中小学生课外学习的应试性特点与问题

采用问卷调查法,抽样调查了4所小学、2所初中1614名中小学生,结合对部分学生、老师和培训机构的访谈和观察,探讨了当前中小学生课外学习的现状、特点与问题。结果发现:(1)中小学生参与最频繁的课外活动仍为应试性学习,包括课外培训补习、家教补习和课外作业;(2)虽然多数学生参加课外应试性学习是自己的意愿,但不少学生是迫于家长要求的;(3)中小学生课外应试性学习的效果不尽人意,虽然对补习科目有一定帮助,但对提升总成绩效果不明显,还会影响课堂表现;(4)繁重的课外应试性培训、家教和作业加剧了学生的课业负担,影响学生的健康;(5)课外应试性学习活动收费较高,给学生家庭带来一定经济负担;(6)补习机构良莠不齐,教师素质需要提高,教学条件有待改善。据此,呼吁社会、家庭、学校和学生要正确看待学生的课外应试性学习,并提出了相应的改进对策与建议。

义务教育优质学校办学标准:目的与维度

阐明构建义务教育优质学校办学标准的目的与维度更为基本和重要。从目的上看,构建义务教育优质学校办学标准,一是有利于学校优势的挖掘;二是有利于学校的合作能力建设;三是有利于促进公平和提升质量;四是有利于在改革创新中贯彻育人为本方针。从维度上看,义务教育优质学校办学标准主要由生成性的学校理念、卓越的课程教学、充满活力的内部管理以及高支持性的外部环境四个方面构成。

谈高职院校如何有效利用MHK考试提高汉语教学质量

学习语言的最终目的是运用语言进行交际,落实到语言交际中,语言能力具体又可分为听、说、读、写四种能力。职业院校的汉语教学有着自己的特殊性和不可比性,应该探索出一条符合自身特色的汉语教学发展之路,充分利用MHK考试制度,提高学生学习的积极性及应用汉语的能力,使汉语为教学服务,为专业所用,从而促进新疆少数民族职业教育的发展。

Study on the Introduction of Plants with Colored Foliage in Zhengzhou Area and Their Adaptability

[Objective] This study aimed to preliminarily select the plants with colored foliage adaptable to Zhengzhou area. [Method] An introduction trial on 42 varieties with colored foliage was conducted, in which major ornamental characteristics, phenological phases and stress resistance of all the introduced plants with colored foliage were observed and the introduced plants were comprehensively evaluated. [Result] Golden-and Compound-leaved Maple, Red-leaved Sakura, Pink-and Compound-leaved Maple, Amur Maple, Purple-leaved Canadian Redbud with good performance were selected preliminarily, which can be applied for landscape in Zhengzhou area. Among them, Golden- and Compound-leaved Maple, Golden- and Silvery-leaved Maple and Purple-leaved Smoketree can either be planted separately, or in a line as boulevard trees, or in groups as ornamental forest; Red-leaved Sakura, Pink- and Compound-leaved Maple and Purple-leaved Canadian Redbud can be planted in groups or separately in gardens, parks or alongside streets or in front of buildings; Amur Maple with high adaptability is a excellent tree species for afforesting barren mountain. [Conclusion] This study has not only provided new excellent germplasm sources for the landscaping in Zhengzhou area, thus favoring the improvement of local landscaping level, but also provides examples and references for the introduction of plants with colored foliage in the other areas.

针对上海市高校经济类在校大学生考证中的态度与能力分析

从2016年6月份国家取消319项之多的职业资格证书至今,各大高校的在校大学生对于考证的热度不仅仍未消散,反而呈现增温的趋势,这一现象不仅与社会改革进程中实施力度有关,也和大学生本身对于考证的态度有关。文章基于对上海市高校经济类大学生群体的分析,来说明大学生在应届毕业生数量逐年增加,就业竞争压力大的情况下,只注重证书不注重能力,疯狂考证的盲目性、应试性和功利性等特征,指出其消极影响,并提出对大学生认真对待考证问题,端正态度的期盼与建议。

Influence of superplasticizers on the early-age crack resistance of concrete

In order to improve the early-age cracking resistance of concrete, different types of superplasticizers are used. Two types of polycarboxlic salt/acid superplasticizers and one retarding naphthalene superplasticizer are selected to investigate the influence of superplasticizers on the early-age cracking resistance of the concrete by using the slab test and the temperature-stress test. The results show that the polycarboxlic salt/acid superplasticizer cannot always improve the cracking resistance capacity of the concrete compared with the naphthalene superplasticizer, which is related to the chemical structure of the polycarboxlic salt/acid superplasticizer. High plastic tensile strength and dynamic elastic modulus at the early stage are beneficial to avoid cracking, and low hydration heat is also helpful. The evolutions of the drying shrilakage stress and the hydration heat temperature stress varying with time can be comprehensively evaluated by means of the slab test and the temperature stress test.

Finite element failure analysis of continuous prestressed concrete box girders

In order to analyze the load carrying capacity of prestressed concrete box girders, failure behaviors of in-situ deteriorated continuous prestressed concrete box girders under loading are experimentally observed and a finite failure analysis method for predicting behaviors of box girders is developed. A degenerated solid shell element is used to simulate box girders and material nonlinearity is considered. Since pre-stressed concrete box girders usually have a large number of curve prestressed tendons, a type of combined element is presented to simulate the prestressed tendons of box girders, and then the number of elements can be significantly reduced. The analytical results are compared with full-scale failure test results. The comparison shows that the presented method can be effectively applied to the failure analysis of in-situ continuous prestressed concrete box girders, and it also shows that the studied old bridge still has enough load carrying capacity.

让兴趣引导学生走进传统文化殿堂

古诗词中凝聚着中华民族优秀的传统文化,对培养中学生对传统文化的兴趣与热爱具有重要的意义。语文教师在教学中,应有意识地将诗词诵读品鉴与普及传统文化有机结合起来,利用课堂诵读、趣味品鉴、非应试性感悟来引导学生亲近古诗词,走进传统文化殿堂。

复习课怎么上

校本教研及教学实践中，我们逐渐形成了一些关于复习课的指导性认识。

Experimental study of seepage characteristics of single rock fracture based on stress states and stress history

Through seepage tests under different loading and unloading confining pressures and different hydraulic gradients,the authors studied the effects of stress states and stress history on fracture permeability evolution for single granite fracture and sandstone fracture. The results show that there exists a linear relationship between the seepage discharge and osmotic pressure in sandstone fissure under each level of confining pressure. With the increasing in the confining pressure,the permeability of the fracture decreases,but the decreasing rate is changeing. During the unloading process,the fracture seepage velocity cannot be fully recovered to the size of the loading process. Therefore,in the unloading process of the confining pressure,the recovery of fracture permeability shows obvious hysteresis effects. The flow rate of the fracture remains unchanged during five cycles of loading and unloading processes of the confining pressure. In each cycle,the evolution character of the flow rate with the confining pressure remains unchanged. These experiments show that the seepage characteristics of sandstone and granite fractures are not the same under the same stress state.

Experimental and simulation of the reactive dividing wall column based on ethyl acetate synthesis

Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.

Strength and elastic properties of sandstone under different testing conditions

A laboratory experimental program performed on Wuhan sandstones was presented under monotonic loading, partial cyclic loading during loading path and sine wave cyclic loading with different strain rates to compare uniaxial compression strength and elastic properties (elastic modulus and Poisson ratio) under different conditions and influence of pore fluid on them. When the loading strain rates are 10^(-5), 10^(-4) and 10^(-3)/s, uniaxial compression strengths of dry sandstones are 82.3, 126.6 and 141.6 MPa, respectively, and that of water saturated sandstones are 70.5, 108.3 and 124.1 MPa, respectively. The above results show that the uniaxial compression strength increases with the increase of strain rate, however, variation of softening coefficient is insignificant. Under monotonic loading condition, tangent modulus increases with an increment of stress (strain) to a maximum value at a certain stress level, beyond which it starts to decline. Under the partial cyclic loading during loading path condition, unloading or reloading modulus is larger than loading modulus, and unloading and reloading moduli are almost constants with respect to stress level, especially unloading modulus. Under the sine wave cyclic loading condition, tangent modulus and Poisson ratio display asymmetric 'X' shape with various strain, and the average unloading modulus is larger than the average loading modulus.

Adaptive designs for sequential experiments

Various adaptive designs have been proposed and applied to clinical trials, bio assay, psychophysics, etc.Adaptive designs are also useful in high cost engineering trials.More and more people have been paying attention to these design methods. This paper introduces several broad families of designs, such as the play-the-winner rule, randomized play-the-winner rule and its generalization to the multi-arm case, doubly biased coin adaptive design, Markov chain model.

Experimental evaluation on well pattern adaptability of ultra-low permeability reservoir using sandstone flat model

As for ultra-low permeability reservoir,the adaptability of common nine-spot well pattern is studied through large-scale flat models made by micro-fractured natural sandstone outcrops.Combined with non-linear porous flow characteristics,the concept of dimensionless pressure sweep efficiency and deliverability index are put forward to evaluate the physical models' well pattern adaptability.Through experiments,the models' pressure distribution is measured and on which basis,the pressure gradient fields are drawn and the porous flow regions of these models are divided into dead oil region,non-linear porous flow region,and quasi-linear porous flow region with the help of twin-core non-linear porous flow curve.The results indicate that rectangular well pattern in fracture reservoirs has the best adaptability,while the worst is inverted nine-spot equilateral well pattern.With the increase of drawdown pressure,dead oil region decreases,pressure sweep efficiency and deliverability index increase; meantime,the deliverability index of rectangular well pattern has much more rational increase.Under the same drawdown pressure,the rectangular well pattern has the largest pressure sweep efficiency.

Model test on vertical bearing capacity of X-section concrete pile raft foundation in silica sand

To reveal the bearing capacity of the X-section concrete piles pile raft foundation in silica sand,a series of vertical load tests are carried out.The X-section concrete piles are compared with circular section pile with the same section area.The load−settlement curves,axial force and skin friction,strain on concave and convex edge of the pile,pile-sand stress ratio,distributions of side and tip resistance are presented.The results show that bearing capacity of the X section concrete pile raft foundation is much larger than that of the circular pile raft foundation.Besides,compared with the circular pile,the peak axial force of X-section piles under raft is deeper and smaller while the neutral point of X-section concrete pile is deeper.Moreover,the strain on the concave edge is much larger than that on the convex edge of the pile,and the convex edge has more potential in bearing capacity as the vertical load increases.The X-section pile has higher pile-sand stress ratios and load-sharing between side resistance and tip resistance.Above all,the X-section concrete pile can significantly increase the bearing capacity of pile-raft foundations in silica sand.

Mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions

To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.

Residents’ Attitudes Towards Tourism in a Globally Important Agricultural Heritage Systems Pilot Site: a Case Study in China

Globally Important Agricultural Heritage Systems (GIAHS) is a wide program to promote the conservation and adap-tive management of such systems and their associated landscapes, biodiversity, knowledge systems and cultures. Rice-Fish Systems (RFS) in Longxian village of China, as a traditional agricultural system, was selected as one of the five pilot sites of GIAHS in 2005. Researchers have paid more attention to the dynamic conser-vation and adaptive management of RFS because it is under severe threats from global development challenges. Tourism is suggested to be brought into the RFS conservation program as an alternative industry. This paper presents a comparative study of residents in three types of farm household in Longxian, seeking attitudes to the RFS conservation and tourism development and ways in which such information may guide future strategies. Results show resi-dents, belonging to the household type in which most family mem-bers are abroad, have the most positive attitudes to RFS conserva-tion and tourism development; while residents, as other household type in which less than 50% of family members are abroad, are the least sensitive group in these three household types, due to the motivation of moving abroad weakening their enthusiasm to participate in the local activities. Implications are discussed in the context of how resident attitudes will affect the future manage-ment of GIAHS conservation and tourism development, and then measures are put forward to foster tourism cooperation and multi-stakeholders process establishment.

Effect of specimen size on energy dissipation characteristics of red sandstone under high strain rate

In this experiment, red sandstone specimens, having slenderness ratios of 0.5, 0.7, 0.9 and 1.1 respectively, were subjected to blow tests using a Split Hopkinson Pressure Bar(SHPB) system at a pressure of 0.4 atmospheres. In this paper, we have analyzed the effect of slenderness ratio on the mechanical properties and energy dissipation characteristics of red sandstone under high strain rates. The processes of compaction, elastic deformation and stress softening deformation of specimens contract with an increase in slenderness ratio, whilst the nonlinear deformation process extends correspondingly. In addition, degrees of damage of specimens reduced gradually and the type of destruction showed a transformation trend from stretching failure towards shear failure when the slenderness ratio increased. A model of dynamic damage evolution in red sandstone was established and the parameters of the constitutive model at different ratios of length to diameter were determined. By comparison with the experimental curve, the accuracy of the model, which could reflect the stress–strain dynamic characteristics of red sandstone, was verified. From the view of energy dissipation, an increase in slenderness ratio of a specimen decreased the proportion of energy dissipation and caused a gradual fall in the capability of energy dissipation during the specimen failure process. To some extent, the study indicated the effects of slenderness ratios on the mechanical properties and energy dissipation characteristics of red sandstone under the high strain rate, which provides valuable references to related engineering designs and academic researches.

Experimental study on gas permeability by adsorption under 3D-stress

Using self-developed gas-seepage experimental installation,under the sameeffective stress conditions,coal permeability experiments on different adsorption characteristicsof gases,different temperatures and different gas adsorption contents were performed,and the influence law of adsorption on coal permeability was studied.At the sametime,experimental analogy showed clearly that gas drawing plucks the permeability variationlaw.The results show that adsorption has a major impact on coal permeability.Thegreater the adsorption,the more the gas adsorption capacity and the coal permeabilitybecomes smaller.Permeability becomes smaller along with confining of pressure andtemperature,and this is in accord with local practice results.

Finite element modeling of pavement responses based on stress-dependent properties of asphalt layer

In order to investigate the stress-dependent properties of hot-mix asphalt （HMA）,a dynamic modulus test was conducted on a group of AC-20 specimens at various stress states and loading frequencies,respectively.A user-defined material （UMAT ）subroutine incorporating stress-dependent constitutive model was developed and finite element （FE）simulation was utilized to confirm the validity of the UMAT.A three-dimensional （3D ）FE model for typical pavement structure was established,considering the HMA layer as a stress-dependent material and other layers as linear elastic materials.Periodic load was applied to the pavement model and the pavement responses were calculated,including dynamic modulus distributions,surface deflection,shear stress and tensile strain in the HMA layer,etc.Both test results and FE model predictions indicate that the dynamic modulus of asphalt concrete is sensitive to stress state and loading frequency.Using the nonlinear stress-dependent model results in greater predicted pavement responses compared with the linear elastic model.It is also found that the effects of stress-dependency on pavement responses become more significant as loading frequency decreases.