全文获取类型
收费全文 | 5761篇 |
免费 | 83篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 73篇 |
综合类 | 3篇 |
化学工业 | 1001篇 |
金属工艺 | 117篇 |
机械仪表 | 162篇 |
建筑科学 | 302篇 |
矿业工程 | 47篇 |
能源动力 | 134篇 |
轻工业 | 397篇 |
水利工程 | 29篇 |
石油天然气 | 21篇 |
无线电 | 508篇 |
一般工业技术 | 791篇 |
冶金工业 | 1669篇 |
原子能技术 | 44篇 |
自动化技术 | 553篇 |
出版年
2022年 | 42篇 |
2021年 | 59篇 |
2018年 | 48篇 |
2017年 | 55篇 |
2016年 | 70篇 |
2015年 | 55篇 |
2014年 | 68篇 |
2013年 | 319篇 |
2012年 | 111篇 |
2011年 | 161篇 |
2010年 | 129篇 |
2009年 | 149篇 |
2008年 | 141篇 |
2007年 | 188篇 |
2006年 | 149篇 |
2005年 | 150篇 |
2004年 | 126篇 |
2003年 | 120篇 |
2002年 | 144篇 |
2001年 | 101篇 |
2000年 | 99篇 |
1999年 | 131篇 |
1998年 | 316篇 |
1997年 | 214篇 |
1996年 | 181篇 |
1995年 | 127篇 |
1994年 | 148篇 |
1993年 | 138篇 |
1992年 | 79篇 |
1991年 | 62篇 |
1990年 | 88篇 |
1989年 | 84篇 |
1988年 | 84篇 |
1987年 | 86篇 |
1986年 | 93篇 |
1985年 | 74篇 |
1984年 | 85篇 |
1983年 | 68篇 |
1982年 | 75篇 |
1981年 | 69篇 |
1980年 | 73篇 |
1979年 | 86篇 |
1978年 | 70篇 |
1977年 | 87篇 |
1976年 | 87篇 |
1975年 | 68篇 |
1974年 | 71篇 |
1973年 | 52篇 |
1971年 | 44篇 |
1970年 | 45篇 |
排序方式: 共有5851条查询结果,搜索用时 15 毫秒
1.
Many models of spoken word recognition posit the existence of lexical and sublexical representations, with excitatory and inhibitory mechanisms used to affect the activation levels of such representations. Bottom-up evidence provides excitatory input, and inhibition from phonetically similar representations leads to lexical competition. In such a system, long words should produce stronger lexical activation than short words, for 2 reasons: Long words provide more bottom-up evidence than short words, and short words are subject to greater inhibition due to the existence of more similar words. Four experiments provide evidence for this view. In addition, reaction-time-based partitioning of the data shows that long words generate greater activation that is available both earlier and for a longer time than is the case for short words. As a result, lexical influences on phoneme identification are extremely robust for long words but are quite fragile and condition-dependent for short words. Models of word recognition must consider words of all lengths to capture the true dynamics of lexical activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
3.
Broadline nuclear magnetic resonance measurements have been carried out for the proton resonance in oriented poly(vinylidene fluoride). The spectra in general show two component lines with distinctly different line widths. The broad component shows a high degree of molecular orientation and can be satisfactorily assigned to the crystalline regions of the polymer. The narrow component corresponds to an oriented non crystalline phase which is sufficiently constrained to allow motion about the chain axis only. An appreciable decrease in the value of the rigid mass fraction was observed in both of the samples over the temperature range examined. Our calculations indicate that this could play an important role in the temperature dependence of the pyroelectric response of this material. 相似文献
4.
Arthur W. Westerberg 《Computers & Chemical Engineering》1985,9(5):421-429
The last dozen years have produced almost 50 English language articles on the synthesis of separation systems [1]. Most work has considered separating a single relatively ideal mixture into sharply split, usually pure-component products using systems of single-feed, two-product distillation columns. Of late, the work has considered heat-integrating these columns to reduce energy consumption. Present research will very likely produce valuable results for nonsharp separations.Earlier approaches developed both algorithmic- and heuristic-based tree search algorithms for discovering the better systems of non-heat-integrated columns. New results permit the design of heat-integrated systems.The paper highlights the above developments. 相似文献
5.
The article proposes a theoretical framework in which moral reasoning about mediated crime and punishment is defined and combined with existing, affect-driven entertainment theory to yield an integrated theory of enjoyment. The authors analyze how crime dramas serve as statements about justice and then address how moral deliberation about the propriety of those statements impacts enjoyment. The authors report research findings to support the analysis of cognitive processing during crime dramas distinct from affective processing. The article also suggests future means by which the integrated theory of enjoyment can be examined. 相似文献
6.
Uncooled DBR laser directly Modulated at 3.125 gb/s as athermal transmitter for low-cost WDM systems
Yiran Liu Davies A.R. Ingham J.D. Penty R.V. White I.H. 《Photonics Technology Letters, IEEE》2005,17(10):2026-2028
An uncooled three-section tunable distributed Bragg reflector laser is demonstrated as an athermal transmitter for low-cost uncooled wavelength-division-multiplexing (WDM) systems with tight channel spacing. A /spl plusmn/0.02-nm thermal wavelength drift is achieved under continuous-wave operation up to 70/spl deg/C. Dynamic sidemode suppression ratio of greater than 35 dB is consistently obtained under 3.125-Gb/s direct modulation over a 20/spl deg/C-70/spl deg/C temperature range, with wavelength variation of as low as /spl plusmn/0.2 nm. This indicates that more than an order of magnitude reduction in coarse WDM channel spacing is possible using this source. 相似文献
7.
Norris Fran H.; Murphy Arthur D.; Baker Charlene K.; Perilla Julia L.; Rodriguez Francisco Gutiérrez; Rodriguez José de Jesús Gutiérrez 《Canadian Metallurgical Quarterly》2003,112(4):646
Prevalence rates of trauma and posttraumatic stress disorder (PTSD) were estimated from a probability sample of 2,509 adults from 4 cities in Mexico. PTSD was assessed according to Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994) criteria using the Composite International Diagnostic Interview (CIDI; WHO, 1997). Lifetime prevalence of exposure and PTSD were 76% and 11.2%, respectively. Risk for PTSD was highest in Oaxaca (the poorest city), persons of lower socioeconomic status, and women. Conditional risk for PTSD was highest following sexual violence, but nonsexual violence and traumatic bereavement had greater overall impact because of their frequency. Of lifetime cases, 62% became chronic; only 42% received medical or professional care. The research demonstrates the importance of expanding the epidemiologic research base on trauma to include developing countries around the world. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
In Exp I, 46 male and 51 female undergraduates witnessed a filmed incident and later described the target. Results show that Ss who observed a composite containing misleading information (either incorrect hair or an added moustache) were significantly more likely to misreport hairstyle and the presence of a moustache than those who did not. In Exp II, 210 17–65 yr old Ss observed a filmed incident and were tested for their recall and recognition of the target either immediately or after delays of 2 or 7 days. Significant bias, consistent with the content of the misleading composite, was present for both cued recall and choice of mug shot in a photo spread. The effect did not increase over delay but was greater when the composite was seen just prior to recall than immediately after the incident. Implications concerning interference with the memory of the witness who produced the composite and for other witnesses exposed to the misleading composite are discussed. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Roberson Debi; Davidoff Jules; Davies Ian R. L.; Shapiro Laura R. 《Canadian Metallurgical Quarterly》2004,133(4):554
This study unites investigations into the linguistic relativity of color categories with research on children's category acquisition. Naming, comprehension, and memory for colors were tracked in 2 populations over a 3-year period. Children from a seminomadic equatorial African culture, whose language contains 5 color terms, were compared with a group of English children. Despite differences in visual environment, language, and education, they showed similar patterns of term acquisition. Both groups acquired color vocabulary slowly and with great individual variation. Those knowing no color terms made recognition errors based on perceptual distance, and the influence of naming on memory increased with age. An initial perceptually driven color continuum appears to be progressively organized into sets appropriate to each culture and language. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
The objective of this paper is to identify and analyse factors that are important for winning acceptance of wind-energy parks on the local level. The developers of wind-energy parks need to know how to manage “social acceptance” at the different stages of planning, realisation and operation. Five case studies in France and Germany focused on factors of success in developing a wind-energy project on a given site and illuminated how policy frameworks influence local acceptance. Our hypothesis is that these factors fall into two categories: institutional conditions, such as economic incentives and regulations; and site-specific conditions (territorial factors), such as the local economy, the local geography, local actors, and the actual on-site planning process (project management). 相似文献