全文获取类型
收费全文 | 9027篇 |
免费 | 230篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 93篇 |
综合类 | 13篇 |
化学工业 | 1799篇 |
金属工艺 | 140篇 |
机械仪表 | 116篇 |
建筑科学 | 497篇 |
矿业工程 | 50篇 |
能源动力 | 213篇 |
轻工业 | 827篇 |
水利工程 | 109篇 |
石油天然气 | 59篇 |
无线电 | 559篇 |
一般工业技术 | 1240篇 |
冶金工业 | 2436篇 |
原子能技术 | 103篇 |
自动化技术 | 1013篇 |
出版年
2022年 | 83篇 |
2021年 | 122篇 |
2020年 | 99篇 |
2019年 | 97篇 |
2018年 | 111篇 |
2017年 | 108篇 |
2016年 | 127篇 |
2015年 | 112篇 |
2014年 | 171篇 |
2013年 | 445篇 |
2012年 | 295篇 |
2011年 | 363篇 |
2010年 | 292篇 |
2009年 | 314篇 |
2008年 | 373篇 |
2007年 | 364篇 |
2006年 | 320篇 |
2005年 | 271篇 |
2004年 | 244篇 |
2003年 | 253篇 |
2002年 | 224篇 |
2001年 | 158篇 |
2000年 | 152篇 |
1999年 | 153篇 |
1998年 | 175篇 |
1997年 | 151篇 |
1996年 | 154篇 |
1995年 | 166篇 |
1994年 | 154篇 |
1993年 | 148篇 |
1992年 | 144篇 |
1991年 | 105篇 |
1990年 | 123篇 |
1989年 | 133篇 |
1988年 | 135篇 |
1987年 | 124篇 |
1986年 | 133篇 |
1985年 | 160篇 |
1984年 | 141篇 |
1983年 | 130篇 |
1982年 | 135篇 |
1981年 | 140篇 |
1980年 | 101篇 |
1979年 | 134篇 |
1978年 | 125篇 |
1977年 | 113篇 |
1976年 | 107篇 |
1975年 | 93篇 |
1974年 | 101篇 |
1973年 | 103篇 |
排序方式: 共有9267条查询结果,搜索用时 15 毫秒
11.
Erv J. Kuhlmann Dick Y. Jung Richard P. Guptill Charles A. Dyke Hyung K. Zang 《Fuel》1985,64(11):1552-1557
The presence of hydroaromatic, hydrogen donor components in a coal-derived solvent is one of the more important factors in the successful operation of a non-catalytic coal liquefaction process. Various hydrogen donor species present in a hydrogenated creosote oil have been identified. Their rate of disappearance under conditions that are consistent with a short residence time coal liquefaction process has been used to rank the reactivities of the various hydrogen donors. 1,2,3,10b-Tetrahydrofluoranthene was found to be an exceptional donor while 4,5-dihydropyrene, the hexahydropyrenes and 9,10-dihydrophenanthrene were found to be quite active. Sym.-octahydrophenanthrene and 2a,3,4,5-tetrahydroacenaphthene exhibited moderate activity. Tetralin and the four methyltetralin isomers were found to be unreactive under the coal liquefaction conditions employed. 相似文献
12.
Reports an error in "Interactive use of lexical information in speech perception" by Cynthia M. Connine and Charles Clifton (Journal of Experimental Psychology: Human Perception and Performance, 1987[May], Vol 13[2], 291-299). In the aforementioned article, Figures 1 and 2 were inadvertently transposed. The figure on p. 294 is actually Figure 2, and the figure on p. 296 is actually Figure 1. The captions are correct as they stand. (The following abstract of the original article appeared in record 1987-23984-001.) Two experiments are reported that demonstrate contextual effects on identification of speech voicing continua. Experiment 1 demonstrated the infuence of lexical knowledge on identification of ambiguous tokens from word–nonword and nonword–word continua. Reaction times for word and nonword responses showed a word advantage only for ambiguous stimulus tokens (at the category boundary); no word advantage was found for clear stimuli (at the continua endpoints). Experiment 2 demonstrated an effect of a postperceptual variable, monetary payoff, on nonword–nonword continua. Identification responses were influenced by monetary payoff, but reaction times for bias-consistent and bias-inconsistent responses did not differ at the category boundary. An advantage for bias-consistent responses was evident at the continua endpoints. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
Penedo Frank J.; Dahn Jason R.; Gonzalez Jeffrey S.; Molton Ivan; Carver Charles S.; Antoni Michael H.; Roos Bernard A.; Schneiderman Neil 《Canadian Metallurgical Quarterly》2003,22(2):220
This study evaluated relations among optimism, perceived stress management skills (PSMS), and positive mood in 46 men who had surgical treatment for localized prostate cancer. The authors found that optimism, PSMS, and positive mood scores were positively correlated. Positive mood was unrelated to demographic and disease-related control variables. In a hierarchical regression model controlling for PSMS, the relationship between optimism and positive mood became nonsignificant, whereas PSMS remained a correlate of positive mood. Results suggest that the relationship between optimism and positive mood may be mediated by belief in being able to use stress management techniques effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
Wiltrout Charles; Dogra Samriti; Linster Christiane 《Canadian Metallurgical Quarterly》2003,117(2):236
Studies on odor mixture perception suggest that although odor components can often be identified in mixtures, mixtures can also give rise to novel perceptual qualities that are not present in the components. Using an olfactory habituation task, the authors evaluated how the perceptual similarity between components in a mixture affects the perceptual quality of the mixture itself. Rats perceived binary mixtures composed of similar components as different from their 2 components, whereas binary mixtures composed of dissimilar components were perceived as very similar to their components. Results show that for both types of mixtures, pretraining to Component A reduces subsequent learning about Component B in rats trained in the presence of A. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
Wilcox Sara; Evenson Kelly R.; Aragaki Aaron; Wassertheil-Smoller Sylvia; Mouton Charles P.; Loevinger Barbara Lee 《Canadian Metallurgical Quarterly》2003,22(5):513
This study examined whether widowhood was associated with physical and mental health, health behaviors, and health outcomes using a cross-sectional (N=72,247) and prospective (N=55,724) design in women aged 50-79 years participating in the Women's Health Initiative observational study (85.4% White). At baseline, married women reported better physical and mental health and generally better health behaviors than widowed women. Whereas women who remained married over the 3-year period showed stability in mental health, recent widows experienced marked impairments and longer term widows showed stability or slight improvements. Both groups of widows reported more unintentional weight loss over the 3-year period. Changes in physical health and health behaviors were inconsistent, with generally small effect sizes. Findings underscore the resilience of older women and their capacity to reestablish connections, but point to the need for services that strengthen social support among women who have difficulty during this transition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
17.
18.
Amador F.G. Berman D. Borning A. DeRose T. Finkelstein A. Neville D. Notkin D. Salesin D. Salisbury M. Sherman J. Sun Y. Weld D.S. Winkenbach G. 《Knowledge and Data Engineering, IEEE Transactions on》1993,5(4):611-618
The electronic encyclopedia exploratorium (E3) is a vision of a future computer system-an electronic book describing how thing work. Typical articles in E3 will describe such mechanisms as compression refrigerators, engines, telescopes, and mechanical linkages. Each article will provide simulations, three-dimensional animated graphics that the user can manipulate, laboratory areas that allow a user to modify the device or experiment with related artifacts, and a facility for asking questions and receiving customized, computer-generated English-language explanations. Some of the foundational technology is discussed, focusing on topics in artificial intelligence, graphics, and user interfaces. The initial prototype system and the technical lessons learned from it, as well as the second prototype currently under construction, are described 相似文献
19.
Orthopedists being more engaged in surgery are often asked about problems concerning exercise science. This article will summarize the existing basic knowledge, very close to practice, and put down the leading steps of how to build up a (therapeutical) training programme. A lab block is recommended acting on a preventive as well as on a sportive medical base. 相似文献
20.
Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies. 相似文献