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   919篇
  免费   52篇
  国内免费   11篇
电工技术   2篇
综合类   42篇
化学工业   12篇
金属工艺   9篇
机械仪表   13篇
建筑科学   600篇
矿业工程   5篇
能源动力   8篇
轻工业   40篇
水利工程   20篇
石油天然气   6篇
武器工业   2篇
无线电   16篇
一般工业技术   32篇
冶金工业   6篇
原子能技术   1篇
自动化技术   168篇
  2024年   2篇
  2023年   17篇
  2022年   21篇
  2021年   10篇
  2020年   22篇
  2019年   12篇
  2018年   23篇
  2017年   9篇
  2016年   40篇
  2015年   49篇
  2014年   51篇
  2013年   46篇
  2012年   68篇
  2011年   65篇
  2010年   56篇
  2009年   48篇
  2008年   40篇
  2007年   63篇
  2006年   52篇
  2005年   47篇
  2004年   33篇
  2003年   40篇
  2002年   22篇
  2001年   20篇
  2000年   24篇
  1999年   13篇
  1998年   8篇
  1997年   11篇
  1996年   7篇
  1995年   9篇
  1994年   8篇
  1993年   5篇
  1992年   4篇
  1991年   3篇
  1990年   4篇
  1989年   3篇
  1988年   5篇
  1987年   6篇
  1986年   9篇
  1985年   5篇
  1984年   2篇
排序方式: 共有982条查询结果,搜索用时 15 毫秒
1.
以历史成本会计特点分析为重点,比较、分析了历史成本会计的优点和面临的挑战,指出历史成本会计仍将是基本的会计模式,但多种计量属性并存将是未来财务报告的发展趋势。  相似文献   
2.
Istanbul is one of the most famous historical cities in the world. However, the project alignment selected as the best of a range of alignments cannot avoid passing beneath the historical and cultural heritages of Istanbul as well as under ancient and densely inhabited areas of the city. This paper will explain some of the challenges related to the bored tunnels.

Historical buildings are vulnerable. Yet many existing residential and office buildings are old and constructed on minimal foundations. As a consequence, it is vital that any drawdown of groundwater and any ground settlements have to be minimized.

In addition, the connection between the immersed and bored tunnels will be made directly and totally underground, without the usual intermediate shafts and beneath the deep waters of the Bosphorus Strait. This operation needs the utmost control of the tunnel excavation face to ensure its stability and to minimize water ingress. Based on such considerations, tunnel excavation by tunnel boring machine (TBM) using a slurry shield and having the ability to operate under high pore pressures was recommended as the method of excavation for the main running tunnels.

The paper will explain how the design team from Avrasyaconsult – the Employer’s Representative – arrived at the final minimum, specific and functional requirements of the bored tunneling works which are to be carried out using the ‘FIDIC EPC/Turnkey Project’ conditions.  相似文献   

3.
Water-level change is integral to the structure and function of Great Lakes coastal wetlands, and many studies document predictable relationships between vegetation and water level. However, anthropogenic stressors, such as invasive species, land-use change, and water-level stabilization, interact to shift the historical cycle (of native vegetation migration up- and down-slope) toward dominance by invasive Typha species. Knowing from earlier studies that water-level stabilization alters the historical vegetation cycle, we asked if similar shifts can occur where water levels are not stabilized. Using historical aerial photographs of three coastal wetlands (in Lake Michigan's Green Bay, Wisconsin), we determined that habitat dominated by Typha species has expanded to eliminate wet meadow habitat. Between 1974 and 1992, linear regressions showed strong, significant relationships of both meadow area (R2 ≥ 0.894; p < 0.02) and marsh area (R2 ≥ 0.784; p < 0.05) to water level in all three wetlands. In 2000, meadow area was below that predicted by the historical pattern due to the landward advance of marsh habitat during a year of decreasing water levels. In the same period, land use in the wetland watersheds converted from agriculture to urban. Urbanization and the replacement of native Typha latifolia by the invasive hybrid Typha xglauca may have overwhelmed the beneficial impact of water-level fluctuation. The documentation of vegetation shifts, as herein, is an essential step in the process of preserving and restoring ecological integrity.  相似文献   
4.
闫家瑞 《古建园林技术》1988,(18):17-18转21
福禄宫位于湖南长沙市城西区,始建于清代光绪年间。解放后,福禄宫因未及时修理维护,朽损情况严重,1983年底被拆毁。通过对残留木制装修构件拼凑,推算出该建筑的蝼蜂窠部分测绘图。福禄宫蝼蜂窠类似于北方斗栱中的平身科,是一种装饰性构件。福禄宫的昂嘴采用翼龙飞凤交错排列的形式,部分昂嘴端部另加雕饰花板。蝼蜂窠采用层层叠置出踩的形式,其表面只施以桐油或光油等透明涂料,未施其它色漆及彩绘。  相似文献   
5.
Product family design and product configuration based on data mining technology is identified as an intelligent and automated means to improve the efficiency of product development. However, few of previous literatures have proposed systematic product family design method based on data mining technology. To make up for this deficiency, this research put forward a systematic data-mining-based method for product family design and product configuration. First, the customer requirement information and product engineering information in the historical order are formatted into structural data. Second, principal component analysis is performed on historical orders to extract the customers' differentiated needs. Third, association rule algorithm is introduced to mine the rules between differentiated needs and module instances in the historical orders, thus obtained the configuration knowledge between customer needs and product engineer. Forth, the mined rules are used to construct association rule-based classifier (CBA) that is employed to sort out the best product configuration schemes as popular product variants. Fifth, sequence alignment technique is employed to identify modules for popular product variants, so that the module instances are divided into optional, common and special module, respectively, thereby the product platform is generated based on common modules. Finally, according to new customer needs, the CBA classifier is used to recommend the best configuration schemes, and then popular product variants are configured based on the product platform. The feasibility of the proposed method is demonstrated by the product family design example of desktop computer hosts.  相似文献   
6.
In this paper, we strive towards the development of efficient techniques in order to segment document pages resulting from the digitization of historical machine-printed sources. This kind of documents often suffer from low quality and local skew, several degradations due to the old printing matrix quality or ink diffusion, and exhibit complex and dense layout. To face these problems, we introduce the following innovative aspects: (i) use of a novel Adaptive Run Length Smoothing Algorithm (ARLSA) in order to face the problem of complex and dense document layout, (ii) detection of noisy areas and punctuation marks that are usual in historical machine-printed documents, (iii) detection of possible obstacles formed from background areas in order to separate neighboring text columns or text lines, and (iv) use of skeleton segmentation paths in order to isolate possible connected characters. Comparative experiments using several historical machine-printed documents prove the efficiency of the proposed technique.  相似文献   
7.
This article describes the analysis of emotional state and work productivity using a Web-based Biometric Computer Mouse Advisory System to Analyze a User's Emotions and Work Productivity (Advisory system hereafter) developed by this paper's authors. The Advisory system determines the level of emotional state and work productivity integrally by employing three main biometric techniques (physiological, psychological and behavioral). By using these three biometric techniques, the Advisory system can analyze a person's eleven states of being (stress, work productivity, mood, interest in work) and seven emotions (self-control, happiness, anger, fear, sadness, surprise and anxiety) during a realistic timeframe. Furthermore, to raise the reliability of the Advisory system even more, it also integrated the data supplied by the Biometric Finger (blood pressure and pulse rates). Worldwide research includes various scientists who conducted in-depth studies on the different and very important areas of biometric mouse systems. However, biometric mouse systems cannot generate recommendations. The Advisory system determines a user's physiological, psychological and behavioral/movement parameters based on that user's real-time needs and existing situation. It then generates thousands of alternative stress management recommendations based on the compiled Maslow's Pyramid Tables and selects out the most rational of these for the user's specific situation. The information compiled for Maslow's Pyramid Tables consists of a collection of respondent surveys and analyses of the best global practices. Maslow's Pyramid Tables were developed for an employee working with a computer in a typical organization. The Advisory system provides a user with a real-time assessment of his/her own productivity and emotional state. This article presents the Advisory system, a case study and a scenario used to test and validate the developed Advisory system and its composite parts to demonstrate its validity, efficiency and usefulness.  相似文献   
8.
Many decision-makers in industry, government and academia routinely make decisions whose outcome depends on the evolution of software technology trends. Even though the stakes of these decisions are usually very high, decision makers routinely depend on expert opinions and qualitative assessments to model the evolution of software technology; both of these sources of decision-making information are subjective, are based on opinions rather than facts, and are prone to error. In this paper, we report on our ongoing work to build quantitative models of the evolution of software technology trends. In particular, we discuss how we took specific evolutionary models and merged them into a single (general-purpose) model. The original specific models are derived empirically using statistical methods on trend data we had collected over several years, and have been validated individually; in this paper we further validate the generic (general-purpose) model.  相似文献   
9.
对软件组织项目历史数据的收集与分析进行了探讨。首先介绍了历史数据的收集类别,然后对历史数据的统计和分析进行了研究。在研究过程中,结合大量的实际案例数据对与进度相关的几个重要参数进行了统计、分析并建模。通过构筑进度安排指南,估计工作量和实际工作量的比较,估计进度与实际进度的比较这些历史数据的统计和应用,为软件组织的历史数据统计分析提供了一套切实可行的思路,对软件过程改进工作具有较大的参考价值。  相似文献   
10.
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