全文获取类型
收费全文 | 589篇 |
免费 | 52篇 |
国内免费 | 31篇 |
专业分类
电工技术 | 84篇 |
综合类 | 142篇 |
化学工业 | 13篇 |
机械仪表 | 7篇 |
建筑科学 | 66篇 |
矿业工程 | 7篇 |
能源动力 | 52篇 |
轻工业 | 9篇 |
水利工程 | 8篇 |
石油天然气 | 12篇 |
武器工业 | 3篇 |
无线电 | 9篇 |
一般工业技术 | 67篇 |
冶金工业 | 4篇 |
自动化技术 | 189篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 23篇 |
2019年 | 19篇 |
2018年 | 23篇 |
2017年 | 18篇 |
2016年 | 26篇 |
2015年 | 23篇 |
2014年 | 49篇 |
2013年 | 55篇 |
2012年 | 50篇 |
2011年 | 58篇 |
2010年 | 37篇 |
2009年 | 30篇 |
2008年 | 43篇 |
2007年 | 57篇 |
2006年 | 30篇 |
2005年 | 18篇 |
2004年 | 22篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 14篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有672条查询结果,搜索用时 453 毫秒
21.
This paper provides an overview of research and development in algorithmic trading and discusses key issues involved in the
current effort on its improvement, which would be of great value to traders and investors. Some current systems for algorithmic
trading are introduced, together with some illustrations of their functionalities. We then present our platform named FiSim and discuss its overall design as well as some experimental results in user strategy comparisons. 相似文献
22.
目的研究针对现有专利高效快速地进行规避设计,去实现产品创新设计。方法通过了解我国专利的现状,结合专利规避设计策略,对专利规避设计的具体方法进行分析归纳。深入分析了基于单个专利的功能裁剪方法,基于核心专利群的规避设计,以及针对全方位专利壁垒的专利组合设计,同时对其他相关专利规避设计方法进行了总结。结论专利规避是避开其他竞争对手的专利权利要求而进行创新设计的一种积极可行的专利策略,具有较强的实践应用价值。随着专利规避技术的日趋成熟,对于专利群的规避和专利组合设计的研究会越发受到重视,将TRIZ理论与其他创新设计方法相结合,也将进一步促进专利规避设计的发展。 相似文献
23.
利用德温特创新索引(DII)数据库的专利文献数据,通过产业竞争环境分析和主要竞争对手分析,从竞争情报的视角研究了超级电容器产业的技术竞争态势。通过计算专利技术生命周期、技术研发重点、主要专利优先权国家分布、主要研发机构等指标,明确了我国在该技术领域的位置,提出了发展我国超级电容器产业对策和建议。 相似文献
24.
Renewable energy continues to be a hot topic in the United States affecting security and sustainability. A model to create renewable energy portfolio is established using guidelines drawn by Oregon’s Renewable Portfolio Standard (RPS) legislation with the objective of responding to a 25% of the state electricity demand by renewable resources in 2025. The fuzzy goal programming model is adaptable to accommodate changes in energy costs and future advances in technology maturity. It can also take into consideration the preferences of policy-makers and stakeholders. This model can help to reveal the costs and benefits of complex decisions regarding renewable energy. 相似文献
25.
郑春玲 《数码设计:surface》2010,(2):216-218
以品牌为主导的国内服装产业,目前正在以品牌特许经营的方式,在中国服装市场上到处建设销售网络。同时,作为拥有一定知名度和市场占有率的品牌服装,订货也由最初的代理制转变为买断制,这就给加盟商带来了一定程度的压力和风险,因此作为加盟商如何组织自己的商品组合就变得十分重要,本文将站在加盟商的角度,对商品组合的构成进行详细的分析,以希望能在提升品牌形象的基础上实现利益的最大化。 相似文献
26.
The problem of a multi-period supplier selection and order allocation in make-to-order environment in the presence of supply chain disruption and delay risks is considered. Given a set of customer orders for finished products, the decision maker needs to decide from which supplier and when to purchase product-specific parts required for each customer order to meet customer requested due date at a low cost and to mitigate the impact of supply chain risks. The selection of suppliers and the allocation of orders over time is based on price and quality of purchased parts and reliability of supplies. For selection of dynamic supply portfolio a mixed integer programming approach is proposed to incorporate risk that uses conditional value-at-risk via scenario analysis. In the scenario analysis, the low-probability and high-impact supply disruptions are combined with the high probability and low impact supply delays. The proposed approach is capable of optimizing the dynamic supply portfolio by calculating value-at-risk of cost per part and minimizing expected worst-case cost per part simultaneously. Numerical examples are presented and some computational results are reported. 相似文献
27.
In 1950 Markowitz first formalized the portfolio optimization problem in terms of mean return and variance. Since then, the
mean-variance model has played a crucial role in single-period portfolio optimization theory and practice. In this paper we
study the optimal portfolio selection problem in a multi-period framework, by considering fixed and proportional transaction
costs and evaluating how much they affect a re-investment strategy. Specifically, we modify the single-period portfolio optimization
model, based on the Conditional Value at Risk (CVaR) as measure of risk, to introduce portfolio rebalancing. The aim is to
provide investors and financial institutions with an effective tool to better exploit new information made available by the
market. We then suggest a procedure to use the proposed optimization model in a multi-period framework. Extensive computational
results based on different historical data sets from German Stock Exchange Market (XETRA) are presented. 相似文献
28.
This study proposes a technique based upon Fuzzy C-Means (FCM) classification theory and related fuzzy theories for choosing an appropriate value of the Variable Precision Rough Set (VPRS) threshold parameter (β) when applied to the classification of continuous information systems. The VPRS model is then combined with a moving Average Autoregressive Exogenous (ARX) prediction model and Grey Systems theory to create an automatic stock market forecasting and portfolio selection mechanism. In the proposed mechanism, financial data are collected automatically every quarter and are input to an ARX prediction model to forecast the future trends of the collected data over the next quarter or half-year period. The forecast data are then reduced using a GM(1, N) model, classified using a FCM clustering algorithm, and then supplied to a VPRS classification module which selects appropriate investment stocks in accordance with a pre-determined set of decision-making rules. Finally, a grey relational analysis technique is employed to weight the selected stocks in such a way as to maximize the rate of return of the stock portfolio. The validity of the proposed approach is demonstrated using electronic stock data extracted from the financial database maintained by the Taiwan Economic Journal (TEJ). The portfolio results obtained using the proposed hybrid model are compared with those obtained using a Rough Set (RS) selection model. The effects of the number of attributes of the RS lower approximation set and VPRS β-lower approximation set on the classification are systematically examined and compared. Overall, the results show that the proposed stock forecasting and stock selection mechanism not only yields a greater number of selected stocks in the β-lower approximation set than in the RS approximation set, but also yields a greater rate of return. 相似文献
29.
We consider a problem of dynamic stochastic portfolio optimization modelled by a fully non-linear Hamilton–Jacobi–Bellman (HJB) equation. Using the Riccati transformation, the HJB equation is transformed to a simpler quasi-linear partial differential equation. An auxiliary quadratic programming problem is obtained, which involves a vector of expected asset returns and a covariance matrix of the returns as input parameters. Since this problem can be sensitive to the input data, we modify the problem from fixed input parameters to worst-case optimization over convex or discrete uncertainty sets both for asset mean returns and their covariance matrix. Qualitative as well as quantitative properties of the value function are analysed along with providing illustrative numerical examples. We show application to robust portfolio optimization for the German DAX30 Index. 相似文献
30.
During financial crises investors manage portfolios with low liquidity, where the paper-value of an asset differs from the price proposed by the buyer. We consider an optimization problem for a portfolio with an illiquid, a risky and a risk-free asset. We work in the Merton's optimal consumption framework with continuous time. The liquid part of the investment is described by a standard Black–Scholes market. The illiquid asset is sold at a random moment with prescribed distribution and generates additional liquid wealth dependent on its paper-value. The investor has a hyperbolic absolute risk aversion also denoted as HARA-type utility function, in particular, the logarithmic utility function as a limit case. We study two different distributions of the liquidation time of the illiquid asset – a classical exponential distribution and a more practically relevant Weibull distribution. Under certain conditions we show the smoothness of the viscosity solution and obtain closed formulae relevant for numerics. 相似文献