全文获取类型
收费全文 | 2126篇 |
免费 | 130篇 |
国内免费 | 83篇 |
专业分类
财政金融 | 113篇 |
工业经济 | 125篇 |
计划管理 | 611篇 |
经济学 | 223篇 |
综合类 | 139篇 |
运输经济 | 127篇 |
旅游经济 | 26篇 |
贸易经济 | 178篇 |
农业经济 | 163篇 |
经济概况 | 83篇 |
水利工程 | 551篇 |
出版年
2024年 | 4篇 |
2023年 | 31篇 |
2022年 | 20篇 |
2021年 | 41篇 |
2020年 | 78篇 |
2019年 | 79篇 |
2018年 | 45篇 |
2017年 | 52篇 |
2016年 | 86篇 |
2015年 | 73篇 |
2014年 | 151篇 |
2013年 | 151篇 |
2012年 | 125篇 |
2011年 | 165篇 |
2010年 | 129篇 |
2009年 | 114篇 |
2008年 | 146篇 |
2007年 | 152篇 |
2006年 | 148篇 |
2005年 | 97篇 |
2004年 | 65篇 |
2003年 | 78篇 |
2002年 | 54篇 |
2001年 | 41篇 |
2000年 | 38篇 |
1999年 | 30篇 |
1998年 | 20篇 |
1997年 | 25篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 19篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有2339条查询结果,搜索用时 15 毫秒
1.
《Socio》2018
Research on productive efficiency at the firm level has developed as an important and active strand of research the last decades, both within operations research, management science and economics. Two apparently different definitions of efficiency are examined, but it is shown that when both estimation methods are based on solving linear programming problems the definitions of efficiency are identical. The purpose of the paper is to give the basic ideas of efficiency analyses using DEA as a tool for researchers not so familiar with efficiency analysis and DEA. The concept of shadow prices is given special attention. 相似文献
2.
作为国有企业产权改革主要模式,“混合所有制”改革是否有助于确保国有资产保值增值,是否有助于推动中国经济可持续发展等问题仍存在探讨空间。本文基于对于改革开放以来中国国有企业改革的成就和教训的考察,指出“混合所有制”可以作为竞争性部门国有企业改革的一个过渡形式;对于垄断央企的改革应该充分借鉴国际上自然垄断行业的改革经验,打破行政垄断,推动竞争性框架建立,并切实实现从“管企业”逐步调整为“管资本”,通过改革实现国有资产的保值增值,并为经济创造新的增长点。 相似文献
3.
In this article, linear programming and fuzzy optimization models are developed for planning and management of available land-water-crop system of Mahanadi-Kathajodi delta in eastern India. The models are used to optimize the economic return, production and labour utilization, and to search the related cropping patterns and intensities with specified land, water, fertilizer and labour availability, and water use pattern constraints. Due to extreme backwardness of the study area, it has been decided to keep all the three objectives of the linear programming models at the same priority level to obtain the compromised solution in a fuzzy environment that incorporates the imprecision in fuzzy goals and fuzzy constraints. These non-structural models facilitate the conjunctive use of available surface water and groundwater resources. A comparative evaluation along with the benefit-cost ratios of the existing and proposed farming systems is also presented. 相似文献
4.
The present paper demonstrates the applicability of population based search optimization method, namely, Differential Evolution
(DE) to a case study of Mahi Bajaj Sagar Project (MBSP), India. Ten different strategies of DE are employed to assess the
ability of DE for solving higher dimensional problems as an alternative methodology for irrigation planning. The parameters
considered in DE are population size, crossover constant and weighting factor. Linear Programming (LP) is utilized as a comparative
approach to assess the ability of DE. Comparison of results of LP and the 10 DE strategies for the given parameters indicated
that both the results are comparable even for high dimensional problems. Extensive sensitivity analysis studies, performed
for 3,600 combinations of above parameters for the 10 DE strategies suggested that DE/rand-to-best/1/bin strategy is the best
strategy giving maximum benefits taking minimum CPU time. It is concluded that DE can be utilized for efficient planning of
any irrigation system with suitable modifications. 相似文献
5.
An Interval Fuzzy Multiobjective Watershed Management Model for the Lake Qionghai Watershed, China 总被引:4,自引:0,他引:4
Lijing Wang Wei Meng Huaicheng Guo Zhenxing Zhang Yong Liu Yingying Fan 《Water Resources Management》2006,20(5):701-721
Integrated watershed management is required to ensure the reasonable use of resources and reconcile interactions among natural and human systems. In the present study, an interval fuzzy multiobjective programming (IFMOP) method was used to solve an integrated watershed management problem. Based on system analysis, an IFMOP model suitable for a lake watershed system {IFMOPLWS} was developed and applied to the Lake Qionghai watershed in China. Scenario analysis and an interactive approach were used in the solution process. In this manner, various system components were incorporated into one framework for holistic consideration and optimization. Integrality and uncertainty, as well as the multiobjective and dynamic characteristics of the watershed system, were well addressed. Using two scenarios, two planning schemes were generated. Agriculture, tourism, macroeconomics, cropland use, water supply, forest coverage, soil erosion, and water pollution were fully interpreted and compared to identify a preferable planning alternative for local agencies. This study showed that the IFMOPLWS is a powerful tool for integrated watershed management planning and can provide a solid base for sustainable watershed management. 相似文献
6.
Optimal Operation of Reservoir Systems using Simulated Annealing 总被引:5,自引:0,他引:5
A stochastic search technique, simulated annealing (SA), is used to optimize the operation of multiple reservoirs. Seminal application of annealing technique in general to multi-period, multiple-reservoir systems, along with problem representation and selection of different parameter values used in the annealing algorithm for specific cases is discussed. The search technique is improved with the help of heuristic rules, problem-specific information and concepts from the field of evolutionary algorithms. The technique is tested for application to a benchmark problem of four-reservoir system previously solved using a linear programming formulation and its ability to replicate the global optimum solution is examined. The technique is also applied to a system of four hydropower generating reservoirs in Manitoba, Canada, to derive optimal operating rules. A limited version of this problem is solved using a mixed integer nonlinear programming and results are compared with those obtained using SA. A better objective function value is obtained using simulated annealing than the value from a mixed integer non-linear programming model developed for the same problem. Results obtained from these applications suggest that simulated annealing can be used for obtaining near-optimal solutions for multi-period reservoir operation problems that are computationally intractable. 相似文献
7.
8.
9.
引入无概率分布的区间数表示不确定性影响范围,选取经济效益、供需水效率和COD排放量分别构建经济目标、社会目标和环境目标优化函数,构建了玉环市不确定性模糊多目标规划(IFMOP)水资源配置模型,并计算了不确定性解集。结果表明:IFMOP配置计算成果可实现玉环市区域水量水质协调高效利用和社会-经济-生态系统均衡发展;在75%来水保证率下各行业配置总水量不确定性范围为14 375万~15 154万m3。IFMOP水资源配置模型在信息不充分的条件下能够全面使用各类数据信息进行水资源配置,更好地满足水资源在各行业配置过程中的动态管理需求。 相似文献
10.
The purpose of this paper is to provide evidence that the debate between quantitative and qualitative is divisive and, hence, counterproductive for advancing the social and behavioral science field. We advocate that all graduate students learn to utilize and to appreciate both quantitative and qualitative research methodologies. As such, students will develop into pragmatist researchers who are able to utilize both quantitative and qualitative techniques when conducting research. We contend that the best way to accomplish this is by eliminating quantitative research methodology and qualitative research methodology courses from curricula and replacing these with research methodology courses at different levels that simultaneously teach both quantitative and qualitative techniques within a mixed methodological framework.An earlier version of this article received the 2003 Southwest Educational Research Association (SERA) Outstanding Paper Award. 相似文献