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   25583篇
  免费   3705篇
  国内免费   2145篇
电工技术   1166篇
技术理论   5篇
综合类   2532篇
化学工业   2165篇
金属工艺   1796篇
机械仪表   2247篇
建筑科学   1834篇
矿业工程   888篇
能源动力   529篇
轻工业   624篇
水利工程   813篇
石油天然气   706篇
武器工业   1683篇
无线电   5224篇
一般工业技术   3425篇
冶金工业   1202篇
原子能技术   558篇
自动化技术   4036篇
  2024年   195篇
  2023年   534篇
  2022年   1004篇
  2021年   1120篇
  2020年   1115篇
  2019年   883篇
  2018年   803篇
  2017年   970篇
  2016年   1174篇
  2015年   1312篇
  2014年   1818篇
  2013年   1870篇
  2012年   2028篇
  2011年   2275篇
  2010年   1686篇
  2009年   1583篇
  2008年   1446篇
  2007年   1682篇
  2006年   1419篇
  2005年   1227篇
  2004年   947篇
  2003年   809篇
  2002年   629篇
  2001年   551篇
  2000年   474篇
  1999年   373篇
  1998年   294篇
  1997年   218篇
  1996年   219篇
  1995年   153篇
  1994年   156篇
  1993年   96篇
  1992年   81篇
  1991年   62篇
  1990年   64篇
  1989年   41篇
  1988年   31篇
  1987年   15篇
  1986年   10篇
  1985年   9篇
  1984年   9篇
  1983年   8篇
  1982年   6篇
  1980年   4篇
  1979年   3篇
  1965年   3篇
  1962年   2篇
  1961年   2篇
  1959年   7篇
  1956年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
People have knowledge about relationships (i.e., relational schemas) that is based on their experiences. Because most people have experience with complementary behavior (interaction partners behaving similarly in terms of affiliation but oppositely in terms of control), they expect complementary behavior in their relationships. Like other beliefs about relationships, expectations of complementarity affect self-construal. The authors provide evidence for complementary self-construal; people assimilate to relevant relationship partners on the affiliation dimension and contrast on the control dimension. Consistent with the proposed role of relationship knowledge in these effects, complementary self-construal was moderated by the familiarity of the target, whether people focused on their relationship with or the appearance of the target, and whether the context was relevant for the interpersonal dimension. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
In a change detection paradigm, a target object in a natural scene either rotated in depth, was replaced by another object token, or remained the same. Change detection performance was reliably higher when a target postcue allowed participants to restrict retrieval and comparison processes to the target object (Experiment 1). Change detection performance remained excellent when the target object was not attended at change (Experiment 2) and when a concurrent verbal working memory load minimized the possibility of verbal encoding. (Experiment 3). Together, these data demonstrate that visual representations accumulate in memory from attended objects as the eyes and attention are oriented within a scene and that change blindness derives, at least in part, from retrieval and comparison failure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
53.
卡尔曼滤波器在光电经纬仪中的应用   总被引:6,自引:2,他引:4  
为了解决光电经纬仪电视跟踪系统脱靶量滞后对控制系统跟踪精度及稳定性的影响,将预测滤波技术应用到光电跟踪系统中,提出了极坐标下卡尔曼滤波算法,目标模型采用等速运动并附有时间相关的随机加速度,增加了延时补偿。仿真结果表明,跟踪误差减小,当跟踪目标从视场消失时,控制系统按照预测的目标信息跟踪。  相似文献   
54.
Legal liabilities pertaining to the identification and selection of domain experts is an issue that could adversely impact expert systems developers. Problems pertaining to flawed knowledge, improperly defined expertise, and behavioural and psychological impediments are just some of the issues. This paper examines the torts of strict products liability and negligence that system developers could incur as a result of expert-related difficulties. Parallels from legal scholars and federal and state court decisions are discussed relevant to expert system projects and developers. The paper concludes with a presentation of steps that systems developers can take to minimize potential legal liability.  相似文献   
55.
In the early eighties, at the Boris Kidrich Institute Vincha, a method for measuring specific heat and electrical resistivity of electrical conductors in the millisecond resolution range was developed for measurements from room temperature to 1900 K. Over a period of nearly 10 years, the method was applied to different materials, including pure metals, ferrous, and nickel/ chromium alloys, and to the characterization of candidate materials for thermophysical property reference standards. This paper describes the method and reviews the results obtained in specific heat and electrical resistivity studies of ferromagnetic and other materials. The paper also demonstrates capabilities of the method for describing phase transitions or anomalies in pure metals (Fe, Co, Ni) or alloys (Nichrome, austenitic stainless steel).Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy.  相似文献   
56.
用自制的旋臂式磨蚀实验仪,研究了5种高密度聚乙烯和1种顺丁橡胶改性的高密度聚乙烯,在铁尾矿和铁精矿浆体中的耐磨蚀性。耐磨蚀性最差的是HDPE2200J,耐磨蚀性较差的是HDPE6300M;HDPE5000s,6098和2480的耐磨蚀性较好;HDPE/cis-BR的耐磨蚀性最好。  相似文献   
57.
The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties.  相似文献   
58.
哈兹列特铝板带连铸连轧工艺已被成功地用于铝和铝合金冲击挤压用坯料的生产。在对哈氏四个有关用户扫描的基础上,列举了其产品及其用途,并介绍了相关工艺及其优点。  相似文献   
59.
分析了型钢厂试制热轧美标H型钢低温冲击韧性偏低的原因,并在此基础上提出了对生产工艺的优化与改进。  相似文献   
60.
The prospects for rapid near-term development of a synfuel industry in the USA have decreased, due to depressed world oil prices, synfuel project cost overruns, and the lukewarm support of the Reagan administration. Nonetheless, socioeconomic and environmental impact analysis studies can provide valuable information for determining the regional welfare effects of proposed projects. The author discusses the results of a regional econometric analysis of the synfuel projects planned for Western Kentucky, which focuses on environmental impacts, and reveals the inevitable trade-offs that would accompany synfuel development. Some policy issues are briefly reviewed, especially that of efficient energy pricing.  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