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381.
In this study we utilize content analysis techniques to examine how the issue of global warming and climate change has been characterized during the period of 1992 through 2005 by the Houston Chronicle—the largest regional newspaper in the Texas coastal region. A total of 795 global warming and climate change news articles from the Houston Chronicle are collected, coded and analyzed. Data analyses are organized and presented with regard to issue salience, various issue attributes (issue image, scope, linkage, participant, proposed solution and responsible party), use of science, and scientific information sources cited in the news stories. We find that regional media attention to the global climate change issue generally increases over time and an overwhelming majority of the news articles view the issue as a harmful problem. However, given the scientific consensus that global warming will result in significant devastating climate change consequences to the coastal regions, there are still a fair number of news articles delivering mixed, undetermined or even non-harmful messages. We also find that climate change is often discussed as a national or international-global issue, and frequently linked to a number of other public issues rather than just being viewed as an environmental–ecological problem. Moreover, we find that emphasis on issue solutions is placed more on mitigation strategies than on adaptation behaviors, and that both governmental and non-governmental actions and responsibilities are suggested for dealing with climate change. In addition, our findings indicate that the regional newspaper in Texas obtains scientific information on climate change primarily from academic institutions. Implications of our findings and recommendations for future research are discussed in the concluding section.  相似文献   
382.
从能量转换效益、价值转换效益方面,对坡地林农复会系统10种农作物复种方式进行了研究,并用层次分析法(AHP)对各复种方式进行综合效益评价。结果表明,10种复种方式中,小麦一花生的综合效益最高,5种复种方式较高,其余则较低。据此,提出了系列改进措施,供生产中应用。  相似文献   
383.
江苏沿江经济区多元多熟种植方式及效益评价   总被引:1,自引:0,他引:1  
在江苏沿江经济区设置了23种多元多熟种植方式进行定位对比试验,从增粮、增收和省工3个方面进行了综合评价。结果表明,稻田以“春玉米-水稻”为基础,旱地以春玉米为中心的粮饲经菜4元结构的省工型种植方式是本区集约高效持续种植制度的发展方向。  相似文献   
384.
The bootstrap resampling method is used to help with the intercomparison of air transport models. Time-by-time analysis of variance and follow up simultaneous comparisons are proposed which do not rely on distributional assumptions for the predictions of the models and which allow errors to be postulated in the observed values of the phenomena under investigation. The techniques are demonstrated using some data from the APSIS experiment.  相似文献   
385.
Background, Aim and Scope At present, large-scale paper manufacture involves delignification and bleaching by elemental chlorine free (ECF) or totally chlorine free (TCF) processes. The wastewater is purified by secondary treatment (mechanical, chemical and biological) which removes most of the toxic substances from the discharge. However, we found residual toxicity in the high molecular (> 1000 D) matter (HMWM) of the discharge by test of the RET (reverse electronic transfer) inhibition. This fraction consists mainly of polydisperse lignin (LIG) and carbohydrate (CH) macromolecules. Structural units in these molecules are studied by pyrolysis gas chromatography / mass spectrometry (Pyr-GC/MS). In the present work, our aim was to find out those structural units which could explain the RET toxicity of LIG or CH molecules. We compared statistically RET toxicity values of the HMWM samples from treated wastewaters of pilot pulping experiments and intensity variation of the pyrolysis product gas chromatograms of these samples. This application is a novel study procedure. Methods Pyrolysis products (Py-GC/MS results) and inhibition of RET (reverse electronic transport toxicity) as TU50 and TU20 of HMWM (High Molecular Weight Material; Mw > 1000 D) were compared by multivariate statistics. The samples were from laboratory pilot stages of TCF (Totally Chlorine Free) and ECF (Elemental Chlorine Free) manufacture of softwood pulp. Py-GC/MS was done without and with addition of TMAH (Tetra Methyl Ammonium Hydroxide). The name and structure of each abundant fragment compound was identified from its retention time and mass spectrum compared to authentic reference compounds or literature. Four sets of Toxicity Units (TUs) and GC peak areas of the pyrolysis fragments were obtained. The data were normalized by division with LIG (lignin content of each sample). TU values were dependent and the fragment values independent (explanatory) variables in statistical treatments by SPSS system. Separate analyses of correlations, principal components (PCA) and stepwise multiple linear regression (SMLR) were performed from the four sample sets TCF and ECF with and without TMAH. Results and Discussion From the CH fragments, 2-furfural in TCF, and from the LIG fragments, styrene in ECF showed the highest probabilities to originate from source structures of toxicity. Other possible compounds in concern were indicated to be CH fragment 2-methyl-2-cyclopenten-1-one in ECF and LIG fragments 2-methoxy-4-methylphenol, 4,5-dimethoxy-2-methylphenol and 2-methylphenol in TCF.  相似文献   
386.
Climate change is expected to have important impacts on aquatic ecosystems. On the Boreal Shield, mean annual air temperatures are expected to increase 2 to 4°C over the next 50 years. An important challenge is to predict how changes in climate and climate variability will impact natural systems so that sustainable management policies can be implemented. To predict responses to complex ecosystem changes associated with climate change, we used long-term biotic databases to evaluate how important elements of the biota in Boreal Shield lakes have responded to past fluctuations in climate. Our long-term records span a two decade period where there have been unusually cold years and unusually warm years. We used coherence analyses to test for regionally operating controls on climate, water temperature, pH, and plankton richness and abundance in three regions across Ontario: the Experimental Lakes Area, Sudbury, and Dorset. Inter-annual variation in air temperature was similar among regions, but there was a weak relationship among regions for precipitation. While air temperature was closely related to lake surface temperatures in each of the regions, there were weak relationships between lake surface temperature and richness or abundance of the plankton. However, inter-annual changes in lake chemistry (i.e., pH) were correlated with some biotic variables. In some lakes in Sudbury and Dorset, pH was dependent on extreme events. For example, El Nino related droughts resulted in acidification pulses in some lakes that influenced phytoplankton and zooplankton richness. These results suggest that there can be strong heterogeneity in lake ecosystem responses within and across regions.  相似文献   
387.
兖州矿区开采塌陷土地复垦与综合利用研究   总被引:2,自引:0,他引:2  
兖州煤田地处村庄稠密、土地肥沃的鲁西南平原,是高潜水位矿区,“三下”压煤严重,厚煤层综放高强度开采,采煤塌陷对地表的破坏影响极大。塌陷地在雨季水深面广,一片汪洋;冬春季水浅面积小,土地荒芜。随着开采强度的进一步提高,土地塌陷将越来越严重,农民将逐渐失去赖以生存的土地,土地复垦已势在必行。本文针对兖州矿区的具体地质采矿条件提出了塌陷土地复垦与综合利用对策。  相似文献   
388.
We report two second trimester pregnancy terminations in the same woman following intrauterine ultrasonic findings of hydrops fetalis, polyhydramnios, lack of fetal movements, and short, fixed malformed limbs. One fetus also showed a cystic mass at the back of the head. Radiographic and anatomic studies of the fetuses demonstrated multiple pterygia, flexion contracture of multiple joints, abnormal facial appearance, cleft palate, pulmonary hypoplasia, and gracile bones. The cystic mass of the back of the head was found to be a cystic hygroma. These findings are consistent with the lethal variant of multiple pterygium syndrome. Early prenatal diagnosis of this condition is possible using ultrasonography.  相似文献   
389.
陈淼  冉磊 《地球与环境》2007,35(4):375-379
污染物总量控制是目前我国广泛应用的一种控制区域环境质量达标的方法,为了实施城市大气污染物排放总量控制,实现各功能区污染物浓度达标,采用浓度控制与总量控制相结合的方法。本文提出利用遗传算法进行大气污染总量控制,并在传统遗传算法的基础上做了改进,提出基因库和基因重组的方法。  相似文献   
390.
李帅  张勃  马彬  候启  何航 《自然资源学报》2020,35(5):1216-1227
为了解气候变暖对农作物种植区域的影响,基于5日滑动平均、累积距平、MK检验、多元回归插值方法,选用格点数据对中国农业热量资源进行分析。结果表明:(1)≥5 ℃、≥10 ℃有效积温整体呈上升趋势,且≥5 ℃整体升幅更为显著,两者升幅均表现为南方地区最大,北方次之,青藏高原最小,秦巴山区积温呈现下降现象。(2)在空间分布上,≥5 ℃、≥10 ℃有效积温整体表现出自南向北随纬度更替变化的地带性分布和自东向西随海拔变化的阶梯状分布,东、中部地区受纬度影响明显,西部地区受海拔影响强于纬度。适宜喜凉作物种植的区域远大于喜温作物的适宜种植面积。(3)≥5 ℃、≥10 ℃有效积温均在1997年发生突变,突变后≥5 ℃、≥10 ℃各积温带界线呈现向北、向高海拔移动的趋势,积温整体升高。南方地区≥5 ℃、≥10 ℃积温增幅整体大于北方,青藏高原及高山山区增幅最小,秦岭地区积温增幅为负。(4)≥5 ℃、≥10 ℃有效积温初始日(结束日)整体呈提前(推迟)现象,且多数格点提前(推迟)日数在0~10 d以内,持续时间在突变后整体延长。青藏高原≥5 ℃、≥10 ℃积温初始日(结束日)提前(推迟)天数最大。  相似文献   
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