China''''s first intense beam proton linac

China's first intense beam proton linear acceleratorhas been built at the CAS Institute of High Energy Physics in Beijing, marking a major progress in research into the accelerator-driven system for developing clean nuclear energy in this country.     

转基因食品很安全——罗伯特.霍尔施博士访谈

过去千百年来,人们是通过自然基因突变来选择具有某种特定基因、特定性状的生物体,而现在的转基因技术则是通过分子生物学手段直接改变基因的结构.转基因技术究竟是农业生产中人类改造自然的伟大创举,还是有可能对生态环境造成难以清除的基因污染的潜在危险?《科学美国人》杂志对分子生物学专家霍尔施博士与梅隆博士的专访,揭示出支持者与反对者对转基因食品截然不同的态度《科学美国人》:请问您为什么对转基因作物感兴趣?霍尔施:我对它的兴趣来自于我对农业学术上的热爱,我有一种本能的想法就是如果将分子生物学技术应用于改良作物,这将非常有助于农业生产.现在我们已经实现了在更少的土地上生产出更多的食品,对水源和生物多样性的危害变得更小.利用生物技术解决农业生产中的问题不但是需要的而且是迫在眉睫的.由于人口的增长和收入的增加,在今后25年的时间里,全球对食品的需求将至少增加50%.《科学美国人》:请问在环境保护方面,转基因技术最重要的好处是什么?     

Effectiveness of Spanish intervention for first-grade English language learners at risk for reading difficulties

The effectiveness of an explicit, systematic reading intervention for first-grade students whose home language was Spanish and who were at risk for reading difficulties was examined. Participants were 69 students in 20 classrooms in 7 schools from 3 districts who initially did not pass the screening in Spanish and were randomly assigned within schools to a treatment or comparison group; after 7 months, 64 students remained in the study. The intervention matched the language of instruction of their core reading program (Spanish). Treatment groups of 3 to 5 students met daily for 50 min and were provided systematic and explicit instruction in oral language and reading by trained bilingual intervention teachers. Comparison students received the school's standard intervention for struggling readers. Observations during core reading instruction provided information about the reading instruction and language use of the teachers. There were no differences between the treatment and comparison groups in either Spanish or English on any measures at pretest, but there were significant posttest differences in favor of the treatment group for the following outcomes in Spanish: Letter-Sound Identification (d = 0.72), Phonological Awareness composite (d = 0.73), Woodcock Language Proficiency Battery-Revised Oral Language composite (d = 0.35), Word Attack (d = 0.85), Passage Comprehension (d = 0.55), and two measures of reading fluency (d = 0.58-0.75).     

“妈妈，你究竟在哪里？”

一丝灯光悄然渗过门缝, 落到地板上。我听见隔壁房间里有些许的动静,于是开始热切地企盼,这一次真的能见到母亲或是父亲。我悄悄地从床上爬起来,光着脚丫走到门边, 伸手够到门把。刺眼的灯光霎时间倾泻在我的房间里,一个女人的声音在我面前响起：“宝贝,快回去睡吧。”那不是母亲的声音,而是这座房子里的阿姨。我认识她,却从来不知道她     

把爱寄绐我

这是一位即将退役的海军写给新婚妻子的书信。读罢,不禁想起了林觉民的《与妻书》,“窗外疏梅筛月影,依稀掩映,吾与汝并肩携手,低低切切,何事不语,何情不诉!……”两封“与妻书”,一中一外,一古一今,同中有异。新婚燕尔,分隔两地,借信笺传情,字里行间无不流露出浓情蜜意,这是两者的共同点。但由于所处时代以及环境等种种不同,两者又各有特色:海军的“与妻书”通过一系列的排比句细说深情和思念,将爱情的甜蜜和生活的幸福烘托得恰到好处;而林觉民的《与妻书》,确切说是“与妻诀别书”,却是一字一血泪,一语一悲恸!有心的读者不妨把两者对比来读,相信会有所感悟。——Maisie     

Beam steering in planar photonic crystal based on its anomalous dispersive properties

INTRODUCTION Photonic crystals (PhCs) are increasingly at- tracting attention due to their ability of controlling light propagation on a wavelength scale, by which a fascinating platform for a new generation of inte- grated optical devices and components can be pro- vided. Many studies on PhCs however, focused on new means of tailoring the emission and propagation of light using the photonic band gap (PBG) property whereby the photon density of states is zero. A PhC with a full PBG re…     

Assessment of semi-empirical mass transfer correlations for pervaporation treatment of wastewater contaminated with chlorinated hydrocarbons

INTRODUCTION Chlorinated hydrocarbons, a class of widely used dry-cleaning liquids, industrial organic solvents, and degreasers, increasingly find their way into drinking water sources, thus posing a very serious health and environmental problem (Love and Eliers, 1982). These organic solvents are known for their stability in the environment and cancer-causing po- tency and cannot be effectively and economically eliminated by current conventional treatment tech- nologies. One of the few av…     

超超临界机组机炉协调系统的min-max模糊模型预测跟踪控制

为了提高非线性超超临界火电机组的控制性能,提出了一种改进的min-max模糊模型预测跟踪控制.首先,建立了 T-S模糊模型来近似非线性机炉协调系统的动态特性.然后,基于包含状态变量和输出变量的扩展模糊模型,在保证闭环系统稳定性和输入在给定约束的同时,推导了 min-max模糊模型预测跟踪控制用于输出调节.为了获得更大的...     

Social working memory: Memory for another rat's spatial choices can increase or decrease choice tendencies

In two experiments using a radial-arm maze, pairs of rats made choices among eight maze locations, each containing a large quantity of one of two food types. The choices made by 1 rat affected the choices made by the other rat. Under most conditions, visits by 1 rat increased the tendency of the other rat to subsequently choose that maze location. However, the effect depended on the quality of the food available in a particular location. When it was possible for the rats to observe each other on the maze arms and a rat had experienced that a location contained the less preferred food type, a previous visit to that location by the foraging partner decreased the tendency to visit that location. These effects are attributed to working memory for the spatial choices of another rat, and they indicate that memory produced by a rat’s own visit to a maze location is integrated with memory for the behavior of another rat to determine spatial choice     

学会道歉

有3种基本的道歉类型：事前、中间和事后。每种类型都有自己的最好时机。当你看到要出麻烦时，最好采用事前道歉。这个办法能使父母的教训柔和一些，可以抢他们之前一步行动。“爸爸，我能和你说话能和你说话吗?”(这一直都是个聪明的谈话开头。这使爸爸感到你知道他的存在。) “当然可以。有什么事?”“还记得你借给我的计算器吗?”“是的。”“非常抱歉，我不小心把它丢在公共汽车上了。我回去找过，但没找到。真是对不起，我会还给你一个新的。”“哦，别担心了。那是我去银行存款时免费得到的。我肯定能再找一个。”“噢，我真是很着…