全文获取类型
收费全文 | 2147篇 |
免费 | 436篇 |
国内免费 | 459篇 |
专业分类
测绘学 | 78篇 |
大气科学 | 152篇 |
地球物理 | 618篇 |
地质学 | 1607篇 |
海洋学 | 182篇 |
天文学 | 16篇 |
综合类 | 157篇 |
自然地理 | 232篇 |
出版年
2024年 | 13篇 |
2023年 | 55篇 |
2022年 | 80篇 |
2021年 | 106篇 |
2020年 | 112篇 |
2019年 | 108篇 |
2018年 | 85篇 |
2017年 | 86篇 |
2016年 | 86篇 |
2015年 | 91篇 |
2014年 | 166篇 |
2013年 | 130篇 |
2012年 | 135篇 |
2011年 | 157篇 |
2010年 | 154篇 |
2009年 | 177篇 |
2008年 | 133篇 |
2007年 | 156篇 |
2006年 | 162篇 |
2005年 | 150篇 |
2004年 | 125篇 |
2003年 | 101篇 |
2002年 | 79篇 |
2001年 | 74篇 |
2000年 | 64篇 |
1999年 | 46篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 23篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 27篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有3042条查询结果,搜索用时 0 毫秒
61.
《Geoforum》2017
Geographical political economy increasingly scrutinises the socio-spatial contexts for brands and branding. Less understood is the influence of subcultures – neo-tribal groups sharing passions, a leisure pursuit or practice - on enterprise formation and the pathways through which brands emerge, trading on perceived authenticity. Subcultural contexts, we argue, unleash distinctive trajectories of enterprise formation, reputation-building, value-creation, global expansion and accumulation, and ultimately destruction. Here we focus on how particular subcultural values – of authenticity, competition, risk-taking, and active participation in ‘scenes’ – interact with capitalist growth dynamics, and where over time and space such intersections bring brands unstuck. Using the case of surfing subculture and collapse of corporate surf enterprises (Quiksilver, Billabong), we theorise subcultural brand value creation and its interaction with financialized expansion, culminating in destructive contradictions. Subcultural enterprises with ‘authentic’, ‘back-of-the van’ origins convert subcultural values of credibility, localism, risk-taking, and scene participation into brand value. Trading on place-origins and subcultural authenticity, enterprises expanded in two phases. First by widening distribution using specialist ‘surf’ retailers, and second by offshoring production, public floating, and debt-financing brand acquisitions and massive retail expansion. Dictates of shareholders and investment banks spurred market saturation, and high-volume/low-quality goods. Surfing’s cherished insouciance gave way to unhinged expansionism and unmanageable debt. The subcultural authenticity that spawned brand popularity was undermined, amplifying financial risk. Disenchanted consumers who once co-created successful brands also co-destroyed them. As subcultural brands proliferate, geographical political economy must be attentive to subcultures as spawning-grounds for enterprises with accompanying limits to market growth, (dis)connections, and values. 相似文献
62.
Faouziya Haissen Antonio Garcia-Casco Rafael Torres-Roldan Abdelmouhsine Aghzer 《Journal of African Earth Sciences》2004,39(3-5):375
High-pressure granulites are exposed in the Casares-Los Reales group (internal zones of Betic-Rif belt, S Spain–N Morocco) as part of the crustal envelope of Beni Bousera-Ronda Peridotites. They are mostly metapelitic but include intercalations of mafic composition. The metamorphic history is marked by the preservation of early high-pressure assemblages together with secondary low-pressure assemblages suggesting a state of textural and compositional disequilibrium. The P–T path constrained by geothermobarometry and reaction textures from mafic and pelitic lithotypes passes from 800 °C/15 kbar to 600 °C/5 kbar, to indicating a strong decompression related to cooling, followed by a near-isobaric cooling 430 °C and 4 kbar. Such P–T evolution of granulites is thought to reflect some sort of rapid tectonic collapse of crust previously thickened through collision. 相似文献
63.
近年来,随着现浇结构使用越来越广泛,但建设物现浇板板角出现裂缝的现象越来越多,笔者就板角裂缝的形成原因,进行了简要分析,并提出了其预防措施. 相似文献
64.
分析滑坡区隧道的主要病害特征和滑坡与隧道病害的相互关系。对隧道区的滑坡防治进行系统的分析与研究,针对性地提出了安全、经济的防治方案,为今后隧道区的滑坡防治方案提供参考。 相似文献
65.
根据野外调查、区域地质、环境地质、水文工程地质等资料,对某中学建设项目地质灾害危险性进行现状评估、预测评估和综合性评估,并对评估区进行分区。对扩建场地适宜性进行评价,提出地质灾害防治措施,为该工程建设用地规划和开展地质灾害防治工作提供依据。 相似文献
66.
67.
黄土节理控制着黄土区地下水或者地表水的运输通道,黄土节理的发育致使黄土节理扩张为局部大的拉张裂隙,在拉张力作用下使得黄土高原地区塌滑灾害频繁发生。通过野外调查和分析,提出了黄土开挖边坡塌滑破坏可分为4个阶段:坡脚侵蚀剥落阶段、坡顶拉裂阶段、垂直裂隙扩展阶段、边坡整体塌滑破坏阶段。结合工程实例,通过概化的三维数值分析模型,使用岩土工程软件FLAC3D模拟分析了在3种降雨量条件(40 mm/d、80 mm/d、100 mm/d)下,降雨2 d后概化模型的塌滑破坏情况,这可为工程地质条件相同地区的黄土开挖边坡塌滑变形破坏的分析以及防治提供一种有效分析范例。 相似文献
68.
以地质灾害实地调查成果为依据,总结了泉州市潜在地质安全隐患点的分布特征,在分析成因和风险基础上,立足地质灾害防治实践,重点针对农村房前屋后高陡边坡,探讨了具体防治对策。泉州地处福建省东南沿海,属亚热带海洋性季风气候,境内大部分地区属中低山丘陵区,地貌类型复杂多样,地处构造一岩浆发育区,区域地质环境比较脆弱,加上人类工程活动强烈,地质灾害发生较为频繁[1]。近年来,随着泉州市城乡经济以较快的速度发展,国土资源开发的强度不断加大,大量的不合理的工程建设活动进一步加剧,形成了数量众多的潜在地质安全隐患点,其中以农村房前屋后高陡边坡为主。 相似文献
69.
Risk Assessment,Emergency Preparedness and Response to Hazards: The Case of the 1997 Red River Valley Flood,Canada 总被引:1,自引:0,他引:1
The prevention and/or mitigation offlood disasters requires continual research, numerouscapital investment decisions, and high-qualitymaintenance and modifications of flood-controlstructures. In addition, institutional and privatepreparedness is needed. The experience offlood-control in North America has shown mixedoutcomes: while flood frequency has declined duringthe last few decades, the economic losses havecontinued to rise. Recent catastrophic floods havealso been linked to major structural interventions inthe region. The flood diversions may cause harmfuleffects upon the floodplain inhabitants by influencingflood levels in areas which are not normallyflood-prone. The increasing vulnerability of thefloodplain inhabitants poses new challenges and raisesquestions concerning the existing risk assessmentmethods, institutional preparedness and responses todisaster-related public emergencies, and local-levelpublic involvement in flood mitigation efforts.In the context of the catastrophic 1997 floods of theRed River Valley, Manitoba, Canada, this researchfocuses on two aspects of flood-related emergencygovernance and management: (i) the functions andeffectiveness of control structures, and (ii) theroles, responsibilities and effectiveness oflegislative and other operational measures. The studyconcludes that the flood-loss mitigation measures,both in terms of effects of control structures andinstitutional interventions for emergency evacuation,were not fully effective for ensuring the well-beingand satisfaction of floodplain inhabitants. Althoughorganizational preparedness and mobilization to copewith the 1997 flood emergency was considerable, theirsuccess during the onset of the flood event waslimited. Lack of communication and understandingbetween institutions, a reluctance to implementup-to-date regulations, and minimal publicparticipation in the emergency decision-making processall contributed to the difficulties experienced byfloodplain inhabitants. 相似文献
70.
从城市地学资料入手, 详细研究了西安市的地质环境主题, 采用了相应的模型, 对土地工程能力进行了综合评价, 为制定城市土地利用工程控制措施提供了科学依据. 相似文献