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   1804篇
  免费   5篇
  国内免费   9篇
财政金融   153篇
工业经济   102篇
计划管理   103篇
经济学   320篇
综合类   13篇
运输经济   2篇
旅游经济   4篇
贸易经济   122篇
农业经济   39篇
经济概况   126篇
水利工程   831篇
信息产业经济   2篇
邮电经济   1篇
  2020年   3篇
  2018年   6篇
  2017年   3篇
  2016年   9篇
  2015年   22篇
  2014年   31篇
  2013年   26篇
  2012年   171篇
  2011年   221篇
  2010年   65篇
  2009年   46篇
  2008年   54篇
  2007年   64篇
  2006年   67篇
  2005年   66篇
  2004年   64篇
  2003年   61篇
  2002年   68篇
  2001年   60篇
  2000年   39篇
  1999年   20篇
  1998年   23篇
  1997年   30篇
  1996年   42篇
  1995年   28篇
  1994年   36篇
  1993年   34篇
  1992年   35篇
  1991年   30篇
  1990年   38篇
  1989年   24篇
  1988年   19篇
  1987年   21篇
  1986年   16篇
  1985年   27篇
  1984年   22篇
  1983年   37篇
  1982年   33篇
  1981年   36篇
  1980年   21篇
  1979年   19篇
  1978年   11篇
  1977年   7篇
  1975年   6篇
  1960年   8篇
  1959年   6篇
  1958年   4篇
  1957年   16篇
  1956年   10篇
  1948年   3篇
排序方式: 共有1818条查询结果,搜索用时 31 毫秒
71.
The news that one of the company's senior managers is leaving comes as a complete surprise to Paul Simmonds, CEO of Kinsington Textiles, Inc. Ned Carpenter, KTI's vice president of operations for three years, writes in his resignation letter than he is leaving for a better opportunity. Simmonds soon learns that Carpenter's new job is at Daltex, one of KTI's main rivals in the intensely competitive carpet industry. Hiring Carpenter had helped Simmonds establish his reputation as a topnotch manager. Carpenter came to KTI with lots of ideas and put his enthusiasm to good use. Three years into a five-year change program, Carpenter had turned KTI's operations from one of the worst in the industry to one of the best. He also had helped develop and plan the upcoming launch of a new fiber coating--KTI's first breakthrough in years. In this fictitious case study, Simmonds, along with the company's counsel and vice president of human resources, must figure out how much and what sort of damage control they need. What are they going to tell the company's employees and the media? Should they immediately replace Carpenter with John Brady, the second-in-command of operations? What if Carpenter is taking KTI employees--and strategic information--with him to Daltex? Should Simmonds ask all his managers to sign noncompete agreements-something Carpenter was never asked to do? Should KTI sue Carpenter? Five experts offer advice about communicating with KTI's employees, the media, and Carpenter himself, and about protecting the company's confidential information.  相似文献   
72.
The living company   总被引:7,自引:0,他引:7  
What can explain the longevity gap between a company that survives for centuries--the Swedish company Stora, for example, which is more than 700 years old--and the average corporation, which does not last 20 years? A team at Royal Dutch/Shell Group explored that question. Arie de Geus, a retired Shell executive, writes about the team's findings and describes what he calls living companies-organizations that have beaten the high mortality rate of the average corporation. Many companies die young, de Geus argues, because their policies and practices are based too heavily on the thinking and language of economics. Their managers focus on producing goods and services and forget that the organization is a community of human beings that is in business--any business--to stay alive. In contrast, managers of living companies consider themselves to be stewards of a long-standing enterprise. Their priorities reflect their commitment to the organization's long-term survival in an unpredictable world. Like careful gardeners, they encourage growth and renewal without endangering the plant they are tending. They value profits the same way most people value oxygen: as necessary for life but not the purpose of it. They scuttle assets when necessary to make a dramatic change in the business portfolio. And they constantly search for new ideas. These managers also focus on developing people. They create opportunities for employees to learn from one another. Such organizations are suited for survival in a world in which success depends on the ability to learn, to adapt, and to evolve.  相似文献   
73.
Developing products on Internet time   总被引:2,自引:0,他引:2  
The rise of the World Wide Web has provided one of the most challenging environments for product development in recent history. The market needs that a product is meant to satisfy and the technologies required to satisfy them can change radically--even as the product is under development. In response to such factors, companies have had to modify the traditional product-development process, in which design implementation begins only once a product's concept has been determined in its entirety. In place of that traditional approach, they have pioneered a flexible product-development process that allows designers to continue to define and shape products even after implementation has begun. This innovation enables Internet companies to incorporate rapidly evolving customer requirements and changing technologies into their designs until the last possible moment before a product is introduced to the market. Flexible product development has been most fully realized in the Internet environment because of the turbulence found there, but the foundations for it exist in a wide range of industries where the need for responsiveness is paramount. When technology, product features, and competitive conditions are predictable or evolve slowly, a traditional development process works well. But when new competitors and technologies appear overnight, when standards and regulations are in flux, and when a company's entire customer base can easily switch to other suppliers, businesses don't need a development process that resists change--they need one that embraces it.  相似文献   
74.
75.
76.
大洪水事件频发是造成非洲布基纳法索和萨赫勒地区很多小型坝失事的主要原因.这些小型坝形成的水库通常是很多村庄干旱季节可获得的唯一水源.大型水库的标准管理方法并不适用于这些小型水库.回顾了用于选择这类水坝设计与洪水风险的适当方法,提出了改善其防洪安全性的低成本方案.  相似文献   
77.
The time discretization in the Discontinuous Galerkin (DG) scheme has been traditionally based on the Total Variation Diminishing (TVD) second-order Runge-Kutta (RK2) scheme. Computational efficiency and accuracy with the Euler Forward (EF) and the TVD second-order RK2 time stepping schemes in the DG method are investigated in this work. Numerical tests are conducted with the scalar Burgers equation, 1-D and 2-D shallow water flow equations. The maximum Courant number or time step size required for stability for the EF scheme and RK2 scheme with different slope limiters are compared. Numerical results show that the slope limiters affect the stability requirement in the DG method. The RK2 scheme is generally more diffusive than the EF scheme, and the RK2 scheme allows larger time step sizes. The EF scheme is found to be more efficient and accurate than the RK2 scheme in the DG method in computation.  相似文献   
78.
The temporal scale effect of loading data on nitrate-nitrogen load computation was examined using outputs of watershed modeling tool Hydrologic Simulation Program-FORTRAN (HSPF) for the Amite River in Louisiana, USA. The daily nitrate-nitrogen concentrations simulated using the HSPF were employed first to obtain daily, weekly, bi-weekly, and monthly average data and then to develop load duration curves for the data with four different temporal scales. The duration curves exhibited high variability in the load estimated using daily data as compared with those based on bi-weekly and monthly data. According to daily data, the nitrate-nitrogen load in the winter was found to be 2,780 kg. The nitrate-nitrogen load decreased with increasing temporal (daily, weekly, bi-weekly, and monthly) scale (commonly used in water quality monitoring) of the data. The coefficient of variation, used to quantify the effect of temporal scale on the load, was found to be linearly and inversely correlated with the logarithm of the time scale. Based on the finding, empirical equations were proposed to extrapolate near real-time data for flow and nitrate-nitrogen, greatly simplifying nutrient monitoring and reducing the cost involved in water quality monitoring.  相似文献   
79.
The paper expresses an attempt to tackle the problem due to the presence of micropollutants in wastewater which may be able to disrupt the endocrine system of some organisms. These kinds of compounds are ubiquitously present in municipal wastewater treatment plant (WWTP) effluents. The aim of this paper is to compare the fate of the alkylphenols-APs (4-(tert-octyl)) phenol, t-nonylphenol and 4-p-nonylphenol and the hormones (estrone, 17β-estradiol and 17α-ethinylestradiol) in a submerged anaerobic membrane bioreactor (SAMBR) pilot plant and in a conventional activated sludge wastewater treatment plant (CTP). The obtained results are also compared with the results obtained in a previous study carried out in an aerobic MBR pilot plant. The results showed that the APs soluble concentrations in the SAMBR effluent were always significantly higher than the CTP ones. Moreover, the analyses of the suspended fraction revealed that the AP concentrations in the SAMBR reactor were usually higher than in the CTP reactor, indicating that under anaerobic conditions the APs were accumulated in the digested sludge. The aerobic conditions maintained both in the CTP system and in the aerobic MBR favoured the APs and hormones degradation, and gave rise to lower concentrations in the effluent and in the reactor of these systems. Furthermore, the results also indicated that the degradation of APs under aerobic conditions was enhanced working at high solid retention time (SRT) and hydraulic retention time (HRT) values.  相似文献   
80.
We have investigated and determined the potentiality of different water sources, both for drinking and domestic purposes, in diarrheal disease transmission in diarrhea endemic foci of urban slums in Kolkata, India in a one and half year prospective study. Out of 517 water samples, collected from different sources, stored water (washing) showed higher prevalence of fecal coliforms (58%) (p < 0.0001) in comparison with stored (drinking) samples (28%) and tap/tubewell water (8%) respectively. Among different sources, stored water (washing) samples had the highest non-permissible range of physico-chemical parameters. Fecal coliform levels in household water containers (washing) were comparatively high and almost 2/3 of these samples failed to reach the satisfactory level of residual chlorine. Interestingly, 7% stored water (washing) samples were found to be harboring Vibrio cholerae Improper usage of stored water and unsafe/poor sanitation practices such as hand washing etc. are highlighted as contributory factors for sustained diarrheal episodes. Vulnerability of stored water for domestic usage, a hitherto unexplored source, at domiciliary level in an urban slum where enteric infections are endemic, is reported for the first time. This attempt highlights the impact of quality of stored water at domiciliary level for fecal-oral contamination vis-à-vis disease transmission.  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