canonical algebra.By constructing a t-structure in the stable category of the vector bundle category,we show that the"missing part"is equivalent to the heart of the t-structure,hence it is abelian.Moreover,it is equivalent to the category of finitely generated modules on the path algebra of type An-1.