Three-dimensional methods in seismic exploration

Two-dimensional seismic prospecting methods are inadequate to solve the three-dimensional geological problems that arise in petroleum exploration. The three-dimensional seismic technique is a data collection and processing system that samples the subsurface adequately. The structure and lithology of rocks are mapped accurately by imaging their acoustic reflectivity with the scalar wave equation. In oil industry economics, the expense of three-dimensional seismic methods is justified by their usefulness for discovering additional reserves and for reducing the growing costs of developing oil and gas fields.     

Army ants on the move: relation between food supply and emigration frequency

Underfed colonies of Neivamyrmex nigrescens in the laboratory emigrated on 62 percent of the nomadic days, as compared with only 28 percent for overfed colonies. Because the emigration frequency in the field is similar to that of underfed colonies, nomadic raids may not bring in enough food to satiate the larval broods. Since emigrations take time away from raiding, the food-related mechanism underlying emigrations may have evolved under more stringent ecological conditions.     

韩国一次性收获的红椒品种—Saeng-ryeog216

根据栽培面积以及为农民提供的收入而言,红辣椒在韩国一直是仅次于水稻而居第二位的重要农作物。按人均计算,韩国人均年辣椒粉的消费量达2.5kg以上,可能是世界最高记录。辣椒在韩国主要用作泡菜(韩国称之为Kimchi)香辛料和菜肴中的     

我国部分地区猪繁殖与呼吸综合征病毒分离株ORF5基因的遗传变异分析

参考Genbank发表的猪繁殖与呼吸综合征病毒（PKRSV）ATCC VR-2332的ORF5基因序列，设计并合成了一对引物．对来自福建、浙江、山东等地的PRRSV分离毒株进行RT-PCR扩增．获得约748bp的DNA片断，将其分别克隆入pMD18-T载体中，并进行测序。应用DNAStar软件分析所测序列，并与ATCCVR-2332、CH-1a、MLV、Lv等毒株的ORF5序列进行比较，结果表明：SHDl与F114、MLV、ATCCVR-2332同源性高达98．5％，与CH-1a同源性为91．0％，与其它毒株同源性为86．6％~88．4％；F114与MLV、ATCCVR-2332同源性为99．3％～99．7％．其余分离毒株在遗传关系上和CH-1a又分为明显的两个群．显示近年来各地PRRSV分离毒株与cH-1a株的遗传差异越来越大。     

遗传标记及其在家禽育种中的应用

1 SNP SNP是染色体中遗传变异的最普通形式,如在人体已经检测基因组DNA中每1,000到2,000个单位有1个SNP,在某些区域估计每300个单位有一个SNP.基于SNP的高分辨率,遗传图谱在一些人的染色体上通常没有得到发展.正如其名称所指,SNP是发生在基因(启动子、外显子、或内含子)或基因之间(基因间隔区)的单个碱基改变或核苷酸变异.编码序列中的SNP以同义(不会导致氨基酸改变)或非同义(导致氨基酸改变)来分类.非同义SNP由于对蛋白质表达及最终对表现型的潜在影响而受到重视.相反,同义SNP可能对基因表达有微小的影响(除那些在启动子和其它基因组区域中,对DNA-蛋白质作重要的核苷酸或与RNA稳定性有关的核苷酸).同义和非同义SNP在基因图谱研究中均是很好的遗传标记.     

VB与Fortran混合编程的重磁数据处理可视化系统

利用VB与Fortran混合编程技术,开发了重磁数据处理可视化系统,该系统使用工程化管理,包含地形改正、坐标转换、空间域滤波、频率域滤波等许多常用模块。该系统充分发挥了2种编程语言的优点,不仅利用了Fortran程序资源,还扩展了一些新的功能,在实际应用中效率更高、交互性能更佳。     

柴油机机油的换油周期

柴油机机油经过一段时间使用后,会脏污、氧化变质,润滑、冷却、清洗、密封等性能将显著恶化,在主要性能指标下降到一定程度后必须更换。若换得太早,既浪费资源,又浪费时间;若换得过晚,则将加剧发动机磨损或产生故障。一般来说,机手应按