培养“预学”习惯 落实先学后教

本文探讨了“以学定教”理念中“先学后教”的教学理念在小学英语教学中的实践与运用。笔者认为结合小学英语学科教学的特点，“预学”应纳入成为小学英语课堂教学中的重要环节。教师要重视培养良好的“预学”习惯，细化预习内容，明确预习要求，提供预习方法，促进学生有效地自学和思考，帮助学生提高课前预习质量，并切实地根据学生的预习反馈，以学定教，调整教案，提高课堂教学实效。

“预学”让数学课堂教学更高效

随着现代化科学技术的飞速发展,数学课堂教学模式也日新月异,时代进步的今天,更是刮起了“预学”的热风,为更好提高课堂效益,更贴近学生的认知需求,我们主动的投入到新课堂教学模式的实验研究中,希望通过实践与研究,探索出能够提高课堂高效预学模式,并以点带面,在其他年级和学科中推广。

从“预学”走向“会学”——基于“学”角度的“预学”设计重构

教师希望学生能够多'预学',因为学生进行了'预学',会对教材文本进行个性化的解读,也会对学习内容有更深的感悟,这样,课堂教学活动才能够顺利高效地开展,而且学生在课堂中也会充满活力。

遵循认知规律,让学生从“预学”走向“会学”

教学经验表明,在小学语文教学中开展“预学”,课堂教学会变得比较轻松。但这必须建筑在理想的“预学”上,只有理想的“预学”,学生才可获取阅读感悟,也才能促使学生提高语文学习能力。

小学数学“预学后教,以学定教”有效性探究

在小学数学教学中,教师要根据教材内容,结合小学阶段学生的特点,努力培养学生独立的预学意识和能力。通过课前预学,可以让学生产生对数学知识的疑问,学习时有备而来;在课堂活动的参与中,教师更能针对学生的预学情况进行有针对性的指导,利于提升数学课堂的教学效率,提高学生的数学综合素养。

“预学单”在小学语文阅读教学中的运用

在小学语文阅读教学中，有效的“预学单”是引导学生进行阅读预学的重要载体，是引导学生进行阅读教学的重点。在设计“预学单”时，要兼顾文本的语用训练点。教师可以运用文本的显性语用基点，如结合文章题目、文本语言、课后习题进行“预学单”设计；也可以运用文本隐性语用基点，如利用文章字词的字理以及关键句之间的联系来设计“预学单”；还可以运用文体特点来设计“预学单”。教师要在了解学生、认真钻研文本的基础上，紧扣语用训练点设计“预学单”，从而让“预学单”充分发挥其应有的功能。

Prognositic value of anoikis and tumor immune microenvironment-related gene in the treatment of osteosarcoma

Objective:Osteosarcoma is a highly aggressive primary malignant bone tumor commonly seen in children and adolescents,with a poor prognosis.Anchorage-dependent cell death(anoikis)has been proven to be indispensable in tumor metastasis,regulating the migration and adhesion of tumor cells at the primary site.However,as a type of programmed cell death,anoikis is rarely studied in osteosarcoma,especially in the tumor immune microenvironment.This study aims to clarify prognostic value of anoikis and tumor immune microenvironment-related gene in the treatment of osteosarcoma.Methods:Anoikis-related genes(ANRGs)were obtained from GeneCards.Clinical information and ANRGs expression profiles of osteosarcoma patients were sourced from the therapeutically applicable research to generate effective therapies and Gene Expression Omnibus(GEO)databases.ANRGs highly associated with tumor immune microenvironment were identified by the estimate package and the weighted gene coexpression network analysis(WGCNA)algorithm.Machine learning algorithms were performed to construct long-term survival predictive strategy,each sample was divided into high-risk and low-risk subgroups,which was further verified in the GEO cohort.Finally,based on single-cell RNA-seq from the GEO database,analysis was done on the function of signature genes in the osteosarcoma tumor microenvironment.Results:A total of 51 hub ANRGs closely associated with the tumor microenvironment were identified,from which 3 genes(MERTK,BNIP3,S100A8)were selected to construct the prognostic model.Significant differences in immune cell activation and immune-related signaling pathways were observed between the high-risk and low-risk groups based on tumor microenvironment analysis(all P<0.05).Additionally,characteristic genes within the osteosarcoma microenvironment were identified in regulation of intercellular crosstalk through the GAS6-MERTK signaling pathway.Conclusion:The prognostic model based on ANRGs and tumor microenvironment demonstrate good predictive power and provide more personalized treatment options for patients with osteosarcoma.

Electroless Ni-P plating on Mg-Li alloy by two-step method

Pretreated Mg-Li alloy sheets were pre-plated in a NiCO3？2Ni（OH）2？4H2O solution to form a thin Ni-P alloy film and then plating in a NiSO4？6H2O solution was carried out to obtain a protective coating.The surface morphology,structure and corrosion resistance of the coating were studied.The results showed that a flat,bright and compact plating layer,which was integrated into the matrix metal,was obtained.The P content of the Ni-P coating reached 13.56%（mass fraction）.The hardness value of the Ni-P coating was about HV 549.The polarization curve showed that the corrosion potential of the Ni-P coating reached ？0.249 V（vs SCE）.A long passivation region was found on the polarization curve,and this phenomenon indicated that the coating has an excellent anti-corrosion property.

基于相关向量机的电站锅炉NO_x燃烧优化

为了降低电站锅炉NOx排放量,采用一种新的机器学习方法——相关向量机对某330 MW煤粉汽包锅炉的一、二次风速以及含氧量等26个输入参数和NOx输出结果进行建模,并用万有引力算法对模型的参数进行优化,获得最优模型。与粒子群算法、遗传算法优化相关向量机以及万有引力算法优化支持向量机等进行了比较,选择锅炉输入参数中的可调变量为优化变量,以NOx低排放量为目标进行优化,获得低NOx排放的输入参数。结果证明：万有引力优化相关向量机算法建立的模型精确度比其它几种算法高,对模型进行低NOx优化后,NOx输出值由最初的的906.65 mg/m3变为550.600 mg/m3,下降幅度约为38.9%,实现了NOx排放量大幅度降低。

Effect of pre-deformation on aging creep of Al-Li-S4 alloy and its constitutive modeling

A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical properties and microstructures were determined under basic thermodynamics conditions of aging forming. The results show that pre-deformation shortens the time of primary creep and raises the second steady-state creep rate. Then, the total creep strain is greater, but in the range of test parameters it is still smaller than that without pre-deformation. In addition, transmission electron microscopy（TEM） observation shows that pre-deformation promotes the formation of T1 phase and θ′ phase and makes them distribute more dispersively, while inhibits the generation of δ′ phase, which leads to the improvement of mechanical properties of the alloy. A unified constitutive model reflecting the effects of aging mechanism, stress levels and different pre-deformations was established. The fitting results agree with the experimental data well.

Hot corrosion behavior of Ni-xCr-6.8Al based alloys

The hot corrosion behaviors of as-cast and preoxidized Ni-xCr-6.8Al based alloys in the mixture of Na2SO4＋25% NaCl at 873 K were studied. The results show that the mass loss of Ni-xCr-6.8Al based alloys decreases with the increase of Cr content. Preoxidation improves the resistance to corrosion regardless of the concentration of Cr. The kinetics of as-cast Ni-12Cr-6.8Al and Ni-16Cr-6.8Al based alloys fits the parabolic law well, while that of the as-cast Ni-20Cr-6.8Al based alloy fits the power law. The kinetics of all the preoxidized samples obey the logarithmic law. The mechanism of the as-cast alloys can be well explained by the acid-base melting model. The behavior of the preoxidized alloys is found to be mainly determined by the properties of the oxide layer formed during the preoxidation to a large extend.

Bending properties and fracture mechanism of C/C composites with high density preform

C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.

Relationship Between Histopathology and Clinical Prognosis of Invasive Pituitary Adenoma

Objective: To study the relationship between histopathology and clinical prognosis of invasive pituitary adenoma subjected to transsphenoidal surgery. Methods: The enrolled were 82 patients with invasive pituitary adenomas undergoing transsphenoidal surgery during Jan. 2000 - May 2003 in our department with full MR imaging findings, pathology data and follow-up information. The follow-up duration was 5-30 months. Results: MR imaging findings of invasive pituitary adenoma included: depression of the sellar floor, involvement of sphenoid sinus and cavernous sinus, breakthrough of diaphragma sellae, encasement of internal carotid artery, etc. Pathological examination revealed that the invasion rate of dura in sella turcica was the highest among the structures around tumor. Pituitary adenoma apoplexy was found in 20 cases (24.4%). The total removal rate for PRL-secreting adenomas was significantly lower than that for non-secreting adenomas (P<0.01), but non-, GH-, ACTH-secreting adenomas had no significant differences. The recurrence rate of PRL-secreting adenomas was higher than that of non- and GH-secreting adenomas (P<0.05). Conclusion: Among invasive pituitary adenomas, the therapeutic effects of non-and GH-secreting pituitary adenomas are better than that of PRL-secreting adenomas. Invasive biological behaviors of invasive pituitary adenomas result in radical operation failure and postoperative recurrence.

Significance of the Expression of CyclinD1 and Ki67 Antigen in Nasopharyngeal Carcinoma

Objective: To detect the expression of cyclinD1 and Ki67 in nasopharyngeal carcinoma (NPC) and their correlation with the biological behaviors and prognosis. Methods: 56 cases of biopsy specimens of NPC which had been embedded with para?n in 1996 in our hospital were collected and immunostained with cyclinD1 and Ki67 monoclonal antibodies by means of the streptavidin peroxides method. The patients were followed up periodically, and then their biological behaviors and prognosis were statistically analyzed. Results: The percentage of cyclinD1 and Ki67 positive cells in the NPC specimens ranged from 0–54% and 0–31% respectively. The staining was nuclear. Of the 56 cases, 30 cases (56.6%) highly expressed cyclinD1 or Ki67 HPI and 26 cases (46.4%) lowly expressed cyclinD1, while only 16 cases (28.6%) showed Ki67 HPI (high proliferated index) and 40 cases (71.4%) showed Ki67 LPI (low proliferated index). Patients who lowly expressed cyclinD1 or highly expressed Ki67 had a higher radiosensitivity and a better prognosis. Conclusion: CyclinD1 and Ki67 immunohistochemical staining is considered to be useful, not only as an independent factor of radiosensitivity and prognosis respectively, but also as a means of determining the optimum treatment for each individual patient with NPC.

Dechromization and dealumination kinetics in process of Na_2CO_3-roasting pretreatment of laterite ores

A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99%and 82%, respectively, under the optimal particle size of 44–74μm, Na2CO3-to-ore mass ratio of 0.6：1, and temperature of 1000 ℃. Dechromization within the range of 600–800 oC is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 ℃ with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8%Ni and 95.6%Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.

Influence of pre-deformation on age-hardening response and mechanical properties of extruded Mg-6%Zn-1%Mn alloy

The effect of cold plastic deformation between solution treatment and artificial aging on the age-hardening response and mechanical properties of alloy was investigated by micro-hardness test,tensile test,optical microscopy（OM） and TEM observation.After solution treatment at 420 ℃ for 1 h,three kinds of pre-deformation strains,i.e.0,5% and 10%,were applied to extruded ZM61 bars.Age-hardening curves show that pre-deformation can significantly accelerate the precipitation kinetics and increase peak-hardness value;however,as pre-deformation strain rises from 5% to 10%,there is no gain in peak hardness value.The room temperature（RT） tensile properties demonstrate that increasing the pre-deformation degree can enhance the yield strength（YS） and ultimate tensile strength（UTS） but moderately reduce elongation（EL）;furthermore,the enhancement of YS is larger than that of UTS.No twin can be observed in 5% pre-deformed microstructure;however,a large number of twins are activated after 10% pre-deformation.The peak-aged TEM microstructure shows that pre-deformation can increase the number density of rod-shaped β 1 ＇ precipitates which play a key role in strengthening ZM61 alloy.

Prediction of Secondary Structure and B Cell Epitope of GH Protein from Acipenser sinensis

[ Objective] The aim was to predict the secondary structure and B cell epitope of growth hormone （GH） protein from Acipenser sinensis. [Method] With the amino acid sequence of GH protein from A. sinensis as the base, the secondary structure of GH protein from A. sinensis was predicted by the method of Gamier-Robson, Chou-Fasman and Karpius-Schulz, and its cell epitope was predicted by the method of Kyte- Doolittle, Emini and Jameson-Wolf. [Result] The sections of 18 -23, 55 -55, 67 -73, 83 -86,112 -114,151 -157 and 209 -211 in the N terminal of GH protein molecule had softer structure and these sections could sway or fold to produce more complex tertiary structure. The sections of 19 -23, 51 -71,84 -95, 128 -139, 164 -176 and 189 -195 in the N terminal of GH protein could be the epitope of B cell and there were flexible regions in these sections or near these sections of GH protein molecule. So the dominant regions could be in these sections or near these sections. [ Conclusion] The research provided the basis for the preparation of monoctonal antibody of GH protein from A. sinensis and provided the reference for the discussion for the molecular regulation mechanism of A. sinensis.

Effect of thermo-mechanical treatment process on microstructure and mechanical properties of 2A97 Al-Li alloy

2A97 Al-Li alloy was processed by thermo-mechanical treatment at different pre-stretch deformations of 0, 3% and 6%. The microstrucatre observation results reveal that some δ＇ and T1 precipitates are found in a（Al） matrix of 2A97 alloy processed by the heat treatment with no pre-stretch deformation. When the pre-stretch deformation is 3% and 6%, respectively, amounts of tiny T1 and a few of S＇ precipitates precipitates are observed in the microstructures of 2A97 alloy. The tensile test results show that the tensile properties of 2A97 alloys are improved via thermo-mechanical treatment. When the pre-stretch deformation is from 0, 3% to 6%, the ultimate tensile strength values of the 2A97 alloys increase gradually from 447.7, 516.5 to 534.3 MPa, and the elongations decrease from 17.6%, 12.8% to 10.2%, respectively. Moreover, with increasing pre-stretch deformation amount from 0 to 6%, the in-plane anisotropy value of 2A97 alloys becomes more obvious.

Expression of vascular endothelial growth factor and its prognostic significance in gastric carcinoma

AIMS To investigate the clinical significance of vas- cular endothelial growth factor (VEGF) expression in gastric carcinoma. METHODS The expression of VEGF in 128 gastric carcinomas was investigated by immunohistochemical staining with a polyclonal antibody against VEGF. Cor- relations between the expression of VEGF and various clinicopathologic factors and prognosis were studied. RESULTS The VEGF-rich expression rate was 64.1% in gastric carcinoma. VEGF-rich expression rate of patients with stage Ⅲ and stage Ⅳ disease was greater than that of patients with stage f disease (P <0.05). Significant differences of expression rate ex- isted with respect to growth pattern,serosal invasion and lymph node metastasis. The VEGF-rich rate was much higher in tumors with expanding growth pattern (71.8%) or serosal invasion (73.5%) than in those with infiltrative growth pattern (52.0%) or non-serosal invasion (53.3%) (P<0.025,respectively),and it was also significantly higher in patients with lymph node metastases (75.0%) than in those without such metastases (50.0%) (P<0.05). In addition,postop- erative survey of 86 patients who had been followed up for at least 5 years demonstrated that the 5-year sur- vival rate of patients with VEGF-rich tumors was signifi- cantly lower than that of patients with VEGF-poor tu- mors (P<0.05). CONCLUSIONS The expression of VEGF may be as- sociated with the invasion and metastasis and may also be a useful prognostic indicator of gastric carcinoma.

Parameters optimization of electroless deposition of Cu on Cr-coated diamond

Electroless copper plating on diamond particles precoated with 1%Cr was carried out to evaluate the effects of various experimental parameters on coating quality and deposition rate to obtain the optimized reaction parameters. The formulated samples under optimized parameters were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectra and optical microscopy. The best parameters, where uniform and maximum coating thickness was achieved, are etching with 20%NaOH for 30 min, sensitization and activation with SnCl2 and PdCl2 for 5 and 20 min, respectively. The composition of the copper solution bath was 16 g/L CuSO4＆#183;5H2O, 35 mL/L formaldehyde （HCHO）, 23 g/L KNaC4H4O6 at 60 ℃, pH=13 and stirring at （350±15） r/min under ultrasonication.