稻田甲烷排放的初级模式

本文建立了一个区域尺度稻田生态系统ＣＨ４排放的初步模式，该模式能从理论上反映稻田ＣＨ４产生、传输与排放的机理，并提供了一种估计不同区域气候和土壤条件下稻田生态系统ＣＨ４排放总量的有效方法。模式主要包括三个部分：水稻的生长、土壤有机物的分解和ＣＨ４的产生、传输及排放过程。模式分别模拟了早稻和晚稻ＣＨ４的排放，模拟结果与实测比较接近，ＣＨ４的季平均排放量，模拟值与实测值的偏差在１０％左右。模式的敏感性实验表明，温度是稻田ＣＨ４排放规律的主要控制因子。

高中物理建模能力培养的现状及对策

建模能力实际上就是把一个实际问题抽象成相应模型,借助理论知识对实际问题进行解决的一种能力。如今,新课标更是将模型构建当作物理方面核心素养当中的核心要素,模型教学可以打破以往教学模式,推动教学改革逐步深入。基于此,本文在对高中时期物理学科建模能力实际培养状况加以分析的基础上,对培养高中生物理建模能力的对策展开探究,希望能为实际教学提供些许参考。

从一道习题思考简谐运动的振动能量

在学习第九章机械振动时，学生找来这样的一道习题。

离子注入及退火对GaAs/Si晶体完整性影响的研究

本文用4.2MeV ~7Li离子卢瑟福背散射沟道技术研究了Si上外延GaAs膜在MeV Si离子注入及红外瞬态退火后的再生长过程。实验表明,离子注入可使GaAs外延膜内形成一无序网络,当注入剂量低于某一阈值时,850℃,15秒退火后,损伤区可完全再结晶,再结晶后的GaAs层的晶体质量特别在界面区有很大的改善;当剂量超过该阈值时,出现部分再结晶。激光Raman实验也表明,经过处理后的GaAs层Raman谱TO/LO声子的比率比原生长的样品有很大的降低。

Model for Methane Emission from Rice Fields and Its Application in Southern China

A process model has been developed. The model has been used to calculate the methane emission from rice fields. The influence of climate conditions, field water management, organic fertilizers and soil types on methane emission from rice fields are considered. There are three major segments which are highly interactive in nature in the model:rice growth, decomposition of soil organic matter and methane production, transport efficiency and methane emission rate. Explicit equations for modeling each segment mentioned above are given. The main results of the model are: 1. The seasonal variation of methane emission of the model output agrees with that of field experiments. The deviation of seasonal average methane emission rate between modeled value and experimental data is about 10%. 2. In the whole rice growing period, model output is similar to experimental data in the seasonal variation of transport ability of rice plant. 3. Soil organic matter content and soil physics and chemistry are major factors that determine the total season average emission rate, while soil temperature controls the temporal variation of methane emission from rice fields.

REGROWTH OF MBE-GaAs FILMS ON Si SUBSTRATES BY HIGH ENERGY ION-IMPLANTATION AND SUBSEQUENT ANNEALING

4.2MeV ^(7)Li channeling technique,laser Raman scattering spectrometry,and TEM have been utilized to study the regrowth of MBE-GaAs films of〜μm thick on Si substrates by Si^(+) implantation(0.6-2.6MeV)and subsequent rapid thermal annealing.The results showed that crystalline disorder was greatly reduced in the recrystalized layers especially at the interface.

搞好企业的活力——参观天津青年联合实业公司

「民办公助」的集体企业这次访问中国,本来就希望能参观城市的集体所有制企业,其原因主要是当前在解决中国城市的青年就业问题方面,集体所有制企业发挥了很重要的作用。在我们参观天津市青年联合实业公司时,赵树华经理热情洋溢地讲到:该公司以「民办公助」的形式创建许多集体所有制企业,为解决“待业青年”就业问题开辟了一条崭新的道路。三年来公司所属各个企业仍稳步发展,这是由于采取下列方针创办小规模集体企业。