全文获取类型
收费全文 | 6219篇 |
免费 | 537篇 |
国内免费 | 479篇 |
专业分类
电工技术 | 276篇 |
技术理论 | 1篇 |
综合类 | 616篇 |
化学工业 | 1089篇 |
金属工艺 | 553篇 |
机械仪表 | 441篇 |
建筑科学 | 370篇 |
矿业工程 | 260篇 |
能源动力 | 97篇 |
轻工业 | 172篇 |
水利工程 | 64篇 |
石油天然气 | 175篇 |
武器工业 | 51篇 |
无线电 | 561篇 |
一般工业技术 | 941篇 |
冶金工业 | 641篇 |
原子能技术 | 27篇 |
自动化技术 | 900篇 |
出版年
2024年 | 16篇 |
2023年 | 74篇 |
2022年 | 87篇 |
2021年 | 140篇 |
2020年 | 128篇 |
2019年 | 143篇 |
2018年 | 159篇 |
2017年 | 213篇 |
2016年 | 197篇 |
2015年 | 225篇 |
2014年 | 307篇 |
2013年 | 354篇 |
2012年 | 455篇 |
2011年 | 479篇 |
2010年 | 371篇 |
2009年 | 373篇 |
2008年 | 389篇 |
2007年 | 461篇 |
2006年 | 415篇 |
2005年 | 337篇 |
2004年 | 281篇 |
2003年 | 284篇 |
2002年 | 211篇 |
2001年 | 180篇 |
2000年 | 135篇 |
1999年 | 133篇 |
1998年 | 108篇 |
1997年 | 97篇 |
1996年 | 62篇 |
1995年 | 66篇 |
1994年 | 48篇 |
1993年 | 37篇 |
1992年 | 35篇 |
1991年 | 33篇 |
1990年 | 29篇 |
1989年 | 21篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 24篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 3篇 |
1979年 | 7篇 |
1964年 | 3篇 |
1963年 | 4篇 |
1959年 | 2篇 |
1956年 | 3篇 |
1955年 | 6篇 |
排序方式: 共有7235条查询结果,搜索用时 15 毫秒
32.
A series of short fibre reinforced styrene butadiene rubber (SBR) composites were prepared by incorporating sisal fibres of
different lengths and different concentrations. The vulcanization behaviour and the properties of the vulcanizates were measured
by the relevant ASTM procedures. The processing characteristics such as green strength and mill shrinkage were improved by
the addition of fibres. The properties like tensile strength, tear strength, moduli at 10% and 20% elongations were found
to be maximum for composites containing longitudinally oriented fibres of length 6 mm. Mixes containing 35 phr loading of
fibres and bonding agent showed better mechanical performance than others. The failure behaviour of tensile and tear specimens
have been analysed by scanning electron microscopy techniques.
Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995 相似文献
33.
34.
H. Heckhausen and J. Kuhl's (1985) goal typology provided the conceptual foundation for this research, which examined the independent and integrated effects of achievement orientation and goal-setting approaches on trainees' self-regulatory activity. Using a complex computer-based simulation, the authors examined the effects of 3 training design factors--goal frame, goal content, and goal proximity--cutting across these 2 theoretical domains on the nature, focus, and quality of the self-regulatory activities of 524 trainees. Results revealed that all 3 factors had a significant influence on self-regulation, with goal content exhibiting the greatest influence. In line with expectations, congruent learning frame and content compared with congruent performance frame and content was beneficial for trainees' self-regulatory activity, incongruent combinations of goal frame and content were better than congruent performance frames and content, and effects for the incongruent combinations cutting across the domains were asymmetrical. Theoretical extensions for further disentangling these distinct domains and training design implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
35.
Hemanshu Bhatt Kimberly Y. Donaldson D. P. H. Hasselman Kenneth Chyung Mark P. Taylor 《Journal of the American Ceramic Society》1991,74(6):1463-1465
A study concerning the effect of fiber orientation on the thermal conductivity of a uniaxial carbon-fiber-reinforced borosilicate glass was conducted. For thin specimens, and thick specimens with specimen sides cut parallel to the fiber direction, the dependence of thermal conductivity on fiber orientation showed excellent agreement with theoretical behavior predicted for a composite infinite in extent. In contrast, the thermal conductivity data for rectangular thick specimens fell well below the data for the thin and angled specimens. For fiber orientation of 45° and higher, at which the heat was directed toward the side of the specimen rather than across, the thermal conductivity values showed excellent agreement with theoretical behavior predicted for a finite composite strip with insulated sides. 相似文献
36.
Hexagonal AlN films have been obtained by arc ion plating at different negative biases ,X-ray diffraction and scanning electron microscopy results show that AlN films with smooth surfaces and (002) preferred orientation are obtained at low biases ,whereas those with coarse surfaces and (100) preferred orientation are obtained at high biases,The formation mechanism of AlN is analyzed and the experiment results are discussed,The effect of bias on adhesion strength has also been examined. 相似文献
37.
熊华军 《机械工业高教研究》2008,(1):53-56
在生存论看来,以实存论为基底的大学教学价值取向,遗忘了追问人的生存意义。实际上,生存意义是在欲、技、道的游戏中生成的。大学教学价值向“寻求意义”的转向,实质上是“理智培育”、“技术培训”、“情感培养”三类传统价值取向在当代的共同表现形式.而非彼此对立。 相似文献
38.
Bamboo strips treated with caustic solutions of different concentrations, e.g., 5%, 10%, 15%, 20%, 25%, and 50%, were subjected to mechanical testing giving stresses on tensile strength, percent elongation at break, flexural strength, flexural modulus, and toughness. The change in average density was ?15%, and the weight loss value shows a maximum of 21.94% at 50% alkali treatment. The mechanical properties of bamboo strips increase steadily with increasing concentration of caustic soda, showing a comparable increased value at 15 and 20%, and then exhibiting a gradual fall. The percent elongation at break corroborates these observations showing a continuous decreasing trend. The properties under investigation exhibit a clear transition in between 15 and 20% alkali concentration. The morphology of strips was studied by scanning electron microscope and polarizing light microscope. The crystal structure of both untreated and treated strips was compared by XRD analysis. In both cases, the breakdown of the crystal structures of the cellulose fibers and the recrystallization or reorientation of the degraded chains that are devoid of hemicellulose are quite apparent. However, at a very high concentration (to the extent of 25%) the breakdown of structure predominates much more over the reorientation or recrystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
39.
Guimond Serge; Dambrun Micha?l; Michinov Nicolas; Duarte Sandra 《Canadian Metallurgical Quarterly》2003,84(4):697
Social dominance orientation (SDO) has been proposed as an important variable in the explanation of prejudice. We distinguish between three conceptualizations of SDO: SDO as a personality trait (personality model), SDO as a moderator of the effects of situational variables (Person X Situation model), and SDO as a mediator of the effect of social position on prejudice (group socialization model [GSM]). Four studies (N = 1,657) looking at the relations between social positions, SDO, and prejudice in a natural setting and in a laboratory setting provide strong support for the GSM. In contrast to previous correlational findings, there is evidence of a cause (dominant social position), an effect (prejudice increases), and a mediator (SDO). These results suggest new perspectives on the integration of individual and contextual determinants of prejudice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.
用真空蒸发制备了酞菁氧钒 (VOPc)薄膜 ,并在磁场中进行了热处理。用X光电子能谱、X射线衍射、紫外 可见吸收光谱、原子力显微镜等手段对制备的薄膜进行了表征。结果表明沉积的酞菁氧钒薄膜为α 型 ,成分接近酞菁氧钒的分子式。制备的薄膜在磁场中进行了热处理 ,发现磁场使酞菁氧钒薄膜性质发生改变 :UV VIS吸收谱Q带发生红移 ;XRD谱图衍射峰强度明显增强 ,峰位略有变化 ;原子力显微镜 (AFM)分析发现晶粒大小无明显变化。以上结果说明磁场的存在使得VOPc分子在热处理过程中发生了定向的排列 相似文献