首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   29445篇
  免费   872篇
  国内免费   5篇
财政金融   5211篇
工业经济   1969篇
计划管理   4316篇
经济学   5606篇
综合类   310篇
运输经济   136篇
旅游经济   384篇
贸易经济   3873篇
农业经济   1235篇
经济概况   2694篇
水利工程   4490篇
信息产业经济   1篇
邮电经济   97篇
  2021年   222篇
  2020年   325篇
  2019年   501篇
  2018年   594篇
  2017年   638篇
  2016年   645篇
  2015年   411篇
  2014年   627篇
  2013年   2592篇
  2012年   979篇
  2011年   1002篇
  2010年   737篇
  2009年   845篇
  2008年   860篇
  2007年   920篇
  2006年   921篇
  2005年   778篇
  2004年   786篇
  2003年   588篇
  2002年   573篇
  2001年   565篇
  2000年   608篇
  1999年   527篇
  1998年   564篇
  1997年   560篇
  1996年   519篇
  1995年   498篇
  1994年   504篇
  1993年   515篇
  1992年   554篇
  1991年   536篇
  1990年   458篇
  1989年   362篇
  1988年   371篇
  1987年   342篇
  1986年   383篇
  1985年   539篇
  1984年   492篇
  1983年   447篇
  1982年   435篇
  1981年   480篇
  1980年   422篇
  1979年   418篇
  1978年   396篇
  1977年   263篇
  1976年   314篇
  1975年   277篇
  1974年   218篇
  1973年   237篇
  1972年   186篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A conceptual framework of anonymity in Group Support Systems   总被引:2,自引:2,他引:0  
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   
102.
Our paper provides a brief review and summary of issues and advances in the use of latent structure and other finite mixture models in the analysis of choice data. Focus is directed to three primary areas: (1) estimation and computational issues, (2) specification and interpretation issues, and (3) future research issues. We comment on what latent structure models have promised, what has been, to date, delivered, and what we should look forward to in the future.  相似文献   
103.
Rudy Moenaert, William Souder, Arnoud De Meyer, and Dirk Deschoolmeester report the results of their study of forty technologically innovative Belgian companies to examine the interaction between marketing and R&D. They studied one commercially successful and one commercially unsuccessful technological product innovation project in each participating company and collected data from one marketing and one R&D respondent per project. Communication flows between marketing and R&D are increased under conditions involving formalization of projects, decentralization, positive interfunctional climate, and role flexibility.  相似文献   
104.
This paper explores the relationship between organizational context and the interpretation of strategic issues by examining the hypothesis that CEOs' interpretations of foreign investment in the USA are influenced by the organizational context in which they are embedded. Three aspects of organizational context - the global business experience of the firm; the firm's level of organizational inertia (as represented by firm age and size); and the resources available for responding - are examined as predictors of CEOs' perceptions of foreign investment as a threat or an opportunity. Analysis of data from 320 organizations, controlled by industry, shows that global business experience, firm size, and perceived capability are significant predictors of the perception of threat and opportunity. the discussion addresses the implications of these findings for future research on issue interpretation and organizational context.  相似文献   
105.
In this paper we offer a method for deciding how to aggregate a set of elementary industries. The method is then applied to the problem of estimating a wage equation that allows for industry-specific effects. Our method explicitly formalizes the trade-off between goodness-of-fit and parsimony implicit in an aggregation problem. By varying the parameter of the assumed loss function, one obtains a whole sequence of aggregation levels. Further, the resulting sequence is consistent; that is, groupings formed at one level of aggregation will never be undone when one aggregates further.  相似文献   
106.
This paper examines occupational performance in Australia across three racial groups in Australia: Indigenous Australians; Asian people, defined as all those whose language spoken at home was either Chinese, Vietnamese or other forms of a South-east or East Asian language; and white people, defined as the residual category. The paper has as its starting point, observed differences in occupational attainment among the three groups in Australia and sets out to account for these observed differences on the basis of both race and non-racial attributes such as, age, education and area of residence.  相似文献   
107.
Endocrine disrupting chemicals (EDCs) are the focus of current environmental issues, as they can cause adverse health effects to animals and human, subsequent to endocrine function. The objective of this study was to remove a specific compound of EDCs (i.e. pentachlorophenol, C(6)OCL(5)Na, molecular weight of 288 g/mol) using low pressure reverse osmosis membrane (LPROM). A cross flow module of LPROM was used to observe the effects of operating parameters, i.e. pH, operating pressure and temperature. The design of the experiment was based on MINITAB(TM) software, and the analysis of results was conducted by factorial analysis. It was found that the rejection of pentachlorophenol was higher than 80% at a recovery rate of 60 to 70%. The rejection was subjected to increase with the increase of pH. The flux was observed to be increased with the increase of operating pressure and temperature. This study also investigated the interaction effects between operating parameters involved.  相似文献   
108.
Solute transport processes occur within a wide range of water engineering structures, and urban drainage engineers increasingly rely on modelling tools to represent the transport of dissolved materials. The models take as input representative travel time and dispersion characteristics for key system components, and these generally have to be identified via field or laboratory measurements. Computational Fluid Dynamics (CFD) has the potential to reveal the underlying hydraulic processes that control solute transport, and to provide a generic means of identifying relevant parameter values. This paper reports on a study that has been undertaken to evaluate the feasibility of utilising a CFD-based approach to modelling solute transport. Discrete phase modelling has been adopted, as this is computationally efficient and robust when compared with the time-dependent solution of the advection-dispersion equation. Simulation results are compared with published laboratory data characterising the dispersion effects of surcharged manholes, focusing specifically on an 800 mm diameter laboratory manhole for a flowrate of 0.002 m(3)/s and a range of surcharge depths. Preliminary indications are that the CFD results adequately replicate the measured downstream temporal concentration profiles, and that a threshold surcharge depth, corresponding to a change in hydraulic regime within the manhole, can also be identified.  相似文献   
109.
Recent studies suggest the apparent delay in the stock-price response to earnings announcements (i.e., post-earnings announcement drift) is caused by investors who underestimate the autocorrelation of seasonally-differenced earnings (persistence). I present results that suggest: (1) a firm's future persistence is predictable on the basis of its past persistence; (2) the immediate stock-price response to earnings is positively related to historical persistence; (3) post-earnings-announcement drift is independent of historical persistence; and (4) consistent with (2) and (3), the difference between a firm's current observed persistence and that implied in stock prices is independent of its historical persistence. These results extend prior research by demonstrating that investors are aware not only that seasonally-differenced earnings are autocorrelated, but that investors recognize firm-specific differences in the magnitude of the autocorrelation.  相似文献   
110.
Nitrification kinetics are important for process design, optimization, and capacity rating of activated sludge wastewater treatment plants. A Water Environment Research Foundation (WERF) project on Methods for Wastewater Characterization in Activated Sludge Modeling (WERF, 2003) focused significantly on the development of procedures for measuring the nitrifier maximum specific growth rate, micro(AUT). In addition, the importance of (and lack of data for) the nitrifier decay rate, b(AUT), was identified. This paper describes three bench-scale methods for measuring micro(AUT): the Low F/M SBR, Washout and High F/M methods. During the WERF project, the importance of pH and temperature control was investigated briefly; this paper summarizes further experimental work performed to address these issues. A summary of micro(AUT) measurements in a number of locations and using the different measurement techniques is provided.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号