问“课”哪得“新”如许 需往“写”“记”“思”“读”“问”中行

在我们的身边,不乏有这样的一群老师:读了很多书,平时工作认真负责,对待教学内容,认真备课上课。但是在教学过程中,发现自己教学效果不佳,学生听课效率偏低。对于活泼爱动的小学生来讲,如果老师的课堂语言贫乏,单调,太过直白,太过平淡,他们是没有什么兴趣坚持40分钟听下去的。

Improving comprehensive properties of Cu-11.9Al-2.5Mn shape memory alloy by adding multi-layer graphene carried by Cu_(51)Zr_(14)inoculant particles

In order to improve the comprehensive properties of the Cu-11.9Al-2.5Mn shape memory alloy(SMA),multilayer graphene(MLG)carried by Cu_(51)Zr_(14)inoculant particles was incorporated and dispersed into this alloy through preparing the preform of the cold-pressed MLG-Cu_(51)Zr_(14)composite powders.In the resultant novel MLG/Cu-Al-Mn composites,MLG in fragmented or flocculent form has a good bonding with the Cu-Al-Mn matrix.MLG can prevent the coarsening of grains of the Cu-Al-Mn SMA and cause thermal mismatch dislocations near the MLG/Cu-Al-Mn interfaces.The damping and mechanical properties of the MLG/Cu-Al-Mn composites are significantly improved.When the content of MLG reaches 0.2 wt.%,the highest room temperature damping of 0.0558,tensile strength of 801.5 MPa,elongation of 10.8%,and hardness of HV 308 can be obtained.On the basis of in-depth observation of microstructures,combined with the theory of internal friction and strengthening and toughening theories of metals,the relevant mechanisms are discussed.

Infrasound Event Classification Fusion Model Based on Multiscale SE-CNN and BiLSTM

The classification of infrasound events has considerable importance in improving the capability to identify the types of natural disasters.The traditional infrasound classification mainly relies on machine learning algorithms after artificial feature extraction.However,guaranteeing the effectiveness of the extracted features is difficult.The current trend focuses on using a convolution neural network to automatically extract features for classification.This method can be used to extract signal spatial features automatically through a convolution kernel;however,infrasound signals contain not only spatial information but also temporal information when used as a time series.These extracted temporal features are also crucial.If only a convolution neural network is used,then the time dependence of the infrasound sequence will be missed.Using long short-term memory networks can compensate for the missing time-series features but induces spatial feature information loss of the infrasound signal.A multiscale squeeze excitation–convolution neural network–bidirectional long short-term memory network infrasound event classification fusion model is proposed in this study to address these problems.This model automatically extracted temporal and spatial features,adaptively selected features,and also realized the fusion of the two types of features.Experimental results showed that the classification accuracy of the model was more than 98%,thus verifying the effectiveness and superiority of the proposed model.

“功夫在诗外”──略谈写作前的准备

初学写作者都会碰到怎样才能提高写作水平的问题，本文从“深入实际，积累生活”；“注意阅读，借鉴技巧”；“坚持不懈，多练多记”三方面作了简明扼要的论述。

语感教学方法初探

语文教学中加强语感教学和学生语感能力的培养,是提高语文教学质量的关键,可以改变传统的教学模式,使语文教学走上自主、自觉、灵活多样的路子。通过多种方法有目标的训练,可以提高学生的语文综合素质。

Step memory polynomial predistorter for power amplifiers with memory

To reduce the number of digital predistortion coefficients, a step memory polynomial （SMP）predistorter is presented. The number of predistortion coefficients is decreased by adjusting the maximum nonlinear order for different memory orders in the traditional memory polynomial （MP）predistorter. The proposed SNIP predistorter is identified by an offline learning structure on which the coefficients can be extracted directly from the sampled input and output of a PA. Simulation results show that the SMP predistorter is not tied to a particular PA model and is, therefore, robust. The effectiveness of the SMP predistorter is demonstrated by simulations and experiments on an MP model, a parallel Wiener model, a Wiener-Hammerstein model, a sparsedelay memory polynomial model and a real PA which is fabricated based on the Freescale LDMOSFET MRF21030. Compared with the traditional MP predistorter, the SMP predistorter can reduce the number of coefficients by 60%.

Sampling Strategy Within a Wild Soybean Population Based on Its Genetic Variation Detected by ISSR Markers

In order to determine an appropriate sampling strategy for the effective conservation of wild soybean (Glycine soja Sieb. et Zucc.) in China, a natural population from Jiangwan Airport in Shanghai was studied for its genetic diversity through the inter-simple sequence repeat (ISSR) marker analysis of a sample set consisting of 100 randomly collected individuals. A relatively large genetic diversity was detected among the samples based on estimation of DNA products amplified from 15 selected ISSR primers, with the similarity coefficient varying from 0.17 to 0.89. The mean expected heterozygosity (He) was 0.171 4 per locus, and Shannon index (1) was 0.271 4. The Principal Coordinate Analysis (PCA) further indicated that genetic diversity of the Jiangwan wild soybean population was not evenly distributed, instead, was presented by a mosaic or clustered distribution pattern. Correlation study between genetic diversity and number of samples demonstrated that genetic diversity increased dramatically with the increase of number of samples within 40 individuals, but the increase became slow and rapidly reached a plateau when more than 40 individuals were included in the analysis. It is concluded that (i) a sample set of approximately 35-45 individuals should be included to represent possibly high genetic diversity when conservation of a wild soybean population ex situ is undertaken; and (ii) collection of wild soybean samples should be spread out as wide as possible within a population, and a certain distance should be kept as intervals among individuals for sampling.

Microsatellite DNA Marker Analysis of Genetic Diversity in Wild Common Carp (Cyprinus carpio L.) Populations

Thirty microsatellite loci were used for analyzing six wild populations of common carp （Cyprinus carpio L.）. Observed （Ho） and expected （He） heterozygosity values, polymorphic information content （PIC）, and number of effective alleles （Ae） were all detected. Genetic similarity index and genetic distance were computed based on the allele frequency. The Hardy-Weinberg Equilibrium was checked according to the test of χ^2. Genetic differentiation and hierarchical partition of genetic diversity were evaluated by FST and Nm. A clustering dendrograrn was made based on the results of UPGMA methods using the PHYLIP software package （version 3.63）. There were totally 8,136 fragments ranging from 125 bp to 414 bp in length. Three to thirteen alleles were amplified in 30 loci and 210 alleles in all six populations. The average number of alleles in each locus was seven. The result showed that 1） the level of genetic variability was moderate in the six populations. Polymorphic information contents of the six wild common carp populations were 0.44, 0.52, 0.53, 0.57, 0.63, and 0.64 respectively. Effective alleles were from 1.04 to 4.72, the average numbers in each population were 2.19, 2.60, 2.42, 2.43, 2.45, and 2.33. The average expected heterozygosity values were 0.50, 0.59, 0.56, 0.56, 0.57, and 0.54 respectively; 2） the highest genetic similarity index that came from the populations of BR and ZL was 0.8511 and the lowest index was 0.6688, and it came from the populations of BR and HN. There was a correlation between the clustering result and the geographical distribution.

Genetic Diversity Analysis of Glutinous Sorghum Germplasm Resources Based on SSR Markers

In order to evaluate the genetic relationships between glutinous sorghum germplasms, 25 pair of SSR markers were used to analyze the genetic diversity of29 varieties. The result showed that a total of 59 alleles were identified with an average of 2.28 alleles per locus. The average effective number of alleles（NE） was1.81.The average polymorphism information content（PIC） varied widely from 0.17 to0.62 with an average value of 0.34.The similarity coefficients of the 29 glutinous sorghum germplasms ranged from 0.203 to 0.949 with an average value of 0.593.Clustering analysis with UPGMA showed that the varieties could be divided into two groups at the genetic similarity coefficient of 0.475.The varieties from different geographic originswere clustered into one subclass, and the varieties with similar agronomic traits were clustered into one subclass, which indicated that the genetic relationships among materials was not in accordance with their geographical origins,and the glutinous sorghum germplasm resources showed abundant genetic diversity in the study.

Genetic Diversity of SSR Markers in Cultivated Hordeum vulgare L.in Qinghai Province

[Objective]The aim was to analyze genetic diversity of SSR markers in Hordeum vulgare L.in Qinghai Province and lay a foundation for screening and protecting some excellent H.vulgare cultivars.[Method]SSR markers were used to evaluate the genetic diversity of 42 cultivated H.vulgare from Qinghai Province.[Result]42 H.vulgare showed polymorphism in 7 SSR markers locus.A total of 24 alleles were identified,and the number of alleles per locus ranged from 1 to 6,with an average of 3.0.According to SSR markers polymorphism,42 H.vulgare could be divided into 4 groups,namely I,II,III and IV.[Result]The study indicated that cultivated H.vulgare from Qinghai Province is rich in genetic diversity,which will provide reference for selecting parent of H.vulgare breeding.

RAPD and ISSR Markers of Fertility Restoring Gene for Aegilops kotschyi Cytoplasmic Male Sterility in Wheat

LK783 was found to be a good fertility restorer for K-type male sterility of wheat (Triticum aestivum L.). RAPD and ISSR (inter-simple sequence repeat polymorphism) markers were employed to map the major restoring gene in LK783. Maintainer and restorer DNA pools were established using the extreme sterile and fertile plants among KJ5418A//911289/LK783 F 1 population, respectively. Four hundred and eighteen RAPD primers and 33 ISSR primers were used for screening polymorphisms between the two pools, and amplification bands using a RAPD primer of OPK18 and an ISSR primer of UBC-845 were found polymorphic between the two pools. Linkage analysis showed that OPK18 450 and UBC-845 800 were linked to the restoring gene in LK783. The distance between the restoring gene and OPK18 450 was (15.07±6.28) cM (centiMorgan), with the distance between the restoring gene and UBC-845 800 being (8.20±4.85) cM. The marker of UBC-845 800 was located on chromosome 1BS by amplifying nulli-tetrasomics and 1B ditelosomics of Chinese Spring with the primer of UBC-845, indicating that the restoring gene in LK783 was located on 1BS. The breeding for new fertility restorer lines of K-type cytoplasmic male sterility of wheat would be facilitated by using the two markers.

高中诗歌教法略谈

我认为，学诗的“感、读、背、写、评”五个阶段，在素质教育的今天是可行的，并且是行之有效的，是不违背学生的学习规律并更适合学生学习的心理过程的，是实现素质教育、培养学生创新能力的有效途径和方法。

Establishment and Application of a Multiplex PCR System for the Detection of Blast Resistance Genes Pi-ta and Pi-b in Rice

Rice blast is one of the important diseases in major rice producing areas of China. The main blast resistance genes Pi-ta and Pi-b showed broad-spectrum and durable resistance to rice blast in many rice growing areas of China, which have been widely utilized in rice breeding and commercial production. In this study, on the basis of detection and verification of the genotypes of 22 rice varieties har- boring known blast resistance genes （Pi-ta and Pi-b） and blast susceptibility genes （pi-ta and pi-b）, two multiple PCR systems for these genes were established by us- ing the functional markers of blast resistance genes Pi-ta and Pi-b as well as blast susceptibility genes pi-ta and pi-b, respectively. Specifically, multiple PCR system I could simultaneously detect blast resistance genes Pi-ta and Pi-b, while system II could detect simultaneously blast susceptibility genes pi-ta and pi-b. In addition, the genotypes of 336 high generation breeding materials were detected with these two multiple PCR systems. The results were highly consistent with those of conventional single mark detection, indicating that these two multiplex PCR systems were stable, reliable and time-saving. The established multiplex PCR systems may serve as a rapid and efficient method to identify and screen rice germplasm resources and can be applied in marker-assisted selection to polymerize multiple genes for blast resis- tance in rice breeding.

Genetic Diversity of Maize (Zea mays L.) Landraces from Southwest China Based on SSR Data

Genetic diversity of 54 maize landraces from southwest China was tested using bulk DNA samples and 42 microsatellite （SSR） loci distributed on 10 chromosomes of maize. A total of 256 alleles were detected among the landraces. At each locus, the number of alleles varied from 2 to 9, with an average of 6.1. On the basis of the genetic similarity coefficients, clustering analysis separated the landraces into four groups. The landraces collected from the same region were mostly grouped together. To reveal the genetic structure and genetic diversity within landraces, 165 individuals from 11 landraces were analyzed. Individual DNA samples proved to be superior to bulk DNA samples in identifying genetic diversity of landraces. A total of 330 alleles were detected in the 11 landraces. According to the results of the individual DNA sampling analysis, estimates of the mean number of alleles ‘A’, the effective allelic number ‘Ae’, the observed heterozygosity ‘Ho’, and expected heterozygosity ‘He’ were 7.86, 3.90, 0.69, and 0.37, respectively. An obvious genetic deviation from Hardy-Weinberg expectation was observed both among and within landraces and a considerable genetic variation was revealed within rather than among landraces. In addition, genetic diversity of landraces was greater in Sichuan than in the other three regions. It can be concluded that maize landraces in southwest China were initially introduced to Sichuan and from there to adjacent areas.

Investigation on Genetic Characteristics of Salvia miltiorrhiza Bge. by Using cpSSR Technology

[Objective] This study aimed to analyze the genetic characteristics of Salvia miltiorrhiza by using cpSSR （chloroplast microsatellites） molecular marker method. [Method] Twelve pairs of SSR primers with ideal cpSSR amplification result, good repeatability and clear amplification bands were selected for cpSSR detection and analysis of S. miltiorrhiza samples from 31 sampling locations in 25 counties of 8 provinces in China. [Result] S. miltiorrhiza shows an overall medium level in the cytoplasmic inheritance （cpSSR） and varying degrees of differences in the regions. Based on Shannon’s Information index （I） and Nei’s genetic diversity index, the cytoplasmic genetic diversity in different provinces shows a decreasing order of Shanxi, Henan, Shandong, Hebei, Sichuan, Jiangsu, Shaanxi, Anhui. Genetic variations of S. miltiorrhiza in eight provinces were found mainly among populations. Gene flow among populations with in a province is less than that among different provinces. [Conclusion] Comprehensive analysis shows that S. miltiorrhiza cultivated in genuine producing areas and traditional main producing areas are mainly introduced from the local before introduction of some foreign germplasm resources during cultivation. The exchange of S. miltiorrhiza germplasm resources exists very early among genuine producing areas such as Sichuan, Shandong and Henan, while S. miltiorrhiza germplasm resources in new producing areas are mainly introduced from genuine producing areas. However, no geographical correlation was observed in the genetic differentiation, which further reveals that there is a wide range of genetic exchange among S. miltiorrhiza germplasm resources in China, resulting from the artificial introduction from allopatry.

有效提高小学生习作能力的五个途径

在多年的教学实践中，笔者深切地体会到：在小学语文教学中，最让教师感到焦虑的就是作文教学。特别是三四年级的学生，他们年龄小，理解能力有限，知识面狭窄，视野并不开阔，看、听、说、写都处在启蒙阶段，要想在一节或两节作文课中，让他们写出比较好的文章是极为困难的。怎样才能使小学中年级学生提高写作水平呢？笔者认为：实行多读、多看、多说、多记、多写的训练，是提高他们习作能力的有效途径。

Construction of AFLP Molecular Marking System in Mangifera indica L.

[Objective ] The study aimed to construct the AFLP molecular marking system in Mangifera indica. [ Method ] Four varieties of Mangifera indica were used to explore new ways for high-quality DNA, and AFLP analysis of 31 varieties of Mangifera indica was carried out to detect the varietal genetic diversity. [ Result] 14 pairs of primers with stronger polymorphism, better banding patterns and higher resolution were screened out from 64 pairs of selective amplification primers. Then they were used to analyse the fingerprint of 31 varieties of Mangifera indica, the results showed that the ratio of polymorphic bands amplificated by the 14 pairs of primers reached 97% in 31 varieties of Mangifera.[ Conclusion] It was suggested that AFLP was suitable for detecting the polymorphism of Mangifera indica resources.

Genetic Diversity of Hordeum bogdanii Wilensky Native to Xinjiang, China, Based on STS-PCR Markers

The genetic diversity among 32 accessions of Hordeum bogdanii Wilensky native to Xinjiang, China, was evaluated by 22 STS_PCR primer sets derived from RFLP clones of the wheat ( Triticum aestivum L.) or barley ( Hordeum vulgare L.) mapping. Out of the 22 STS_PCR markers, only three markers gave products which did not generate polymorphic bands upon digestion with Hin fⅠ, Hha Ⅰ, Hae Ⅲ and Rsa Ⅰ, while 19 out of 22 markers (86.4%) and 46 out of 88 marker/enzyme combinations (52.3%) revealed polymorphisms. Among the 32 H. bogdanii accessions, a total of 315 bands were observed in 88 STS_PCR marker/enzyme combinations, with 3.6 bands each. One hundred and twenty_three out of 315 bands (39.0%) were polymorphic, among which 1 to 6 polymorphic bands were generated by each polymorphic marker/enzyme combination. The STS_PCR_based genetic diversity index ( GD ) among 32 H. bogdanii accessions ranged between 0.078 to 0.352, with a mean of 0.198. Based on the GD matrix, a dendrogram showing the genetic relationships between accessions was constructed using the unweighted pair_group method with arithmetic average (UPGMA). Results showed that all 32 accessions could be distinguished by STS_PCR markers. The accessions originated from the same region were distributed within different groups or subgroups. This study indicates that the genetic diversity of H. bogdanii is not closely correlated with the geographical distribution.

Genetic Polymorphism in GDF8 Region of HU Sheep Based on Microsatellite DNA

[ Objective ] This study was to analyze the genetic polymorphism in GDF8 Region of HU sheep. [Method] Four microsatellite loci including BMS1591, TEXAN-2, FCB128 and BM81124 mapped on GDF8 region of chromosome No. 2 of sheep that may be correlated with growth performance were chosen to detect the molecular genetics foundation of growth performance of Hu sheep. [ Result] Four microsatellite loci detected were high in heterozygosity, more in effective alleles number and rich in polymorphic information, all the three indices passed through the high polymorphic level （PIC 〉0.5）. [ Conclusion ] The four microsatellite loci detected could be used to estimate the genetic polymorphism of growth performance of Hu sheep.