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   33317篇
  免费   882篇
  国内免费   72篇
电工技术   377篇
综合类   41篇
化学工业   6832篇
金属工艺   871篇
机械仪表   636篇
建筑科学   1868篇
矿业工程   256篇
能源动力   1028篇
轻工业   2772篇
水利工程   338篇
石油天然气   239篇
武器工业   5篇
无线电   2161篇
一般工业技术   5219篇
冶金工业   6656篇
原子能技术   328篇
自动化技术   4644篇
  2022年   205篇
  2021年   394篇
  2020年   338篇
  2019年   405篇
  2018年   492篇
  2017年   516篇
  2016年   525篇
  2015年   473篇
  2014年   748篇
  2013年   2147篇
  2012年   1260篇
  2011年   1608篇
  2010年   1188篇
  2009年   1273篇
  2008年   1451篇
  2007年   1484篇
  2006年   1272篇
  2005年   1182篇
  2004年   1061篇
  2003年   1028篇
  2002年   1041篇
  2001年   643篇
  2000年   620篇
  1999年   577篇
  1998年   602篇
  1997年   502篇
  1996年   607篇
  1995年   547篇
  1994年   533篇
  1993年   534篇
  1992年   487篇
  1991年   321篇
  1990年   438篇
  1989年   424篇
  1988年   379篇
  1987年   425篇
  1986年   382篇
  1985年   515篇
  1984年   491篇
  1983年   443篇
  1982年   464篇
  1981年   445篇
  1980年   353篇
  1979年   365篇
  1978年   329篇
  1977年   307篇
  1976年   268篇
  1975年   318篇
  1974年   243篇
  1973年   279篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
Abstract. Historians of science have labeled followers of the 18th cosmologist John Hutchinson (1674– 1737) as anti‐Newtonian. While Hutchinson was clearly anti‐Newtonian, this was not the case with later followers like George Horne and William Jones. Horne and Jones sought a rapprochement between Newton and Hutchinson; in their hands, interpretations of Newton's works were refashioned to support Hutchinson's biblically based cosmos and Trinitarian natural philosophy. Newton's thought could be used by conservative Anglican Churchmen to battle religious heterodoxy. This raises problems for traditional Enlightenment historiography which views Newtonianism as a set of ideas which supported and reinforced emerging modern forms of political and religious thought.  相似文献   
182.
Five individuals participated in an extensive practice study (10 1-hr sessions, 11,000 trials total) on a self-paced identity-judgment n-back task (n ranging from 1 to 5). Within Session 1, response time increased abruptly by about 300 ms in passing from n = 1 to n > 1, suggesting that the focus of attention can accommodate only a single item (H. Caravan, 1998; B. McElree, 2001). Within Session 10, response time was dramatically reduced and increased linearly with n for n ≤ 4, with a slope of about 30 ms. The data suggest that working memory consists of a focus of attention governed by a limited-capacity search, expandable through practice, and a content-addressable region outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
183.
There are a large number of standards concerned with gasketed joints in the UK that are derived from the applications and practice of different industries. Many other countries also have equivalent standards. John Hoyes, technical director of Flexitallic and chairman of the British Standards Committee concerned with gaskets describes the European initiatives to rationalize the standards and improve the technical basis by which they will lead a user to select the joint design and material.  相似文献   
184.
Many organisations suspect that their internal security threat is more pressing than their external security threat. The internal threat is predominantly the result of poor user security behaviour. Yet, despite that, security awareness programmes often seem more likely to put users to sleep than to improve their behaviour. This article discusses the influences that affect a user's security behaviour and outlines how a well structured approach focused on improving behaviour could be an excellent way to take security slack out of an organisation and to achieve a high return for a modest, low-risk investment.  相似文献   
185.
The present study estimated the unique contribution of self-efficacy to work-related performance controlling for personality (the Big 5 traits), intelligence or general mental ability, and job or task experience. Results, based on a meta-analysis of the relevant literatures, revealed that overall, across all studies and moderator conditions, the contribution of self-efficacy relative to purportedly more distal variables is relatively small. Within moderator categories, there were several cases in which self-efficacy made unique contributions to work-related performance. For example, self-efficacy predicted performance in jobs or tasks of low complexity but not those of medium or high complexity, and self-efficacy predicted performance for task but not job performance. Overall, results suggest that the predictive validity of self-efficacy is attenuated in the presence of individual differences, though this attenuation does depend on the context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
186.
The judged likelihood of a focal outcome should generally decrease as the list of alternative possibilities increases. For example, the likelihood that a runner will win a race goes down when 2 new entries are added to the field. However, 6 experiments demonstrate that the presence of implausible alternatives (duds) often increases the judged likelihood of a focal outcome. This dud-alternative effect was detected for judgments involving uncertainty about trivia facts and stochastic events. Nonnumeric likelihood measures and betting measures reliably detected the effect, but numeric likelihood measures did not. Time pressure increased the magnitude of the effect. The results were consistent with a contrast-effect account: The inclusion of duds increases the perceived strength of the evidence for the focal outcome, thereby affecting its judged likelihood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
187.
A meta-analytic review of group comparison design studies evaluating peer-assisted learning (PAL) interventions with elementary school students produced positive effect sizes (ESs) indicating increases in achievement (unweighted mean ES = 0.59, SD = 0.90; weighted ES, d = 0.33, p  相似文献   
188.
A combination of dynamic shear rheology, thermomechanical analysis (TMA), scanning electron microscopy (SEM), Near-Edge X-ray Absorption Fine Structure (NEXAFS), and fracture toughness testing was utilized to characterize the thermal, mechanical, chemical, and fracture properties of alumina (α-Al2O3)-filled epoxy resins as a function of average filler size, size distribution, particle shape, loading, and epoxy crosslink density. In general the cured properties of the filled composites were robust. Small changes in particle size, shape, and size distribution had little impact on the final properties. Resin crosslink density and filler loading were the most critical variables, causing changes in all properties. However, most applications could likely tolerate small changes in these variables also. SEM and NEXAFS characterization of the fracture surfaces revealed that the fracture occurs at the filler interface and the interfacial epoxy composition is similar to the bulk resin, indicating a weak epoxy-alumina interaction. These results are critical for implementation of particulate-filled polymer composites in practical applications because relaxed material specifications and handling procedures can be incorporated in production environments to improve efficiency.  相似文献   
189.
Five studies examined the hypotheses that when people experience positive affect, those low in self-esteem are especially likely to dampen that affect, whereas those high in self-esteem are especially likely to savor it. Undergraduate participants' memories for a positive event (Study 1) and their reported reactions to a success (Study 2) supported the dampening prediction. Results also suggest that dampening was associated with worse mood the day after a success (Study 2), that positive and negative affect regulation are distinct, that self-esteem is associated with affect regulation even when Neuroticism and Extraversion are controlled (Studies 3 and 4), and that self-esteem may be especially important for certain types of positive events and positive affect regulation (Study 5). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
190.
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