构建C4水稻——一场新绿色革命的挑战

国际上正在探讨新绿色革命的突破口,企图在现有良好株型的基础上,提高叶片的光合效率,其中构建C4水稻可能是一条有效的途径.本文简述了转C4基因水稻的工作意义、技术途径、生理特点以及进一步研究的问题,为中国培育高光效超高产新品种提供参考.     

Petrographic and geochemical characterization of seep carbonate from Alaminos Canyon,Gulf of Mexico

Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral （98%）. Peloids, clotted microfabirc and botryoidal aragonite are developed in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ^13C value of bioclasts in carbonate is from -4.9‰ to -0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ^13C value from -31.3‰ to -23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. ^14C analyses give the radiocarbon age of about 10 ka. Rare earth elements （REE） analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g^-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.     

Comparison of the carbon isotope composition of total organic carbon and long-chain n-alkanes from surface soils in eastern China and their significance

Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition(δ 13C) of total organic carbon(TOC) and higher plant-derived long-chain n-alkanes,with the latter reported as weighted mean values.The two sets of δ 13C values are significantly correlated and show similar trends in spatial variation.The spatial distribution of δ 13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes.This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing conditions for C4 plants.Furthermore,δ 13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ 13C of a soil samples remains relatively constant.Our data demonstrate that in eastern China,soil δ 13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation.This work suggests that -22‰ and -32‰ are good estimated end members for the weighted mean δ 13C values of long-chain n-alkanes(C27,C29 and C31 n-alkanes) from soils under dominant C4 or C3 vegetation,allowing us to reconstruct paleovegetation trends.     

嵌入式系统引导程序BootLoader的设计与实现

嵌入式Linux是将普通Linux操作系统进行裁剪、修改,使之能在嵌入式计算机系统上运行的一种操作系统.主要研究了以ARM7TDMI为内核的S3C44B0X处理器和基于uClinux操作系统的Blob,特别重点介绍Blob的移植和用户命令的添加过程.     

线性分子C3的解析势能函数

应用群论及原子分子反应静力学方法推导C3分子的电子态及其离解极限,在B3P86/CC-PVTZ水平上,对C3分子基态进行优化计算,得出基态C3的单重态能量最低,其稳定构型为的D∞h构型,平衡核间距Re=0.1288 nm、能量为-114.3852 a.u..同时计算出基态的简正振动频率:对称伸缩振动频率ν(Π)=69.4978 cm-1,弯曲振动频率ν(∑g)=1242.4749 cm-1和反对称伸缩振动频率ν(∑u)=2153.1569 cm-1.在此基础上,使用多体项展式理论方法,导出了基态C3分子的全空间解析势能函数,该势能函数准确再现了C3 (D∞h)平衡结构.     

实验室器材管理系统的设计与实现

针对实验室中器材设备繁复琐碎的特点,为使繁琐的管理工作简单化,应用C++Builder6的多层数据库技术,采用ACCESS数据库,设计并实现用计算机进行实验室的器材管理.     

C语言程序设计教学探讨

C语言是在国内外广泛使用的一种计算机语言,是计算机专业及相关专业的专业基础课。另外,C语言也是全国计算机等级考试的科目之一。文章根据实际教学实践,分析了当前C语言教学中所存在的问题,并就如何激发同学们的学习兴趣,培养同学们程序设计能力,进行了一定的分析与探讨．以提高课堂教学效果。     

I2C总线从器件接口的FPGA实现

很多设计中都是为FPGA设置一个基于I2C总线的主控制器接口,而将FPGA作为I2C总线上的从器件则很少,但事实上,低速主控单片机和受控高速FPGA从处理器组成的系统应用场景很广.因此本文分析了I2C总线的操作过程,得到了状态机,在此基础上用VHDL语言实现了遵从I2C总线协议的从器件接口.实践表明,所设计的从器件接口工作良好,具有一定的实用价值.     

基于C＋＋Builder的概率论与数理统计知识点演示系统

以Windows XP为操作平台,使用C＋＋Builder 6．0作为开发工具,完成概率论与数理统计知识点演示系统。系统主要包括：用户登录、泊松分布实验、二项分布实验、投掷骰子实验、二维正态分布实验、中心极限定理等。实践证明,本系统有助于提高概率论与数理统计课程的教学工作质量和教学效果。     

论B2C与C2C两种模式的融合和发展趋势

目前电子商务流行B2C和C2C两种模式。通过对当当网和淘宝网的分析,不难发现,B2C和C2C这两种模式各有优缺点,具有很强的互补性。从发展趋势来看,伴随而来的将是一种全新的电子商务运营模式,一个跨模式的全方位电子商务平台很快就会诞生;融合B2C和C2C,不仅可能,而且将是未来电子商务发展的必然趋势。