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   3166篇
  免费   147篇
  国内免费   277篇
测绘学   206篇
大气科学   37篇
地球物理   472篇
地质学   594篇
海洋学   188篇
天文学   3篇
综合类   93篇
自然地理   1997篇
  2024年   1篇
  2023年   29篇
  2022年   125篇
  2021年   110篇
  2020年   136篇
  2019年   138篇
  2018年   137篇
  2017年   158篇
  2016年   135篇
  2015年   115篇
  2014年   151篇
  2013年   285篇
  2012年   245篇
  2011年   144篇
  2010年   112篇
  2009年   132篇
  2008年   132篇
  2007年   159篇
  2006年   145篇
  2005年   140篇
  2004年   122篇
  2003年   95篇
  2002年   86篇
  2001年   53篇
  2000年   75篇
  1999年   66篇
  1998年   55篇
  1997年   38篇
  1996年   38篇
  1995年   32篇
  1994年   33篇
  1993年   23篇
  1992年   27篇
  1991年   16篇
  1990年   9篇
  1989年   12篇
  1988年   19篇
  1987年   11篇
  1986年   17篇
  1985年   11篇
  1984年   8篇
  1983年   11篇
  1982年   3篇
  1981年   1篇
排序方式: 共有3590条查询结果,搜索用时 15 毫秒
91.
This paper is based on 6 months of ethnographic, multi-sited research in Malaysia, and investigates the relatively recent phenomenon of edible birds’ nest farming in urban areas (‘swiftlet farming’). Swiftlet farms are typically converted shophouses or other buildings which have been modified for the purpose of harvesting the nests of the Edible-nest Swiftlet (Aerodramus fuciphagus). I use the controversy over urban swiftlet farming in the Malaysian city of George Town, Penang, to examine discourses used by key stakeholders to shape debates over the place of non-human animals in cities. By considering everyday experiences of urban swiftlet farming, I explore how this burgeoning industry is perceived amongst residents, and how it is deemed to be (in)appropriate within the political, economic and cultural landscape of George Town. Yet, I also consider how farmers have sought to contest these discourses on ideological and normative grounds. In so doing, I place the cultural animal geographies literature in conversation with emergent literature on landscape and urban political ecology. Such a framing allows for a critical evaluation of the controversies surrounding this case, and their implications for human-animal cohabitation in cities. The paper reflects on the implications of this case for how we regulate human-animal relations and live in contemporary cities, and the crucial role of animals in altering urban form, aesthetics and everyday life, particularly in non-Western contexts.  相似文献   
92.
With the application of innovative anchor concepts and advanced technologies in deepwater moorings, anchor behaviors in the seabed are becoming more complicated and pose a great challenge to the analytical methods. In the present work, a large deformation finite element (FE) analysis employing the coupled Eulerian–Lagrangian technique is performed to simulate the installation/mooring line, and then is applied to analyzing comprehensive anchor behaviors in the seabed. By connecting cylindrical units with each other using connector elements, the installation/mooring line is constructed. With the constructed installation/mooring line, FE simulations are carried out to investigate comprehensive anchor behaviors in the seabed, including long-distance penetration of drag anchors, keying of suction embedded plate anchors and non-catastrophic behavior of gravity-installed anchors. Through comparative studies, the accuracy of the proposed method is well examined. A parametric study is also undertaken to quantify the effects of the frictional coefficient, initial embedment depth, and soil weight on the profile of the embedded anchor line and the shackle load. The present work demonstrates that the proposed FE model, which incorporates the installation/mooring line and the anchor, is effective in analyzing the comprehensive anchor behaviors in the seabed.  相似文献   
93.
Foraging behavior and diet of breeding seabirds may be analysed simultaneously with the combined use of remote sensing devices and stable isotope analysis. Imperial shag, Phalacrocorax atriceps, breeding at Punta León colony, Argentina, were equipped with global positioning system (GPS) loggers to record foraging trips and blood samples were taken after removal of the devices in order to analyse their nitrogen and carbon stable isotope composition in whole blood and plasma. Whole blood was correlated to plasma isotopic composition for each individual (n = 35), linking diet in the short and medium term. Sexes did not differ in isotopic signatures. The maximum distance reached and the total number of dives that individuals made on two consecutive foraging trips were correlated to their plasma nitrogen isotopic signature. Individuals that went further from the colony and dived fewer times presented more positive signatures, indicative of benthic prey consumption (e.g. Raneya brasiliensis). Diet was predominantly benthic with some individuals incorporating pelagic prey (Engraulis anchoita) and even cephalopods (Octopus tehuelchus). Within breeding pairs (n = 9), different combinations of foraging and prey preferences were observed. Estimated trophic levels of these individuals were similar to those of the same species in other colonies further south along the Patagonian coast.  相似文献   
94.
Strata behaviors are mainly affected by regional geodynamic background. The influence of rock mass stress and energy distribution on strata behaviors in the Tongxin mine is studied in terms of regional tectonic movement, seismic activity and tectonic stress field. The results show that the extrusion lifting movement of Kouquan fault adjacent to the Tongxin mine results in the stress concentration in the rock of the Carboniferous coal bed and accumulation of a large amount of elastic energy and forms structural background of Tongxin mine. Due to various seismic activities in the mine area, the strain energy is known to reach much higher levels, up to 0.5×108 J1/2. Since the stratigraphic structure is sensitive to the mining operation, the strain energy could cause strong strata behaviors. A special geological structure model of the Tongxin mine is established based on the geodynamic division method. The distribution of regional structure stress field is determined by the rock mass stress analysis system. Based on this model, Tongxin mine is divided into five areas with high stress, eight areas with low stress and eight areas with gradient stress. The strong strata behaviors mostly occur in high stress areas. These results could provide guidance to predict the strength of regional or mine pressure and control strata behavior in different areas.  相似文献   
95.
Recent years have witnessed a large increase in the amount of information available from the Web and many other sources. Such an information deluge presents a challenge for individuals who have to identify useful information items to complete particular tasks in hand. Information value theory (IVT) from economics and artificial intelligence has provided some guidance on this issue. However, existing IVT studies often focus on monetary values, while ignoring the spatiotemporal properties which can play important roles in everyday tasks. In this paper, we propose a theoretical framework for task-oriented information value measurement. This framework integrates IVT with the space-time prism from time geography and measures the value of information based on its impact on an individual’s space-time prisms and its capability of improving task planning. We develop and formalize this framework by extending the utility function from space-time accessibility studies and elaborate it using a simplified example from time geography. We conduct a simulation on a real-world transportation network using the proposed framework. Our research could be applied to improving information display on small-screen mobile devices (e.g., smartwatches) by assigning priorities to different information items.  相似文献   
96.
Charging undergraduate geography students with the task of designing a recreational trail in their local community offers an engaging experiential opportunity with potential to advance geographic learning in a real-world setting. This article presents an assignment in which students were asked to develop a recreational trail proposal for an undeveloped local conservation area and the results of a survey that asked the students to reflect and report upon the educational value of this experience one year later. Results of the survey validated the assignment's lasting value to the students across the cognitive, psychomotor, and affective learning domains.  相似文献   
97.
To date, only limited research has focused on the individual in rural geography compared to the importance given to the rural community. With the sociocultural turn and moral positions in rural geography, however, the individual is acquiring more relevance but encapsulated in analytical traditions of locality community and of marginal situations and people. This article synthesizes the most significant works about the individual, especially within rural geography, and its key dimensions are identified: citizenship (political and normative dimension), emotional aspects (the extraordinary moments in peoples' lives), everyday life (the relationship between the individual and the rural place), and difference and otherness (between and within others). To develop an individual rural geography, these four dimensions, which reflect different aspects of the rural individual, must be used in a complementary manner. The relevance of each dimension suggests different types of individualities in rural areas. Ultimately, this article proposes a “new humanism” in contrast with antihumanistic poststructural approaches.  相似文献   
98.
Although there have been noticeable improvements in recent years, geography continues to be a predominantly male discipline. The percentage of women receiving PhDs in geography has tracked lower than the U.S. average of female PhDs. Previous studies of women's contribution to geography have focused on personal accounts or on the study of some of the most prominent practitioners, with a few studies using basic data on PhDs awarded and Association of American Geographers membership to determine trends. This article provides a comprehensive overview of doctoral degrees in geography by gender, over time, and across all universities in the United States by examining an alternative database, that of doctoral dissertations. The analysis yields three separate types of results. First, historical and contemporary variations among U.S. universities are examined. Second, data indicate that male and female doctoral students differ in the sex of their advisor. Third, a simple regression model explains some of the discrepancies in the proportion of female doctoral students by department. In sum, this article provides a comprehensive empirical study of the factors that might contribute to the continued disparities in female doctoral students in geography.  相似文献   
99.
通过对国际上的政治地理学旗舰性杂志《Political Geography》2005-2015年期间391篇成果的分析,总结出国际政治地理学研究的主要研究议题为:边境与边界,环境政治,空间与尺度,领土和主权以及安全问题,选举地理,社会和文化政治,其中空间与尺度,领土和主权以及安全问题,社会和文化政治几个方向研究成果占较大比例,而其他三个方向则相对较少.通过研究方法分析发现,国际政治地理学主要采用定性分析的方法,尤其是民族志和文本分析的方法,定量分析的使用存在一定的局限性.最后,从该杂志的研究对象和研究机构两个方面的分析归纳出:欧美主导的发达国家(尤其是英国和美国)对世界政治地理学话题的学术霸权与世界南,北差异发展具有一定的相关性.在中国综合国力日渐增强,参与国际事务能力不断提高以及作为新兴的地缘政治力量崛起的社会历史背景下,政治地理学经世致用之能亟待被展现.因此,中国政治地理学发展作为发展中国家的声音势必将越来越洪亮.  相似文献   
100.
褚亚平先生是中国著名的地理教育学家和地名学家.他长期从事地理教育研究与实践,完善了中学地理教学法学科体系,创造性的提出地理教材"三系统"理论,提出以学生为本,促进学生全面发展与深入教学研究,培养高质量师资队伍并行的地理教育理论,他对地理教育的研究成果推动了中国地理教育学的发展.他重视地名研究与管理人才培养,撰写专著力图构建地名学的基础理论,并对新时期地名管理,地名规划,地名商品化等问题提出自己的看法.  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