共查询到20条相似文献，搜索用时 15 毫秒
1.
《中国科学院院刊(英文版)》2009,23(1):62-63
While observing the world around us via an optical telescope withinformation carried by visible light, which constitutes only a small portion of the electromagnetic spectrum, astronomers use the remainder of the spectrum to reveal extensive data about celestial objects. For instance, they use telescopes operating in the radio spectrum to explore the universe. 相似文献
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针对蠕虫仿真中大量小型对象的特点,对GTNetS的内存管理机制进行系统研究,提出小型对象内存分配技术.实验结果表明,小型对象分配技术可以有效减少系统的最大内存使用量,进而提高蠕虫仿真的规模和效率. 相似文献
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该文对宇宙岩石学基本原理、宇宙凝胶态矿物学基本原理、玛瑙形成的基本原理、各种玛瑙的形成原理、二氧化硅液态熔体分异原理进行了较深入地演绎阐述。作者通过长期对大量的玛瑙实物和玛瑙产地进行仔细观察和深入研究发现，玛瑙是在太空中形成的。在太空中运行的二氧化硅凝胶态熔球遭到砾石雨或砂尘暴撞击以后，在振动力和波动力的作用下，球体内就会建造出平面或曲面层状构造，冷却为固相后就形成了玛瑙。该文在结合实物的基础上，比较全面、系统地归纳出30余种玛瑙的形成原理。文中还例举了与各种玛瑙构造相同的各类岩石的形成原理。 相似文献
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本文选取中国政府于2012-2019年颁布63份政策文本为研究对象,以创新活动最集中的北京、上海、深圳作为样本,构建政策主体、政策目标、政策对象及政策工具四维研究框架,以政策收集-政策分析-政策评估-政策优化为研究脉络,对中国吸引外资研发机构政策进行量化分析和文本挖掘。研究结果显示：政策扶持更加精准和全面,政策主体之间的关联性增强,机构合作更加广泛和深入;政策目标呈现多维性,重点在于获取创新资源和提升创新能力;政策对象上重视吸引独立企业研发主体,非独立企业研发实体等成为重要吸引对象;政策工具上使用环境类工具最多,供给类工具居次及需求类工具最少。尽管在政策主体、政策目标、政策对象和政策工具方面均存在差异,但随着政策演进逐渐呈现规范化和全面化的趋势。针对现行中国吸引外资研发机构政策弱点,笔者提出提升政策执行力、完善微观政策等建议。 相似文献
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Pasalic D Marinkovic N Feher-Turkovic L 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2012,22(1):63-75
With considering serum concentration of the uric acid in humans we are observing hyperuricemia and possible gout development. Many epidemiological studies have shown the relationship between the uric acid and different disorders such are obesity, metabolic syndrome, hypertension and coronary artery disease. Clinicians and investigators recognized serum uric acid concentration as very important diagnostic and prognostic factor of many multifactorial disorders. This review presented few clinical conditions which are not directly related to uric acid, but the concentrations of uric acid might have a great impact in observing, monitoring, prognosis and therapy of such disorders. Uric acid is recognized as a marker of oxidative stress. Production of the uric acid includes enzyme xanthine oxidase which is involved in producing of radical-oxigen species (ROS). As by-products ROS have a significant role in the increased vascular oxidative stress and might be involved in atherogenesis. Uric acid may inhibit endothelial function by inhibition of nitric oxide-function under conditions of oxidative stress. Down regulation of nitric oxide and induction of endothelial dysfunction might also be involved in pathogenesis of hypertension. The most important and well evidenced is possible predictive role of uric acid in predicting short-term outcome (mortality) in acute myocardial infarction (AMI) patients and stroke. Nephrolithiasis of uric acid origin is significantly more common among patients with the metabolic syndrome and obesity. On contrary to this, uric acid also acts is an "antioxidant", a free radical scavenger and a chelator of transitional metal ions which are converted to poorly reactive forms. 相似文献
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Richards JL 《Isis; an international review devoted to the history of science and its cultural influences》2011,102(3):506-510
Mathematics is the most chameleon of subjects, whose meaning is differently defined in different circumstances. This essay considers the mathematics of Augustus De Morgan as an illustration of the ways that the essence of the subject, the very objects that are included within it, has been adjusted in response to cultural factors. Since these cultural factors are the same ones that shape scientific development, the argument is that the history of mathematics and the history of science are always inextricably bound to one another. 相似文献
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通过研究建筑工程施工安全与建筑设计关系,对施工安全事故进行简单随机抽样后的统计、分析,表明大量施工安全事故都与建筑设计因素有关,尤其是地基基础工程、砌筑工程、装饰工程、坠物伤人事故和坍塌事故都与建筑设计密切相关。因此,灾后重建工程在设计阶段就应充分考虑施工安全问题,落实建筑安全设计理念。 相似文献
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Indexing remains one of the most popular tools provided by digital libraries to help users identify and understand the characteristics of the information they need. Despite extensive studies of the problem of automatic index construction for text-based digital libraries, the construction of multimedia digital libraries continues to represent a challenge, because multimedia objects usually lack sufficient text information to ensure reliable index learning. This research attempts to tackle the problem of automatic index construction for multimedia objects by employing Web usage logs and limited keywords pertaining to multimedia objects. The tests of two proposed algorithms use two different data sets with different amounts of textual information. Web usage logs offer precious information for building indexes of multimedia digital libraries with limited textual information. The proposed methods generally yield better indexes, especially for the artwork data set. 相似文献
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《中国科学院院刊(英文版)》2008,22(3):133-134
While observing a sample of quasars with broad absorption line （BAL） in their spectra, Prof. WANG Junxian and his colleagues Prof. WANG Tinggui and Dr. ZHOU Hongyan with the Center for Astrophysics at the University of Science and Technology of China （USTC） discovered that unlike most of BAL quasars, two of the observed do not show intrinsic X-ray absorption, indicating a different composition of matter in their outflows. This might help us better understand how black holes devour and project gases, according to the astronomers. 相似文献
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正确而熟练地掌握试样的称量方法是分析化学实验中最基本的操作技能之一。熟练地掌握分析天平的使用,并能根据不同的称量对象和不同的天平类型,采用相应的称量方法和操作步骤。针对机械天平,主要涉及三种常用的称量方法,其中最常用的是递减称量法。 相似文献
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空间次序作为组织变革的重要特征之一,反映了变革对象层面的基本规律,揭示模式对过程管理具有直接借鉴意义。基于历史文献归纳理论上可行的次序维度,将研究重点集中在多维度条件下的次序模式的形式上,突出强调通过次序维度间的相关性分析和重要性排序来构建多维次序模式。研究表明:单一维度空间次序模式以先强示范意义部门后其他部门为代表;双重维度空间次序维度模式以先重要性强且层次高部门后其他部门为代表;三维度空间次序模式以先推进难度小、对新鲜事物感兴趣且可控性强部门后其他部门为代表。 相似文献
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Michael Madary 《Ethics and Information Technology》2014,16(3):219-225
This article offers an analysis of intentionality for virtual objects and explores some of the ethical implications of this analysis. The main example which serves as a motivation for the article is the case of a Chinese gamer who, in 2005, committed murder in retaliation for the theft of a virtual object, the theft of his virtual dragon sabre. The intentional analysis reveals that the way in which we experience virtual objects shares a structural similarity with the way in which we experience physical objects. Both virtual and physical objects are accessible through action and intersubjectively available. The final part of the article introduces three ethical points based on the intentional analysis. First, virtual objects can have the same ethical significance as physical objects. Second, it will be important to consider empirical results on the factors which influence one’s subjective level of immersion in the virtual world. Finally, the intentional analysis of virtual objects suggests specific questions for future research. 相似文献
15.
观察活动是人们感知客观世界的重要方式,是认识活动的开端和基础。学生观察能力高低对记忆能力、想象能力和思维能力的发展具有非常重要的影响。本文从观察在科学实验教学中的地位,以及初中学生在科学实验观察过程中存在的问题等方面进行了简单的阐述;并通过实例着重对培养学生观察力的途径及方法进行了探讨;指出了科学实验中教师有目的、有计划、科学地指导学生进行观察,使学生学会观察,对培养学生的观察能力和良好的科学态度有重要意义。 相似文献
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构建热带西太平洋科学观测网是中科院战略性先导科技专项"热带西太平洋海洋系统物质能量交换及其影响"的重点任务之一。热带西太平洋环流系统深刻影响着暖池、厄尔尼诺/南方涛动(ENSO)和东亚季风的发展,对全球和我国气候变化研究意义重大。随着2015年15套深海潜标及数据的成功回收,世界上最大规模的热带西太平洋科学观测网的初步建成,我国科学家获得了热带西太平洋代表性海域连续一年涵盖海洋上层和中深层水体的温度、盐度和洋流等观测数据,这是世界上首次在这一地区获取高质量、高时空分辨率的定点连续数据,填补了国际上对该海域中深层环流大规模同步观测的空白,为我国大洋观测网的建设和运行积累了宝贵经验,起到了示范作用。该网络将会为我国大洋环流及其对我国气候效应的研究探索提供持续的数据支撑,将提高我国气候和海洋环境的预测能力。 相似文献
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现今大学的教学推行＂以人为本＂的教育理念,通过教师与学生在教学实践中经常地、有针对性地对学习内容的交流和探讨,有利于调动学生全面和独立的学习积极性。但是,经过对学生学习的观察和研究,中国高校在教育上实行＂以人为本＂的目的是引导学生发挥其自身的内在能动性成为学习中的主体,实现＂以人为本＂理念的本质。文章以深圳大学现行＂教学＋引导＂的措施和做法,探讨实现＂以人为本＂理念在大学教育改革中正效应的最大化。 相似文献
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20世纪90年代以来,我国改革开放进入了新的阶段,区域经济政策目标相应地进行了渐进式的调整。本文通过对20世纪90年代以来我国区域经济政策目标演变的分析,结合区域经济和谐发展对公平与效率的要求,对我国未来的区域政策目标发展趋势进行了展望,并对如何实现该目标提出了政策建议。 相似文献
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Mouna Torjmen-Khemakhem Karen Pinel-Sauvagnat Mohand Boughanem 《Information processing & management》2013
Multimedia objects can be retrieved using their context that can be for instance the text surrounding them in documents. This text may be either near or far from the searched objects. Our goal in this paper is to study the impact, in term of effectiveness, of text position relatively to searched objects. The multimedia objects we consider are described in structured documents such as XML ones. The document structure is therefore exploited to provide this text position in documents. Although structural information has been shown to be an effective source of evidence in textual information retrieval, only a few works investigated its interest in multimedia retrieval. More precisely, the task we are interested in this paper is to retrieve multimedia fragments (i.e. XML elements having at least one multimedia object). Our general approach is built on two steps: we first retrieve XML elements containing multimedia objects, and we then explore the surrounding information to retrieve relevant multimedia fragments. In both cases, we study the impact of the surrounding information using the documents structure. 相似文献
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在K均值算法基础上,提出了改进的K均值算法(K+均值)。此方法计算每个数据对象所在区域的密度选择相互距离,最远的k个处于高密度区域的点作为初始聚类中心。将K均值算法和K+均值算法分别应用于入侵检测,试验结果表明:K+均值算法能够避免K均值算法固有的缺点,并且有比较高的检测性能。 相似文献