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31.
    
This paper illustrates the development of an object-oriented Bayesian network (OOBN) to integrate the safety risks contributing to an in-flight loss-of-control aviation accident. With the creation of a probabilistic model, inferences about changes to the states of the accident shaping or causal factors can be drawn quantitatively. These predictive safety inferences derive from qualitative reasoning to conclusions based on data, assumptions, and/or premises, and enable an analyst to identify the most prominent causal factors leading to a risk factor prioritization. Such an approach facilitates a mitigation portfolio study and assessment. The model also facilitates the computation of sensitivity values based on perturbations to the estimates in the conditional probability tables. Such computations lead to identifying the most sensitive causal factors with respect to an accident probability. This approach may lead to vulnerability discovery of emerging causal factors for which mitigations do not yet exist that then informs possible future R&D efforts. To illustrate the benefits of an OOBN in a large and complex aviation accident model, the in-flight loss-of-control accident framework model is presented.  相似文献   
32.
    
Log-periodic precursors have been identified before most and perhaps all financial crashes of the Twentieth Century, but efforts to statistically validate the leading model of log-periodicity, the Johansen–Ledoit–Sornette (JLS) model, have generally failed. The main feature of this model is that log-harmonic fluctuations in financial prices are driven by similar fluctuations in expected daily returns. Here we search more broadly for evidence of any log-periodic variation in expected daily returns by estimating a regime-switching model of stock returns in which the mean return fluctuates between a high and a low value. We find such evidence prior to the two largest drawdowns in the S&P 500 since 1950. However, if we estimate a log-harmonic specification for the stock index for the same time periods, fixing the frequency and critical time according to the results of the regime-switching model, the parameters do not satisfy restrictions imposed by the JLS model.  相似文献   
33.
We investigate the impact of fiscal stimuli at different levels of the government debt‐to‐GDP ratio for a sample of 17 European countries from 1970 to 2010. This is implemented in an interacted panel VAR framework in which all coefficient parameters are allowed to change continuously with the debt‐to‐GDP ratio. We find that responses to government spending shocks exhibit strong nonlinear behavior. While the overall cumulative effect of a spending shock on real GDP is positive and significant at moderate debt‐to‐GDP ratios, this effect turns negative as the ratio increases. The total cumulative effect on the trade balance as a share of GDP is negative at first but switches sign at higher levels of debt. Consequently, depending on the degree of public indebtedness, our results accommodate long‐run fiscal multipliers that are greater and smaller than one or even negative as well as twin deficit and twin divergence behavior within one sample and time period. From a policy perspective, these results lend additional support to increased prudence at high public debt ratios because the effectiveness of fiscal stimuli to boost economic activity or resolve external imbalances may not be guaranteed.  相似文献   
34.
    
One of the most important challenges for startup companies is securing financing. Indeed, it is crucial for startups to demonstrate their projects’ profitability to potential investors. We develop a model of single‐stage startup financing with signaling under ambiguity. Nature determines the ability of a technology entrepreneur (startup), who strategically chooses a costly patent level to signal his ability to potential investors. Because the project undertaken by a startup may involve highly innovative technology and may not be well known to agents, they might face ambiguity about the value of the project. To examine ambiguity effects on startup financing, we provide three different financing models in view of the degree of ambiguity: (i) no ambiguity; (ii) only investors face ambiguity; (iii) all agents face ambiguity. In each model, we derive perfect Bayesian equilibria and refine them into a unique equilibrium by imposing the Intuitive Criterion of Cho and Kreps (Quarterly Journal of Economics, 102, 1987, 179) or its extension. We analyze the refined equilibria from the perspectives of agents’ equity shares and expected profits, and equilibrium patent levels.  相似文献   
35.
    
In the analysis of clustered and longitudinal data, which includes a covariate that varies both between and within clusters, a Hausman pretest is commonly used to decide whether subsequent inference is made using the linear random intercept model or the fixed effects model. We assess the effect of this pretest on the coverage probability and expected length of a confidence interval for the slope, conditional on the observed values of the covariate. This assessment has the advantages that it (i) relates to the values of this covariate at hand, (ii) is valid irrespective of how this covariate is generated, (iii) uses exact finite sample results, and (iv) results in an assessment that is determined by the values of this covariate and only two unknown parameters. For two real data sets, our conditional analysis shows that the confidence interval constructed after a Hausman pretest should not be used.  相似文献   
36.
We estimate the Federal Reserve's, the Bank of England's, and the Bank of Japan's responses to house prices. We show that generalized method of moments estimates of a Taylor rule augmented with house prices are biased and dispersed. We then use full‐information methods and estimate the policy rule together with a VAR for the nonpolicy variables. These estimates are also biased. We propose an alternative approach and estimate a dynamic stochastic general equilibrium model embedded with a monetary rule with a direct response to house prices. We find that house prices played a separate role in the reaction functions of these central banks.  相似文献   
37.
    
We estimate a structural term-structure model of U.S. real rates, where arbitrageurs accommodate demand pressures exerted by domestic and foreign official investors. Official demand affects rates by altering the aggregate price of duration risk, and thereby bond risk premiums. Although foreign central banks' demand contributed to reduce long-term real rates mainly in the years prior to the global-financial crisis, the Federal Reserve's demand lowered rates during the quantitative easing period. Overall, the two-factor model, augmented to account for changing liquidity conditions, offers a good representation of real rates during the 2001–16 period; however, we flag some caveats and possible extensions.  相似文献   
38.
Using the Bayesian multivariate Beveridge-Nelson decomposition method, this paper estimates China's output gap based on a multivariate dynamic model featuring distinct interactions among real output, inflation, money, and the exchange rate in China during the period 1980-2010. The authors compare the statistical nature and potential forecasting effects of the resulting multivariate gap measure on monetary policy with those of the output gap measures based on univariate models. The empirical results show that only the measure based on the multivariate system significantly predicts monetary policy, which indicates that the output gap estimated by the multivariate system contains more information than the traditional measures for macroeconomic policy adjustments do.  相似文献   
39.
    
The increase in interconnectivity and developments in technology have caused cyber security to become a universal concern. This paper highlights the dangers of the evolution of cyber risk, the challenges of quantifying the impact of cyber-attacks and the feasibility of the traditional actuarial methodologies for quantifying cyber losses. In this paper, we present a practical roadmap for assessing cyber risk, a roadmap that emphasizes the importance of developing a company and culture-specific risk and resilience model. We develop a structure for a Bayesian network to model the financial loss as a function of the key drivers of risk and resilience. We use qualitative scorecard assessment to determine the level of cyber risk exposure and evaluate the effectiveness of resilience efforts in the organization. We highlight the importance of capitalizing on the knowledge of experts within the organization and discuss methods for aggregating multiple assessments. From an enterprise risk management perspective, impact on value should be the primary concern of managers. This paper uses a value-centric/reputational approach to risk management rather than a regulatory/capital-centric approach to risk.  相似文献   
40.
    
Nanomaterials are known to cause biological effects to humans through various routes of exposure such as injection, intravenous, oral, and inhalation. The risk analyses through conventional qualitative or semi-quantitative approaches, such as control banding tools with limited safety data, and information on the risks posed by nanomaterials, have created uncertainties in decision-making by various stakeholders. Therefore, an integrated Nanomaterial Risk (NanoRisk) framework that incorporates the Bayesian Network (BN) model, control banding, and process parameters focusing on humidity, the mass of nanomaterials, and operating temperatures was developed to assess the hazards of nanomaterials and their potential biological effects to human health as a result of exposure. The proposed risk assessment was applied to nanomaterials used in the paint and coating industry (nano-silica, nano-titanium, and nano-silver), and the nodes of the BN model were constructed from physiochemical properties, biological effects, routes of exposure, and types of studies extracted from published data. The flexible analytic approach of the BN model allows for a valuable prediction of hazard exposure towards nanomaterials, thus facilitating decision-making. Furthermore, the integrated framework proposes suitable control measures to reduce the hazard exposure according to the hazard level at different modes of operation. The distinctive feature of NanoRisk demonstrates comprehensive analysis and results that are comparable with previously developed methods.  相似文献   
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