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991.
针对许多企业在CAD系统选购中存在片面的、错误的观念和做法,分析了导致CAN系统选购工作失败的原因,提出了“立足实用,兼顾先进,不盲目追求‘新、全’、高档次和高水平”的软、硬件购买原则,强调了软件选购要考虑软件公司和销售商的背景、软件的性能和功能及软件的易学易用等几个方面的问题.还详细论述了为什么要选国产名牌的微型机作为主机和要选主流的CPU芯片的问题.本文还就盗版软件的禁用和工程图纸扫描录入系统以及如何建立CAD网络系统提出了建议. 相似文献
992.
Two different poly(organophosphazene)s-bearing single-substituents (two cinnamyloxide side groups per repeating unit) and phenoxide-co-substituents (one phenoxide and one cinnamyloxide group per repeating unit) were prepared to study their photochemical reaction behavior. Structural formulas confirmed by the NMRs (1H, 31P) and IR were ? [NP(OCH2CH = CH ? C6H5)2]n ? ( I ) and ? [NP(OCH2CH = CH ? C6H5)0.8 (O ? C6H5)1.2]n ? ( II ). Molecular characterization yielded $ \overline {M_w {\rm s}} $ of the order of 103 kg/mol for both the polymers. The onset temperature of decomposition found by TGA was about 250°C. DSC measurements gave Tgs as 1°C for I and 3°C for II . Their photolytic crosslinking behaviors were monitored by UV spectroscopy. The single-substituents polymer I showed a faster rate of photo reaction than the polymer II . The potential use for practical photosensitive application is considered to be greater for the polymer I . 相似文献
993.
介绍了一种以PIC16C711微控制器为数据处理核心的粮食温度,水分快速 的构成,叙述了数据处理系统的工作机理,硬件构成和软件流程。 相似文献
994.
995.
研究了不同气氛下快速预热处理(RTA)后,硅片中的流动图形缺陷(FPDs)密度和随后两步热处理形成的魔幻清洁区(MDZ)之间的关系.硅片经过高温快速预热处理后,再经过800℃(4h)+1000℃(16h)常规退火,以形成MDZ.研究发现,当硅片在Ar气氛或N2/O2(9%)混合气氛下RTA预处理后,FPDs密度较低,随后热处理出现的氧沉淀诱生缺陷密度较高、清洁区较宽.对于N2/O2混和气氛,随着O2含量的增加,FPDs和氧沉淀诱生缺陷密度变小,纯O2气氛下预处理后硅片中FPDs和氧沉淀诱生缺陷密度最低.因此,可以通过调节N2/O2混合气氛中两种气氛的比例来控制空洞型微缺陷和硅片体内氧沉淀诱生缺陷的密度. 相似文献
996.
The German zoologist and geneticist Ludwig Plate was a pupil and successor of the “German Darwin” Ernst Haeckel as the director
of the Institute of Zoology at Jena University. Plate campaigned for a revival of the original Darwinism. His research program,
which he labelled “old-Darwinism”, proclaimed the synthesis of selectionism with “moderate Lamarckism” and orthogenesis.This
article reconstructs and analyses Plate’s “old-Darwinian” synthesis and sheds light on Plate’s controversial biography, especially
his conflict with Haeckel.
Our research was supported by the Deutsche Forschungsgemeinschaft (HO 2143/5–2). 相似文献
997.
High impedance fault detection utilizing incremental variance ofnormalized even order harmonic power
Wook Hyun Kwon Gi Wen Lee Young Moon Park Man Chul Yoon Myeong Ho Yoo 《Power Delivery, IEEE Transactions on》1991,6(2):557-564
A novel method for the detection of high-impedance faults is proposed which uses the incremental variance of a normalized even order ratio measure. Staged fault tests were extensively carried out in Korean electric power systems. From the analysis of the staged fault test data, it was found that there exists an intermittent arcing phenomenon in most high-impedance faults and that the waveforms of this arcing fault current have an asymmetrical shape in each cycle. Based on these facts, three criteria, (even-order power, even-order ratio, and even-order incremental variance) for fault detection are presented, all of which are based on the changes of normalized even-order harmonic power in fault currents. These criteria are compared through the analysis of staged fault data and normal switching event data. It is shown that the even-order incremental variance criterion is superior to the other two criteria and that, with this criterion, high-impedance faults can be distinguished from normal switching events, including special loads such as electric furnaces and subways. Microprocessor-based protective relays, which can detect high-impedance faults by using the proposed methods, have been constructed, installed in Korea Electric Power Corporation substations, and tested during the last two years. Details of these field tests are given 相似文献
998.
有机氟聚合物的应用研究进展 总被引:11,自引:3,他引:8
有机氟聚合物是一类重要的有机高分子化合物,本文主要介绍了该类聚合物的物化性质、应用以及未来的发展前景。 相似文献
999.
The effect of variables on efficiency of SO2 removal from a simulated waste gas by use of ammonia solution was studied. The variables were gas, feed solution and recirculation
flow rate, SO2 concentration in the gas phase, NH3 concentration in the ammonia solution, and pH in scrubber effluent solutions.
The scrubber was 3“ — OD methyl metacrylate column packed with 1 •4” — plastic Rasching rings in 90 cm packed height.
Solution analysis was performed by Palmrose method and pH meter. The following empirical equations were obtained by regression
analysis; EFF = 33.52 G0.0552 F0.118 R0.772 EFF = 64.10 S0.143 N0.0153 kG = 3.51 x 10-6 G1.160 L0.647 相似文献
1000.
BACKGROUND: To examine the seasonality of suicides in Australia and New Zealand during the period 1981 to 1993. METHODS: A chi-square test and a harmonic analysis were used to detect the seasonality of the suicide data. RESULTS: The reduced amplitude and a smaller proportion of variance accounted for by seasonality suggested the seasonal effect on suicide is greatly diminished. The absence of biseasonal distribution of female suicides was also consistently found in the two countries. The finding was contrary to the reported results in seventies in many Western countries. CONCLUSIONS: The change in living condition, roles of males and females and communication pattern resulted in the reduction of climatic and environment effect in the seasonality of suicides were suggested. LIMITATIONS: The results would be better if a longer series of suicide date were available. 相似文献