1736年以来长江中下游梅雨变化

利用清代雨雪分寸资料,复原了1736~1911年长江中下游地区的梅雨入出日期、雨期长度,重建了1736年以来长江中下游地区梅雨雨量变化序列,分析了梅雨的变化特征;并根据梅雨期长度与东亚夏季风指数之间的关系,分析了1736年以来东亚夏季风的强弱及与之对应的雨带位置阶段性变化特征.结果表明:长江中下游地区入、出梅日期及雨期长度均存在明显的年-年代际变化,雨期长度除具有2,7~8,20~30及40a的年际与年代际周期外,还具有百年波动的信号.1736年以来,雨期长短、中国东部季风雨带位置移动与东亚夏季风强弱变化

过去2000年中国东部地区的极端旱涝事件变化

利用据历史文献中汉代以来的旱涝灾害记载重建的逐年旱涝等级,结合已重建的东部地区干湿指数序列,通过定义判别历史时期极端旱涝事件的标准,分华北、江淮和江南3个区域辨识了过去2000年的重大旱涝事件。结果表明,各个区域的重大旱、涝多发时段分别是:华北地区出现在100～150年、550～650年、1050～1100年与1850～1900年;江淮地区出现在250～450年与1600～1850年;江南出现在350～400年、1100～1200年与1900～1950年。整个东部地区则出现在100～150年、250～35

基于历史文献重建的近2000年中国温度变化比较研究

文中对不同学者利用不同来源中国历史文献资料重建的温度变化代用序列进行了比对,分析了同一地区不同序列之间及不同地区间序列的异同,以及造成这些异同的主要原因。结果表明:(1)不同学者重建的同一地区温度(或冷暖)变化序列具有较高的相似性;不同学者所估计的30a平均温度相对变幅完全一致(即在99.9%置信水平下,二者通过无显著性差别的检验)的时段平均占所有时段的73.4%,还有8.6%的时段虽在幅度大小上有差异但冷暖定性一致,二者共计占82%。(2)不同地区间的温度变化序列也具有较高的相关性,且重建区域相距越近其

1962—2007年北京地区木本植物秋季物候动态

根据中国物候观测网络北京观测站点的物候资料及气候资料,分析了1962—2007年北京地区20种主要木本植物秋季物候对气候变化的响应情况.结果表明:1962—2007年间,北京地区秋季物候开始日期基本保持不变,但结束日期有所推迟,推迟的幅度为3.2d.10a-1,导致该区秋季延长了约14d;研究期间,北京地区木本植物秋季叶始变色期均表现为推迟趋势,平均推迟幅度为4.9d.10a-1;平均最低气温是影响北京地区木本植物叶始变色期早晚的主要气候因子.气候增暖可能是导致近40年北京地区木本植物秋季物候期推迟的主要

西安木本植物物候与气候要素的关系

根据1963–2007年中国物候观测网西安观测站的物候和气温、降水资料,分析了西安站34种木本植物春季展叶始期、展叶盛期、始花期和盛花期等4个关键物候期的变化趋势、对气候变化的阶段响应特点及其与气温、降水变化的关系。结果表明,1963年以来,西安地区气温呈显著上升趋势,特别是1994年前后,气温发生明显突变,上升趋势更加明显;西安春季物候变化主要呈现提前趋势。在45年中,观测到的34种植物的展叶始期平均提前1天,展叶盛期平均提前1.4天,始花期平均提前9天,盛花期平均提前12天;以突变点为界,34个物种1

过去300年中国土地利用、土地覆被变化与碳循环研究

历史时期的土地利用与土地覆被变化是影响陆地生态系统碳循环的重要因素.过去300年间,我国土地利用与覆被发生了较大变化,林地面积迅速减小,垦殖扩张明显,均对陆地生态系统的碳循环产生了重要的影响.采用通过第一手历史文献资料重建的历史土地数据,分析了过去300年我国土地利用变化的主要特征,研究表明:在研究时段,耕地面积持续增加,从清前期1661年的60.78×106hm2增加到20世纪末的96.09×106hm2;森林面积从1700年的248.13×106hm2降至1949年的109.01×106hm2.受土地

Reconstructing temperature change in Central East China during 601-920 AD

Chinese Academy of Sciences [KZCX2-YW-Q1-01, KZCX2-YW-315]; National Natural Science Foundation of China [40625002]

1876-1878 severe drought in North China: Facts, impacts and climatic background

Chinese Academy of Sciences [KZCX2-YW-315-2]; National Natural Science Foundation of China [40701021, 40625002]; National Key Technology R&D Program of China [2007BAC03A01]

Starch grains from dental calculus reveal ancient plant foodstuffs at Chenqimogou site, Gansu Province

National Natural Science Foundation of China [40771205]; National Science Fund for Distinguished Young Scholars [40625002]; Chinese Academy of Sciences [KZCX2-YW-315]

Temperature variation through 2000 years in China: An uncertainty analysis of reconstruction and regional difference

Chinese Academy of Sciences [KZCX2-YW-315, KZCX2-YW-Q1-01]; National Natural Science Foundation of China [40625002, 90502009, 200905006]; Office of Science (BER), U. S. Department of Energy ; EU/FP7 [212250]

Variations in the Summer Monsoon Rainbands Across Eastern China over the Past 300 Years

Chinese Academy of Sciences [KZCX2-YW-315-2]; National Natural Science Foundation of China [40701021, 40625002]

Relationship between precipitation and the infiltration depth over the middle and lower reaches of the Yellow River and Yangtze-Huaihe River Valley

National Natural Science Foundation of China [40701021, 40625002, 40331013]; National Knowledge Innovation Program of Chinese Academy of Sciences [KZCX2-YW-315-2]

Polyamide thin film composite membranes prepared from isomeric biphenyl tetraacyl chloride and m-phenylenediamine

Three novel of isomeric tetra-functional biphenyl acid chloride: 3,3',5,5'-biphenyl tetraacyl chloride (mm-BTEC), 2,2',4,4'-biphenyl tetraacyl chloride (om-BTEC), and 2,2',5,5'-biphenyl tetraacyl chloride (op-BTEC) were synthesized, and used as new monomers for the preparation of the thin film composite (TFC) reverse osmosis (RO) membranes through interfacial polymerization with m-phenylenediamine (MPDA). The results of membrane performance test showed that membranes prepared from om-BTEC and op-BTEC had higher flux at the expanse of rejection compared with membranes prepared from mm-BTEC.

Sulfonated poly(arylene-co-imide)s as water stable proton exchange membrane materials for fuel cells

A novel sulfonated poly(arylene-co-imide)s were synthesized by Ni(0) catalytic copolymerization of sodium 3-(2,5-dichlorobenzoyl)benzenesulfonate and naphthalimide dichloride monomer. The synthesized copolymers with the - SO3H group on the side-chain of polymers possessed high molecular weights revealed by their high viscosity and the formation of tough and flexible membranes. Because of the introduction of electron donating phenoxy groups into naphthalimide moieties, the hydrolysis of the imide rings was depressed. The resulting copolymers exhibited excellent water stability. The copolymer membranes display no apparently change in appearance, flexibility, and toughness after a soaking treatment in pressurized water at 140 degrees C for 250 h.

Fabrication and characterization of microstructured and pH sensitive interpenetrating networks hydrogel films and application in drug delivery field

Novel microstructured and pH sensitive poly(acryliac acid-co-2-hydroxyethyl methacrylate)/poly(vinyl alcohol) (P(AA-co-HEMA)/PVA) interpenetrating network (IPN) hydrogel films were prepared by radical precipitation copolymerization and sequential IPN technology. The first P(AA-co-HEMA) network was synthesized in the present of IPN aqueous solution by radical initiating, then followed by condensation reaction (Glutaraldehyde as crosslinking agent) within the resultant latex, it formed multiple IPN microstructured hydrogel film. The film samples were characterized by IR, SEM and DSC. Swelling and deswelling behaviors and mechanical property showed the novel multiple IPN nanostuctured film had rapid response and good mechanical property. The IPN films were studied as controlled drug delivery material in different pH buffer solution using cationic compound, crystal violet as a model drug.