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排序方式: 共有57条查询结果,搜索用时 31 毫秒
1.
上海市的发展战略;空间布局模式和环境管理是文章讨论的三个主要问题。作者认为:(1)战略设想要立足于上海的发展,“开发浦东、振兴上海、服务全国、面向世界;”(2)新的空间布局模式应为“逐步形成新的CBD,强化和完善金融和服务功能”;(3)城市发展和环境建设要协调。文章着重讨论了上海城市发展中出现的环境问题及其治理的对策和措施。 相似文献
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濮阳市是新兴的石油化工基地,国家级卫生城市和园林城市,由于人口的增长、工农业的迅猛发展,地下水超量开采而引起的地面沉降、地裂缝等一系列环境地质问题,针对所出现的环境地质问题提出相应的防治措施. 相似文献
3.
豫北平原浅层地下水资源可持续开发利用 总被引:1,自引:0,他引:1
豫北平原隶属黄河、海河两大流域,在平原区松散岩类中蕴藏着较丰富的地下水.随着工农业和城市化的发展,地下水资源的开发利用程度在逐步升高,合理地开发利用地下水资源的重要性日趋显著.主要论述了浅层含水岩组的特征、水动力条件、开发利用现状及与地下水开采相关的环境地质问题.分析了天然资源量的组成,说明了可采资源量的计算方法,指出有开采潜力区和超采区的分布.针对所存在的问题,提出了浅层地下水资源可持续开发利用的措施. 相似文献
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Laplace方程Cauchy问题的一种数值解法 总被引:2,自引:1,他引:2
研究了Laplace方程Cauchy问题的数值求解,该问题是一个典型的病态问题。利用格林(Green)公式将Laplace方程的Cauchy问题转化为Hausdorff矩问题。本文利用一种新方法,即矩问题的积分方程方法,求解矩问题,设计了二维Laplace方程Cauchy问题稳定的算法,给出了近似解的误差估计,并对二维Cauchy问题进行了数值模拟。 相似文献
6.
H. Hellmann 《洁净——土壤、空气、水》1996,24(5):218-225
IR Spectroscopy and Further Analyses of New Fabric Rinse Agents Distearyldimethylammoniumchloride (DSDMAC) that dominated the fabric softener market in Germany in the past is now substituted by three new types of ester-based agents, i.e. imidazoline ester, ester quats, and diester quats what poses new challenges to surface water analytics. The IR spectra and the chromatographic behaviour of these three agents are more or less similar to those of naturally occuring fatty esters. The paper reports about the use of IR spectroscopy, its benefit in the sense of fingerprinting principle, the identification of substances by functional groups, and the analytical tracing of transformation products. The latter relates to the formation of salts with anions that are easily detectable, the clean up, and the final spectroscopic determination. While in 1994 DSDMAC was still determinable in concentrations of 10…20 mg/kg in suspended solids from the Middle Rhine River, the concentration of the substitutes was below the detection limit of 2 mg/kg and 1…2 μg/L in 1995. 相似文献
7.
环境蠕变对农业病虫草鼠害的潜在影响 总被引:2,自引:2,他引:0
重点讨论了在全球气候变暖的大背景下,农业病虫草鼠害加重和新的病虫草鼠出现也作为一种蠕变现象正在遭受气候变化的影响和冲击。其主要表现在农业有害生物(病、虫、草、鼠)地理分布范围扩大、越冬界限北移、农田害虫害鼠发育时间缩短、繁殖代数增加、种群增长率加快、发生提早、危害加重、病毒病增加、新病虫草鼠出现等等。 相似文献
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The conception of pollen source area has attracted broadly attention since it was proposed in the 1960s. In this paper,it can be subdivided into Normal Source Area of Pollen (NSAP) and Relevant Source Area of Pollen (RSAP) based on reviewing former studies and our recent work of vegetation survey and pollen analysis in the Northern China. The NSAP means a source area of pollen input a sedimentary basin,indicating a distance area beyond where the pollen contents of major pollen types do not show evident increase with increased distance. The RSAP means a source area of pollen assemblages in a basin has the closest relationship with surrounding plants,indicating a distance area beyond where the relationship between pollen assemblage and surrounding vegetation do not show obvious increase with increased distance. The changes of sedimentary basins radii and pollen grain size influence the NSAP and RSAP evidently. Wind speed also changes the NSAP, but does not significantly affect RSAP. The pollen of a sedimentary basin is composed of local pollen,regional pollen and extra regional pollen,which usually account for 30%~45%,25%~60% and 10%~30%,respectively. Local pollen which refers to the pollen coming within the RSAP range,is a reflection of the surrounding vegetation,and has important implications to the reconstruction and succession of local vegetation. Regional pollen which refers to the pollen coming from within the range of NSAP and excluding the range of local pollen,is the important carrier of studies for vegetation restoration and climate change. The pollen that comes outside the range of NSAP is called Extra regional pollen,which is mainly from greater distance by upper air flow,and has no indicator significance to the regional vegetation. 相似文献
10.
Michael F. Jischa 《洁净——土壤、空气、水》2008,36(3):255-263
Central elements of the challenges of the future are the population, supply and disposal trap, the question of how the increasing world population will be supplied with long‐lasting and effective sources of energy, raw materials and food? How do we deal with the problems of greenhouse effect, ozone hole, forest dieback, ground erosion, desertification and other environmental threats? Driven by the dynamics of the technical progress the world is in the midst of experiencing the transition from an industrial to an information society. The process of globalization is intrinsically tied to the information society and plays a vital role in the path to a new, digital development of the world. Therefore, new challenges have been added to the traditional ecological challenges at the beginning of the 21st century, which the world community must react swiftly to. 相似文献