一种特殊重置期权的定价

在完全市场环境下,对文献所介绍的创新的重置期权,在幂型支付的情形下,当债券价格B(t)为时间t的确定性函数时,以鞅论和随机分析为数学工具得到了其定价公式.     

红壤农业生态系统的养分循环、平衡及管理

An experiment was conducted in a red soil derived from Quaternary red clay in the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, located in Yingtan (28° 15' 30' N, 116° 55' 30' E), Jiangxi Province. The results show that the major ways of nutrient loss are leaching and nitrogen volatilization. Rationalizing crop distribution, stimulating nutrient recycling, and improving internal nutrient flow are effective measures to decrease nutrient loss and to promote nutrient utilization efficiency. The important ways of regulating nutrient cycling and balance in the agroecosystem of the red soil are to establish optimal eco-agricultural models, practice balanced fertilization and combine the cropping system with the livestock system.     

Climate change mitigation via afforestation,reforestation and deforestation avoidance: and what about adaptation to environmental change?

Climate change is affecting the world’s ecosystems and threatening the economic system, livelihoods and availability of natural resources. Forest ecosystems can be carbon sources or sinks and are therefore integrated in international climate policy. Forest-related carbon mitigation projects are threatened by climate change through altered environmental conditions and forest processes, as well as through synergistic effects of climate change impacts with already existing socioeconomic and environmental stressors. Data on risk management and adaptation strategies were collected by a survey of 28 current forest projects targeting climate change mitigation. Ten of these represent the officially implemented afforestation (A) and reforestation (R) activities under the UNFCCC and the Kyoto protocol. Additionally, the official methodologies for AR activities under the CDM (Scope 14) were examined for potential climate change adaptation requirements. As a result, the adaptation of forest mitigation projects to climate change is found to be insufficient. A systematic approach for the inclusion of climate change risk management and adaptation is developed and guidelines for the design of “climate-change-proof” afforestation, reforestation and deforestation avoidance projects are proposed. A broader mainstreaming of the issue is required and clear policy regulations are necessary, especially for the post-Kyoto process.     

Alkaloids: Future prospective to combat leishmaniasis

Leishmaniasis, a vector-borne parasitic disease resulting from infection of macrophages by obligate intracellular parasites of genus Leishmania, has been considered a major tropical disease by the World Health Organization. Generic pentavalent antimonials have been the mainstay for therapy in the endemic regions because of its efficacy and cost effectiveness. However, the growing incidence of resistance for the pentavalent antimony complex in endemic and non-endemic regions has seriously hampered their use in these regions. The second line drugs such as amphotericin B, paromomycin and miltefosine are the other alternatives, but they merely fulfill the desired requirements of a safe drug. The recent researches focused on plants have shown a wise way to get a true and potentially rich source of drug candidates against leishmaniasis, where alkaloids have been found more effective. The present review initially highlights the current status of leishmaniasis, synergy of the disease with HIV, therapeutic options available and in later sections summarizes all alkaloids, which have shown significant antileishmanial activities.     

面向县域经济:县级图书馆的一项战略选择

从县级图书馆的实际出发,阐明了面向县域经济是县级图书馆的一项重要战略选择,阐明了县级图书馆如何为县域经济服务。     

黑土区农田氮磷淋溶消减措施

黑土是我国重要的土壤资源,承载了全国50%以上的玉米产量。但过量的化肥施入和不合理的农业管理造成黑土土壤氮磷大量残留,氮磷淋溶风险增强。相关研究表明,尽管黑土区旱地农田氮磷淋溶损失相对较低,肥料残留效应仍致使其潜在淋溶风险增强。因此,本研究综合分析了环境因子和农业管理措施对黑土区农田氮磷淋溶特征的影响规律,明确了黑土氮磷淋溶消减措施,并针对玉米农田和蔬菜地提出消减策略。具体结果如下:施肥和降水是影响黑土农田氮磷淋溶的重要因素,灌溉是影响蔬菜地氮磷淋溶的关键农田管理措施;按需施肥、有机无机配施、避免雨热同期追肥、节水灌溉、免耕秸秆覆盖、不同作物轮作和添加生物炭等均是适合于当地气候和土壤条件的氮磷淋溶阻控措施。建议玉米农田采用一次性基肥施入,有机肥占比50%～70%,采用免耕秸秆覆盖技术;蔬菜地在常规施肥和灌溉频次下分别降低20%的施肥量和灌溉量,推荐蔬菜秋季收获后秸秆粉碎深埋等管理措施。本研究明确了黑土区农田氮磷淋溶消减策略,有助于实现黑土区农业绿色可持续发展和绿色生态环境的构建。     

施肥对稻田甲烷排放的影响

本文综述了N肥和有机肥的种类、施用量、施用方式和施用时间对稻田CH4排放的影响,提出了减少稻田CH4排放的施肥策略,并指出了今后的研究重点:加强对稻田CH4排放机理的研究;针对以往研究中的不足,全面深入研究施肥对稻田CH4排放的影响;进一步研究稻田温室气体排放的交互作用。     

中国硝酸盐脆弱区划分与面源污染阻控

近年来,我国由农业源引发的水体污染愈发严重,这不仅对生态环境造成了影响,同时也让人类赖以生存的饮用水安全受到威胁。因此,如何有效阻控农业面源污染,保护水资源和生态安全意义重大。欧美等国家通过划分硝酸盐和磷污染风险区,以此为依据制定了相关区域法案政策,实施重点区域面源污染阻控和水污染防治,获得了很好的面源污染消减效果。因此,本文分析了欧美等国家通过划分硝酸盐脆弱区制定区域养分管理法案法规,消减水体硝酸盐面源污染风险的经验;阐述了我国硝酸盐脆弱区初步划分的结果,提出了我国针对硝酸盐脆弱区的农业面源污染区域阻控的建议,旨在为我国农业绿色发展和绿色生态环境构建提供科学依据。     

叶面肥阻控水稻富集镉的研究进展

为探究不同叶面肥阻控水稻富集镉的机制,以期为解决农田重金属镉污染和食品安全问题提供科学的依据。本研究归纳了镉对水稻的生长危害,水稻叶与叶面肥的特征包括水稻叶与水稻的养分吸收、叶面肥的种类、叶面肥的特点及叶面肥阻控水稻富集镉的机理。指出影响叶面肥阻控水稻富集镉的效果因素,如天气、温度、利用率、喷施次数和浓度等,提出与其他阻控措施相结合、开展其他种类叶面肥研究、继续叶面肥理论基础研究及加强统一管理和规范操作技术等一系列展望。     

稻-鸭生态种养技术减排甲烷的研究及经济评价

【目的】稻－鸭生态种养技术是中国传统农业的精华，研究其减排CH4的效果，为进一步开发利用这一经典农艺提供理论基础和实践依据。【方法】采用田间试验及经济学方法研究稻-鸭生态种养技术减排CH4的效果及经济效益。【结果】稻田CH4排放通量的日变化与气温日变化基本一致。稻田CH4排放通量的高峰值出现在晚稻分蘖盛期，免耕养鸭稻田、免耕不养鸭稻田和翻耕不养鸭稻田的CH4排放通量分别为24.1、32.2和40.5 mg·m-2·h-1。在晚稻分蘖始-分蘖盛期，稻-鸭生态种养技术对稻田CH4排放的控制效果明显，分别比免耕不养鸭稻田、翻耕不养鸭稻田的CH4排放量减少2.333、4.723 g·m－2。晚稻整个生育期间，免耕养鸭稻田CH4排放量比免耕不养鸭稻田、翻耕不养鸭稻田分别减少3.373和5.590 g·m－2。采用免耕稻-鸭生态种养技术农户的财务净效益比采用免耕不养鸭技术和翻耕不养鸭技术农户分别增加2 166、4 207 yuan/ha。减去CH4排放的环境成本，采用稻－鸭生态种养技术的农户的经济效益为5 000 yuan/ha，比采用免耕不养鸭技术和翻耕不养鸭技术的农户分别增加2 206和4 274 yuan/ha。【结论】稻-鸭生态种养技术既能增加农户的财务收入，又能减少稻田CH4排放量，具有较好的环境效益，是一种很有发展潜力的可持续农业生产模式。