检索结果-南通市图书馆

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

SAR原始数据压缩的快速矢量量化器

系统工程与电子技术 2004年第10期26卷 1534-1536页

作者：赵宇鹏万锋雷宏中国科学院电子学研究所

回顾了矢量量化的各种快速算法,指出其在应用到SAR原始数据压缩中的局限性。为了将矢量量化应用到SAR原始数据实时压缩,提出一种基于查表的矢量量化器的设计方案,其中整合了其他的矢量量化算法。最后用各种快速算法以及BAQ算法进行了对... 详细信息

回顾了矢量量化的各种快速算法,指出其在应用到SAR原始数据压缩中的局限性。为了将矢量量化应用到SAR原始数据实时压缩,提出一种基于查表的矢量量化器的设计方案,其中整合了其他的矢量量化算法。最后用各种快速算法以及BAQ算法进行了对实际数据压缩的实验比较,证明本算法在不降低量化速度的基础上,提高了原始数据量化信噪比。

关键词：矢量量化合成孔径雷达原始数据压缩快速搜索算法

在线全文

学校读者我要写书评

暂无评论

基于计算机图形学的SAR图像几何畸变仿真

系统仿真学报 2009年第9期21卷 2503-2508,2512页

作者：张帆洪文中国科学院电子学研究所微波成像国家级重点实验室北京100080 中科院研究生院北京100039

分析了传统的SAR图像几何畸变仿真方法,对其重采样方法和几何模型进行修正使其能够适用于机载SAR图像几何畸变仿真。指出了传统仿真方法在计算效率和精度方面的不足,并提出了能够提高这两项指标的基于计算机图形学的SAR图像几何畸变仿... 详细信息

分析了传统的SAR图像几何畸变仿真方法,对其重采样方法和几何模型进行修正使其能够适用于机载SAR图像几何畸变仿真。指出了传统仿真方法在计算效率和精度方面的不足,并提出了能够提高这两项指标的基于计算机图形学的SAR图像几何畸变仿真方法。通过该方法在DEM数据阴影区计算、典型目标几何畸变仿真中的应用,证明了该方法能够高效地计算阴影遮挡和高精度地重采样。

关键词：合成孔径雷达(SAR) 图像仿真几何畸变计算机图形学

GENETIC DIVERSITY AMONG chinese SIKA DEER (CERVUS NIPPON) POPULATIONS AND RELATIONSHIPS BETWEEN chinese AND JAPANESE SIKA DEER

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2006年第4期51卷 433-440页

作者： Lü Xiaoping WEI Fuwen LIMing YANG Guang LIU Hai Key Laboratory for Animal Ecology and Conservation Biology Insti-tute of Zoology Chinese Academy of Sciences Beijing 100080China graduate school of the {2. academy of sciences Beijing 100039China Institute of Genetic Resources Nanjing Normal University Nanjing 210097 China

Sika deer (Cervus nippon) is a cervid endemic to mainland and insular Asia and endan-gered. We analyzed variation in the mitochondrial DNA (mtDNA) control region for four subspecies to understand the genetic diversity, population structure and evolutionary history in china. 335 bp were se-quenced and eight haplotypes were identified based on 2. variable sites among the populations. Sika deer in china showed lower genetic diversity, sug-gesting a small effective population size due to habi-tat fragmentation, a low number of founder individu-als, or the narrow breeding program. AMOVA analy-sis indicated that there was significant genetic subdi-vision among the four populations, but no correlation between the genetic and geographic distance. Phy-logenetic analyses also revealed that {2. sika deer may be divided into three genetic clades, but the genetic structure among {2. populations was inconsistent with subspecies designations and pre-sent geographic distribution. Including the sequence data of Japanese sika deer, the results indicated that {2. populations were more closely related to Southern Japanese populations than to the Northern Japanese one, and the Taiwan population was closer to populations of Northeastern china and Sichuan than to those of Southern china.

关键词：中国梅花鹿遗传多样性衔接重复数量日本梅花鹿

The diurnal variations, semiannual and winter anomalies of the ionospheric TEC based on GPS data in china

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第1期 57-61页

作者： HUO Xingliang 1,2.*, YUAN Yunbin 1, OU Jikun 1, WEN Debao 1,2.and LUO Xiaowen 1,2.1. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, chinese academy of {2., Wuhan 430077, china 2. graduate school of chinese academy of {2., beijing 100039, china) Key Laboratory of Dynamic Geodesy，Institute of Geodesy and Geophysics，chinese academy of {2.，Wuhan 430077，china graduate school of {2. academy of sciences，beijing 100039，china Key Laboratory of Dynamic Geodesy，Institute of Geodesy and Geophysics，chinese academy of {2.，Wuhan 430077，china

With the spherical harmonic (SH) function model and the dual frequency GPS P code phase data from the Crustal Movement Observation Network of china (CMONOC) during the period from year 2.00 to 2.02. time series of total electron content (TEC) in the area of china is calculated. The diurnal variations, semiannual, and winter anomalies of the ionosphere in the area of china are analyzed and discussed, especially according to the results of year 2.01.

关键词： Global Positioning System spherical harmonic function model total electron content semiannual anomaly winter anomaly.

Degradation of organic matterin the sediments of Hongfeng Reservoir

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2005年第20期 123-126页

作者： WEI Zhongqing1,2. LIU Congqiang1, LIANG Xiaobing1, WANG Fushun1 & WANG Shaofeng1, 2.1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, chinese academy of {2., Guiyang 550002. china 2. graduate school of the chinese academy of sciences, beijing 100039, china

In this work, the distribution of organic carbon, DNA and lipids in the sediments of Hongfeng Reservoir were described in addition to SO42. profile in pore water. The con- tents of organic carbon in the sediments range from 2..3 to 76.8 mg·g?1, with the peak value appearing at the depth of 8 cm bellow the sediments water interface (SWI), and tend to decrease gradually with sedimentation depth. The concentra- tions of SO42. decreased from 40.50 mg·L?1 to 12.00 mg·L?1 at SWI in top 4 cm sediment, and was kept at 12.0 mg·L?1 bel- low that depth. Newly produced organic carbon can be con- served as long as 14 years in the sediments. The contents of DNA were relatively high in top 9 cm surface sediments, as revealed by agarose gel images, close to those of organic car- bon and sulphate reduction index (SRI). This study shows that bacteria played an important role in organic matter degradation; SO42. is the primary electron acceptor under anaerobic condition in this reservoir; DNA in the lake sedi- ments can provide important information for the study of cycling of nutrient elements in the lake.

关键词： lake sediment DNA organic carbon electrophoresis sulfate.

磷氮硼(PNB)系催化剂处理对粘胶纤维热裂解行为的影响

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

新型炭材料 2004年第4期19卷 254-260页

作者：李辉温月芳杨永岗刘朗中国科学院山西煤炭化学研究所炭材料重点实验室

　催化剂是制备粘胶炭纤维的关键之一,利用含硼、含磷氮和含磷氮硼三种物质作为制备炭纤维的催化剂,通过TG MS手段分析了三种催化剂对粘胶纤维在惰性气氛下热解行为的影响。结果表明:三种催化剂的加入均使粘胶纤维的裂解反应向低温侧移... 详细信息

　催化剂是制备粘胶炭纤维的关键之一,利用含硼、含磷氮和含磷氮硼三种物质作为制备炭纤维的催化剂,通过TG MS手段分析了三种催化剂对粘胶纤维在惰性气氛下热解行为的影响。结果表明:三种催化剂的加入均使粘胶纤维的裂解反应向低温侧移动,并大大提高了粘胶纤维在600℃时的热解收率,三种催化剂均能提高粘胶纤维裂解产物中水和二氧化碳的生成;含硼类催化剂不能抑制焦油、醛酮和呋喃类物质的生成,而含磷氮和含磷氮硼催化剂对焦油、醛酮和呋喃类物质的抑制作用较强。磷氮硼并用时的催化效果优于单独使用磷氮或硼,二者对粘胶纤维的裂解具有协同催化作用。

关键词：粘胶纤维炭纤维热裂解磷氮硼 TG-MS 催化剂

A novel coupling configuration for thermoacoustically-driven pulse tube coolers: Acoustic amplifier

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2005年第18期 146-148页

作者： DAI Wei1, LUO Ercang1, HU Jianying1,2.& CHEN Yanyan1,2.1. Technical Institute of Physics and Chemistry, chinese academy of {2.,beijing 100080, china 2. graduate school of chinese academy of {2., beijing 100039, china

Thermoacoustically-driven pulse tube cooler can provide cryogenic cooling power with no moving com-ponents. Up to now, pulse tube cooler is directly coupled with the thermoacoustic engine and obtainable pressure ratio for the pulse tube cooler is limited by the capability of the ther-moacoustic engine. The authors propose here the concept of acoustic amplifier, which is actually a long tube connecting the engine with the pulse tube cooler. Theoretical calculation shows that suitable length and diameter of the tube can lead to a pressure wave amplification effect which means that pressure wave amplitude coming from the thermoacoustic engine can be much amplified to drive the pulse tube cooler. Based on this, a 2.8 m long copper tube with 8 mm inner diameter is used as the acoustic amplifier in experiments. The experimental results show that due to the amplification effect, pressure wave amplitude at the inlet of the pulse tube cooler is over 2.5 times of that at the engine outlet. Typically, with 1.67 kW heating power, the pressure ratio provided by the engine is 1.11 while at the inlet of the pulse tube cooler the pressure ratio is 1.32. which leads to a lowest no-load temperature of 65.7 K.

关键词： thermoacoustic pulse tube cooler acoustic amplifier.

Isolation and characterization of rice lesion mimic mutants from a T-DNA tagged population

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第1期 18-24页

作者： LI Shutian 1,2. PEI Zhongyou 1, LUO Lijuan 3, TIAN Yingchuan 1 and HE Chaozu 1* (1. National Key Laboratory of Plant Genomics, Institute of Microbiology, The chinese academy of {2., beijing 100080, china 2. graduate school of the chinese academy of sciences, beijing 100039, china 3. College of Agronomy, South china University of Tropical Agriculture, Danzhou 571737, china)

A rice (Oryza sativa L. ssp. japonica cv. Nipponbare) T-DNA tagged population consisting of about 7000 individual lines was generated and screened for rice lesion mimic mutants in the T 1 generation. Ten lines were found to develop spontaneous lesions in the absence of pathogen infection and displayed distinct lesion phenotypes. These mutants were tentatively designated as lm1—lm10 (for lesion mimic), respectively. Lesion formation of lm mutants was developmentally regulated, and all the mutants showed stunted growth and reduced fertility. Genetic analysis demonstrated that all the mutations were recessive, and five partially fertile mutants (lm4—lm8) were derived from different loci. Mimic lesions occurring on the leaves of lm mutants resulted from cell death as revealed by trypan blue staining. Six of them (lm3—lm8) exhibited enhanced resistance to five bacterial blight isolates, indicating their wide-spectrum resistance to this pathogen. These results imply that some lesion mimic mutations of rice might be involved in disease resistance signaling pathways, and that isolation of these mutated genes may be useful for elucidating molecular mechanisms of plant disease resistance. Among the mutants, only one mutant, lm6, was preliminarily shown to cosegregate with the inserted T-DNA in its T 1 generation, making it feasible to isolate the gene responsible for the phenotype of this mutant.

关键词： T-DNA tagging lesion mimic hypersensitive response Xanthomonas oryzae pv. Oryzae Oryza sativa.

SiO_2.载磷钨杂多酸催化的甲苯与乙酸酐酰化反应

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

燃料化学学报 2005年第5期33卷 622-625页

作者：胡拖平秦张峰王建国中国科学院山西煤炭化学研究所煤转化国家重点实验室

以SiO2.载12.磷钨酸(PW)为催化剂,对甲苯与乙酸酐(AA)的酰化反应进行了研究。采用XRD、BET、TGA和NH3-TPD等对PW/SiO2.化剂进行了表征。结果表明,PW负载量及焙烧温度对PW/SiO2.酸性、PW在SiO2.的分散状态以及酰化催化活性有明显的... 详细信息

以SiO2.载12.磷钨酸(PW)为催化剂,对甲苯与乙酸酐(AA)的酰化反应进行了研究。采用XRD、BET、TGA和NH3-TPD等对PW/SiO2.化剂进行了表征。结果表明,PW负载量及焙烧温度对PW/SiO2.酸性、PW在SiO2.的分散状态以及酰化催化活性有明显的影响。PW的负载量40%(按质量计)、焙烧温度300℃制备的PW(40%)/SiO2.化剂,其PW在载体表面的分散度好,酸量及酸强度适宜,对甲苯与乙酸酐的酰化反应具有较高的催化活性。在130℃,催化剂/乙酸酐(质量比)2.2.,催化反应效果最佳。

关键词：杂多酸 12.磷钨酸二氧化硅甲苯乙酸酐酰化反应