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171.
The status of invasive dreissenid mussels (Dreissena polymorpha and D. bugensis) and native amphipods (Diporeia spp.) in Lake Ontario was assessed in 2003 and compared with historical data. D. polymorpha (zebra mussels) were rarely observed in 2003, having been displaced by D. bugensis (quagga mussels). D. bugensis expanded its depth range from 38 m depth in 1995 to 174 m in 2003 and this dreissenid reached densities averaging 8,000/m2 at all sites < 90 m. During the same time period, Diporeia populations almost completely disappeared from 0–90 m depth, continuing a declining trend from 1994–1997 reported in previous studies. The average density of Diporeia in the 30–90 m depth interval decreased from 1,380/m2 to 63/m2 between 1997 and 2003. Prior to 2003, areas deeper than 90 m represented a refuge for Diporeia, but even these deep populations decreased, with densities declining from 2,181/m2 in 1999 to 545/m2 in 2003. Two common hypotheses for the decline of Diporeia in the Great Lakes are food limitation and a toxin/pathogen associated with dreissenid pseudofeces. The Diporeia decline in deep waters preceded the expansion of D. bugensis to these depths, and suggests that shallow dreissenid populations remotely influence profundal habitats. This pattern of decline is consistent with mechanisms that act from some distance including nearshore dreissenid grazing and downslope transport of pseudofeces.  相似文献   
172.
The behaviour of stock prices on the Colombo Stock Exchange (CSE) is examined with a view to determine its consistency with the weak form of the Efficient Markets Hypothesis (EMH). Runs, Autocorrelation and Cointegration tests are applied to daily, weekly and monthly CSE index data for the period of January 1991–November 1996. Results of Runs, Correlation and Cointegration tests overwhelmingly reject the serial independence hypothesis, leading to the conclusion that the behaviour of stock prices in the Colombo Stock Exchange is not consistent with the weak form of the Efficient Markets Hypothesis. Tests of the-day-of-the-week-effect, however, show that there is no evidence of such a phenomenon on the Colombo Stock Exchange stock prices. Results of the tests of the-month-of-the-year-effect lead to the conclusion that CSE prices do not display any month-specific behaviour.  相似文献   
173.
Migration from the mountain areas of pre-industrial Europe has been seen as the product of poverty. While hardship controlled the strategies of the more marginalized households, better placed families used their migration experience to establish themselves in commerce. Over generations they used contacts and kinship systems to develop important informal trading networks. It is difficult to establish the effects of this hidden activity on local mountain economies, but dowry payments and post mortem inventories are used to expose the impact of inflowing capital and its circulation.  相似文献   
174.
Gordonia amarae is a right-angled branching filament belonging to the mycolic acid-containing Actinobacteria which is commonly found in many foaming activated sludge wastewater treatment plants. Although studies on different substrates as sole carbon sources by pure cultures of G. amarae have been carried out, none have examined substrate uptake by this organism in situ. Uptake of several hydrophilic and hydrophobic substrates by G. amarae was evaluated in situ using a combination of fluorescence in situ hybridization and microautoradiography. G. amarae could assimilate a range of both hydrophilic and hydrophobic substrates. From the data, G. amarae appears to be physiologically active under aerobic, anaerobic and anoxic condition (NO2 and NO3) for some substrates. This might explain why attempts to control foaming caused by G. amarae using anoxic and anaerobic selectors have been unsuccessful. This study emphasizes that bacteria can behave differently in situ to pure cultures and that it is important to evaluate the in situ physiology of these bacteria if we are to better understand their role in the wastewater treatment process.  相似文献   
175.
In this work, we designed, fabricated and tested a disposable, flow-through amperometric sensor for free chlorine determination in water. The sensor is based on the principle of an electrochemical cell. The substrate, as well as the top microfluidic layer, is made up of a polymer material. The advantages include; (a) disposability from low cost; (b) stable operation range from three-electrode design; (c) fluidic interconnections that provide on line testing capabilities; and (d) transparent substrate which provides for future integration of on-chip optics. The sensor showed a good response and linearity in the chlorine concentration ranging from 0.3 to 1.6 ppm, which applies to common chlorination process for drinking water purification.  相似文献   
176.
Planning food services for a campus setting   总被引:1,自引:0,他引:1  
Providing appropriate food services in a campus setting is increasingly important due to more demanding customers and because clients have less time to go off-campus when they need to eat. Using a university campus as an example, this research looks at customer satisfaction with existing food services and explores various methods for determining where to locate new facilities. This campus currently has great needs for additional food services, and it is shown clearly where additional food services are required. Also, the methods used are compared in terms of their effectiveness in finding the solution.  相似文献   
177.
Supply chain management (SCM) is implemented by integrating corporate functions using business processes within and across companies. Several process‐oriented frameworks for SCM have been proposed but only two of these provide sufficient detail to enable implementation. We evaluate the Supply‐Chain Operations Reference (SCOR) framework and The Global Supply Chain Forum (GSCF) framework using four criteria and identify their relative strengths and weaknesses.  相似文献   
178.
The objective of this paper is to examine the effects of marking‐to‐market of futures contracts on the price differential between futures and forward contracts based on the predictions of the Cox, Ingersoll and Ross (1981) (CIR) model. Cox et al ., (1981) derive a series of propositions with respect to the relationship between futures and forward prices and a set of testable implications. These are tested empirically in this paper using Australian data from November 1991 to June 1997. The results provide evidence of the presence of significant futures and forward price differences, where the futures price is consistently below the forward price. Only partial support is found for the Cox et al ., (1981) propositions, implying that the effect of marking‐to‐market is not able to fully account for the price differential. Therefore, it is not possible to rule out the influence of other institutional factors on the futures‐forward price difference.  相似文献   
179.
Local and regional governments account for an important share of total government spending and, given the decentralization trend in OECD nations, this is likely to increase. How should this spending be governed? This article argues that direct democracy is best suited to organize decision–making at the state and local level. To support this, we present the main theoretical arguments on why and how referenda and initiatives affect fiscal policy outcomes. The basic argument concerns voter control. Under representative democracy, citizens only have direct control at election time. With referenda and initiatives, citizens can selectively control their representatives on specific policies whenever they deviate sufficiently from citizens' preferences. As a result, fiscal policy outcomes are likely to more closely reflect voter preferences. We empirically test this on Swiss data since Switzerland provides a 'natural laboratory' for local governance. The governance structures of Swiss cantons and localities with respect to fiscal issues range from classic parliamentary democracy to pure direct democracy, and an important part of spending and taxation is controlled at these levels. Specifically, we estimate an econometric model of fiscal behaviour using data from 1986 to 1997 for the 26 Swiss cantons, and 1990 data on 134 local communities. It is shown that mandatory referenda on fiscal issues at both levels have a dampening effect on expenditure and revenue, and at the local level also on public debt. Combining this with existing empirical evidence leads to a relatively uncontested result, namely that elements of direct democracy are associated with sounder public finances, better economic performance and higher satisfaction of citizens.  相似文献   
180.
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