Methane emissions from terrestrial plants over China and their effects on methane concentrations in lower troposphere

Methane (CH₄) is the most important greenhouse gas and reactive trace gas in the atmosphere. Recently, it has been reported that terrestrial plants can emit CH₄ under aerobic conditions, which may call for reevaluation of the inventory of CH₄ emissions in China. In this paper, those emissions over China and their effects on CH₄ concentrations in lower troposphere were investigated. Firstly, based on the work of Keppler et al., the aerobic plant CH₄ emission model (PLANTCH4) for China was established. And by using the database of normalized difference vegetation index (NDVI) derived from NOAA/AVHRR, the distribution of net primary productivity (NPP) over China was simulated, and thereby, for the first time, the amount and distribution of the newly identified source in China were estimated. Secondly, with the aid of the three-dimensional atmospheric chemistry model system (MM5-CALGRID), the effects of the emissions were studied. The results show that the annual aerobic plant CH4 emissions over China amount to 11.83 Tg, i.e. nearly 24% of Chinese total CH₄ emissions. And the major fraction (about 43%) comes from forests. When those emissions are considered in modeling, computed countrywide mean surface concentration of CH₄ is 29.9% higher than without them, with a maximum increase of 69.61 μg·m⁻³ in the south of Yunnan Province. In conclusion, to study CH₄ emissions from terrestrial plants over China may have important implications for correctly estimating the contribution of China to global CH₄ budget, and may call for a reconsideration of the role of CH₄ in global and regional environment and climate change. Supported by National High-Tech Research & Development Program of China (Grant No. 2006AA06A307), National Basic Research Program of China (Grant Nos. 2006CB403706 and 2006CB403703), and the Program for New Century Excellent Talents in University, and Nanjing University Talent Development Foundation     

我国婚约制度立法中的主要问题考量

婚约制度虽属民间习惯法范畴,但于司法实践中亦发生较多基于婚约而产生之民事纠纷。我国目前没有专门婚约方面的立法：本文在比较研究的基础上,针对我国实际现状,对订约主体条件、婚约的解除与撤销、诉讼主体的确认、彩礼归属、损害赔偿责任等婚约制度中的主要问题进行了分析研究。     

Climate change impacts on crop yield,crop water productivity and food security-A review

This paper provides a comprehensive review of literature related to the assessment of climate change impacts on crop productivity using climate,water and crop yield models.The existing studies present that climate change models with higher spatial resolution can be a way forward for future climate projections.Meanwhile,stochastic projections of more than one climate model are necessary for providing insights into model uncertainties as well as to develop risk management strategies.It is projected that water availability will increase in some parts of the world,which will have its own effect on water use efficiency and water allocation.Crop production can increase if irrigated areas are expanded or irrigation is intensified,but these may increase the rate of environmental degradation.Since climate change impacts on soil water balance will lead to changes of soil evaporation and plant transpiration,consequently,the crop growth period may shorten in the future impacting on water productivity.Crop yields affected by climate change are projected to be different in various areas,in some areas crop yields will increase,and for other areas it will decrease depending on the latitude of the area and irrigation application.Existing modelling results show that an increase in precipitation will increase crop yield,and what is more,crop yield is more sensitive to the precipitation than temperature.If water availability is reduced in the future,soils of high water holding capacity will be better to reduce the impact of drought while maintaining crop yield.With the temperature increasing and precipitation fluctuations,water availability and crop production are likely to decrease in the future.If the irrigated areas are expanded,the total crop production will increase;however,food and environmental quality may degrade.     

基于Ｍａｌｍｑｕｉｓｔ生产率指数的高技术新产品开发效率研究 ——以长三角为例

基于Malmquist生产率指数的分解,采用6个投入指标和2个产出指标,对长三角地区1997-2002年和2002-2007年两个时期的高技术新产品开发效率进行了测度。得出结论：①长三角地区高技术新产品开发效率的提高,前一个时期主要来自于技术进步率的提高,后一个时期则主要来自于资源配置效率的提高;②浙江高技术新产品开发的规模效率有显著提高,但仍然小于1,没有达到规模报酬水平,需要通过联合开发等方式实现新产品开发的规模效益;③2002-2007年,上海高技术新产品开发效率的提高主要得益于规模效率的提高。     

和谐生产力理论探析

和谐生产力主要是指生产力发展对生产力的各要素及要素之间的关系的要求。具体来说,包括人与自然之间的和谐亦即可持续发展理论,人与社会之间的和谐亦即民主法制下政治、经济、文化建设,人与人之间的和谐亦即公平正义和诚信友爱准则,人自身的和谐亦即人的全面、自由发展相统一。通过推动生产力的各要素之间的关系,以达到和谐生产力。     

结合我国国情提升我国外贸产业的国际竞争力

外贸产业竞争力是一国参与对外贸易产业的整体的竞争力,主要体现在商品生产的比较成本的差异。要提升我国的外贸产业的国际竞争力,应从我国的国情出发,充分发挥我国的生产要素的比较优势,并在促进产业组织的优化升级和技术的升级与创新的同时．合理有效地配置现有资源,有选择地重点提高整体产业的竞争优势,实现比较优势和竞争优势有机的结合。从而有效地提升我国外贸产业国际竞争力。     

热／化学复合采油技术研究现状与进展

热／化学复合采油技术是针对解决蒸汽采油中存在的问题而发展起来的一种稠油开采方法。简要介绍了该技术的作用原理和现场应用情况,指出热／化学复合采油技术是一种提高稠油采收主的有效方法。对国内外室内实验和数值模拟的研究成果分别进行了阐述对比,综合评价了各项研究的优劣及适应范围,指出了研究中存在的问题及下一步研究方向。     

射孔斜井产能预测新方法

从Besson公式的基础上引入双径向流模型,采用等值渗流阻力法,分射穿污染带与未射穿污染带两种情况推导出射孔斜井的产能公式。考虑了孔深、孔密、孔径、相位、污染带的半径与污染程度、压实带的厚度与压实程度、井斜角等因素对产能的影响。利用本文所推导的公式对射孔斜井产能进行参数敏感性分析,认为:产能指数对井斜角、孔深、孔密、压实程度、相位、孔径、压实带厚度的敏感性依次降低;产能指数对射孔参数和压实带参数的敏感性在未射穿污染带时比射穿污染带时高。     

区域可持续发展的瓶颈问题和研究方法探讨

我国的可持续发展战略最终要通过区域可持续发展规划和发展措施来实现,区域可持续发展规划的拟定和发展措施的确定要考虑到方方面面,尤其土地资源生产潜力、土地资源承载力、环境状况（尤其是水土流失）等瓶颈问题的研究是确定区域可持续发展规划和措施的关键,从理论探讨了区域可持续发展中存在的瓶颈问题,指出了目前研究中存在的问题,并提出了参考的研究方法。     

确定采油指数和地层压力的方法研究

为了正确使用系统试井资料,对用指示曲线确定油井采油指数和油藏地层压力的理论方法进行了研究,得出如下结论:对于注水保持压力开采的油藏,油井泄油范围的外边界压力为一常数、泄油范围内的平均地层压力为一变量,应用指示曲线只能确定油井泄油范围的外边界压力Pe和以Pe定义的油井采油指数Jo(Pe);而对于衰竭开采的油藏,油井泄油范围内的平均地层压力为一常数、泄油范围的外边界压力为一变量,应用指示曲线则只能确定油井泄油范围内的平均地层压力P和以P定义的油井采油指数J_o(P)。