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   1745篇
  免费   179篇
  国内免费   68篇
电工技术   134篇
综合类   128篇
化学工业   86篇
金属工艺   32篇
机械仪表   37篇
建筑科学   188篇
矿业工程   14篇
能源动力   71篇
轻工业   100篇
水利工程   96篇
石油天然气   17篇
武器工业   6篇
无线电   125篇
一般工业技术   211篇
冶金工业   439篇
原子能技术   13篇
自动化技术   295篇
  2024年   6篇
  2023年   26篇
  2022年   43篇
  2021年   51篇
  2020年   52篇
  2019年   56篇
  2018年   56篇
  2017年   70篇
  2016年   74篇
  2015年   66篇
  2014年   94篇
  2013年   99篇
  2012年   99篇
  2011年   136篇
  2010年   91篇
  2009年   98篇
  2008年   87篇
  2007年   112篇
  2006年   106篇
  2005年   90篇
  2004年   78篇
  2003年   99篇
  2002年   75篇
  2001年   54篇
  2000年   19篇
  1999年   30篇
  1998年   14篇
  1997年   14篇
  1996年   12篇
  1995年   6篇
  1994年   14篇
  1993年   4篇
  1992年   5篇
  1991年   2篇
  1990年   4篇
  1989年   4篇
  1988年   2篇
  1987年   3篇
  1982年   2篇
  1981年   2篇
  1978年   2篇
  1965年   2篇
  1964年   2篇
  1963年   5篇
  1961年   8篇
  1959年   1篇
  1958年   1篇
  1957年   1篇
  1956年   3篇
  1955年   3篇
排序方式: 共有1992条查询结果,搜索用时 953 毫秒
61.
在秦山三期重水堆双机组调试成功实践的基础上,分析、探讨了缩短核电站工程调试工期的若干方法,这些方法对大型项目的管理及其优化具有一定的参考价值。  相似文献   
62.
消费者网上购买行为感知风险动态模型研究   总被引:6,自引:0,他引:6  
感知风险对消费者购买行为的解释作用越来越重要。消费者网上购物过程中的感知风险不同于传统环境中的感知风险。本研究在探讨网上购物感知风险的含义、纬度及影响因素的基础上提出了网上购买行为感知风险的动态模型,模型中包括了影响消费者风险感知的因素、细化的消费者感知风险纬度以及可接受风险水平对消费者总体感知风险和减少风险行为的调节作用。  相似文献   
63.
The authors surveyed 347 public sector employees on 4 measurement occasions to investigate the conceptual distinctiveness of the psychological contract and perceived organizational support (POS) and how they are associated over time. Results support the distinctiveness of the 2 concepts. In terms of their interrelationships over time, by drawing on psychological contract theory the authors found little support for a reciprocal relationship between POS and psychological contract fulfillment. Under an alternative set of hypotheses, by drawing on organizational support theory and by separating psychological contract fulfillment into its 2 components (perceived employer obligations and inducements), the authors found that perceived employer inducements were positively related to POS, which, in turn, was negatively related to perceived employer obligations. The results suggest that POS and the components of psychological contract fulfillment are more important in predicting organizational citizenship behavior than psychological contract fulfillment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
64.
Participants (N = 216) were administered a differential implicit learning task during which they were trained and tested on 3 maximally distinct 2nd-order visuomotor sequences, with sequence color serving as discriminative stimulus. During training, 1 sequence each was followed by an emotional face, a neutral face, and no face, using backward masking. Emotion (joy, surprise, anger), face gender, and exposure duration (12 ms, 209 ms) were varied between participants; implicit motives were assessed with a picture-story exercise. For power-motivated individuals, low-dominance facial expressions enhanced and high-dominance expressions impaired learning. For affiliation-motivated individuals, learning was impaired in the context of hostile faces. These findings did not depend on explicit learning of fixed sequences or on awareness of sequence-face contingencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
65.
The authors investigated the relationship between stress at initial cancer diagnosis and treatment and subsequent quality of life (QoL). Women (n = 112) randomized to the assessment-only arm of a clinical trial were initially assessed after breast cancer diagnosis and surgery and then reassessed at 4 months (during adjuvant treatment) and 12 months (postadjuvant treatment). There were 3 types of stress measured: number of stressful life events (K. A. Matthews et al., 1997), cancer-related traumatic stress symptoms (M. J. Horowitz, N. Wilner, & W. Alvarez, 1979), and perceived global stress (S. Cohen, T. Kamarck, & R. Mermelstein, 1983). Using hierarchical multiple regressions, the authors found that stress predicted both psychological and physical QoL (J. E. Ware, K. K. Snow, & M. Kosinski, 2000) at the follow-ups (all ps  相似文献   
66.
The “median” method for the reduction of the effect of noise and trigger jitter on waveform data is described. The effectiveness of this method was examined using simulations and experiments and, for typical jitter and noise observed in electrical pulse metrology, is shown to provide reconstructed waveforms with transition durations that accurately match those of the input signal. Also, for aberrations, an upper bound on the error in the amplitude of the aberration is provided.  相似文献   
67.
随着化工及军工企业的扩建,防爆起重机作为一种特殊用途的起重机需求量与日俱增,寻求设计出更为先进实用的产品来满足生产的需要已成为起重机生产厂的目标。目前在防爆起重机的变频调速不很成熟的前提下,对双速电机的控制方案作进一步改进已成为必要。  相似文献   
68.
对国内外有关混凝土耐久性的研究成果进行系统分析,重点解决了混凝土耐久性中的众多影响因素、程度的确定及其量化表示等问题,利用神经网络技术解决了知识表示及其推理技术中的复杂性和不确定性问题,设计了推理机,建立了知识库,建立了考虑耐久性破坏因素的碱集料反应、冻性、钢筋锈蚀、硫酸盐侵蚀的混凝土耐久性专家系统。  相似文献   
69.
In behavioral tests, rats performed learned escape responses to thermal stimulation of the paws by 44.0. 47.0. or 0.3 degrees C. Licking, guarding, and jumping reflexes were evaluated at these temperatures. The frequency, latency, and duration of escape and reflex responses were compared and were related to hind-paw skin temperatures measured during stimulation of awake and anesthetized rats. The duration and latency of escape from heat were appropriately related to stimulus intensity. Escape occurred reliably for each intensity. Reflexes occurred unreliably and at long latency to 44.0 or 0.3 degrees C and were not appropriately related to heat intensity. The reflexes were relatively insensitive to thermal nociceptive stimulation other than heating of the skin at a high rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
70.
Prior theory and research suggests a positive relation between perceived victimization and overt anger. The authors proposed and tested a theoretical extension of this link by investigating possible moderating effects of individual and contextual variables. A sample of 158 employees of a municipality was used to test hypotheses that the relationship between perceived victimization and overt anger is moderated by hostile attributional style and perceptions of organizational norms. The results showed that the relation between perceptions of direct victimization and overt anger was stronger when the employee had a more rather than less hostile attributional style and when the employee perceived the organizational norms as more rather than less oppositional. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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