全文获取类型
收费全文 | 253篇 |
免费 | 12篇 |
国内免费 | 17篇 |
专业分类
测绘学 | 25篇 |
大气科学 | 17篇 |
地球物理 | 25篇 |
地质学 | 136篇 |
海洋学 | 14篇 |
综合类 | 16篇 |
自然地理 | 49篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 11篇 |
2013年 | 15篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 14篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有282条查询结果,搜索用时 15 毫秒
101.
芜湖市土地利用综合效益评价 总被引:3,自引:0,他引:3
通过建立芜湖市土地利用综合效益评价指标体系,利用相关分析法确定指标间的相关系数进而确定各评价指标权重,构建芜湖市土地利用效益综合评价模型及预测模型,最后运用数理统计方法对结果进行分析。分析:1990~2005年芜湖市土地利用综合效益水平总体处于上升趋势,土地利用综合效益指数达到94.3。结果表明:芜湖市土地利用正沿着一条以生态建设为中心,生态、社会、经济建设为一体的可持续的道路发展,并且成果显著。预测:2010年芜湖市土地利用综合效益指数达到99.6,但是增加幅度较往年减少。建议:由于芜湖市土地利用经济效益波动较大,政府要协调好经济建设与生态建设、社会建设的关系。 相似文献
102.
根据环境意识结构,设计了旅游企业环境意识调查问卷,其主要的指标体系包括:旅游环境知识水平、旅游环境态度、旅游环境评价和旅游环境行为四个方面。对指标体系各部分之间以及每一指标部分的每一题目之间的相对重要性进行权重的确定,而且对各部分的每道题目的各个选项予以赋分数。基于权重和赋分,结合调查问卷的实际情况,设计了指标体系各部分评价模型和环境意识总体评价模型,以此来计算草原旅游发展中旅游企业环境意识水平的综合得分。经过分析得出,旅游企业环境意识模式是“环境行为制约型”模式,从总体来看,环境知识不是制约旅游旅游企业环境意识水平的关键问题,环境评价和环境态度也不是主导因素,而旅游企业的环境行为是至为重要的因素。 相似文献
103.
104.
A personal computer-based geographic information system (GIS) is used to develop a geographic expert system (GES) for mapping and evaluating volcanogenic massive sulfide (VMS) deposit potential. The GES consists of an inference network to represent expert knowledge, and a GIS to handle the spatial analysis and mapping. Evidence from input maps is propagated through the inference network, combining information by means of fuzzy logic and Bayesian updating to yield new maps showing evaluation of hypotheses. Maps of evidence and hypotheses are defined on a probability scale between 0 and 1. Evaluation of the final hypothesis results in a mineral potential map, and the various intermediate hypotheses can also be shown in map form.The inference net, with associated parameters for weighting evidence, is based on a VMS deposit model for the Chisel Lake deposit, a producing mine in the Early Protoerzoic Snow Lake greenstone belt of northwest Manitoba. The model is applied to a small area mapped at a scale of 1:15,840. The geological map, showing lithological and alteration units, provides the basic input to the model. Spatial proximity to contacts of various kinds are particularly important. Three types of evidence are considered: stratigraphic, heat source, and alteration. The final product is a map showing the relative favorability for VMS deposits. The model is implemented as aFortran program, interfaced with the GIS. The sensitivity of the model to changes in the parameters is evaluated by comparing predicted areas of elevated potential with the spatial distribution of known VMS occurrences. 相似文献
105.
以农牧交错区的阿鲁科尔沁旗为例,选取7个典型村,运用参与式农村评估(PRA)、GIS与遥感技术相结合的方法,探讨农牧交错区农村居民点土地利用形态特征及其与农牧户生计的关系。结果表明:①半农半牧型农村居民点由纯牧型农村居民点演变而来。人口增加导致人地矛盾突出和草原开垦耕种,农牧户生计策略转为畜牧业和种植业结合,农村居民点向半农半牧型转变;②半农半牧型农村居民点内部用地类型逐渐多样化。从改革开放前居民点内部以农村宅基地占主导,到改革开放后居民点内部公共设施用地、商服用地、工矿仓储用地迅速扩大;③由于农牧户生计活动的多样化和非农化,农村宅基地内部不但包括居住用地(住房),还包括生产性用地和生产辅助性用地(如牲畜的棚圈、菜园和粮草仓库等)。研究认为,半农半牧型农村居民点人均居民点用地和户均宅基地都远大于国家规定的用地标准,是与半农半牧的生产方式和生计需求紧密相关的。 相似文献
106.
《Urban geography》2013,34(8):1212-1248
For some two millennia Istanbul has been one of the world's greatest cities, and is today classified as an "Alpha-" world city in the Globalization and World Cities (GaWC) group's 2010 rankings. Istanbul is an emerging global city that is facilitating Turkey's transnational integration into the global economy, and as of June 2009 the city had the second largest office stock among all Southeast European countries. This paper investigates the determinants of office rent levels in the city's Central Business District (CBD) and the spatial variation of rents in a polycentric metropolis. The paper uses a stepwise regression and a Mamdani-type fuzzy rule-based model to estimate office space rents, and compares empirical results with those of a conventional OLS regression analysis. Rents are driven not only by physical characteristics and locational services, but also the terms of lease contracts. New CBD locations that command the highest rents on spacious, high-rise office spaces with comparatively few employees conform well with contemporary accounts of world-city financial districts, and confirm the significance of urban office infrastructures for globally oriented financial elites beyond the familiar roster of Global North world cities. The traditional center retains the core purpose identified nearly a century ago, in Marshall's analysis of centralization during the most vibrant period of the industrial age. Despite all the transformations of transnational urbanist polycentricity, the traditional CBD is still the place with the most diverse mix of activities, and the greatest variation in rents. 相似文献
107.
新疆县域产业结构转换能力综合评价 总被引:12,自引:1,他引:12
产业结构的演进和转换是经济发展的本质特征,也是促进经济持续稳定协调发展的关键。文章从影响区域产业结构转换的技术创新能力、需求能力、供给能力、对外贸易发展、经济政策等因素出发,从5个方面构建了由13个指标组成的区域产业结构转换能力评价指标体系,并在此基础上采用主成分分析、层次分析和均方差3种方法的组合评价法对新疆县域产业结构转换能力进行研究,并提出相应建议。 相似文献
108.
Quantitative assessment of mineral resources with an application to petroleum geology 总被引:2,自引:0,他引:2
The probability of occurrence of natural resources, such as petroleum deposits, can be assessed by a combination of multivariate statistical and geostatistical techniques. The area of study is partitioned into regions that are as homogeneous as possible internally while simultaneously as distinct as possible. Fisher's discriminant criterion is used to select geological variables that best distinguish productive from nonproductive localities, based on a sample of previously drilled exploratory wells. On the basis of these geological variables, each wildcat well is assigned to the production class (dry or producer in the two-class case) for which the Mahalanobis' distance from the observation to the class centroid is a minimum. Universal kriging is used to interpolate values of the Mahalanobis' distances to all locations not yet drilled. The probability that an undrilled locality belongs to the productive class can be found, using the kriging estimation variances to assess the probability of misclassification. Finally, Bayes' relationship can be used to determine the probability that an undrilled location will be a discovery, regardless of the production class in which it is placed. The method is illustrated with a study of oil prospects in the Lansing/Kansas City interval of western Kansas, using geological variables derived from well logs. 相似文献
109.
文章利用地形地貌资料4502个数据,肝癌死亡调查资料8343例,研究了肝癌死亡率与人群生存的地形地貌类型的相关性。在此基础上综合评价了与肝癌有相关性的地形地貌类型对肝癌产生和发展的影响 相似文献
110.
Guo Ruiqing 《地球科学与环境学报》1997,(1)
矿床在空间的分布是不均匀的,它受到区域地质构造的控制,又受到大量随机因素的影响,具有一定的统计规律.研究这种统计规律,就可以进行预测。本文尝试用“单元矿床值概率分布法”预测铁矿资源。 相似文献