首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   343篇
  免费   21篇
  国内免费   23篇
测绘学   32篇
大气科学   12篇
地球物理   22篇
地质学   65篇
海洋学   9篇
天文学   2篇
综合类   22篇
自然地理   223篇
  2023年   2篇
  2022年   9篇
  2021年   12篇
  2020年   6篇
  2019年   8篇
  2018年   8篇
  2017年   12篇
  2016年   11篇
  2015年   7篇
  2014年   14篇
  2013年   44篇
  2012年   18篇
  2011年   23篇
  2010年   8篇
  2009年   17篇
  2008年   13篇
  2007年   15篇
  2006年   16篇
  2005年   16篇
  2004年   17篇
  2003年   10篇
  2002年   13篇
  2001年   13篇
  2000年   16篇
  1999年   8篇
  1998年   7篇
  1997年   10篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
排序方式: 共有387条查询结果,搜索用时 15 毫秒
61.
兴文世界地质公园的旅游循环经济模式探讨   总被引:1,自引:0,他引:1  
随着旅游经济的飞速发展,旅游环境问题日趋严重。本文将循环经济的新理念引入到兴文世界地质公园的旅游中,可构建旅游循环经济的新型发展模式。在兴文旅游循环经济中形成三大循环:旅游小循环——四大景区内部的旅游资源的循环利用;旅游中循环——旅游业与其他产业部门之间的循环,组织生态产业链联结不同的产业部门,形成共享资源和互换副产品的产业组合;旅游大循环——整个社会的循环,大力发展绿色消费市场和资源回收产业,完成"旅游资源——旅游产品——旅游再生资源"的闭合环路。这三种旅游循环模式的整合使整个兴文县经济、社会及环境相互协调,从而实现旅游资源的循环利用和旅游环境的可持续发展。  相似文献   
62.
There are various Permian fossil heritages in Xingwen World Geopark.However,during constructing Geopark in recent years,the fossil heritages have suffered more serious damages,and thus the protection models of the fossil heritage are worth studying.This paper describes the fossil heritages’ types,abundance and preservation of the current status quo in the geopark.It turns out that natural factors and human factors are the main reasons why lead to the destruction of fossil heritages.At last,it puts forward the corresponding measures in order to protect the integrity of fossil heritages in the world geopark.  相似文献   
63.
雪龙船南北极考察走航图的制作   总被引:6,自引:0,他引:6  
“雪龙船南北极考察走航图”是采用新编《系列世界地图》制作的成果。极地考察是一项全球性的重要的科学活动,雪龙船是我国目前唯一的极地科学考察破冰船,表现雪龙船极地科学考察航行路线的走航图,将成为我国南北极考察活动与社会公众沟通的新形式和重要媒介之一。  相似文献   
64.
65.

Global distributions are commonly described by maps and tables which emphasize the dispersion of a distribution. The Mean Spheroidal Center (M.S.C.) defines the average location of a world distribution. It is an objectively determined point within the sphere's surface. The M.S.C. calculations are demonstrated using the world's 25 largest cities in each of four time periods.  相似文献   
66.
A city can be topologically represented as a connectivity graph, consisting of nodes representing individual spaces and links if the corresponding spaces are intersected. It turns out in the space syntax literature that some defined topological metrics can capture human movement rates in individual spaces. In other words, the topological metrics are significantly correlated to human movement rates, and individual spaces can be ranked by the metrics for predicting human movement. However, this correlation has never been well justified. In this paper, we study the same issue by applying the weighted PageRank algorithm to the connectivity graph or space–space topology for ranking the individual spaces, and find surprisingly that: (1) the PageRank scores are better correlated to human movement rates than the space syntax metrics, and (2) the underlying space–space topology demonstrates small world and scale free properties. The findings provide a novel justification as to why space syntax, or topological analysis in general, can be used to predict human movement. We further conjecture that this kind of analysis is no more than predicting a drunkard's walking on a small world and scale free network.  相似文献   
67.
Abstract

Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable.  相似文献   
68.
《Urban geography》2013,34(3):209-228
Legal cases are increasingly used in the social sciences as the raw material for social analysis. While this is entirely laudable as a research strategy, the analytical methods used in the social sciences to study cases are too often simplistic and reductionist. Positivism is too often the preferred analytical mode. I argue that the legal texture of cases ought to be retained by social scientists, just as we ought to be more aware of the problematic nature of interpretation, an issue embedded within legal discourse. In contrast to those who contend that the interpretive turn in the social sciences is nihilistic and subjective, I suggest reasons for understanding the interpretive turn as an organized social practice dependent upon social standards of right and wrong. These issues are illustrated by reference to a recent court case involving a corporation that secretly and illegally relocated production so as to avoid its pension obligations.  相似文献   
69.
贵州凤冈县田坝村茶园土壤硒的含量及评价   总被引:2,自引:0,他引:2  
运用氢化物原子荧光光谱法,较系统测定了研究区三大茶园土壤硒的含量。分析结果表明,土壤中硒的平均含量值为1.22 mg/kg,平均值均高于全国土壤硒含量(0.29 mg/kg)及贵州省土壤硒含量(0.369 mg/kg)的水平。据我国硒元素生态景观界限值的划分等级标准,研究区属于富硒的土壤环境,对当地今后种植富硒茶、调整农业种植结构、有效利用特种土地、生态环境学研究,可提供地球化学方面的基础资料和参考依据,具有重要的现实意义。  相似文献   
70.
武振国  李雪敏 《地下水》2011,(1):97-98,181
屋顶花园是屋顶文化的延续和发展,是屋顶景观的再创造.它的营建可以为城市创造良好景观与环境,减少碳排放量、高效利用雨水、节约地下水,直接提高城市居民生活空间的舒适化和居住环境质量,而且合理的屋顶花园布局必然产生巨大的社会效益、经济效益和生态效益.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号