诱道的I(L)-Fuzzy拓扑空间的超F1紧性和局部超F1紧性

王戈平通过使用Kubiak定义的I(L)—值下半连续函数把诱道的模糊拓扑空间推广为诱道的I(L)—Fuzzy拓扑空间，即对每一个LF拓扑空间(L^X，δ)都对应着唯一的一个诱道的I(L)—Fuzzy拓扑空间(I(L)^X，ω(δ))。本文以此为基础，讨论了诱道的I(L)—Fuzzy拓扑空间中超F1紧性和局部超F1紧性，得出了算子ω保持超F1紧性和局部超F1紧性。     

论现代化进程中我国农业剩余劳动力的转移

本文通过对我国农业剩余劳动力现状的分析 ,提出顺利实现农业剩余劳动力的转移是当前我们工作的最紧迫任务 ,也是我国在社会主义现代化建设中所提出的必然要求。实现成功转移的途径是 :积极推进农业产业化 ;大力促进城镇化建设 ;实现土地经营权的自由转让 ;大力发展第三产业。     

元认知策略在英语专业听力教学中的运用

近年来 ,学习策略一直是外语教学研究的焦点。元认知策略是指成功学习一门外语而采取的管理步骤 ,包括制定计划 ,监控学习过程 ,评估学习效果。本文探讨了元认知策略在英语专业听力教学中的有效运用 ,试图用元认知策略来指导英语专业听力教学 ,从而提高英语专业学生的听力理解能力     

The application of podcasting as an instructional tool to improve Turkish EFL learners’ speaking anxiety

The present study was designed to investigate: (a) the effect of podcasts in EFL students’ oral performance, (b) the effect of podcasts in EFL students’ speaking anxiety, (c) the relationship between speaking anxiety and oral performance, and (d) EFL students’ perceptions of using podcasts. This study was conducted in a high school in Istanbul, Turkey. The students in two ninth-grade classes in the subject school were given the anxiety questionnaire, consisting of 24 items related to general foreign language class anxiety and in-class activities. A total of 30 students with the highest anxiety levels were chosen among these students. The oral performances of these students were evaluated through the Test of Spoken English and the students were also interviewed about their speaking anxiety and their oral performances. For 12 weeks, the control group followed the course book and did the speaking activities in it, while the experimental group created podcasts in addition to those activities. At the end of 12 weeks, the participants were given the anxiety post-test, the post-interview, and the oral performance post-test. The perceptions of the students in the experimental group of podcasts were examined through three interviews during the study. The results of the study showed that students who used podcasts had higher oral performance and lower speaking anxiety levels than the students who didn’t use podcast; and there was a negative relationship between the participants’ oral performances and speaking. The analysis of the interviews on podcasts revealed that the students believed podcasts helped them feel not or less anxious, and more confident; improve their oral performances and pronunciation; and expand their vocabulary.     

某些4-氨基-1-氮杂-1,3-丁二烯(Ⅱ)新化合物及其3-氯(Ⅲ)和3-溴(Ⅳ)衍生物的合成

用希夫碱(Ⅰ)在无水三氯化铝(AlCl_3)或二异丙胺锂(LDA)与氯化锌乙醚溶液(ZnCl_2·OEt_2)存在下加成于腈类化合物,制备了一些新的4-氨基-1-氮杂-1,3-丁二烯(Ⅱ)。用N-氯琥珀酰亚胺(NCS)和N-溴琥珀酰亚胺(NBS)与带有3-位烯胺氢原子的化合物Ⅱ合成了3-氯(Ⅲ)和3-溴(Ⅳ)衍生物。全部化合物Ⅱ、Ⅲ和Ⅳ都经MS、~1H和~(13)C NMR定性,文中给出了其MS、~1H和~(13)C NMR数据。     

信用证结算的欺诈风险及防范

近年来利用信用证结算进行欺诈的案件越来越多,严重干扰了正常的国际贸易秩序。相对于其他欺诈方式,这类欺诈更具隐蔽性和复杂性,加之人们疏于防范,因而危害极大。本文从信用证欺诈产生的原因入手,分析了买卖双方在信用证结算中常见的欺诈表现形式,并据此提出了相应的对策和建议。     

Isolation and physiological characteristics of a premature senescence mutant in rice （Oryza sativa L.）

A rice pse(t) (premature senescence, tentatively) mutant line, was isolated from 4500 independent T-DNA inserted transgenic lines. The symptoms of premature senescence appeared more severely than those of the control plants (Zhonghua 11,japonica) at the last development stage. To characterize the mutant and provide basic information on the candidate genes by mapping to a physical region of 220-kb, experiments were carried out in two phytotrons under controlled temperature of 24 ℃ and28 ℃, respectively. The content of chlorophyll, soluble protein and MDA (malondialdehyde), net photosynthesis, the antioxidant enzyme activities of SOD (superoxide dismuase) (EC 1.15.1.1) and POD (peroxidase) (EC 1.11.1.7) and the peptidase activities of leaves were measured from top to bottom according to the leaf positions at the flowering stage. Compared with the control plant,the mutant showed the following characteristics: (1) Higher net photosynthesis rate (Pn) appeared in the 1 st and 2nd leaves, contents of chlorophyll and soluble protein were also higher in the 1 st leaf; (2) The activities of SOD, POD and peptidase were higher according to the leaf position from top to bottom; (3) The symptom of premature senescence was accelerated in the mutant at 28℃treatment. The MDA content and the SOD and POD activities between the 24 ℃ and 28 ℃ treatment mutants were not significantly different. Content of chlorophyll and soluble protein of leaves mutant decreased rapidly at 28 ℃ treatment. The results show that pse(t) is sensitive to high temperature. The probable function of PSE(T) is discussed.     

Targeting of human aFGF gene into silkworm, Bombyx mori L.Through homologous recombination

The long-arm and short-arm genes of fibroin light chain (L-chain) of silkworm, Bombyx Mori L., and the gene of human acidic fibroblast growth factor were cloned respectively and subsequently inserted into a transfer vector pVL1392 used as a tool to target the L-chain region of the silkworm genome. Genomic DNA from their offsprings was extracted and the expected targeting was detected using polymerase chain reaction and DNA sequencing, as well as protein analysis. The results showed that positive events occurred and that the FGF gene was integrated into the L-chain locus through homologous recombination.     

Improvement of xylanase production by Aspergillus niger XY-1 using response surface methodology for optimizing the medium composition

Objective: To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF). Methods: Statistical methodology including the Plackett-Burman design (PBD) and the central composite design (CCD) was employed to investigate the individual crucial component of the medium that significantly affected the enzyme yield. Results: Firstly, NaNO3, yeast extract, urea, Na2CO3, MgSO4, peptone and (NH4)2SO4 were screened as the significant factors positively affecting the xylanase production by PBD. Secondly, by valuating the nitrogen sources effect, urea was proved to be the most effective and economic nitrogen source for xylanase production and used for further optimization.Finally, the CCD and response surface methodology (RSM) were applied to determine the optimal concentration of each sig-nificant variable, which included urea, Na2CO3 and MgSO4. Subsequently a second-order polynomial was determined by mul-tiple regression analysis. The optimum values of the critical components for maximum xylanase production were obtained as follows: x1 (urea)=0.163 (41.63 g/L), x2 (Na2CO3)=-1.68 (2.64 g/L), x3 (MGSO4)=1.338 (10.68 g/L) and the predicted xylanase value was 14374.6 U/g dry substrate. Using the optimized condition, xylanase production by Aspergillus niger XY-1 after 48 h fermentation reached 14637 U/g dry substrate with wheat bran in the shake flask. Conclusion: By using PBD and CCD, we obtained the optimal composition for xylanase production by Aspergillus niger XY-1 in SSF, and the results of no additional expensive medium and shortened fermentation time for higher xylanase production show the potential for industrial utilization.