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   805篇
  免费   85篇
  国内免费   110篇
电工技术   16篇
综合类   44篇
化学工业   6篇
金属工艺   8篇
机械仪表   61篇
建筑科学   7篇
矿业工程   3篇
轻工业   6篇
石油天然气   4篇
武器工业   4篇
无线电   329篇
一般工业技术   20篇
冶金工业   19篇
原子能技术   1篇
自动化技术   472篇
  2023年   5篇
  2022年   6篇
  2021年   12篇
  2020年   10篇
  2019年   10篇
  2018年   13篇
  2017年   24篇
  2016年   37篇
  2015年   33篇
  2014年   57篇
  2013年   51篇
  2012年   61篇
  2011年   68篇
  2010年   49篇
  2009年   39篇
  2008年   59篇
  2007年   59篇
  2006年   50篇
  2005年   34篇
  2004年   50篇
  2003年   46篇
  2002年   43篇
  2001年   19篇
  2000年   18篇
  1999年   19篇
  1998年   27篇
  1997年   19篇
  1996年   12篇
  1995年   11篇
  1994年   7篇
  1993年   10篇
  1992年   9篇
  1991年   3篇
  1990年   4篇
  1989年   5篇
  1988年   6篇
  1987年   1篇
  1986年   3篇
  1984年   2篇
  1983年   3篇
  1978年   1篇
  1976年   5篇
排序方式: 共有1000条查询结果,搜索用时 15 毫秒
91.
This article presents information on the development and validation of the Facial Expression Coding System (FACES; A. M. Kring & D. Sloan, 1991). Grounded in a dimensional model of emotion, FACES provides information on the valence (positive, negative) of facial expressive behavior. In 5 studies, reliability and validity data from 13 diverse samples, including students, psychiatric patients, and community adults, are presented, and results indicate that raters can reliably agree on instances of positive and negative expressive behavior. Validity studies indicate that FACES ratings are related in predictable ways to another observational coding system, facial muscle activity, individual-difference measures of expressiveness and personality, skin conductance, heart rate, and reports of experienced emotion. FACES can be a useful tool for assessing expressive behavior in a variety of contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
92.
在分析现行移动通信网和固定电话网用户编号方案的特点及存在问题的基础上,建议在第三代移动通信网中采用长途区号 3G用户号码的编号方案。  相似文献   
93.
基于GPS的低成本车载导航设备的研究实现   总被引:4,自引:0,他引:4  
首先分析车载导航设备的核心功能,说明低成本实现方案的可行性.在此基础上,给出低成本车载导航设备的硬件框架,并对关键部件进行功能阐述.而后从导航原理、嵌入式GIS、图形开发、编码规范、程序运行、内存使用几个方面论述设备的软件系统.接着,通过实验证明该低成本车载导航设备较好地实现了车载导航设备的核心功能.最后,通过与高档车载导航设备的成本对比,体现了该设备的成本低.  相似文献   
94.
With the rapid growth of Internet services, virtual world has witnessed an increasingly large number of online users who have a variety of needs such as accessing various websites to gather information, easing business transactions, and sharing updates. As a result, information security has become a major concern among online users, and the verification of access codes is now the main practice used to keep information systems safe. However, some issues arise as the result of coding and managing behavior, and this research seeks to address these issues. After following the Focus Group method and interviewing 13 college students, this research finds that forgetting the access code is one of the biggest challenges to most online users simply because of the longer duration and the time when the users have a need to access the websites again, their memory will eclipse. In addition, online users usually develop self-constructed rules to cope with elusive code. These rules include: creating some sets of code that may not be meaningful to outsiders; taking different degrees of complex measures to register authentication codes, dependent upon the importance of the websites to the online users; writing the authentication codes on a scratchpad and sticking it on the computer screen; and keeping the codes in a notebook or computer file. The above practices nevertheless run the risk of being usurped by hackers, and it is found that hacking frequently takes place among closest friends, as they are quite familiar with the coding behavior of the victims. While assisting coding management does not help in this regard, as it is generally too expensive, online users troubled by the forgetting of access codes often end up with re-applying for a new set of authentication codes after unsuccessfully trying to login. All these self-constructed rules, nevertheless, constitute threat to information security. The research, in conclusion, calls for an education campaign to promote healthy coding behavior and effective coding management. The obtained findings provide valuable references for both academicians and practitioners to understand the online users’ coding behaviors and to effectively manage them accordingly to improve the resulting information security.  相似文献   
95.
Parallel architectures involve communication with the aim of fast receiving of complete information at each node. Several architectures have been proposed to overcome the problem of high communicational and computational time complexity for transferring and receiving information. To reduce the complexity of such communication, we have implemented Linear Network Coding (LNC) in the parallel environment. For verification of our approach, we have considered some parallel architecture for implementing network coding approach and examined our results on these networks in a generic environment. We have formulated a standard approach for parallel networks, showing that by applying this approach effect of faulty nodes, information size and communication complexity exponentially decreases with code length.  相似文献   
96.
介绍用多变量卡诺图设计Ⅴ/Ⅶ编码器和Ⅶ/Ⅴ译码器的方法。特点是直观、简便、易于掌握。阐述了Ⅴ/Ⅶ编码器和Ⅶ/Ⅴ译码器在数据传输系统中的应用以及用多变量卡诺图进行设计的具体步骤和方法,并提供了具体的逻辑电路图。  相似文献   
97.
Responds to comments (see records 2003-01789-008, 2003-01789-009, 2003-01789-010, 2003-01789-011, 2003-01789-012, and 2003-01789-013) on the mini-series on evidence-based interventions (EBIs) in school psychology (see records 2003-01789-005, 2003-01789-006, and 2003-01789-007). The author focuses on clarifications regarding decisions made by the Task Force and Manual Subcommittee on what constitutes EBIs, realizations about critical issues surrounding these decisions, and specifications for the future. In clarifying the purpose of the Procedural and Coding Manual, 4 design ideals or standards that underlie the conceptualization of the EBI coding structure are reviewed. The design ideals provide underlying assumptions for evaluating intervention studies within the discipline, and include: (1) build researcher-practitioner alliance, (2) respond to the unique issues of school psychology, (3) promote and enhance scientific study, and (4) reflect the broad, diverse nature of the field. Next, central issues raised across the commentary articles are discussed with respect to two sets of juxtaposed considerations: Provide Comprehensive Information vs Maintain Practicality, and Invoke Rigorous Research Design Features vs Reflect School Context Features. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
98.
宽带IP城域网及其应用   总被引:1,自引:0,他引:1  
文章结合南京电信公众宽带IP城域网的建设,对宽带IP城域网的网络结构、用户接入安全、网络管理和认证计费作了阐述,并简要介绍了应用于宽带IP城域网上的一些业务。  相似文献   
99.
We had presented a simple technique, which is based on the theory of Diophantine equation, for parametrization of popular biorthogonal wavelet filter banks (BWFBs) having the linear phase and arbitrary multiplicity of vanishing moments (VMs), and constructed a type of parametric BWFBs with one free parameter [15]. Here we generalize this technique to the case of two parameters, and construct a type of parametric BWFBs with two free parameters. The closed-form parameter expressions of the BWFBs are derived, with which any two-parameter family of BWFBs having preassigned VMs can be constructed, and six families, i.e., 9/11, 10/10, 13/11, 10/14, 17/11, and 10/18 families, are considered here. Two parameters provide two degrees of freedom to optimize the resulting BWFBs with respect to other criteria. In particular, in each family, three specific rational-coefficient BWFBs with attractive features are obtained by adjusting the parameters: the first is not only very close to a quadrature mirror filter (QMF) bank, but has optimum coding gain; the second possesses characteristics that are close to the irrational BWFB with maximum VMs by Cohen et al.; and the last which has binary coefficients can realize a multiplication-free discrete wavelet transform. In addition, two BWFBs are systematically verified to exhibit performance competitive to several state-of-the-art BWFBs for image compression, and yet require lower computational costs. This work was supported by the Natural Science Foundation of Jiangsu province, China under Grant 07KJD520005.  相似文献   
100.
介绍MIMO技术的定义和历史,从空间复用、传输分集技术、波束成型等方面对MIMO技术进行说明,并对MIMO在3G(HSPA+)中的应用做了简单的描述。  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