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   12262篇
  免费   999篇
  国内免费   1423篇
电工技术   323篇
综合类   1061篇
化学工业   71篇
金属工艺   86篇
机械仪表   632篇
建筑科学   175篇
矿业工程   136篇
能源动力   30篇
轻工业   99篇
水利工程   88篇
石油天然气   30篇
武器工业   60篇
无线电   1147篇
一般工业技术   197篇
冶金工业   55篇
原子能技术   23篇
自动化技术   10471篇
  2024年   2篇
  2023年   21篇
  2022年   44篇
  2021年   69篇
  2020年   101篇
  2019年   80篇
  2018年   81篇
  2017年   127篇
  2016年   192篇
  2015年   259篇
  2014年   575篇
  2013年   599篇
  2012年   835篇
  2011年   977篇
  2010年   992篇
  2009年   1112篇
  2008年   1349篇
  2007年   1420篇
  2006年   1345篇
  2005年   1149篇
  2004年   941篇
  2003年   772篇
  2002年   572篇
  2001年   452篇
  2000年   329篇
  1999年   164篇
  1998年   65篇
  1997年   29篇
  1996年   11篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   4篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1983年   1篇
  1982年   1篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ABSTRACT

Nonprofit organizations (NPOs) are strategically using their own personal website to present themselves to the public and share information. Despite the potential benefits of enhanced public confidence and trust, reduced operating costs, improved donor decision making, and increased donations, many nonprofit organizations have resisted the adoption of web disclosure. Informed by the literature on information systems (IS) adoption and technological innovation, this study examines the primary factors that influence the adoption and resistance of web disclosure. Our sample consisted of 176 survey responses from an initial group of 3,323 U.S. NPOs. The statistical results indicate that attitude toward disclosure, compatibility of disclosure with current practices, and financial readiness have a positive influence on web disclosure adoption. The findings have implications for research and practice.  相似文献   
2.
Feeling thermometer questions are widely used in political science research to estimate people’s attitudes and feelings toward a political object, like a political figure or an organization. Given the popularity of the feeling thermometer question in population surveys, more work is needed to explore the measurement of this question type. This study examines the data collection mode effect on feeling thermometers. Using the 2012 American National Election Studies, we find that the measurement of feeling thermometers is not exactly comparable between face-to-face and Web surveys. Face-to-face respondents tend to provide warmer feelings, while Web respondents give relatively more reliable responses in comparison. In both survey modes, respondents are most likely to select the response options that are verbally labeled although the effect is more striking in face-to-face than Web survey. The item nonresponse between these two modes does not differ in a meaningful way. This study ends by discussing future research directions on feeling thermometer questions.  相似文献   
3.
随着Web的发展,在该领域存在的问题也逐渐显露出现,为了从根本上解决Web前端应用过程中存在的问题,需要对Web前端设计进行系统化分析。近年来,Web前端在实际应用过程中因结构设计不完善出现了很多问题,严重影响Web工作的正常运转,针对Web前端问题而提出的研究与防范措施迫在眉睫。目前,基于Web前端结构设计工作的特殊性,可以看出Web前端设计项目至关重要。文章主要介绍了Web前端的具体结构设计以及Web前端在实际应用过程中存在的问题,并提出了相应的解决对策。  相似文献   
4.
Spam网页主要通过链接作弊手段达到提高搜索排名而获利的目的,根据链接作弊的特征,引入链接相似度和作弊系数两个指标来判定网页作弊的可能性。借鉴BadRank算法思想,从Spam网页种子集合通过迭代计算链接相似度和作弊系数,并根据与种子集合的链接指向关系设置权重,将待判定的网页进行度量。最后选取Anti-Trust Rank等算法作对比实验,结果验证了本文算法在准确率和适应性方面优于对比算法。  相似文献   
5.
文章主要介绍了实现机票预订系统的管理过程,该设计的完成也切实的体现了系统管理实施的优点。首先让大家了解了该系统开发的背景、研究现状及其发展趋势,让读者清楚设计该系统的目的及意义。然后较为详细地叙述了系统设计的可行性分析、需求分析、概要设计和功能的实现,其中主要以技术可行性和功能需求为主要叙述对象。最后把系统测试的方法和设计该系统出现的问题及修改完善的方法加以说明让大家更好的了解设计的过程。系统的功能主要包括基本的查询系统、订票系统、退票系统;主要的工作处理包括机票预订处理和退票处理;信息资料查询主要是管理员对客户信息查询、用户对航班信息查询、机票预定查询和退票信息查询;这些功能都满足了客户对机票预订系统的使用需求和对信息检索的要求。  相似文献   
6.
The electricity consumption in the buildings sector has been steadily increasing during the last decade, up to the point that energy efficiency in this sector has become a major problem for governments, utilities, customers, and the environment. The foreseen high penetration of distributed micro-generation facilities based on renewables can help to reduce the environmental footprint of buildings and households, although the complexity of managing effectively the electric grid increases dramatically under these conditions. The IEEE 2030 standard for interoperability in the Smart Grid remarks upon the importance of well-defined data models in such complex scenarios and puts emphasis on the benefits of ontologies and OWL (Web Ontology Language) for this purpose. This paper presents an OWL-based ontology that formally defines the vocabulary and taxonomy and captures the engineering and business semantics of this domain of knowledge (i.e., energy efficiency in the so-called nZEN – nearly Zero-Energy Neighborhoods). This ontology has been defined under the scope of the EU (European Union) research project ENERsip. The paper also highlights the main benefits the ontology brought to all the phases of the project life cycle, as well as how future work can make the most out of it.  相似文献   
7.
This study aimed to investigate the effects of brand anthropomorphism on consumer-brand relationships in a social media marketing context. We hypothesized that anthropomorphism on a brand’s Facebook fan page can strengthen the relationships between brands and consumers by yielding both social presence and a positive inference regarding the brand’s quality as a relationship partner. Our longitudinal experiment confirmed the effects of brand anthropomorphism on consumer-brand relationships on social media and the mediating role of social presence. The results suggest that when the anthropomorphized brand had relationships with consumers, a favorable attitude was shown toward the brand. Further, the participants perceived the anthropomorphized brand as a trustworthy relationship partner, giving more “Likes” for the posts from the anthropomorphized brand than those from the non-anthropomorphized brand. Further, the results confirmed that these favorable relationships were maintained even after the participants became aware of a brand transgression.  相似文献   
8.
Web缓存是用来解决网络访问延迟和网络拥塞问题,缓存替换策略直接影响缓存的命中率。为此,提出一种朴素贝叶斯(NB)分类器重访概率预测的Web缓存替换策略;根据用户之前访问日志,通过分区操作提取多项特征来表示每次访问的对象,并构建特征数据集;训练NB分类器,用来确定缓存中对象被再次访问的概率,为对象分配权重;结合LRU策略来合理删除一些对象。仿真结果表明,提出的策略在保证较高命中率的同时有效降低了执行时间。  相似文献   
9.
随着经济的发展和市场竞争的加剧,企业必须能够快速且准确地满足市场和用户的各种需求。Web服务组合正是由于单个Web服务不能满足企业及用户的需求而产生的一种技术,而如何确保组合的正确性来实现服务增值是一个尚未完全解决的问题。针对此问题,提出了一种基于符号模型检测器NuSMV对Web服务组合进行验证的方法,并提出了基于消息会话的Web服务有限状态自动机的形式化定义。最后实例验证了Web服务组合交互的正确性和有无死锁状态现象,进一步证明了方法的可行性。  相似文献   
10.
Target design methodologies (DfX) were developed to cope with specific engineering design issues such as cost-effectiveness, manufacturability, assemblability, maintainability, among others. However, DfX methodologies are undergoing the lack of real integration with 3D CAD systems. Their principles are currently applied downstream of the 3D modelling by following the well-known rules available from the literature and engineers’ know-how (tacit internal knowledge).This paper provides a method to formalize complex DfX engineering knowledge into explicit knowledge that can be reused for Advanced Engineering Informatics to aid designers and engineers in developing mechanical products. This research work wants to define a general method (ontology) able to couple DfX design guidelines (engineering knowledge) with geometrical product features of a product 3D model (engineering parametric data). A common layer for all DfX methods (horizontal) and dedicated layers for each DfX method (vertical) allow creating the suitable ontology for the systematic collection of the DfX rules considering each target. Moreover, the proposed framework is the first step for developing (future work) a software tool to assist engineers and designers during product development (3D CAD modelling).A design for assembly (DfA) case study shows how to collect assembly rules in the given framework. It demonstrates the applicability of the CAD-integrated DfX system in the mechanical design of a jig-crane. Several benefits are recognized: (i) systematic collection of DfA rules for informatics development, (ii) identification of assembly issues in the product development process, and (iii) reduction of effort and time during the design review.  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