Antimicrobial peptides of multicellular organisms.

Multicellular organisms live, by and large, harmoniously with microbes. The cornea of the eye of an animal is almost always free of signs of infection. The insect flourishes without lymphocytes or antibodies. A plant seed germinates successfully in the midst of soil microbes. How is this accomplished? Both animals and plants possess potent, broad-spectrum antimicrobial peptides, which they use to fend off a wide range of microbes, including bacteria, fungi, viruses and protozoa. What sorts of molecules are they? How are they employed by animals in their defence? As our need for new antibiotics becomes more pressing, could we design anti-infective drugs based on the design principles these molecules teach us?     

头孢菌素类抗生素的研究进展

头孢菌素类抗生素药物是临床上用于治疗细菌感染所导致疾病的常用药物,已发展到第4代.目前头孢菌素类药物的研究热点在于寻找对耐药的革兰氏阳性致病菌敏感,尤其是对耐甲氧西林金葡萄球菌(MRSA)敏感的头孢烯酸类化合物及对高活性化合物进行结构修饰,改善其药学性质.就研发中的头孢菌素类化合物的结构、抗菌谱和抗菌活性作一简要综述.     

On Some Tips For English Learning

English is more and more important nowadays.A great number of people begin to learn English in order to be able to use it freely at work,study and learn from other countries.How can you learn English well? How do you improve your speaking? How do you improve your listening? Are there any best and quickest methods to learn English? In my humble opinoin,writing more,reading more and listening more are the most effective way or even the only way to improve your English.     

Action plans used in action observation

How do we understand the actions of others? According to the direct matching hypothesis, action understanding results from a mechanism that maps an observed action onto motor representations of that action. Although supported by neurophysiological and brain-imaging studies, direct evidence for this hypothesis is sparse. In visually guided actions, task-specific proactive eye movements are crucial for planning and control. Because the eyes are free to move when observing such actions, the direct matching hypothesis predicts that subjects should produce eye movements similar to those produced when they perform the tasks. If an observer analyses action through purely visual means, however, eye movements will be linked reactively to the observed action. Here we show that when subjects observe a block stacking task, the coordination between their gaze and the actor's hand is predictive, rather than reactive, and is highly similar to the gaze-hand coordination when they perform the task themselves. These results indicate that during action observation subjects implement eye motor programs directed by motor representations of manual actions and thus provide strong evidence for the direct matching hypothesis.     

Single cocaine exposure in vivo induces long-term potentiation in dopamine neurons

How do drugs of abuse modify neural circuitry and thereby lead to addictive behaviour? As for many forms of experience-dependent plasticity, modifications in glutamatergic synaptic transmission have been suggested to be particularly important. Evidence of such changes in response to in vivo administration of drugs of abuse is lacking, however. Here we show that a single in vivo exposure to cocaine induces long-term potentiation of AMPA (alpha-amino-3-hydroxy-5-methyl-isoxazole propionic acid)-receptor-mediated currents at excitatory synapses onto dopamine cells in the ventral tegmental area. Potentiation is still observed 5 but not 10 days after cocaine exposure and is blocked when an NMDA (N-methyl-d-aspartate) receptor antagonist is administered with cocaine. Furthermore, long-term potentiation at these synapses is occluded and long-term depression is enhanced by in vivo cocaine exposure. These results show that a prominent form of synaptic plasticity can be elicited by a single in vivo exposure to cocaine and therefore may be involved in the early stages of the development of drug addiction.     

规范导师制,充分发挥导师的主观能动性

导师工作架起了教师与学生沟通的桥梁。如何规范导师制?如何充分发挥导师的主观能动性?这是值得我们探索的问题。     

Surface tension: floater clustering in a standing wave

How do waves affect the distribution of small particles that float on water? Here we show that drifting small particles concentrate in either the nodes or antinodes of a standing wave, depending on whether they are hydrophilic or hydrophobic, as a result of a surface-tension effect that violates Archimedes' law of buoyancy. This clustering on waves may find practical application in particle separation and provides insight into the patchy distribution on water of, for example, plastic litter or oil slicks.     

A simple game for the study of trust in distributed systems

Trust is an important aspect of the design and analysis of secure distributed systems. It is often used informally to designate those portions of a system that must function correctly in order to achieve the desired outcome. But it is a notoriously diffcult notion to formalize. What are the properties of trust? How is it learned, propagated, and utilized successfully? How can it be modeled? How can a trust model be used to derive protocols that are effcient and reliable when employed in today’s expansive networks? Past work has been concerned with only a few of these issues, without concentrating on the need for a comprehensive approach to trust modeling. In this paper, we take a first step in that direction by studying an artificial community of agents that uses a notion of trust to succeed in a game against nature. The model is simple enough to analyze and simulate, but also rich enough to exhibit phenomena of real-life interactive communities. The model requires agents to make decisions. To do well, the agents are informed by knowledge gained from their own past experience as well as from the experience of other agents. Communication among agents allows knowledge to propagate faster through the network, which in turn can allow for a more successful community. We analyze the model from both a theoretical and an experimental point of view.     

稀土基纳米抗菌材料研究进展

抗生素滥用导致了细菌耐药性的增加和超级细菌的出现，使开发新型抗菌药物迫在眉睫.稀土元素具有独特的理化性质，在抗菌领域的应用得到了越来越多的关注.文章主要介绍了三类稀土基纳米抗菌材料：稀土氧化物、稀土配合物、稀土掺杂复合物，简述了这三类材料的抗菌机制和应用现状，同时对材料未来的抗菌应用前景进行了展望.     

Fungal defensins,an emerging source of anti-infective drugs

With the rapid increase of antibiotic-resistantpathogens and the decline of discovery and development ofnew antibiotics, there is an urgent need to exploit alterna-tive anti-infective drugs. Fungal defensin-like peptides areemerging as a class of new source of anti-infective drugsdue to their potent antibacterial activity, low toxicity, andhigh serum stability. Fungal genome sequencing projectscombined with the development of recombinant expressiontechniques will accelerate the discovery of fungal defensin-like peptides.     

现代工业设计的走向问题探讨

现代工业设计走过百年的历程,设计的方向逐渐出现了分岔和偏离。我们应该怎样看待我们周围生活中的设计,周围的人,以及生活的品位,休闲娱乐的方式和对社会价值的认知。工业设计的发展何去何从?设计的统筹规划究竟该如何进行?它该如何向提升人的价值品位和生活质量的设计方向发展。     

重组人干扰素α-2b-卡介苗（hIFN—α-2b—BCG）药物敏感性分析

通过BACTECMGITTM960全自动分枝杆菌培养鉴定／药敏仪对重组人干扰素α-2b卡介苗hIFN-α-2b-BCG）菌株进行利福平等10种抗菌药物的敏感性试验,以野生BCG作对照观察药物对重组BCG菌株活性的潜在影响．结果发现：重组人干扰素α-2b-卡介苗在系统感染上对喹酮类的氧氟沙星、环丙沙星敏感,对氨基糖苷类药物的庆大霉素和卡那霉素耐药．在抗结核类药物中,除对吡嗪酰胺耐药外,外利福平等其他几种抗生素均敏感．因尿液回收率高,几乎所有的抗茵药物都对膀胱中的菌株有影响．     

数学模型方法与中学数学

在现代社会，随着科技发展和计算机的广泛应用，数学模型方法越来越被人们所重视。本文主要探讨如何优化中学数学教育，怎样在中学数学教学中实现数学模型方法，并在中学数学的范围内，用数学模型解应用题，用现有数学模型解数学题．     

172例抗菌药物不良反应报告分析

目的了解抗菌药物致不良反应(ADRs)发生的特点、规律及影响因素,为临床安全合理使用抗菌药物提供参考。方法 172例抗菌药物不良反应报告,按照性别和年龄分布、给药途径、发生时间、药品分布、累及器官/系统、常见ADRs症状处理方法进行回顾性统计和评价。结果在172例ADRs报告中,10岁以下的患者有56例,60岁以上的患者有62例。引起ADRs的抗菌药品有8个大类,47个品种。结论抗菌药物的ADRs发生与药物品种、给药途径、患者情况密切相关,完善ADRs监测和评价,能指导临床合理应用抗菌药物。     

我国传统企业选择电子商务的模式

电子商务的发展使社会经济发生了巨大的变化 ,网络经济可能成为未来经济发展的主流 ,传统企业如何面对网络经济的挑战 ,如何适应这种转变 ,成为当前普遍关心的问题。本文对我国的电子商务发展现状进行了深层的分析 ,并对传统企业介入电子商务的模式进行了分析和探讨     

Structural basis for the interaction of antibiotics with the peptidyl transferase centre in eubacteria.

Ribosomes, the site of protein synthesis, are a major target for natural and synthetic antibiotics. Detailed knowledge of antibiotic binding sites is central to understanding the mechanisms of drug action. Conversely, drugs are excellent tools for studying the ribosome function. To elucidate the structural basis of ribosome-antibiotic interactions, we determined the high-resolution X-ray structures of the 50S ribosomal subunit of the eubacterium Deinococcus radiodurans, complexed with the clinically relevant antibiotics chloramphenicol, clindamycin and the three macrolides erythromycin, clarithromycin and roxithromycin. We found that antibiotic binding sites are composed exclusively of segments of 23S ribosomal RNA at the peptidyl transferase cavity and do not involve any interaction of the drugs with ribosomal proteins. Here we report the details of antibiotic interactions with the components of their binding sites. Our results also show the importance of putative Mg+2 ions for the binding of some drugs. This structural analysis should facilitate rational drug design.     

Antibacterial agents based on the cyclic D,L-alpha-peptide architecture

The rapid emergence of bacterial infections that are resistant to many drugs underscores the need for new therapeutic agents. Here we report that six- and eight-residue cyclic d,l-alpha-peptides act preferentially on Gram-positive and/or Gram-negative bacterial membranes compared to mammalian cells, increase membrane permeability, collapse transmembrane ion potentials, and cause rapid cell death. The effectiveness of this class of materials as selective antibacterial agents is highlighted by the high efficacy observed against lethal methicillin-resistant Staphylococcus aureus infections in mice. Cyclic d,l-alpha-peptides are proteolytically stable, easy to synthesize, and can be derived from a potentially vast membrane-active sequence space. The unique abiotic structure of the cyclic peptides and their quick bactericidal action may also contribute to limit temporal acquirement of drug resistant bacteria. The low molecular weight d,l-alpha-peptides offer an attractive complement to the current arsenal of naturally derived antibiotics, and hold considerable potential in combating a variety of existing and emerging infectious diseases.     

如何做好学生的思想政治工作

培养合格的大学生,做好他们的思想政治工作很重要。怎样才能做好,笔者认为应该由3方面组成,即:领导重视、关心辅导员;辅导员加强政治、道德、知识、能力、性格方面的修养;教师要了解学生心理等方面的特点并结合家庭、社会教育搞好学生工作。     

我国大学应该如何发展?人才应该如何培养?

高等教育作为知识的传承和科学技术累积与发展的场所,对人类的发展具有十分重要的地位.我国大学如何在高教国际化的过程中立于不败之地?人才如何培养才能成为真正意义上的"四有"新人?大学的发展与人才的培养怎样才能有机地结合起来?带着这些问题,在大学几年的学习生活和教学工作基础上,初步探索和总结出了一些具有建设性、指导性的结论与意见,试图对我国高等教育的发展和大学生的培养有所帮助.     

引力波探测:引力波天文学的新时代

 美国LIGO 于2016 年2 月11 日宣布首次探测到了引力波,引起全世界范围的广大反响。本文解答从什么是引力波、引力波是如何产生的、人类为什么坚持不懈地探测引力波、如何探测引力波,介绍国内外引力波探测的现状,并对引力波探测的未来进行展望。