如果人类也有尾巴

人们在闲暇之余总是喜欢到动物园转转,观赏各种珍奇的动物,欣赏各种鸟兽的姿势、鸣叫、皮毛等等,还有尾巴,被看8动物都有尾巴。为了安全,它们都被关在笼子里,而看动物的动物——人,则站在笼子外面。这都是因为人类没有尾巴,这难免使人想象,人类如果也有尾巴……     

如何培养学生在数学教学中的解题能力

中学数学教学的目的,归根结底在于培养学生的解题能力,提高数学解题能力是数学教学中一项十分重要的任务。提高学生解题能力始终贯穿于教学始终,我们必须把它放在十分重要的位置。教学关键是教会学生用所学的知识解决实际问题,即要提高学生的解题能力。文章从培养学生“数形”整合、“方程”思维、“对应”思维、“转化”能力、增强自信等五个方面谈如何培养学生的数学解题能力。那么,如何才能提高学生的解题能力,具体方法上讲主要可以从以下几方面入手：     

有关学生数学应用能力培养的重要性和基本途径

针对如何培养学生的数学应用意识,提高学生应用数学知识解决问题的能力进行了分析。     

试析水泵的节能性与安全性

在水处理中,水泵是极其重要的机器设备,它的正常和高效运行对整个水处理过程起着决定性的作用。但由于一般的污水处理中,水泵都处于高压高腐蚀性等环境,因此,它的安全使用技术是非常重要的。此外,水泵属于一种高能耗设备,在使用过程中的节能问题又是一个关键。本文就将重点探讨水泵在水处理中应该注意的节能性和安全性这两方面的技术问题。     

浅谈新技术在冷却塔系统中的运用

工业生产或冷却工艺过程中产生的废热,一般要用冷却水来导走。冷却塔的作用是将挟带废热的冷却水在塔内与空气进行热交换,使废热传输给空气并散人大气。结合实际,重点介绍了新技术在冷却塔系统中的运用。     

Fabrication of a gel particle array in a microfluidic device for bioassays of protein and glucose in human urine samples

This paper describes a simple method for fabricating a series of poly(ethylene glycol) diacrylate (PEG-DA) hydrogel microstructures inside microfluidic channels as probe for proteins and glucose. In order to demonstrate the feasibility of this newly developed system, bovine serum albumin (BSA) was chosen as a model protein. PEG microcolumns were used for the parallel detection of multiple components. Using tetrabromophenol blue (TBPB) and the horseradish peroxidase/glucose oxidase reaction system, bovine serum albumin (BSA) and glucose in human urine were detected by color changes. The color changes for BSA within a concentration range of 1-150 μM, and glucose within a range of 50 mM-2 M could be directly distinguished by eyes or precisely identified by optical microscope. To show the practicability of the gel particle array, protein and glucose concentrations of real human urine samples were determined, resulting in a good correlation with hospital analysis. Notably, only a 5 μL sample was needed for a parallel measurement of both analytes. Conveniently, no special readout equipment or power source was required during the diagnosis process, which is promising for an application in rapid point-of-care diagnosis.     

Electrophoretic separation of neurotransmitters on a polystyrene nano-sphere∕polystyrene sulphonate coated poly(dimethylsiloxane) microchannel

In this paper, a poly(dimethylsiloxane) microchip with amperometric detector was developed for the electrophoretic separation and determination of neurotransmitters. For increasing the separation efficiency, the microchannel is modified by polystyrene sulphonate∕polystyrene nano-sphere self-assembly coating. A stable electro-osmotic flow (EOF) and higher separation efficiency are obtained in proposed modified microchannel. Under optimized conditions, dopamine, epinephrine, catechol, and serotonin are acceptably baseline separated in this 3.5 cm length separation channel with the theoretical plate number from 4.6?×?10(4) to 2.1?×?10(5) per meter and resolution from 1.29 to 12.5. The practicability of proposed microchip is validated by the recovery test with cerebrospinal fluid as real sample which resulted from 91.7% to 106.5%.     

Microfluidic droplet encapsulation of highly motile single zoospores for phenotypic screening of an antioomycete chemical

Highly motile Phytophthora sojae (P. sojae) zoospores of an oomycete plant pathogen and antioomycete candidate chemicals were encapsulated into microdroplets. Random fast self-motion of P. sojae zoospores was overcome by choosing an appropriate flow rate for a zoospore suspension. To influence stochastic loading of zoospores into a microfluidic channel, a zoospore suspension was directly preloaded into a microtubing with a largely reduced inner diameter. A relatively high single zoospore encapsulation rate of 60.5% was achieved on a most trivial T-junction droplet generator platform, without involving any specially designed channel geometry. We speculated that spatial reduction in the diameter direction of microtubing added a degree of zoospore ordering in the longitudinal direction of microtubing and thus influenced positively to change the inherent limitation of stochastic encapsulation of zoospores. Comparative phenotypic study of a plant oomycete pathogen at a single zoospore level had not been achieved earlier. Phenotypic changes of zoospores responding to various chemical concentration conditions were measured in multiple droplets in parallel, providing a reliable data set and thus an improved statistic at a low chemical consumption. Since each droplet compartment contained a single zoospore, we were able to track the germinating history of individual zoospores without being interfered by other germinating zoospores, achieving a high spatial resolution. By adapting some existing droplet immobilization and concentration gradient generation techniques, the droplet approach could potentially lead to a medium-to-high throughput, reliable screening assay for chemicals against many other highly motile zoospores of pathogens.     

全球公共物品

面对新冠疫情的爆发,中国没有太多考虑经济问题,选择采取严格防控措施.这与西方世界流行的做法形成鲜明对比,即我们都接受某种程度的"灵活"封闭,主要目的是挽救老年人的生命.然而中国人却在创纪录的短时间内扩大了医院的容量,并带回了居住在国外的中国公民,这几乎都不在大多数西方国家的考虑之列.     

美国非本土博士与本土博士的工作角色与薪酬比较———对美国1999—2008年博士学位获得者的调查

对那些参与了美国国家科学基金会博士学位获得者调查（SDR）的非美国本土的博士学位获得者完成学业后的工资、工资增长和就业单位等方面进行了调查,调查结果显示,非美国本土的劳动者在1999年的平均年薪比美国本土的同行低,但是10年后的2008年,非美国本土的劳动者的工资超过了那些美国本土的同行.分析还发现,非美国本土与美国本土的博士10年间工资增长存在差异.差异可能是由于学科专业和市场需求等因素导致的.