案例教学法在工科教学中的应用

本文从目前工科大学生解决机电综合问题的能力十分欠缺的现状出发，提出了将工商管理、医、法、教育等专业广泛使用的“案例教学法”引入工科教学中的构想和实施案例教学法的具体措施。     

Two ancient rounds of polyploidy in rice genome

An ancient genome duplication (PPP1) that predates divergence ofthe cereals has recently been recognized. We report here another potentially older large-scale duplication (PPP2) event that predates monocot-dicot divergence in the genome of rice(Oryza saliva L.), as inferred from the age distribution of pairs of duplicate genes based on recent genome data for rice. Our results suggest that paleopolyploidy was widespread and played an important role in the evolution of rice.     

Manipulating Hubbard-type Coulomb blockade effect of metallic wires embedded in an insulator

Correlated states have emerged in low-dimensional systems owing to enhanced Coulomb interactions.Elucidating these states requires atomic-scale characterization and delicate control capabilities.Herein,spectroscopic imaging-scanning tunneling microscopy was employed to investigate the correlated states residing in 1D electrons of the monolayer and bilayer MoSe2 mirror twin boundary(MTB).The Coulomb energies,determined by the wire length,drive the MTB into two types of ground states with distinct...     

Dual hydration of oceanic lithosphere

<正>Water is crucial to processes of both Earth’s surface and interior, facilitating plate tectonics and making the Earth a habitable planet [1]. Seawater penetrates into oceanic lithosphere through fractures on seafloor and migrates along faults and pores. The hydration process weakens the crustal strength and alters mantle properties. Specifically, it influences seismicity by changing the pressure and friction of rocks, and triggers magma generation by lowering the mantle solidus and mant...     

Lu Junjie＇s Purple Sand Pottery Art： Breakthroughs and Innovations

The exhibition on Lu Junjie＇s purple sand pottery art, held in the National Art Museum of China, offers viewers a rare opportunity to learn about explorations and innovations that the artist has made in this traditional form of art. His masterpieces present us a miraculous picture on the art of purple sand pottery and help us better understand his efforts in creating Innovative artworks by integrating traditions with modern concepts and techniques,     

Polyethylenimine-cyclodextrin-tegafur conjugate shows anti-cancer activity and a potential for gene delivery

Polyethylenimine-cyclodextrin-tegafur (PEI-CyD-tegafur) conjugate was synthesized as a novel multifunctional prodrug of tegafur for co-delivery of chemotherapeutic agent tegafur and enhanced green fluorescent protein (EGFP) reporter plasmid DNA. Conjugation of tegafur to PEI-CyD via chemical linkage was characterized by ¹H NMR spectrometry and ultraviolet (UV) spectrometry. PEI-CyD-tegafur was able to condense plasmid DNA into complexes of around 150 nm with positive charge at the N/P ratio of 25, in accordance with electron microscopy observation of compact and monodisperse nanoparticles. The results of in vitro experiments showed enhanced cytotoxicity and considerable transfection efficiency in B16F10 cell line. Therefore, PEI-CyD-tegafur may have great potential as a co-delivery system with anti-cancer activity and potential for gene delivery.     

革命阵营内的名位之争与辛亥革命的失败

辛亥革命到今年,已经整整一百年了。一百年来,中国发生了翻天覆地的变化,关于辛亥革命的研究也取得了举世瞩目的辉煌成就。站在一百年的当口,我们的中国近代史研究,还能拿出怎样的成果奉献给读者呢?一百年的学术研究不可能穷尽辛亥革命的全部内涵,随着研究的进展,许多深层次的问题还会不断浮现出来,需要给予关注和思考。下面的三篇文章,就是在前人的基础上,凭借百年中国社会嬗变和学术进步,对辛亥革命进行反思的新成果。张皓教授则对革命阵营内部的名位之争做了具体的考证,试图从这个角度给辛亥革命的失败一个合理而有力的解释。这几篇文章都有独到视界,见解也有一定深度,特以笔谈形式编发,以飨读者。     

Small Drawings,Great Art Ren Shuaiying＇s Art Exhibition Held in China＇s National Gallery

In May 2011, Ren Shuaiying's Retrospective Exhibition was held in the National Art Museum of China (NAMOC) in commemoration of this master artist's 100th     

Streptomycin inhibits electrophysiological changes induced by stretching of chronically infarcted rat hearts

Objective

To investigate stretch-induced electrophysiological changes in chronically infarcted hearts and the effect of streptomycin (SM) on these changes in vivo.

Methods

Sixty Wistar rats were divided randomly into four groups: a control group (n=15), an SM group (n=15), a myocardial infarction (MI) group (n=15), and an MI+SM group (n=15). Chronic MI was obtained by ligating the left anterior descending branch (LAD) of rat hearts for eight weeks. The in vivo blockade of stretch-activated ion channels (SACs) was achieved by intramuscular injection of SM (180 mg/(kg·d)) for seven days after operation. The hearts were stretched for 5 s by occlusion of the aortic arch. Suction electrodes were placed on the anterior wall of left ventricle to record the monophasic action potential (MAP). The effect of stretching was examined by assessing the 90% monophasic action potential duration (MAPD₉₀), premature ventricular beats (PVBs), and ventricular tachycardia (VT).

Results

The MAPD₉₀ decreased during stretching in both the control (from (50.27±5.61) ms to (46.27±4.51) ms, P<0.05) and MI groups (from (65.47±6.38) ms to (57.47±5.76 ms), P<0.01). SM inhibited the decrease in MAPD₉₀ during inflation ((46.27±4.51) ms vs. (49.53±3.52) ms, P<0.05 in normal hearts; (57.47±5.76) ms vs. (61.87±5.33) ms, P<0.05 in MI hearts). The occurrence of PVBs and VT in the MI group increased compared with that in the control group (PVB: 7.93±1.66 vs. 1.80±0.86, P<0.01; VT: 7 vs. 1, P<0.05). SM decreased the occurrence of PVBs in both normal and MI hearts (0.93±0.59 vs. 1.80±0.86 in normal hearts, P<0.05; 5.40±1.18 vs. 7.93±1.66 in MI hearts, P<0.01).

Conclusions

Stretch-induced MAPD₉₀ changes and arrhythmias were observed in chronically infarcted myocardium. The use of SM in vivo decreased the incidence of PVBs but not of VT. This suggests that SACs may be involved in mechanoelectric feedback (MEF), but that there might be other mechanisms involved in causing VT in chronic MI.     

辅助生殖技术学龄前单双胎子代的认知发展存在差异么?(英文)简

Objective： To explore whether there exist differences in cognitive development between singletons and twins born after in vitro fertilization （IVF） or intracytoplasmic sperm injection （ICSI）. Methods： A total of 566 children were recruited for the study, including 388 children （singletons, n=175; twins, n=213） born after IVF and 178 children （singletons, n=87; twins, n=91 ） born after ICSI. The cognitive development was assessed using the Chinese-Wechsler Intelligence Scale for Children （C-WISC）. Results： For all pre-term offspring, all the intelligence quotient （IQ） items between singletons and twins showed no significant differences no matter if they were born after IVF or ICSI. There was a significant difference in the cognitive development of IVF-conceived full-term singletons and twins. The twins born after IVF obtained significantly lower scores than the singletons in verbal IQ （containing information, picture ＆ vocabulary, arithmetic, picture completion, comprehension, and language）, performance IQ （containing maze, visual analysis, object assembly, and performance）, and full scale IQ （P〈0.05）. The cognitive development of full-term sin- gletons and twins born after ICSI did not show any significant differences. There was no significant difference between the parents of the singletons and twins in their characteristics where data were collected, including the age of the mothers, the current employment status, the educational backgrounds, and areas of residence. There were also no consistent differences in the duration of pregnancy, sex composition of the children, age, and height between sin- gletons and twins at the time of our study although there existed significant differences between the two groups in the sex composition of the full-term children born after ICSI （P〈0.05）. Conclusions： Compared to the full-term singletons born after IVF, the full-term twins have lower cognitive development. The cognitive development of full-term singletons and twins born after ICSI did not show any significant differences. For all pre-term offspring, singletons and twins born after IVF or ICSI, the results of the cognitive development showed no significant differences.