全文获取类型
收费全文 | 17683篇 |
免费 | 464篇 |
国内免费 | 1篇 |
专业分类
财政金融 | 3005篇 |
工业经济 | 1321篇 |
计划管理 | 2626篇 |
经济学 | 3315篇 |
综合类 | 165篇 |
运输经济 | 122篇 |
旅游经济 | 294篇 |
贸易经济 | 2343篇 |
农业经济 | 716篇 |
经济概况 | 2101篇 |
水利工程 | 2136篇 |
信息产业经济 | 1篇 |
邮电经济 | 3篇 |
出版年
2021年 | 147篇 |
2020年 | 204篇 |
2019年 | 277篇 |
2018年 | 399篇 |
2017年 | 376篇 |
2016年 | 364篇 |
2015年 | 249篇 |
2014年 | 399篇 |
2013年 | 1761篇 |
2012年 | 631篇 |
2011年 | 608篇 |
2010年 | 497篇 |
2009年 | 587篇 |
2008年 | 587篇 |
2007年 | 578篇 |
2006年 | 566篇 |
2005年 | 481篇 |
2004年 | 499篇 |
2003年 | 332篇 |
2002年 | 318篇 |
2001年 | 329篇 |
2000年 | 355篇 |
1999年 | 306篇 |
1998年 | 279篇 |
1997年 | 291篇 |
1996年 | 274篇 |
1995年 | 242篇 |
1994年 | 244篇 |
1993年 | 280篇 |
1992年 | 259篇 |
1991年 | 267篇 |
1990年 | 244篇 |
1989年 | 236篇 |
1988年 | 217篇 |
1987年 | 201篇 |
1986年 | 220篇 |
1985年 | 306篇 |
1984年 | 280篇 |
1983年 | 278篇 |
1982年 | 246篇 |
1981年 | 235篇 |
1980年 | 249篇 |
1979年 | 205篇 |
1978年 | 179篇 |
1977年 | 165篇 |
1976年 | 155篇 |
1975年 | 132篇 |
1974年 | 114篇 |
1973年 | 112篇 |
1972年 | 85篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
As far as flocculation is concerned, the agglomeration of suspended particles into flocs is highly linked to the hydraulic behaviour of the agitation. The Turbomix is a special design of mixing tank; its design was developed to better control the flow during the flocculation stage. It enables a significant decrease in footprint of the process. The combination of the Turbomix and ballasted flocculation has been studied during pilot trials in terms of treatment efficiency. Its controlled hydraulic behaviour explains the efficiency of the process as proved by CFD investigation. 相似文献
52.
Decentralised systems have the potential to provide a viable option for long term sustainable management of household wastewater. Yet, at present, such systems hold an uncertain status and are frequently omitted from consideration. Their potential can only be realised with improved approaches to their management, and improved methods to decision-making in planning of wastewater systems. The aim of this paper is to demonstrate the value of a novel framework to guide the planning of decentralised systems so that asset management and risk management are explicitly considered. The framework was developed through a detailed synthesis of literature and practice in the area of asset management of centralised water and wastewater systems, and risk management in the context of decentralised systems. Key aspects of the framework are attention to socio-economic risks as well as engineering, public health and ecological risks, the central place of communication with multiple stakeholders and establishing a shared asset information system. A case study is used to demonstrate how the framework can guide a different approach and lead to different, more sustainable outcomes, by explicitly considering the needs and perspectives of homeowners, water authorities, relevant government agencies and society as a whole. 相似文献
53.
V C Hammen 《Water science and technology》2007,56(1):253-258
Smoke-haze episodes caused by vegetation and peat fires affect parts of Indonesia every year with significant impacts on human health and climate. The forest fires 1997/1998 were by far the largest in Indonesian history, burning between 5 and 8 million hectares before they were stopped by the monsoon rains in December 1997. Fires sprang up again in 1998 on Kalimantan when monsoon rain paused. Peat forests and peatlands are in particular severely affected. In the 1997/1998 haze event, 2.1-2.5 million hectare of peat swamp forest burnt in Indonesia. The remaining ash contains high concentrations of sulphur and sulphuric compounds which eventually leach into the groundwater, thus polluting groundwater and drinking water. The thicker the peat layer is and the higher the number of fires in the respective area the more sulphuric compounds will leach into the groundwater. Risk areas for the sulphur loads of the ash are identified. 相似文献
54.
55.
Luis C. Nunes Paul Newbold Chung-Ming Kuan 《Oxford bulletin of economics and statistics》1997,59(4):435-448
Nelson and Plosser (1982), in a classic paper, failed to find strong evidence against the null hypothesis of a generating process with a unit autoregressive root for thirteen US macroeconomic time series. Perron (1989) claimed that such evidence was available for a majority of these series if the alternative hypothesis was of trend stationarity with a break in 1929. Zivot and Andrews (1992) treated the break date as endogenous, then finding strong evidence agcainst the null for a minority of these series. Our own analysis extends theirs by permitting a break under the null as well as the alternative hypothesis, and allowing for the sequential nature of the testing. Our empirical findings complete the circle. We find no strong evidence against the unit root hypothesis for any of the thirteen Nelson–Plosser series. 相似文献
56.
Employment Contacts and Minority-White Wage Differences 总被引:1,自引:0,他引:1
We study effects of job contacts on wages in inner-city Boston in 1989 and in the 1982 NLSY. Race/Hispanicity differences in wages are not explained by an absence of contacts among minority youths. Rather, in the Boston data, lower wages of black youths are explained by lower "returns" to their contacts. In the NLSY there is little evidence of lower return to black youths' contacts, but there is evidence of lower returns to Hispanic youths' contacts. 相似文献
57.
Large Non-Union Companies: How Do They Avoid a Catch 22? 总被引:1,自引:0,他引:1
Large non-union companies might be expected to enjoy extensive work-force flexibility deriving from their high-wage, high-involvement strategies. However, where there is a strong local union presence, this might be expected to exert a strong dampening effect on the levels of internal flexibility achieved. Such companies, fearful of union organization, could not then enjoy the freedoms that might be associated with a non-union strategy. Research conducted in the Republic of Ireland on large non-union US companies operating in the electronics industry suggests a conceptual framework indicating how a Catch-22 situation is avoided in these companies. 相似文献
58.
John C. Taylor Stanley E. Fawcett George C. Jackson 《Journal of Business Logistics》2004,25(2):119-137
The purpose of this article is to study the level of “in‐stock” customer service performance being offered in the catalog channel of distribution. The article provides benchmark information for the catalog industry. More importantly, the article serves as one test of the effectiveness of the modern supply chain, where the expectation is for near perfect orders. Customer service levels are studied by using an empirical observation methodology in which catalog retailer's in‐stock performance was measured. Comparisons are made across item type, season, retailer type, and days from catalog receipt. Overall, items were out‐of‐stock during 15.9% of all checkpoints, compared to an 11.8% stock‐out rate in an earlier study of bricks and mortar retailers. 相似文献
59.
We apply a discrete choice approach to model the empirical behaviour of the Federal Reserve in changing the federal funds target rate, the benchmark of short‐term market interest rates in the US. Our methods allow the explanatory variables to be nonstationary as well as stationary. This feature is particularly useful in the present application as many economic fundamentals that are monitored by the Fed and are believed to affect decisions to adjust interest rate targets display some nonstationarity over time. The chosen model successfully predicts the majority of the target rate changes during the time period considered (1994–2001) and helps to explain strings of similar intervention decisions by the Fed. Based on the model‐implied optimal interest rate, our findings suggest that there is a lag in the Fed's reaction to economic shocks during this period. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
60.
Biosecurity and wine tourism 总被引:1,自引:0,他引:1