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An important decision problem during the layout phase of a cross dock is related to the arrangement of inbound and outbound operations within a terminal. Either one side of the terminal is exclusively dedicated to inbound and the other to outbound destinations (vis-à-vis policy) or inbound and outbound destinations can facultatively be assigned all around the terminal (mix policy). The latter policy promises more flexibility, when finally assigning dock doors to truck destinations during operational planning, but comes for the price of ambiguous material flows and potential congestions inside the terminal. Both policies are compared with regard to their impact on operational planning, where deterministic, stochastic and unknown inbound loads are differentiated. Our results show the mix policy being superior in most cases except for unknown inbound loads. 相似文献
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Maziar Sahamkhadam Andreas Stephan Ralf Östermark 《International Journal of Forecasting》2018,34(3):497-506
This study uses GARCH-EVT-copula and ARMA-GARCH-EVT-copula models to perform out-of-sample forecasts and simulate one-day-ahead returns for ten stock indexes. We construct optimal portfolios based on the global minimum variance (GMV), minimum conditional value-at-risk (Min-CVaR) and certainty equivalence tangency (CET) criteria, and model the dependence structure between stock market returns by employing elliptical (Student- and Gaussian) and Archimedean (Clayton, Frank and Gumbel) copulas. We analyze the performances of 288 risk modeling portfolio strategies using out-of-sample back-testing. Our main finding is that the CET portfolio, based on ARMA-GARCH-EVT-copula forecasts, outperforms the benchmark portfolio based on historical returns. The regression analyses show that GARCH-EVT forecasting models, which use Gaussian or Student- copulas, are best at reducing the portfolio risk. 相似文献
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Even though diversified agroforestry systems can provide sustainable livelihoods and a resilient production of different goods, adoption remains limited in Bolivia. We examine major obstacles to agroforestry adoption and possible incentives proposed by farmers and civil-society organizations, and relate them to governance and international mechanisms that might play a role in agroforestry adoption. Market access for produce from diversified agroforestry remains difficult, as does its processing and transport. Moreover, farmers have difficulties in achieving the quantities and homogenous quality demanded by markets in the major cities. But most importantly, farmers and civil-society organizations saw little government support, although ‘ecological production in harmony with Mother Earth’ is prescribed by law and the constitution. Agroforestry farmers needed support most urgently in the initial phase, when investment costs are high and returns low. They suggested affordable credits, subsidies for diversified farming systems, and insurance against fire. We identified important albeit small steps towards developing markets for agroforestry products, but government support – mostly in the form of diesel subsidies, materials, and infrastructure – mainly benefitted large-scale monocultures and cattle ranching. In response to this, interviewees opted for strengthening farmers’ organizations, for demanding support with the help of civil-society organizations, and for disseminating best practices. 相似文献
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Effects of scale economies and production seasonality on optimal hub locations: the case of regional fresh produce aggregation
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Interest in supporting local and regional food systems is rising and food hubs have attracted considerable attention among Federal, State, and local policymakers. This study explores the problem of endogenous hub location in fresh produce value chains in the Northeastern United States. To overcome limitations in the literature, we incorporate the effects of economies of scale and production seasonality into our models. Three experimental models are designed to examine the effects of alternatively applying yearly, quarterly, and monthly data on model solutions. We explicitly assess how interactions of scale economies and seasonality influence the structure and spatial attributes of an optimal regional produce aggregation hub system. The three models generate marketed different solutions and in many respects they lead to different conclusions about developing local/regional supply chains. The monthly model allows for production seasonality and actual hub operation cycle frequency and thus leads to more efficient hub solution with rich policy implications. 相似文献
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Rodrigo Valdes Stephan Von Cramon‐Taubadel Alejandra Engler 《Agricultural Economics》2016,47(5):571-580
This article explores the drivers of regional stock market integration with a focus on the agribusiness sector across relevant regional trade blocs around the world. We implement panel cointegration models to analyze the stock indices of agribusiness firms in the Southern Common Market (MERCOSUR), European Union (EU), Asia‐Pacific Economic Cooperation (APEC), and North American Free Trade Agreement (NAFTA). Based on the literature on market integration and stock return pricing, we identify nine possible determinants of stock market integration, which we separate into three categories: individual market performance, macroeconomic conditions, and agricultural trade. In our analysis, we account for agriculture‐specific factors to control for possible structural shifts in financial markets regimes by including the two main commodity price bubbles during last 20 years. Our results show that most of the variables included in our categories have been important factors in promoting regional stock market integration. Moreover, integration among regional stock markets was strengthened by the implementation of trade agreements. This effect is stronger in trade blocs with fewer members, such as NAFTA and MERCOSUR, compared with larger and more heterogeneous blocs, such as the EU and APEC. 相似文献
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Marcel Fratzscher Bert Rürup Jochen Pimpertz Christoph Butterwegge Stephan Leibfried Kerstin Martens Uwe Schimank 《Wirtschaftsdienst》2017,97(5):315-332
Democracy seems to be at risk. People elect populists and autocrats, who offer simple solutions to social problems. Often, these problems are not even real ones but are only perceived as such. Economists have measures to determine which problems are fact-based, but they cannot draw a clear distinction between academic analysis and normative demand. If politics pursues a correction of a market outcome, any normative criteria other than efficiency have to be outlined explicitly. Nevertheless, some authors consider inequality one of the central contemporary social and economic challenges. Marcel Fratzscher emphasises that the solution is not found in more redistribution via taxes and transfers, but rather through greater equality of opportunity and social and educational mobility. Bert Rürup thinks that to stabilise the acceptance of the compulsory pension scheme, the dominance of the equivalence principle should be reduced. Further, the existence of different federal subsidy schemes should be replaced by a fixed federal contribution rate in alignment with the pension expenditures. In an international comparison, the fiscal burden for households with small and mid-level earned incomes is exceptionally high in Germany. In order to reduce this burden, Rürup suggests a contribution-free allowance for the social insurance contributions. 相似文献
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Based on new administrative data for Germany covering entrances into job creation schemes between July 2000 and May 2001, we evaluate the effects of this active labour market policy programme considering the timing of treatment in the individual unemployment spell. Applying propensity score matching in a dynamic setting where the time until treatment in the unemployment spell is stratified into quarters, regional (East and West Germany) as well as gender differences are considered in the estimation. The results in terms of employment present a heterogeneous, but disappointing picture. For West Germany, most of the estimates are insignificant at the end of the observation period, and only one positive exception could be established. In East Germany, none of the groups experiences an improvement of the labour market situation, but the employment chances tend to be reduced due to participation even 30 months after start of programmes. 相似文献