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1.
社会治理机制的创新是实现“善治”的重要途径,有助于增强政府的公共管理能力,降低社会治理成本.目前,地方政府社会治理机制存在形式单一、机制僵化、运作后劲不足等问题.因此,优化这一机制,必须确立多中心的社会治理格局,弱化社会治理中的权力驱动,丰富社会化治理工具,进而实现创新并获得良好的社会治理效果.  相似文献   
2.
This study investigates the impact of foreign investors on stock price efficiency and return predictability in emerging markets. It finds that stocks fully investible for foreign investors exhibit stronger price momentum than non‐investible stocks. The difference in momentum effects between stocks with different levels of investibility cannot be fully explained by world market risk, size, turnover, or country‐specific factors. Further tests show that fully investible stocks have no post‐earnings‐announcement drift (PEAD), and their short‐term momentum reverses over a longer horizon. These results show that the stronger momentum of highly investible stocks does not appear to be driven by foreign investors' underreaction to firm‐specific information, but is more likely to be generated by their positive feedback trading.  相似文献   
3.
Despite the explosive growth of the Chinese aviation sector and the major industry reforms undertaken in recent decades, the Chinese domestic market remains highly concentrated with a significant element of regulation and governmental control in areas such as market entry and airline fleet planning. In this study, we investigate the frequency strategies and aircraft choices of airlines operating in this concentrated growth market. Our empirical investigation suggests that airlines mainly accommodate rapid traffic growth by flying more frequently, although increased aircraft size also contributes to market expansion. We also find a negative relationship between market concentration and flight frequency. Due to the more balanced market structure resulting from mergers among leading airlines since 2002, there has been a moderate reduction in market concentration at route level, contributing to a 3.7% increase in traffic volume from 2002 to 2008. The results of our study suggest that Chinese travelers have yet to fully enjoy the benefits of market liberalization, and airports should prioritize increasing capacity related to aircraft movements over the accommodation of larger aircraft.  相似文献   
4.
This paper examines the cost structures of the leading integrated air cargo carriers, FedEx Express and UPS Airlines. A total cost model is estimated for the two carriers using quarterly data on domestic operations and costs over a nine-year period (2003–2011). The estimated model indicates that the integrated industry exhibits increasing returns to traffic density and constant returns to scale. Accounting for carrier-specific differences in cost structure and network size, FedEx Express is found to be more cost-efficient than UPS Airlines. Looking at the carriers individually, UPS Airlines exhibits substantial economies of traffic density and constant returns to scale while FedEx Express' cost structure is characterized by weak economies of density and constant returns to scale. The combined effect of returns to density and returns to scale on the cost structures of integrated carriers is captured by economies of size. Both FedEx Express and UPS Airlines exhibit economies of size, indicating that carriers in the integrated industry can be more cost efficient by making appropriate adjustments to their network size as their output grows. Moreover, the relative cost-efficiencies of the carriers are reversed when their network-size differences are not controlled.  相似文献   
5.
The present paper introduces an integrated approach to solving the generalized lock scheduling problem. Three interrelated sub problems can be discerned: ship placement, chamber assignment and lockage operation scheduling. In their turn, these are closely related to the 2D bin packing problem, the assignment problem and the (parallel) machine scheduling problem respectively. In previous research, the three sub problems mentioned were considered separately, often using (heuristic) interaction between them to obtain better solutions. A mixed integer linear programming model is presented and applied to instances from both inland locks and locks in a tide independent port. The experiments show that small instances incorporating a wide range of real-life constraints can be solved to optimality.  相似文献   
6.
This paper addresses a novel sustainable hub location problem (SHLP) in which two new environmental-based cost functions accounting for air and noise pollution of vehicles are incorporated. To cope with uncertain data incorporated in the model, a mixed possibilistic–stochastic programming approach is proposed to construct the crisp counterpart. A simulated annealing (SA) and an imperialist competitive algorithm (ICA) with a new solution representation are developed to solve real-sized instances whose performances are compared with a proposed lower bound. Finally, some computational experiments are provided to demonstrate the effectiveness of the proposed model and solution approaches.  相似文献   
7.
This article studies a container drayage problem with flexible orders defined by using requiring and releasing attributes as a unified formulation of various order types. A determined-activities-on-vertex (DAOV) graph introduces a temporary vertex set to formulate different truck statuses. The problem is formulated as a mixed-integer nonlinear programming model based on the DAOV graph. Four strategies including a window partition based (WPB) strategy are presented and evaluated extensively to solve the problem. Results indicate that the WPB method could solve the problem effectively and efficiently. Furthermore, this method is robust considering the operating time biases compared to other algorithms.  相似文献   
8.
A marine container terminal operator may have a situation with excessive calling requests to be served especially when some new service contracts are under consideration. For this situation, we propose a strategic berth template problem (BTPS) that selects the ships among the requesting ones to be served and arrange their berth-windows within a limited planning horizon. The BTPS employs the subgradient optimization procedure, which is an improved version of the procedure that the authors developed for the operational berth allocation problem. A wide variety of numerical experiments indicate the improved subgradient procedure works well for the BTPS.  相似文献   
9.
HPLC 法测定豆腐黄浆水中有机酸质量浓度   总被引:1,自引:0,他引:1  
建立利用反相高效液相色谱法同时快速的测定豆腐黄浆水中柠檬酸、苹果酸、酒石酸、草酸、富马酸、琥珀酸6种有机酸的方法.采用Agilent Eclipse XDB-C18色谱柱;紫外检测器,检测波长为210 nm;流动相为甲醇∶0.01 mol/L KH2PO4-H3PO4缓冲溶液(3∶97,pH值为2.85);流速为0.8 mL/min;柱温为25℃;进样量为20μL.在最佳色谱条件下,柠檬酸、苹果酸、草酸等6种有机酸能同时、快速的分离.线性相关系数r>0.9824,检出限为0.5558~1.2948μg/mL,相对标准偏差0.13%~4.2%,该方法具有分析速度快,重现性好,精密度高,定量准确等特点.适用于豆腐黄浆水中有机酸的定量分析,对黄浆水开发利用有重要意义.  相似文献   
10.
为了探索适合高职学生学习特点的教学方法,提高教学质量,本文就研学结合教学理念的内涵、实施路径、特征和目的进行了探索和研究,并在微观经济学课程中进行试验。结果显示教学效果良好,教学质量得到提升,学生的学习兴趣得以提高,主动参与的积极性增加,培养了学生分析问题和解决问题的能力,为专业训练和实践打好基础。论文最后就研学结合教学理念在微观经济学课程实施中存在的问题进行了剖析,并提出了进一步探索和努力地方向。  相似文献   
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