基于高分辨率遥感影像的乌拉山北坡中小型铁矿开采对生态环境的影响分析－以五不台铁矿采矿工程为例

在GIS平台支持下利用建设前、后的矿区SPOT 5高分辨率卫星影像,对矿区的土地利用动态变化进行解译,并得到矿区的工程占地面积,通过建立转移矩阵获得矿区的土地利用类型转化情况,从而分析铁矿开采对矿区生态环境的影响。     

中国农业温室气体减排潜力及其政策意涵

通过农业温室气体减排GTAP-E模型及其数据库构建,模拟了中国农业温室气体减排潜力及其政策意涵,其结论为：农业温室气体减排5%,我国GDP将降低0.059%,社会福利将提高11.6亿美元;水稻的价格上升22.08%,其他农作物价格上升2.9%;牛羊类的价格上升163.43%,猪禽类的价格上升0.57%,其他畜产品价格下降0.98%。农业温室气体减排5%降低了我国农产品在国际市场上的竞争力,使得农产品的出口大大下降,但是却提高了其他部门的出口,导致我国净出口增加了45.5亿美元,农业征收排放税的税收收入为223.11亿美元。     

The variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes

Taking 29 Chinese lakes and 29 Italian lakes as two separate case studies, the paper presented the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. The exergies (Ex) and structural exergies (Exst) were calculated based on phytoplankton biomass (BA) and zooplankton biomass (BZ). A trophic state index (TSI) scaling from 0 to 100 was developed to classify trophic status for Chinese and Italian lakes based on three indicators, chlorophyll-a concentration (Chl-a, in mg/m³), total phosphorus (TP in mg/m³) and transparency in Secchi disk depth (SD in m). The relationships between TSI and Ex, Exst, total biomass, BZ/BA ratios were analyzed. The following results were obtained: (1) with the increase of TSI in Chinese and Italian lakes, there is an increasing trend for Ex, and a decreasing trend for Exst, generally. The obvious negative correlations exist between TSI and Exst, at the significant level of 0.01 for Italian lakes, and 0.05 for Chinese lakes. The obvious positive correlations exist between TSI and Ex, at the significant level of 0.01 for Chinese lakes, and for Italian lakes in Spring, Autumn and the all-year. (2) The structural exergy is more dependent on the ratio of phytoplankton biomass to zooplankton biomass (BZ/BA) than the exergy, and the exergy is more dependent on total biomass than the structural exergy. (3) The phytoplankton biomass (BA) and zooplankton biomass (BZ) are increased with the increasing TSI in Chinese and Italian lakes, and phytoplankton biomass (BA) increases more rapidly then zooplankton biomass (BZ) does. This results in the definite decrease of BZ/BA ratio with the increasing trophic status index. Such changes of BA, BZ and BZ/BA ratio could explain successfully the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. From the two separate case studies of Chinese lakes and Italian lakes, it could be concluded that exergy and structural exergy are feasible to serve as the system-level ecological indicators to give appropriate information on the trophic status of different lakes.     

毛兰素诱导结肠癌SW480细胞凋亡的分子机制

毛兰素是名贵中药材石斛的活性化合物之一,研究了其对人结肠癌SW480细胞的增殖抑制作用及其诱导的细胞凋亡分子机制.实验表明,毛兰素能显著抑制结肠癌SW480细胞的增殖,且随着药物浓度与时间增加,抑制率呈明显的剂量时间效应,48 h半数抑制浓度IC50为24.5 nmol/L;毛兰素能显著诱导结肠癌SW480细胞凋亡,并诱导细胞周期阻滞于G2-M期;分子机制研究显示,毛兰素通过下调XIAP、Bcl-xL蛋白表达以及激活Caspase-9、Caspase-7、Caspase-3和PARP活性从而诱导SW480细胞凋亡.结果表明毛兰素可能对结肠癌的防治具有潜在药用价值.图6参17     

中国近代灾荒史理论探析

中国近代灾荒史是中国灾荒史的断代史.中国近代灾荒史作为一个研究的有机系统,是由灾害、灾荒、灾因、灾荒社会问题、灾荒救治等子系统组成,各系统又有自己的组成要素,这些架构了中国近代灾荒史的学科体系.中国近代灾荒史与灾害学、社会学、经济史、政治军事史、外交史之间有密切的关系,深入研究中国近代灾荒史,加强灾荒史教育,对今天防灾...     

中日规范中关于液化和侧向扩流场地桥梁桩基抗震设计考虑之比较

评述了我国液化场地和侧向扩流场地桥梁桩基抗震设计规范.总结了中日两国液化场地和侧向扩流场地桥梁桩基的抗震设计方法与技术细节,阐述了日本规范中液化场地和侧向扩流场地桥梁桩基抗震设计中的液化地基土反力折减系数的确定方法,以及土体液化侧向扩流对桩作用力的计算模式.指出我国规范中在液化和侧向扩流场地桩的抗震分析方法、不同土层分...     

Soil erosion response to climatic change and human activity during the Quaternary on the Loess Plateau, China

We review published stratigraphic, archaeological and pedosedimentary evidence in order to reconstruct the history of soil erosion in China. Documentary evidence of climatic and flood events of the Yellow River and modern hydrological and meteorological data are synthesised to analyse the history of past human activity and its effects on soil erosion intensity during four nested periods of time during the Quaternary. The most intensive period of erosion during the Quaternary was in the Holocene. During the Holocene, intervals of intensive soil erosion occurred at 7500–7000 BP, 200 BCE–0 CE, 1000–1600 CE (Christian era) and during the 1930s, 1950s and the later part of the 1960s of the last century. Large-scale human activity including warfare during early Chinese history, population migration, the inner wars in 1930s, the Cultural Revolution and the recent national campaign to aid soil and water conservation are all closely related to the rate of soil erosion on the Loess Plateau and to sediment loads in the Yellow River. Overall, soil erosion during the transition from dry-cool to wet-warm climates was more intense than during wet-warm and cool-dry climatic episodes, but serious accelerated soil erosion has occurred during the last 2,500 years because of man-induced devastation of vegetation and other anthropogenic disturbance of the environment. Modern rates of soil erosion on the Loess Plateau are a combination of both intensive natural and human-induced erosions and are some four times greater than occurred in the geological past. The recent implementation of soil and water conservation measures has decreased sediment load in the Yellow River by 25%.     

杉木人工林生态系统的生物地球化学循环Ⅰ:养分归还动态

在福建南平地区 ,对林龄和密度不同的两片杉木人工林的凋落物和森林降水化学进行了 3a(1994～1996 )的定位研究 .株密度n =2 370hm-2 的 16a生林分 (标记为FFC)和株密度n =1180hm-2 的 41a生林分 (标记为XQF)的年凋落量分别为 6 2 10 .7kghm-2 和 3 146 .2kghm-2 ,其中落叶分别占总重量的 76 %和 6 8% .凋落物中 5种主要营养元素的年归还量分别为 173.92kghm-2 和 84.2 0kghm-2 ,其数量大小顺序均为Ca >N >Mg >K>P ,并在 4月份和 11月份出现两次峰值 .在两监测样地 ,降水通过林冠后养分富集现象均十分明显 .降雨、穿透雨和树干径流中养分浓度呈现显著的季节变化 ,均以夏季最低 ,冬季最高 ,春秋季居中 ,这种格局强烈受降雨量的控制 .在两林分中降水引起的 5种元素的年淋溶量分别为 173 .33kghm-2 和 10 7.5 3kghm-2 ,大小顺序为K >Ca >Mg ,而N(及FFC的P)出现负值 ,表明其被林冠层直接吸收 .林龄和密度对生态系统的养分归还具有重要影响 .图 5表 4参 15     

长江水系四大家鱼种质资源的保护和合理利用

四大家鱼是我国淡水养殖和捕捞的主要对象，本文从影响长江水第四大家鱼种质资源的主要因素出发，对目前鱼类养殖场普遍存在的四大家鱼种质退化的原因进行了分析，提出了保护长江水系四大家鱼天然产卵场，利用长江故道保护和合理利用长江四大家鱼种质资源，保护四大家鱼人工养殖群体的遗传性能，建立长江水系四大家鱼种质资源监测体系等对策。     

中国地理资源期刊集群微信融平台经营的实践与经验

随着官媒时代的终结,以微信公众号为代表的新媒体的盛行,强烈地冲击着传统纸媒。微信公众号能够增加期刊与读者群之间的“粘性”,从而扩大期刊的学术影响力和社会知名度。在中国地理资源期刊网微信公众号的运行实践基础上,系统总结期刊微信融平台经营的实践与经验,并以《地理研究》等数据为例,阐述微信推送对期刊产生的综合作用,以期为科研微信融平台的运行提供指导和借鉴意义。研究结果表明：（1）科研微信融平台上生产好微推需遵守十四条原则、十一条创意要求;（2）坚持不懈地在微信公众号上发送消息,可以增加编辑与读者之间的交流、拓展读者范围、增加文章的下载量和被引量,从而树立学术期刊的品牌形象,提升期刊的学术影响力;（3）集群化的科研微信融平台的运行,一定要注意共同维护平台形象、谁制作谁负责、合理安排发文量和发文时间、个刊微平台实现互补等。持续地创意和推出微推,需要长期坚持,把期刊编辑和学术研究、移动互联时代、全媒体手段等积极“融”起来,实现期刊由传统纸质出版向富媒体出版、期刊由文献生产者向学科与社会集成型知识服务提供平台的两大根本性转型,才是期刊的根本出路。