国际留学生对中国和中国人的看法之调查研究

本文通过调查问卷收集了来自北京某大学232名国际留学生对中国和中国人的看法。数据分析显示,超过一半的留学生对中国和中国人持有好感,认为中国的很多方面令人欣喜;同时,也有很多留学生认为中国存在很多问题,认为不少中国人吵闹、不讲礼貌等。这些结果说明随着我国经济的快速发展和对外交流的增多,外国人对中国的了解也越来越多。据此,我们提出了一些建议。

Expression and functional analysis of the rice plasma-membrane intrinsic protein gene family

Plasma membrane intrinsic proteins （PIPs） are a subfamily ofaquaporins that enable fast and controlled translocation of water across the membrane. In this study, we systematically identified and cloned ten PIP genes from rice. Based on the similarity of the amino acid sequences they encoded, these rice PIP genes were classified into two groups and designated as OsPIP1-1 to OsPIP1-3 and OsPIP2-1 to OsPIP2-7 following the nomenclature of PIP genes in maize. Quantitative RT-PCR analysis identified three root-specific and one leaf-specific OsPIP genes. Furthermore, the expression profile of each OsPIP gene in response to salt, drought and ABA treatment was examined in detail. Analysis on transgenic plants over-expressing of either OsPIP1 （OsPIP1-1） or OsPIP2 （OsPIP2-2） in wild-type Arabidopsis, showed enhanced tolerance to salt （100 mM of NaCl） and drought （200 mM ofmannitol）, but not to salt treatment of higher concentration （150 mM of NaCl）. Taken together, these data suggest a distinct role of each OsPIP gene in response to different stresses, and should add a new layer to the understanding of the physiological function of rice PIP genes.

Characterization and optimization of AlGaN/GaN metal-insulator semiconductor heterostructure field effect transistors using supercritical CO2/H2O technology

The impact of supercritical CO2/H2O technology on the threshold-voltage instability of AlGaN/GaN metal-insulator semiconductor high-electron-mobility transistors(MIS-HEMTs) is investigated. The MIS-HEMTs were placed in a supercritical fluid system chamber at 150℃ for 3 h. The chamber was injected with CO2 and H2O at pressure of 3000 psi(1 psi ≈ 6.895 kPa). Supercritical H2O fluid has the characteristics of liquid H2O and gaseous H2O at the same time, that is, high penetration and high solubility. In addition, OH-produced by ionization of H2O can fill the nitrogen vacancy near the Si3N4/GaN/AlGaN interface caused by high temperature process. After supercritical CO2/H2O treatment, the threshold voltage shift is reduced from 1 V to 0.3 V. The result shows that the threshold voltage shift of MIS-HEMTs could be suppressed by supercritical CO2/H2O treatment.

Performance Enhancement of Al Ga N/Ga N MIS-HEMTs Realized via Supercritical Nitridation Technology

This paper proposes a method of repairing interface defects by supercritical nitridation technology,in order to suppress the threshold voltage shift of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MIS-HEMTs).We find that supercritical NH3 fluid has the characteristics of both liquid NH3 and gaseous NH3 simultaneously,i.e.,high penetration and high solubility,which penetrate the packaging of MIS-HEMTs.In addition,NH2^-produced via the auto coupling ionization of NH3 has strong nucleophilic ability,and is able to fill nitrogen vacancies near the GaN surface created by high temperature processes.After supercritical fluid treatment,the threshold voltage shift is reduced from 1 V to 0 V,and the interface trap density is reduced by two orders of magnitude.The results show that the threshold voltage shift of MIS-HEMTs can be effectively suppressed by means of supercritical nitridation technology.

Motivation to Study a Second Foreign Language: A Case of Chinese University Learners of German

Not much research has been done on motivation to study a second,third or even fourth foreign language though learners of such languages have been increasing.To contribute to this,the present study examined German learning motivation of Chinese university students at different proficiency levels.A total of 297 German learners at three different proficiency levels at a university in Beijing filled in the questionnaires,of whom 191 answered the open-ended question and 50 were informally interviewed.Analyses of the data revealed the following major findings;(1)most respondents at cach proficiency level had limited access to and little chance to use German,liked the language,studied it(very)hard and did not think the language was difficult,(2)students at different proficiency levels studied German for similar reasons such as major study/research,further education,future career,interest in foreign language learning and German,and(3)students at higher proficiency levels perceived German to be more difficult and worked harder on it.Students at higher proficiency levels were both integratively and instrumentally more motivated to study German and had greater motivation intensity as well.It is clear that students at different proficiency levels were motivated to study German and that students at the advanced level tended to be more integratively motivated than those at the beginning level.Based on these findings,some suggestions are discussed.

A review of the interaction between diet composition and gut microbiota and its impact on associated disease

Dietary intake has an impact on the development of gut microbiota.Humans require carbohydrates,protein,fat,and other nutrients on a daily basis to provide energy for the growth,maintenance,and repair of body tissues.These nutrition-induced changes in gut microbiota may be used to alter host physiology,including disease development and progression,such as obesity and diabetes.More research is needed to fully understand how diet influences microbiota and how microbiota influence host health.The pathways of carbohydrate,protein,and fat metabolism,as well as their interactions and regulatory mechanisms,are described in this review,as well as how diet shapes the microbiota,how dietary-microbiome crosstalk may affect disease development and progression,and how this information could be used to maintain intestinal health.

管式固定床反应器柱状颗粒床层流体流动模拟与实验研究

针对管式固定床反应器内管束数量多、规模大等特点,选取单个管束作为特征结构。对装填不同直径柱状颗粒的管束,采用程序坐标定位的方法,建立柱状颗粒床层的物理模型。采用DEM与CFD联合数值仿真方法,探究反应管内径与柱状颗粒的等比表面积球当量直径之比(管径比Di/dp)对柱状颗粒床层流体流动的影响,并建立单管固定床反应器试验台,采用差压测试方法进行实验研究。结果表明,当Di/dp由5.37增至12.75时,床层空隙率和流体分布均匀性均得到改善,壁面效应的影响由床层中心减弱到管壁。基于数值模拟及实验结果对Di/dp=12.75的柱状颗粒床层进行床层压降Ergun公式常系数修正,CFD模拟计算的结果与拟合公式吻合较好。研究结果能为固定床反应器压降预测提供参考。

An anther-specific chalcone synthase-like gene D5 related to rice pollen development

It was shown in a previous analysis that D5 gene from rice (Oryza sativa L.) was an anther-specific gene encoding a chalcone synthase-related protein. In this study, D5 gene was found specifically expressed in tapetum cells as well as in the peripheral cells of the vascular bundle of rice anthers by RNA in situ hybridization. In order to study its function, D5 was transformed into rice in both sense and antisense directions driven by a rice Actin 1 promoter. It has been observed that the pollen grains from the antisense D5 transgenic rice plants are abnormal, indicating that D5 plays a critical role in rice pollen development.

Design,synthesis and biological evaluation of pyridyl substituted benzoxazepinones as potent and selective inhibitors of aldosterone synthase

Exorbitant aldosterone is closely associated with various severe diseases,including congestive heart failure and chronic kidney disease.As aldosterone synthase is the pivotal enzyme in aldosterone biosynthesis,its inhibition constitutes a promising treatment for these diseases.Via a structure-based approach,a series of pyridyl substituted 3,4-dihydrobenzo[f][1,4]oxazepin-5(2 H)-ones were designed as inhibitors of aldosterone synthase.Six compounds(5 j,5 l,5 m 5 w,5 x and 5 y)distinguished themselves with potent inhibition(IC50<100 nmol/L)and high selectivity over homogenous 11β-hydroxylase.As the most promising compound,5 x exhibited an IC_(50) of 12 nmol/L and an excellent selectivity factor(SF)of157,which are both superior to those of the re ference fadrazole(IC_(50)=21 nmol/L,SF=7).Importantly,5 x showed no inhibition against steroidogenic CYP17,CYP19 and a panel of hepatic CYP enzymes indicating an outstanding sa fety profile.As it manifested satis factory pharmacokinetic pro perties in rats,compound5 x was considered as a drug candidate for further development.

Structural and expressional analysis of a cDNA that expresses predominantly in rice stamens

The development of stamen is an important stage during the sexual reproduction in higher plants. Studying the genes that predominantly or even specifically expressed in stamens will aid in understanding the molecular mechanism of stamen development. The structure of a rice CHS-like gene (D5) which predominantly expressed in anthers has been analysized, showing high structural similarity with two other anther-specific genes (A1 and BA42) from Brassica napus. Northern analysis also reveals that the three genes share a similar expression pattern and that the expression of D5 may relate to the early development of pollens. It is concluded that D5, A1 and BA42 represent a group of diverged CHS-like genes which are related to stamen development.