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171.
Macrophysical climatic modeling (MCM) is based on the relationship between large-scale atmospheric dynamics and synoptic climatology to develop simulations of late Pleistocene and Holocene climate in specific localities. Climatic events are calculated at 200-year intervals for the last 14,000 and 500 years for the period from 14,000 to 40,000 B.P. The model has been applied to more than 200 localities in Africa. We present examples from different parts of the continent at locations of archaeological significance. The results indicate that the transition from glacial maximum to postglacial conditions shows both temporal and inter- and intraregional variability. In addition to long-term differences among early, middle, and late Holocene climatic regimes, the model also shows incidences of sharp, abrupt events at some intervals. The applications of MCM invite comparison with inferences based on proxy data and assist in formulating and cross-examining socioecodynamic models based on climatic change, e.g., the continuity of cultural interactions along the Mediterranean littoral, the emergence and spread of cattle pastoralism, and the depopulation of the Sahara during the glacial maximum. 相似文献
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173.
This paper describes the use of electron spin resonance spectroscopy to estimate the degree of heating of quartzite cobbles from hearths on the floor of the archaeological remains of an eighteenth-century Dutch colonial slave lodge. A novel technique based on the comparison of line intensities for the E’and O-2 centres in quartz distinguished successfully between cobbles which had been heated to estimated temperatures ranging from 300 °C to 450° C and controls from an adjacent stream bed. This inexpensive and simple technique could be applied to a wide range of archaeological problems involving the thermal history of objects consisting of or containing quartz. 相似文献
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175.
ABSTRACT. Average monthly price data from twelve hinterland markets and the Houston port price for wheat are studied in a cointegration framework using the Engle-Granger "two-step" procedure and Johansen's maximum likelihood procedure. Out-of-sample forecasts from an error correction model are compared to those from a vector autoregression fit to levels and a univariate autoregression fit to first differences. This comparison suggests that modeling these (cointegrated) data as a levels vector autoregression, rather than as an error-correction process, results in significantly higher error bias, but lower error variance, at long horizons. 相似文献
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177.
James A. Bill 《Iranian studies》1993,26(3-4):403-406
178.
The US. and France have adopted contrasting models of motor fuel tax and highway finance policy. Fuel tax revenues are dedicated to state and federal highway funds in America, keeping taxes quite low, but preventing them from contributing to the general treasury. French motor fuel taxes are higher and make up nearly 11 percent of the central government's general revenues, excluding social security contributions. French highway finance relies heavily on tolls. Pressure from the US. federal deficit has reduced the highway trust fund's ability to protect highway spending from budgetary competition. Political and procedural changes in Congress make it likely that the U.S.will move away from exclusive dedication of motor fuel taxes. 相似文献
179.
Traditional infrastructure evaluation focuses primarily on technical criteria, such as the completion of a designated, interconnected system of facilities or a particular project's capacity to reduce costs borne by suppliers or end users. In the contemporary policymaking environment, however, nontechnical criteria are often of great importance in determining the success or failure of a particular infrastructure enterprise. Institutional considerations, for example, can often delay the implementation of a project or undermine its effectiveness. This paper examines the importance of non-technical criteria in infrastructure evaluation through a case study of the implementation of a major highway investment program in advanced communication and control technologies, known as intelligent vehicle -highway systems (IVHS). The case study focuses on the role of institutional issues as well as environmental issues, in the implementation of IVHS in the US. surface transportation system. The case emphasizes, first, the significance of institutional and environmental issues, and second, mechanisms for evaluating these issues in the context of a major infrastructure investment program. 相似文献
180.
Laura A. Reese 《政策研究杂志》1993,21(3):492-506
In examining local economic development incentives, scholars have found it useful to employ typologies of development practices. Such typologies have been based on assumptions that techniques reflect functional categories, such as marketing and financial incentives, or can be organized by the nature of costs and benefits, or by the nature of incentive goals. While useful heuristic devices, little effort has been made to test these typologies empirically. This research note provides an empirically based typology of local economic development incentives, using data from 967 cities collected by the International City Management Association. 相似文献