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101.
102.
Thomas L. Nordblom David J. Pannell Scott Christiansen Nerses Nersoyan Faik Bahhady 《Agricultural Economics》1994,11(1):29-42
Medic (Medicago spp.) pastures are widely grown in rotation with dryland cereal crops in Mediterranean climate zones of Australia. Attempts since the 1960's to introduce this system to Mediterranean west Asia and north Africa (the native region of medic) have not lead to significant adoption; farmers in the region recognize medic, but as a weed and natural pasture plant. This first detailed economic evaluation of the rotational medic system was conducted using a whole-farm linear programming model based on the agricultural system of north-west Syria. The model represents in detail impacts of rotation on yields, labor requirements of alternative farm activities, availability of family and hired labor, subsistence income requirements, livestock feed sources and uses at different times and a choice of sheep stocking rates. Biological data for the analysis are based on a large six-year cropping and grazing experiment near Aleppo on terra-rossa soil with rainfall mainly in winter and averaging about 330 mm annually. The trial compared a dryland medic-wheat system and traditional two-year rotations of wheat with: fallow, watermelon, lentil and vetch. Results indicate that, given current prices and yields from the trial, medic is less profitable than traditional rotations. The model was used to investigate situations in which medic would be economically preferred. Selection of a medic rotation by the model was found to be particularly sensitive to the area of the farm and the price of labor. On small farms, labor availability per hectare is high, favouring the production of labor intensive crops such as lentil and watermelon. On larger farms, labor costs of these enterprises are substantial, increasing the relative profitability of medic, especially if labor prices increase. Interestingly, the relative desirability of medic is more sensitive to its impact on subsequent wheat crops than to the level of pasture production. We also found that modest increases in the prices of sheep products (especially milk) have a major impact on the economic performance of medic. These insights will allow improved focusing and targeting of future research and extension activities. 相似文献
103.
A conceptual framework of anonymity in Group Support Systems 总被引:2,自引:2,他引:0
Joseph S. Valacich Leonard M. Jessup Alan R. Dennis J. F. Nunamaker Jr. 《Group Decision and Negotiation》1992,1(3):219-241
As the development and use of automated systems for collaborative work grows, the need for a better understanding of these systems becomes more important. Our focus is on one type of system, a Group Support System (GSS) and, in particular, on one important aspect of a GSS—anonymity. A conceptual framework for the study of anonymity in a GSS is presented, which describes the general classes of variables and their relationships. These variables include the factors that influence anonymity in a GSS, types of anonymity, and the effects of anonymity on a message sender, receiver, group process, and outcome. Each of these variables is discussed with working propositions presented for important group process and outcome measures. The objectives of this article are to highlight the importance and complexity of anonymity, to act as a guide for empirical investigations of anonymity, and to influence future GSS development and use. 相似文献
104.
105.
J. J. Graafland 《De Economist》1992,140(4):501-514
Summary In most traditional macroeconomic models for The Netherlands the wage equation is specified by a Phillips curve, in which wage growth is negatively related to the unemployment rate. This paper shows, however, that wage formation can better be described by the so-called wage curve, in which the wage level, instead of wage growth, depends negatively on the unemployment rate.The author thanks S.K. Kuipers and D.A.G. Draper and other colleagues of the Central Planning Bureau for their useful comments. 相似文献
106.
Paul J. Serwinek 《Journal of Business Ethics》1992,11(7):555-566
This study examines the effects of demographic characteristics on ethical perceptions. While earlier research has produced conflicting results regarding the predictive power of these variables, significant and definite insights were obtained with proper controls. The following predictors of ethical attitudes are examined: age, gender, marital status, education, dependent children status, region of the country and years in business, while controlling for job status. A nation-wide random sample of employees was used in obtaining a response rate of fifty-three percent (total n of 423). Indices of aspects of business ethical attitudes were constructed using factor analysis. Linear multiple regression analysis indicated the significant predictive variables. Age was found to be a most-significant predictor. Older workers had stricter interpretations of ethical standards. Gender and region predicted attitudes about job-discrimination practices only, with women and persons from the Midwest most strongly opposed to the practice. All the other variables proved to be unreliable ethics predictors.Paul Serwinek is a research affiliated with Wayne State University. He has done extensive research in business management and consulting work in the field of insurance agency employee job satisfaction.SPSS PC Plus Computer Program used. 相似文献
107.
108.
Christopher P. A. Bennett Ricardo A. Godoy 《Bulletin of Indonesian Economic Studies》1992,28(1):85-99
Improving the quality of Indonesia's coffee exports has been a priority of government and the Association of Indonesian Coffee Exporters for some years. Efforts to achieve this objective have, however, been hampered by misconceptions about the reasons why coffee producers and traders at each point in the marketing network do not deliver a higher quality product. The research reported here shows that price premia for higher quality coffee are not large enough to encourage greater quality enhancement. The world market for low to medium grades, used in the production of instant coffee, is much larger than that for high-quality coffee, and this preference is transmitted in the form of low incentives to improve the product. Failure to understand this has led to government policies which at best do not solve the quality problem and at worst exacerbate it. 相似文献
109.
Models for which the MLE and the conditional MLE coincide 总被引:1,自引:0,他引:1
The MLE, CMLE and MMLE coincide in a linear regression model with fixed individual effects. In this case, there is no incidental parameters problem and the MLE is consistent. The equivalence of these estimators is important because CMLE=MLE implies both the consistency of the MLE and the efficiency of the CMLE. In general, we cannot expect to find a CMLE or MMLE, since there may be no fixed-dimension sufficient statistic for the effects, nor an appropriate transformation of the data whose distribution does not depend on the effects. However, we show that the MLE, CMLE and MMLE do coincide in systems of seemingly unrelated regressions and in systems of simultaneous equations. We establish this result for systems in which (exogenous) variables in addition to (or other than) the intercept may have coefficients which vary over individuals, provided that the set of such variables is the same in every equation.The financial support of the National Science Foundation is gratefully acknowledged. 相似文献
110.
D. P. O'Brien 《英国劳资关系杂志》1992,30(2):253-285
This paper is concerned with one central question: the choice between theories, and the role played by data in that choice. It deals with the uses economists may make of data and the importance of understanding the institutional basis that gives rise to the data - an area in which labour economists have traditionally been particularly strong - and with the relevance of assumptions. It deals with the ultimate need to choose between competing theories (despite the role of conventionalism) on the basis of data rather than retreating into a comfortable 'methodological pluralism'. It considers the role of test replication, with reference to the practice in natural science (and its role there in checking scientific fraud) and concludes that, despite extensive technical problems of testing, economists have to accept a data check if the rhetoric of mathematical technicality is not to overwhelm the need to explain. Parallels are drawn with experience in physics (and the implications of the development of Chaos and Catastrophe for a naively predictionist view are noted), medicine and history (of which, it is argued, modern economists are far too neglectful). 相似文献