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   47237篇
  免费   1923篇
  国内免费   1918篇
电工技术   1646篇
技术理论   18篇
综合类   5035篇
化学工业   5788篇
金属工艺   1331篇
机械仪表   2279篇
建筑科学   7751篇
矿业工程   3032篇
能源动力   1579篇
轻工业   3664篇
水利工程   2135篇
石油天然气   3905篇
武器工业   263篇
无线电   1689篇
一般工业技术   2295篇
冶金工业   4383篇
原子能技术   151篇
自动化技术   4134篇
  2024年   88篇
  2023年   297篇
  2022年   799篇
  2021年   1016篇
  2020年   980篇
  2019年   660篇
  2018年   588篇
  2017年   814篇
  2016年   1017篇
  2015年   1094篇
  2014年   2654篇
  2013年   2340篇
  2012年   2921篇
  2011年   3517篇
  2010年   3025篇
  2009年   2905篇
  2008年   2482篇
  2007年   3280篇
  2006年   3384篇
  2005年   3101篇
  2004年   2641篇
  2003年   2370篇
  2002年   1931篇
  2001年   1686篇
  2000年   1425篇
  1999年   987篇
  1998年   724篇
  1997年   514篇
  1996年   392篇
  1995年   282篇
  1994年   223篇
  1993年   146篇
  1992年   131篇
  1991年   80篇
  1990年   69篇
  1989年   62篇
  1988年   39篇
  1987年   29篇
  1986年   41篇
  1985年   46篇
  1984年   28篇
  1983年   17篇
  1982年   18篇
  1981年   21篇
  1980年   14篇
  1979年   14篇
  1965年   12篇
  1963年   11篇
  1959年   12篇
  1955年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
本文从景观设计的角度,阐述了蒙山风景名胜区生态旅游的发展,分析了蒙山风景名胜区发展生态旅游的有利条件和存在的问题,并在此基础上提出生态旅游可持续发展的对策与建议。  相似文献   
62.
CBSD(Component-Based Software Development)已经成为嵌入式软件开发的主流技术。在嵌入式环境下,有大量功能相似的构件,在开发过程中基于QoS的构件选择已成为研究热点。然而这些构件的QoS声明与提供者给出的往往并不一致。为此,提出一种基于修正QoS值的构件选择方法,该方法将QoS信任度作为权重,修正QoS值,再结合模糊逻辑,推理出该构件的综合服务能力。通过嵌入式VOD仿真实验,验证了算法的有效性,保证了构件选择的客观性和准确性。  相似文献   
63.

Context

In recent years, many usability evaluation methods (UEMs) have been employed to evaluate Web applications. However, many of these applications still do not meet most customers’ usability expectations and many companies have folded as a result of not considering Web usability issues. No studies currently exist with regard to either the use of usability evaluation methods for the Web or the benefits they bring.

Objective

The objective of this paper is to summarize the current knowledge that is available as regards the usability evaluation methods (UEMs) that have been employed to evaluate Web applications over the last 14 years.

Method

A systematic mapping study was performed to assess the UEMs that have been used by researchers to evaluate Web applications and their relation to the Web development process. Systematic mapping studies are useful for categorizing and summarizing the existing information concerning a research question in an unbiased manner.

Results

The results show that around 39% of the papers reviewed reported the use of evaluation methods that had been specifically crafted for the Web. The results also show that the type of method most widely used was that of User Testing. The results identify several research gaps, such as the fact that around 90% of the studies applied evaluations during the implementation phase of the Web application development, which is the most costly phase in which to perform changes. A list of the UEMs that were found is also provided in order to guide novice usability practitioners.

Conclusions

From an initial set of 2703 papers, a total of 206 research papers were selected for the mapping study. The results obtained allowed us to reach conclusions concerning the state-of-the-art of UEMs for evaluating Web applications. This allowed us to identify several research gaps, which subsequently provided us with a framework in which new research activities can be more appropriately positioned, and from which useful information for novice usability practitioners can be extracted.  相似文献   
64.
Re-engineering of the design process for concurrent engineering   总被引:20,自引:0,他引:20  
According to the requirements of concurrent engineering, three interdependency relationships (uncoupled relationship, coupled relationship and decoupled relationship) between design activities are presented in this paper. And the coupled relationship plays an important role in concurrent product design process. To represent the precedence relationships among design activities, a directed graph is used to describe the design process. And the interdependency relationship between activities is illustrated by a Design Structure Matrix which is the transpose of the accessibility matrix of the corresponding graph. Using the DSM, an algorithm of recognizing the coupled activities during the design process is presented. Moreover, an algorithm to figure out the order levels of activities during the design process is proposed. And both algorithms are illustrated with a die design example.  相似文献   
65.
The implementation of product development process management (PDPM) is an effective means of developing products with higher quality in shorter lead time. It is argued in this paper that product, data, person and activity are basic factors in PDPM With detailed analysis of these basic factors and their relations in product developmed process, all product development activities are considered as tasks and the management of product development process is regarded as the management of task execution A task decomposition based product development model is proposed with methods of constructing task relation matrix from layer model and constraint model resulted from task decomposition. An algorithm for constructing directed task graph is given and is used in the management of tasks. Finally, the usage and limitation of the proposed PDPM model is given with further work proposed.  相似文献   
66.
在建筑方案设计阶段和工程完成后,三维动画为筛选、优化设计方案、评估城市景观、协调工程与环境的关系,都创造了有利条件。主要介绍建三维动画的简介,制作过程,及得到的启示,最后介绍了建筑三维动画的优势和广阔发展前景。  相似文献   
67.
Offshore outsourcing to vendors in foreign countries causes unique challenges which need to be understood and managed effectively. This paper explores cultural differences in IS offshoring arrangements involving German client organizations that outsource application development activities to Indian vendors. For this purpose, a research framework is developed based on both theoretical considerations and specific empirical observations from multiple case studies. The goal is to (1) explore the nature of cultural differences in offshore outsourcing arrangements in depth and to (2) analyze the relationship between those cultural differences and offshore outsourcing success. Based on the case findings, implications and practices for the management of offshore development projects are outlined. The results indicate that cultural differences in terms of power distance, IS designer values, and an active versus passive working attitude critically affect several dimensions of relationship quality, thereby influencing offshore outsourcing success. A clear definition of roles and mechanisms, strong leadership, and an active management of culture by adapting to either the client’s or the vendor’s national culture appeared to be effective ways to manage cultural differences.
Armin HeinzlEmail:
  相似文献   
68.
展望21世纪新技术革命中的传感器   总被引:5,自引:2,他引:3  
在回顾了以往产业革命中传感器的作用 ,比较工程传感器与人的感官的异同点之后 ,阐述了预计将于 2 1世纪爆发的新产业革命中传感器的使命及发展趋势  相似文献   
69.
《化学反应工程》多媒体课件的开发及应用   总被引:17,自引:11,他引:6  
本文介绍用VB语言开发《化学反应工程》多媒体课件的性能特点,讨论实现中的一些主要技术及课件的使用情况。  相似文献   
70.
我国塑料热稳定剂生产现状与研究进展   总被引:6,自引:0,他引:6  
介绍了国内塑料热稳定剂生产、市场和发展趋势。目前我国塑料热稳定剂无论是品种和产品质量等与国外先进水平仍有较大的差距,提出了我国热稳定剂的发展建议。  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