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   4236篇
  免费   83篇
  国内免费   40篇
电工技术   223篇
综合类   242篇
化学工业   516篇
金属工艺   259篇
机械仪表   385篇
建筑科学   313篇
矿业工程   204篇
能源动力   230篇
轻工业   280篇
水利工程   26篇
石油天然气   222篇
武器工业   88篇
无线电   459篇
一般工业技术   172篇
冶金工业   272篇
原子能技术   29篇
自动化技术   439篇
  2024年   1篇
  2023年   21篇
  2022年   34篇
  2021年   46篇
  2020年   61篇
  2019年   38篇
  2018年   34篇
  2017年   38篇
  2016年   51篇
  2015年   83篇
  2014年   170篇
  2013年   150篇
  2012年   230篇
  2011年   255篇
  2010年   221篇
  2009年   175篇
  2008年   194篇
  2007年   271篇
  2006年   245篇
  2005年   252篇
  2004年   241篇
  2003年   255篇
  2002年   223篇
  2001年   187篇
  2000年   159篇
  1999年   160篇
  1998年   143篇
  1997年   97篇
  1996年   96篇
  1995年   86篇
  1994年   52篇
  1993年   28篇
  1992年   18篇
  1991年   11篇
  1990年   5篇
  1989年   7篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   5篇
  1983年   2篇
  1982年   3篇
  1980年   1篇
排序方式: 共有4359条查询结果,搜索用时 31 毫秒
1.
ABSTRACT

With a greater number of B2B firms integrating customers into the new product development (NPD) process, how to utilize customer involvement in NPD is an important decision because it may be a double-edged sword carrying both bright and dark sides. Utilizing a sample of 193 B2B firms across various industries, we validate previous research that suggests market orientation positively influences NPD performance and subsequently examine how this relationship may either be enhanced or diminished contingent upon how customers are utilized in the NPD process. The results show that the market orientation–NPD performance relationship is enhanced by having customers participate in a greater number of activities throughout NPD (customer participation breadth) and diminished when customers are involved at deeper levels (customer participation depth). This research suggests that the exact involvement of customers is a critical decision and has clear implications for the dialogues about customer involvement and management of customer relationships.  相似文献   
2.
Designing wholesale electricity spot markets even after three decades of experience in dozens of countries continues to be a challenging task. The challenges arise from a myriad of options that exist without adequate level of unbiased guidance, and experiences in real-life markets where successes and failures are also open to the interpretation of experts. This is particularly a critical issue in the developing world where wholesale spot markets are yet to be established in 80 % of the countries and the experience in the remaining 20 % countries with an operational market, is mixed. There are certain trends in selection of market design that leave significant room for improvement including fallacies that should be avoided. Implementation of markets have also been problematic in most cases including unrealistic timetable and inadequate consideration of transition mechanism that have also hampered market development. In this article, we present our views on how policy makers, stakeholders and development institutions should think about the choices around market design and some of the common pitfalls around its implementation.  相似文献   
3.
The aim of this paper is to investigate the long and short-run relationship between spot and futures prices of the energy, precious metals, and base metals markets. We analyze daily data from January 1985 to February 2019. The empirical findings based on the cointegration test, which follows a nonlinear process, suggest that the spot prices of energy and metals assets have long-run relationships with their futures prices. Nonparametric Granger causality test results also indicate bi-directional causality among futures and spot prices. These findings indicate that the energy and metals markets are informationally efficient in the sense of Fama (1970).  相似文献   
4.
Buying firms’ sales and reputation will be greatly damaged by any non-responsible behaviors on the part of suppliers, especially when those suppliers, like small and medium-sized enterprises (SMEs), have restricted resources and capabilities. To eradicate these risks, a growing number of buying firms have introduced socially responsible supplier development (SRSD). SRSD, including monitoring and evaluating suppliers, can provide them with incentives and assistance. Based on configuration theory and contingency theory, fuzzy-set qualitative comparative analysis (fsQCA) is adopted in this study to examine how SRSD practices adopted by buying firms, supply chain partnership, and market turbulence affect the corporate social responsibility (CSR) performance of their SME suppliers. We find that, as core factors, supplier monitoring, supplier assistance, and supply chain partnership can work together with peripheral conditions to achieve superior CSR performance. In addition, even at different levels of market turbulence, superior CSR performance can be realized through different causal configurations.  相似文献   
5.
With the growing role of distributed energy resources, the electricity network is challenged by numerous technical problems, such as capacity congestion and over- or under-voltage. An often-discussed response, especially in the European zonal electricity system, is to implement regional flexibility markets. We contribute to this discussion by providing a comprehensive classification framework for the design of flexibility products by combining technical requirements with classical auction theory. The framework structures 23 product parameters in four stages of abstraction. By applying the framework to five market approaches used in current German research projects, we demonstrate its usefulness for consistent comparison of flexibility products at a high level of detail. This framework can empower national and international policymakers and practitioners in assessing flexibility markets holistically, thereby facilitating the implementation of sound solutions.  相似文献   
6.
This study aims to design and implement new learning methodologies and resources that seek to advance the development and assessment of one of the fundamental students’ competencies from any Business Administration Degree, such as critical thinking, that is, this is an exploratory study on computing for human learning, specifically, learning of key competencies for business. We are going to use audiovisual case methodology through the use of short film clips, usually real stories, to help students understand the practical implications of theoretical concepts explained in the classroom. A theoretical model test uses data from 32 business students from the Open University of Catalonia. The first results show positive attitudes toward a new technological resource ‘audio-visual cases’. They indicate that the use of this tool can improve the comprehension of a problem and its origins and, at the same time, stimulate learning. In addition, this tool helps to develop critical thinking competency. This study offers important contributions to an e-learning environment and their applicability to the workplace, since it is the first type of research about the impact of audiovisual cases in the acquisition of critical thinking competency. Furthermore, this methodology promotes collaborative learning.  相似文献   
7.
对核电厂设备闸门提升与导向装置在设备闸门封头开启与关闭过程中的运动特性进行了分析研究,该研究借助动力学仿真软件ADAMS展开,分别对提升与导向装置可能出现的同步提升操作和不同步提升操作两种工况进行了仿真分析。分析结果表明:在同步提升操作工况下,设备闸门封头两侧导向箱位移一致,提升与导向装置不会产生卡滞;在不同步提升操作工况下,设备闸门封头两侧导向箱最大允许高度差为54 mm,否则提升与导向装置将产生卡滞。   相似文献   
8.
While wind and solar generation has increased dramatically over the past decade, there has been a much larger increase in gas generation (eia, 2019). This is driven in part by low gas prices but also in part by how electricity markets are organized. The intermittent nature of wind and solar generation increases the need for more flexible and reliable generation; a role gas plants fill well. However, current market structures and rules unfairly tip the balance in their favor compared to energy storage systems. They have created market barriers restrictive enough to prevent market participation of a technology key to a 100 % renewable grid: supercapacitors. Adjusting markets to remove the market barriers to supercapacitor and other energy storage systems will allow for increased renewable penetration while simultaneously improving grid performance and reducing costs.  相似文献   
9.
Science Based Innovation relies on effective Technology Transfer efforts. Defining strategies that increase high-technology projects success in the market is a necessary and challenging activity. This comprises elements like market uncertainty and the need for timely decision making within an environment of limited resources (economic, time, human, among others). In this context, Technology Intelligence (TI) generates useful knowledge to reduce risk and improve decision making. This work provides a tool to identify and qualitatively measure different risks; highlighted by previous TI activities. Such risks, their level and mitigation alternatives are also discussed. Furthermore, we create a simple, yet useful tool to calculate a risk score for technology projects at early stages of development. This tool was developed in a Technology Transfer Office to foster the development of entrepreneurial ventures.  相似文献   
10.
The liberalization of television markets and the emergence of commercial channels has changed the position of public television, bringing an end to monopolies. Public television now competes for audiences with private television. In this paper, the authors analyze the changes to the market position of public television in Germany, Spain, France, the United Kingdom (UK), and Italy between 1995 and 2019. In this 25-year period, all of these countries have had a liberalized TV market. The aim of this paper is to demonstrate the ways in which public television competes with commercial television, assessing the consequences of this on market power. This analysis allows us to detect similarities and dissimilarities between public television and television markets in large Western European countries. The results show the decline of the market share of public television in all countries, except Germany. Furthermore, public television has remained market leading in all countries, with the exception of Spain. One of the ways to compete with commercial television is to start new public channels and acquire a large audience.  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