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91.
顾颉刚先生是我国近现代著名的历史学家,“古史辨”派的创始人。其一生著述丰硕,涉及古史考辨、民俗学研究、历史地理学研究等学科领域。不仅提出了著名“层累地造成的中国古史”的理论,并在档案史料的搜集、考证、辨伪及应用等方面也提出了许多独到的见解,至今仍是史学工作者及档案工作者的宝贵财富。  相似文献   
92.
李粉玲 《价值工程》2015,(20):29-31
地铁项目工程在施工过程易受地形地貌以及水文等自然条件的制约,因此会经常出现工程变更的情况,会直接影响工程造价的变迁。基于这种情况,结合地铁三号线的相关做法和经验,分析地铁项目工程变更管理中存在的问题与相应的完善措施。希望对地铁项目工程的变更管理起到一些借鉴。  相似文献   
93.
山东省苹果种植面积的时空演变特征分析   总被引:2,自引:0,他引:2  
[目的]利用1978~2015年山东省苹果种植相关数据,实证分析山东省苹果种植面积的时空演变规律及其内在影响因素。[方法]从省域、区域、地市层面分析山东省苹果种植面积的时空演变规律,并运用多元线性回归模型实证分析山东省苹果种植面积变动的具体影响因素。[结果]山东省苹果种植面积从1978年的18.330万hm~2增至2015年的29.968万hm~2,总体增加,并以1995年为拐点先增后减,呈"倒U"形分布。从区域层面看,胶东半岛苹果种植面积稳步增加,泰沂山区、鲁西鲁北平原苹果种植面积持续萎缩,直接导致山东省苹果种植面积的不断减少和苹果主产区向胶东半岛的迁移。从地市层面看,山东省17地市中仅有胶东半岛的烟台、威海两地市苹果种植面积有所增加,其余15地市苹果种植面积均有不同程度的减少。说明山东省苹果主产区呈东进西退、北进南退的变迁特征。[结论]山东省苹果种植面积变动是资源禀赋、种植成本、种植业内部比较效益、种植传统和种植惯性、非农就业机会、非农就业收入、国家政策、地区政策、技术进步等众多因素共同作用的结果。基础设施条件、种植传统和种植惯性、非农就业机会、非农就业收入、地区政策的影响更为显著。其中,种植传统与种植惯性、地区政策对山东省苹果种植面积产生显著正向影响;非农就业机会和非农就业收入产生显著负向影响;基础设施条件向耕地的倾斜也产生显著不利影响。而种植成本、种植比较效益、国家政策、技术进步等因素的影响并不显著。  相似文献   
94.
Australia's carbon tax has been in place since July 2012. Following the 2013 federal election and change of government, it is likely that the tax will be abolished. This paper evaluates Australia's carbon tax experience and draws lessons for policymakers in other jurisdictions who may be considering following the Australian example and implementing their own carbon taxes or cap and trade schemes. Overall, the policy was poorly thought through, badly implemented, and lacked majority public support before it began. Australia's carbon tax experience is an interesting case study in how not to go about implementing climate change policy.  相似文献   
95.
解放后至改革开放的30年间,中国经济与工业建设蓬勃发展,诞生了众多优秀的民族品牌。本文结合具体时代背景、意识形态和大量经典案例.从品牌特征、现实作用以及图形美学三方面对该时期的国货品牌进行深入剖析,阐述了该时期国货品牌传统文化与现代特色相融合的独特魅力。  相似文献   
96.
[目的]探究塔城地区气候的时空变化趋势及其与气象因子的关系.[方法]文章利用塔城地区7个气象站点1961~2013年的逐日气象资料,探究了气温、降水、日照时数、积温和潜在蒸散量的时空变化特征.[结果]1961~2013年塔城地区年平均气温、降水量和积温呈增加趋势,日照时数和潜在蒸散量呈减少趋势.1961~2013年塔城地区平均气温、降水量、日照时数、年潜在蒸散量、积温分别在1997、1967、1996、1989、1985年发生增加突变.平均气温、降水量、日照时数、积温存在明显的多尺度周期特征,即30年的大周期和15年的小周期变化.塔城地区平均气温的空间分布差异明显;大致呈现西高东低的空间分布特征;降雨量空间分布大致呈现西多东少的经线分布特征;日照时数大致呈现南短北长的维度地带性特征;潜在蒸散量存在自南向北逐渐减少的空间分布特征;积温的空间分布呈明显的自南向北逐渐减少的维度地带性特征.[结论]在全球气候变化下,较全面了解到新疆塔城地区气候变化趋势特征,对建立塔城地区气象预测与农业生产之间的预警,促进农业健康发展有很大的理论依据.  相似文献   
97.
Shortfalls in global food production, coupled with the growing visibility of climate change's disruptive effects, have underlined for many observers the importance of devoting rural lands to their ‘optimal’ use, where they can make maximal contributions to the global imperatives of feeding the human population and maintaining vital environmental services. In this context observers have endorsed rural land use planning as a way to insure that, at least in theory, lands get devoted to their best uses. In practice, land use planning in the developing world has resembled ‘organized anarchy’. Small landholders with insecure land tenure, overseas investors seeking large land deals, NGOs representing indigenous peoples, government officials, and staff from international environmental NGOs and multilateral organizations have come together in strategic action fields to struggle over and sometimes negotiate land use plans for contested landscapes. These plans represent a strategic, spatially explicit response to the climate change–biodiversity–food security crisis.  相似文献   
98.
Land use change is strongly modifying the traditional landscape of hilly productive Mediterranean sites. An example of these circumstances is the Langhe region (Piemonte, NW Italy), where woody plantations such as vineyards and orchards have been cultivated on hillslopes for centuries. In this paper we assess landscape changes occurred in the Diano study area (2651 ha) in the 1954–2000 period and we ascertain land use transition paths and rates of this rural ecosystem. Land use mapping obtained from object-oriented analysis of aerial photographs was used to quantify land use changes between 1954 and 2000. To examine the spatio-temporal patterns of land use change over time, a set of spatial statistics capturing different dimensions of landscape change was identified. An increase of landscape heterogeneity from 1954 to the present was observed due to the expansion of orchards and the fragmentation of field crops. A significant portion (55%) of current orchards surface is represented by former field crops, 24% by vineyards and 15% by forests. The strong expansion of hazelnut orchards concurred to the fragmentation of traditional rural landscape was dominated by vineyards, field crops and forests. Hazelnut orchards expansion was mainly located in places where grapes cultivation was less remunerative. A further expansion of hazelnut in the area should be planned, discussed and carefully monitored through change detection studies in order to avoid potential unsustainable use of the land.  相似文献   
99.
Modern tools for cost-effective conservation reserve site planning require the planner to have information about spatial distributions of conservation costs and benefits. Climate change creates unprecedented uncertainty about future land values and species habitat ranges, such that conservation scientists cannot map costs and benefits with certainty anymore. This paper contributes to the literature on the economics of conservation in the face of climate change uncertainty. It advances a new method for using modern portfolio theory to choose lands to protect that yield total conservation returns with less uncertainty. It explores the implications for portfolio recommendations of variation in the correlations between ecological and land-value responses to climate change. It also tests the robustness of the method to shortcuts that might be taken to simplify analysis, identifying problems that arise if conservation costs are ignored in portfolio analysis and demonstrating when portfolio recommendations are sensitive to how ecological benefits are quantified.  相似文献   
100.
The thesis of this study is that the convergence of genetics, genomics and proteomics spurs new technological paradigms in medicine, which are generating a R&D corporate change: division of scientific labour of the drug discovery process by strategic alliances among firms in order to reinforce the integrative capabilities in different biomedical research fields and collective and cumulative learning between in-house R&D and external sources of innovation. This study shows, by key a case study of pharmaceutical companies, as scientific and technological paradigms in medicine are main drivers of industrial and R&D corporate change to enhance and accelerate the discovery process of ground-breaking drugs for more and more personalised healthcare.  相似文献   
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