共查询到19条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
《电视字幕·特技与动画》2006,(10):64-65
“闪烁在宇宙深处的行星状星云,原来是绚丽多彩的恒星坟墓;而在丝丝缕缕的超新星遗迹中,恒星正把一生中所形成的新的重元素抛还给宇宙空间。我们冲进发光的气体云,一颗明亮的恒星照亮了身边的稀薄气体;在明亮星云的身后,冷而暗的气体云是恒星诞生的摇篮,新生恒星在这里发出了它 相似文献
5.
6.
本文论述了天文馆的概念;天象仪和天文馆的起源与发展;中国天文馆的发展,中国天象仪的发展,中国天文馆的现状分析;世界天文馆的发展趋势,中国天文馆事业的发展与探索。 相似文献
8.
借助嫦娥探月的东风,近日京城掀起一股航天科普热,不论是中国科技馆屡创新高的参观人流,还是北京天文馆即将举办的月球摄影比赛,抑或是书店里的航天科普书籍热销, 相似文献
9.
谢璐哲 《电子产品维修与制作》2010,(21):101-101
前一段时间出于机器感染了病毒,重新安装了操作系统,但是使用几天后每当打开音频文件,总会提示没有找到音频设备或WindowMediaPlayer没有正确安装。重新安装声卡驱动并升级到WindowsMediaPlayer10.0版本后,故障仍然没有解决。以为是音响硬件故障,拿到其他机器测试后正常 相似文献
10.
有一百多年历史,常年为美国总统竞选提供资金支持,曾经是"正直、专业"的代名词,这样一家巨头公司,你能把它和"诈骗"一词联系在一起吗?但这种事真的发生了——被公司CEO描述成"为上帝工作"的高盛集团最近因涉嫌欺诈再次被推向风口浪尖。
资本来到世间,从头到脚,每个毛孔都沾满了血和肮脏的东西。马克思这句话,今天似乎在高盛身上得到了印证。这家屹立于资本市场长达141年的投行巨鳄,几经磨难而不倒,甚至在金融危机中都捞得盆满钵满。但,从近期美国证交会对其提起的诉讼中,人们却清晰地看到了资本的原罪。深陷"欺诈门"的高盛被另一些人看做是政治斗争的牺牲品——金融危机后推行金融改革,显然很利于民主党在未来中期大选中赢得筹码。但不管怎样,谁也无法否认,处处充斥着欺诈的华尔街资本市场亟待监管,只是难度颇大:一方面,白宫与高盛等资本巨头有千丝万缕的联系,这从奥巴马当年从高盛拿过100万美元总统竞选资金就可见一斑;另一方面,本轮金融危机也早已告诉人们,华尔街资本市场的诸多积弊是长期缺乏监管的后果。
看来,是改变游戏规则的时候了。不过,不论对谁来说,这都绝非易事。 相似文献
11.
12.
本文以北京天文馆的发展历程为线索,对中国天文馆事业的发展历程进行了回顾和梳理,总结了发展中存在的问题,并提出相关建议. 相似文献
13.
Lars R. Knudsen 《Journal of Cryptology》2000,13(4):417-436
In this paper we analyze the block cipher SAFER K. First, we show a weakness in the key schedule, that has the effect that
for almost every key there exists on the average three and a half other keys such that the encryptions of plaintexts different
in one of eight bytes yield ciphertexts also different in only one byte. Moreover, the differences in the keys, plaintexts,
and ciphertexts are in the same byte. This enables us to do a related-key chosen plaintext attack on SAFER K, which finds
the secret key. Also, the security of SAFER K, when used in standard hashing modes, is greatly reduced, which is illustrated.
Second, we propose a new key schedule for SAFER K avoiding these problems. Third, we do differential cryptanalysis of SAFER
K. We consider truncated differentials and apply them in an attack on five-round SAFER K, which finds the secret key much
faster than by an exhaustive search.
Received 21 December 1997 and revised 29 May 1998 相似文献
14.
15.
16.
Weijun Luo Xiaoliang Wang Lunchun Guo Hongling Xiao Cuimei Wang Junxue Ran Jianping Li Jinmin Li 《Microelectronics Journal》2008,39(12):1710-1713
The effect of thickness of the high-temperature (HT) AlN buffer layer on the properties of GaN grown on Si(1 1 1) has been investigated. Optical microscopy (OM), atomic force microscopy (AFM) and X-ray diffraction (XRD) are employed to characterize these samples grown by metal-organic chemical vapor deposition (MOCVD). The results demonstrate that the morphology and crystalline properties of the GaN epilayer strongly depend on the thickness of HT AlN buffer layer, and the optimized thickness of the HT AlN buffer layer is about 110 nm. Together with the low-temperature (LT) AlN interlayer, high-quality GaN epilayer with low crack density can be obtained. 相似文献
17.
在京津冀一体化国家战略的前提下,随着地市A、地市H、地市G数据中心的逐步建成和核心网、IDC专业的布局调整,某运营商省干100Gbit/s OTN系统需进行适当调整。本文提出了3种调整方案,并进行了对比分析,提出了最适合该运营商的省干100Gbit/s OTN系统调整思路。 相似文献
18.
Leopoldina Fortunati Anna Maria Manganelli Pui-lam Law Shanhua Yang 《Telematics and Informatics》2010
China is the primary market for the mobile phone (with almost 700 million of these devices) and one of the world’s leading countries in ICT production. Inside Mainland China, the capital Beijing and the other coastal industrialized towns have been the first to adopt and appropriate the mobile phone. Until now a certain amount of qualitative research has been devoted to the study of ICTs in China. However, quantitative studies are scarce. Here we present the results of a research based on empirical data specifically focused on mobile communication and carried out in Beijing. A structured questionnaire was personally administered to 487 respondents. This study investigates mobile phone use, its implementation in public spaces, attitudes towards its increasing complexity, opinions on its advantages and disadvantages, and its status in comparison to other technologies of information, communication and mass media in the capital of Mainland China. One main result of this study is that a very positive image of the mobile phone among our respondents was accompanied by only two disadvantages: its being a threat to privacy and its presenting the logistical problem that there is no obvious means to carry it. This latter concern should send a strong message to the fashion industry: the diffusion of the mobile phone has worsened the problem of how to wear these “little essential objects”, which up to now still continues to be unresolved. 相似文献
19.
北京的空气质量尤其是夏天经常出现的霾天污染状况,是奥运期间全世界共同关注的问题.2008年8月奥运期间,中国科学院开展了北京及周边地区奥运大气环境监测工作,具体包括地面连续点监测,地基监测和卫星遥感监测等不同形式的监测.卫星监测可以获得霾天大区域分布的范围和光学厚度状况;遥感所超级站监测结果显示奥运期间北京及周边地区霾天的平均水汽含量为68.84%,只比非霾天的64.61%高4.23%.地基监测结果还表明:霾天光学厚度大多在1.0以上,能见度基本在5 km左右;8月非霾天可吸入颗粒物浓度PM2.5和PM10浓度分别为29.58 μg/m3和76.05 μg/m3,但霾天的PM2.5和PM10浓度则分别为68.08 μg/m3和178.81 μg/m3.NO2对流层柱浓度监测结果表明,北京市城区仍然是NO2主要排放源,和天津、唐山,以及河北、山东、山西、河南等地部分地区共同构成NO2对流层柱浓度高值区.根据监测结果分析和模式风廓线后向轨迹数据等分析,北京霾天是在充足的水汽和稳定的大气环境条件下,可溶性细粒子经过吸湿增长后促使能见度急剧下降而成.如超级站的监测结果表明PM10的质量消光截面在空气相对湿度达到95%时有一个迅速增大的过程. 相似文献