"Where" and "what" in vision

The mixture of a few horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted and their positions rapidly determined by a parallel (preattentive) process. However, the discrimination between horizontal and vertical orientation (that is, discrimination of a single conspicuous feature) requires serial search by focal attention. Under recent theories of attention, focal attention has been assumed to be required for the recognition of different combinations of features. According to the findings of this experiment, knowing "what" even a single feature is requires time-consuming search by focal attention. Only knowing "where" a target it is mediated by a parallel process.     

"Dip-Pen" nanolithography

A direct-write "dip-pen" nanolithography (DPN) has been developed to deliver collections of molecules in a positive printing mode. An atomic force microscope (AFM) tip is used to write alkanethiols with 30-nanometer linewidth resolution on a gold thin film in a manner analogous to that of a dip pen. Molecules are delivered from the AFM tip to a solid substrate of interest via capillary transport, making DPN a potentially useful tool for creating and functionalizing nanoscale devices.     

"帝"的甲骨字形

文章分析"帝"与"(礻帝)"的甲骨字形的发展与其异体字。经分析,甲骨文"帝"(■)字有三个部分:(1)"■"可以理解为木匠用来画方形的一种工具(巨),它与四方有关;(2)"木"指位于地心的通天树;(3)上部的一条或两条横线表示"上",即天的意思。甲骨文"(礻帝)"字的异体常表现在(1)部分。商代(礻帝)的祭祀也和后来文献的祭祀不一样。     

Cytidylic acid "a" trihydrate: structure and conformation

Cytidylic acid "a" (cytidine 2'-monophosphate) crystallizes in the triclinic space group P1 with two molecules of cytidine monophosphate (C(9)H(14)O(8)N(3)P) and six molecules of water in the unit cell. X-ray analysis of this crystal shows that in both molecules, the base is in the anti conformation, the ribose ring is C(2')-endo puckered, and the hydroxyl O(5') is gauche-gauche. The two molecules are linked by a short hydrogen bond through the phosphate oxygens.     

Engineering enzyme specificity by "substrate-assisted catalysis"

A novel approach to engineering enzyme specificity is presented in which a catalytic group from an enzyme is first removed by site-directed mutagenesis causing inactivation. Activity is then partially restored by substrates containing the missing catalytic functional group. Replacement of the catalytic His with Ala in the Bacillus amyloliquefaciens subtilisin gene (the mutant is designated His64Ala) by site-directed mutagenesis reduces the catalytic efficiency (kcat/Km) by a factor of a million when assayed with N-succinyl-L-Phe-L-Ala-L-Ala-L-Phe-p-nitroanilide (sFAAF-pNA). Model building studies showed that a His side chain at the P2 position of a substrate bound at the active site of subtilisin could be virtually superimposed on the catalytic His side chain of this serine protease. Accordingly, the His64Ala mutant hydrolyzes a His P2 substrate (sFAHF-pNA) up to 400 times faster than a homologous Ala P2 or Gln P2 substrate (sFAAF-pNA or sFAQF-pNA) at pH 8.0. In contrast, the wild-type enzyme hydrolyzes these three substrates with similar catalytic efficiencies. Additional data from substrate-dependent pH profiles and hydrolysis of large polypeptides indicate that the His64Ala mutant enzyme can recover partially the function of the lost catalytic histidine from a His P2 side chain on the substrate. Such "substrate-assisted catalysis" provides a new basis for engineering enzymes with very narrow and potentially useful substrate specificities. These studies also suggest a possible functional intermediate in the evolution of the catalytic triad of serine proteases.     

Phase Composition of Commercial "Ammonium Carbonate"

A unique crystalline phase was the sole constituent in newly opened containers of commercial reagent-grade "ammonium carbonate." The chemical composition, optical constants, x-ray powder diffraction pattern, infrared absorption spectrum, and density indicate a double salt, ammonium bicarbonate-carbamate (NH(4)HCO(3).NH(4) CO(2)NH(2)), which is unstable in air at ambient temperature and decomposes rapidly to ammonium bicarbonate.     

蜜蜂高产抗螨杂交种“HYR”和“JYR”的选育

    选取卡尼鄂拉蜂、高加索蜂和平湖意蜂为蜂种选育的主要素材,以闭锁集团繁育和人工授精技术为主,RAPD分析为辅,建立和保持3个纯系,在此基础上选育出"HYR"和"JYR"2个高产抗螨杂交蜂种.这2个杂交蜂种除抗螨能力强外,分别具有蜂蜜高产和蜂蜜、王浆双高产的生产性能.与本地意蜂相比,"HYR"和"JYR"蜂种的蜂蜜平均单产分别提高59.40%(P＜0.01)和32.27%(P＜0.01),"JYR"蜂种的王浆平均单产提高69.95%(P＜0.01);2个蜂种的秋季蜂螨寄生率分别为1.97%(P＜0.01)和2.19%(P＜0.01),均显著低于本地意蜂.     

戴东原"群""欲"观念的思想史回溯

本文从戴东原"群"欲"概念上溯先秦儒家礼义起源于饮食男女。饮食之道可以引喻个人与众人生命的安稳与否,男女婚配则可匹配天地五行之义,故所谓饮食男女,实又不仅仅止于饱食与性欲。儒家以血缘为基础,以两性生命之结合为开端,开展各种社群关系的价值,究其实则俱不离形体生命的繁衍;而价值观念的形成,也都不离血气心知合一的身体。自"欲"至"群",人类社会始简终大、始寡终众,儒家伦理价值观念由此而生。戴东原群、欲之论,与先秦儒典旧义有承继发展之关系。先秦儒者重视饮食男女之身体活动的道德价值提升与开展,东原则特别勾勒出一个     

Theoretical evidence for a c60 "window" mechanism

On the basis of semiempirical and high-level ab initio calculations, theoretical evidence is presented of a "window" mechanism operable on the surface of C(60) and other fullerenes. Through this mechanism, large holes may be formed in fullerenes excited to their triplet state, openings through which atoms and small molecules can pass. This work provides a theoretical foundation for experiments that have prepared endohedral noble gas compounds of C(60) under thermal excitation. A method is proposed that could increase the efficiency of the process of noble gas insertion into C(60) and provide a more general means to create endohedral fullerene compounds.     

The life and death of "Bare" viscous bubbles

Air bubbles collect and explode at the surface of many viscous liquids, as observed with polymer foams, in glass furnaces, and during volcanic eruptions. The liquid film separating the bubble from bulk air can have a long lifetime (if it is viscous) even if it is not protected by a surfactant. These "bare" films display unusual dynamic behaviors in drainage and rupture. Two different model systems were studied: a polymer melt (silicone oil) and a molten (borosilicate) glass of comparable viscosity. Although the two systems differ greatly in their relaxation time, they are described by the same set of laws, which can be understood from a relatively simple hydrodynamic model.     

Making ceramics "ductile"

Distributed irreversible deformation in otherwise brittle ceramics (specifically, in silicon carbide and micaceous glass-ceramic) has been observed in Hertzian contacts. The deformation takes the form of an expanding microcrack damage zone below the contact circle, in place of the usual single propagating macrocrack (the Hertzian "cone fracture") outside. An important manifestation of this deformation is an effective "ductility" in the indentation stress-strain response. Control of the associated brittle-ductile transition is readily effected by appropriate design of weak interfaces, large and elongate grains, and high internal stresses in the ceramic microstructure.     

“旱改水”整治研究进展

研究意义：耕地资源是人类社会赖以生存和发展的物质基础，如今全球人地矛盾突出，耕地面积逐年下降，“旱改水”无疑是响应我国整治农用地，守住耕地红线和贯彻落实“占优补优，占水田补水田”的有力举措。数据来源：CNKI和Web of Science数据库。研究方法：文献分析法、归纳统计法。结果发现：（1）旱改水的适宜性评价和潜力系数评估，方法繁多，评价标准不一，评测的结果也参差不齐，未形成较为统一的评价体系；（2）现有的关于适宜旱改水的土地类型研究，土地种类单一，代表性不足，甚至还有大量的适宜性土地类型研究处于空白；（3）现有研究多集中于理论潜力研究，现实潜力研究以及理论潜力与现实潜力对比分析方面的研究发文量较少，可以作为“旱改水”研究的重要发展方向。（4）“旱改水”整治工程技术繁多，现有研究多为广面浅析，对于关键技术的探讨不够深入，缺乏针对性研究。     

关于"问题"的问题研究

问题,是相对于特定的认识主体而言的事物存在着的期待被确定(或被认识)而尚未确定的因素。问题与矛盾是两个既相联系又相区别的具有不同质的概念。问题具有隶属性,结构性,可变性。问题具有认识导向、集体活动组织中心和判断与评价的功能。根据事物的存在、运动与相互作用的状态,问题可以分为描述性问题,说明性问题和协调性问题。解决问题包括发现与确认问题、分析问题与研究对策和解决问题与运用成果几个阶段。     

"Coulomb Staircase" at Room Temperature in a Self-Assembled Molecular Nanostructure

Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms).     

A "Schrodinger Cat" Superposition State of an Atom

A "Schrodinger cat"-like state of matter was generated at the single atom level. A trapped 9Be+ ion was laser-cooled to the zero-point energy and then prepared in a superposition of spatially separated coherent harmonic oscillator states. This state was created by application of a sequence of laser pulses, which entangles internal (electronic) and external (motional) states of the ion. The Schrodinger cat superposition was verified by detection of the quantum mechanical interference between the localized wave packets. This mesoscopic system may provide insight into the fuzzy boundary between the classical and quantum worlds by allowing controlled studies of quantum measurement and quantum decoherence.     

中国“三废”产生排放量的年际变化研究

该文选取1995-2013年中国废水、废气、废弃物的产生排放量作为研究对象,分析了近10a来全国"三废"排放状况。结果表明:全国废水排放从1995年的373亿t上升到2013年的695亿t,上升了近1倍,形势严峻;SO2排放一直处于一种比较顽固稳定的状态;烟(粉)尘排放总量与固体废弃物排放总量均呈降低趋势,但工业SO2、烟(粉)尘排放量却在波动上升,工业固体废弃物年产生量仍达年3亿t之多。进一步开展节能减排、提高循环利用率、提高个人环保意识是必然要求。     

Antibody formation: initiation in "nonresponder" mice by macrophage synthetic polypeptide RNA

The RNA extracted from normal peritoneal macrophages exposed to a linear, random synthetic polypeptide, Glu(60)Ala(30)Tyr(10), initiated an immune response in C57B1/6J mice, although this strain responds very poorly to the antigen itself. From 10 to 150 micrograms of RNA obtained from mouse, rat, or rabbit macrophages was injected intraperitoneally into recipient mice, and specific antibody was detectable by passive hemagglutination 3 to 4 weeks later. Treatment of the RNA with ribonuclease destroyed its ability to initiate a specific immune response. The RNA contained by weight 0.02 percent of the (specific) antigen. The RNA obtained from cells incubated with a second polypeptide, Glu(36)Lys(24)Ala(40), initiated a response specific for this polymer. This RNA even when incubated in vitro with Glu(60)Ala(30)Tyr(10) failed to initiate antibody formation specific for Glu(60)Ala(30)Tyr(10).     

Micromechanical "Trampoline" magnetometers for use in large pulsed magnetic fields

A silicon micromechanical magnetometer was constructed and successfully used in 60-tesla pulsed magnetic fields of less than 100-millisecond duration. The device is small, inexpensive to fabricate, and easy to use. It features a fast mechanical response (up to 50,000 hertz) and extremely high sensitivity yet is relatively robust against electrical and mechanical noise. Quantum oscillations in the magnetization of a 1-microgram sample of an organic superconductor, kappa-[bis(ethylenedithio)tetrathiafulvalene]2Cu(NCS)2, have been observed with this device.     

从“营造生态”到“需求驱动”:学术图书馆如何满足人文学者的数字学术需求

[目的/意义]“营造生态”和“需求驱动”是学术图书馆满足人文学者的数字学术需求、构建数字人文服务体系的两个核心关键词。这两者要求我们从宏观的业态视角理解图书馆的数字人文服务策略,进而从学理层面探寻构建数字人文生态的可行路径。[方法/过程]文章基于课题组的前期积累和相关案例,探讨构建数字人文生态的必要性和可能性。[结果/结论]文章的主要结论包括：（1）强调要尊重客观规律和客观现实,将“数字人文生态”的构建视为数字人文工作首要目标;（2）提出要理清人文学者不同类型的数字学术需求,根据需求展开学术图书馆的类型学研究;（3）学术图书馆可以划分为引领型学术图书馆、支撑型学术图书馆和基础型学术图书馆,应当推动不同类型学术图书馆在数字学术生态中各司其职,对接人文学者不同的需求,在有差异化的服务和合作中构建数字人文生态。