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   1208篇
  免费   23篇
  国内免费   2篇
电工技术   23篇
化学工业   167篇
金属工艺   16篇
机械仪表   22篇
建筑科学   67篇
矿业工程   22篇
能源动力   35篇
轻工业   148篇
水利工程   20篇
石油天然气   2篇
无线电   143篇
一般工业技术   133篇
冶金工业   166篇
原子能技术   2篇
自动化技术   267篇
  2023年   9篇
  2022年   4篇
  2021年   20篇
  2020年   13篇
  2019年   20篇
  2018年   20篇
  2017年   17篇
  2016年   25篇
  2015年   25篇
  2014年   24篇
  2013年   65篇
  2012年   54篇
  2011年   87篇
  2010年   58篇
  2009年   93篇
  2008年   62篇
  2007年   64篇
  2006年   57篇
  2005年   60篇
  2004年   40篇
  2003年   40篇
  2002年   31篇
  2001年   26篇
  2000年   13篇
  1999年   15篇
  1998年   32篇
  1997年   28篇
  1996年   18篇
  1995年   12篇
  1994年   17篇
  1993年   13篇
  1992年   14篇
  1991年   9篇
  1990年   14篇
  1989年   10篇
  1988年   10篇
  1987年   12篇
  1986年   5篇
  1985年   9篇
  1984年   14篇
  1983年   4篇
  1982年   4篇
  1980年   6篇
  1979年   8篇
  1978年   8篇
  1977年   4篇
  1939年   4篇
  1932年   4篇
  1929年   5篇
  1926年   3篇
排序方式: 共有1233条查询结果,搜索用时 0 毫秒
31.
The increasing use of web 2.0 applications has generated numerous online user reviews. Prior studies have revealed the influence of user-generated reviews on the sales of products such as CDs, books, and movies. However, the influence of online user-generated reviews in the tourism industry is still largely unknown both to tourism researchers and practitioners. To bridge this knowledge gap in tourism management, we conducted an empirical study to identify the impact of online user-generated reviews on business performance using data extracted from a major online travel agency in China. The empirical findings show that traveler reviews have a significant impact on online sales, with a 10 percent increase in traveler review ratings boosting online bookings by more than five percent. Our results highlight the importance of online user-generated reviews to business performance in tourism.  相似文献   
32.
33.
在最近几年中,D类放大器因其体积小,效率高,已经进入了消费类音频电子产品、汽车以及便携式音频产品市场.它的效率帮助减小了汽车放大器以及便携式媒体扩展插槽的尺寸,并以较小的波形因子提供了更大的功率,有助实现新式的消费类音频设备.  相似文献   
34.
A practical evaluation of spectrum-based fault localization   总被引:1,自引:0,他引:1  
Rui  Peter  Rob  Arjan J.C.   《Journal of Systems and Software》2009,82(11):1780-1792
Spectrum-based fault localization (SFL) shortens the test–diagnose–repair cycle by reducing the debugging effort. As a light-weight automated diagnosis technique it can easily be integrated with existing testing schemes. Since SFL is based on discovering statistical coincidences between system failures and the activity of the different parts of a system, its diagnostic accuracy is inherently limited. Using a common benchmark consisting of the Siemens set and the space program, we investigate this diagnostic accuracy as a function of several parameters (such as quality and quantity of the program spectra collected during the execution of the system), some of which directly relate to test design. Our results indicate that the superior performance of a particular similarity coefficient, used to analyze the program spectra, is largely independent of test design. Furthermore, near-optimal diagnostic accuracy (exonerating over 80% of the blocks of code on average) is already obtained for low-quality error observations and limited numbers of test cases. In addition to establishing these results in the controlled environment of our benchmark set, we show that SFL can effectively be applied in the context of embedded software development in an industrial environment.  相似文献   
35.
36.
So far the literature on inventory control for perishable products has mainly focused on (near-) optimal replenishment policies for a stylized environment, assuming no lead-time, no lot-sizing, stationary demand, a first in first out withdrawal policy and/or product life time equal to two periods. This literature has given fundamental insight in the behavior and the complexity of inventory systems for perishable products. In practice, many grocery retailers have recently automated the inventory replenishment for non-perishable products. They recognize they may need a different replenishment logic for perishable products, which takes into account e.g. the age of the inventory in the system. Due to new information technologies like RFID, it now also becomes more economically feasible to register this type of information. This paper suggests a replenishment policy for perishable products which takes into account the age of inventories and which requires only very simple calculations. It will be shown that in an environment, which contains important features of the real-life retail environment, this new policy leads to substantial cost reductions compared with a base policy that does not take into account the age of inventories.  相似文献   
37.
The related goals of the research were to delineate the domain of discontinuity, 1st by demonstrating its occurrence in a nonmatrix situation and, 2nd, by establishing the antecedent outcome conditions necessary for producing a discontinuity effect. The 1st goal was met by designing a mixed motive situation involving the production of origami products. Under these conditions, the magnitude of the discontinuity effect did not significantly differ from that in a matrix-only condition. The 2nd goal was met by a separate experiment that used H. H. Kelley and J. W. Thibaut's (1978) analysis of degree of noncorrespondence of outcomes. This experiment demonstrated that as noncorrespondence increased, so did the rate of competitive responding by groups but not by individuals. This pattern was qualified by an interaction with gender such that competitiveness was more markedly affected by noncorrespondence for groups of women than for groups of men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
38.
An anionic surface‐active agent derived from wool proteins was developed as an alternative to the anionic surfactants extensively used in shampoo formulations. The physicochemical properties of this new surface‐active agent prepared form wool proteins and its application for human hair treatments were studied. This new product could be considered a new mild anionic surface‐active agent, as evidenced by the results found by the evaluation of its physicochemical properties. The new wool anionic surface‐active agent was shown to be very substantive to hair, coating the fiber surface, giving rise to a significant improvement in the mechanical properties of the hair fibers, and providing a certain damage‐prevention effect on the hair. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   
39.
The influence of current profile and pulse parameters on droplet formation and transfer was investigated. One profile has an exponential ramp up and down in the current pulse shape, while the second is nearly square shaped. High-speed photography, synchronised with a high-speed data acquisition system, was used to monitor the droplet formation and transfer. It was found that for long-tail current profile, most of droplet formation and detachment occurs before background current is reached. While, for the nearly square pulse, most of droplet formation and transfer occurs during background current, giving a stable and smooth metal transfer. The arc attachment position was found to vary for the different profiles. Droplet speed was measured, and it was found that it is proportional to the peak current and inversely proportional to background current. Dimensionless process parameters were defined and used to predict droplet speed using a neural networks algorithm.  相似文献   
40.
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